Taxonomy of Food Microbes PDF

**Foodborne Bacteria** **Acinetobacter** - *Akinetos*, unable to move - [Gram-negative], affinity to *Neisseriaceiae* - Formerly *Achromobacters* and *Moracellae* are found here - [Strict aerobes] - [Oxidase negative] - Young cells, rod-shaped - Old cells, coccoid-shaped - *...

**Foodborne Bacteria** **Acinetobacter** - *Akinetos*, unable to move - [Gram-negative], affinity to *Neisseriaceiae* - Formerly *Achromobacters* and *Moracellae* are found here - [Strict aerobes] - [Oxidase negative] - Young cells, rod-shaped - Old cells, coccoid-shaped - *Acinetobacter, Moraxella, and Psychrobacter* would be placed in family *Moraxellaceae*, but still not approved - **Mol% G+C content is 39-47** **Aeromonas** - Gas-producing from fermented sugars - Aquatic [gram-negative] - Formerly in the family *Vibrionaceae*, now in *Aeromonadaceae* - Intestines of fish, can also be fish pathogens - **Mol% G+C content is 57-65** **Alcaligenes** - Alkali producers - [Gram negative], sometimes gram-positive - [Rod-shaped], produce alkaline reactions, found in litmus milk - Non-pigmented, widely distributed in nature as [decomposers] - Raw milk, poultry products, and fecal matter - **Mol% G+C content is 58-70** **Alteromonas** - Another monad, marine and coastal water inhabitants found in seafood - Require seawater salinity for growth - [Gram-negative, motile rods, aerobe] **Arcobacter** - *Campylobacter, Helicobacter, and Wolinella* are all classified once as *Campylobacter* - [Gram-negative], [curved or s-shaped rods] - Can grow at 15^o^C, [aerotolerant] - Poultry, raw milk, shellfish, water, cattle, and swine products - [Oxidase positive] and [catalase positive] - Causes abortion and enteritis in some animals and humans caused by *Arcobacter butzleri* **Bacillus** - [Gram-positive], [spore-forming], [aerobes] - [Mostly mesophiles,] though psychrotrophs and thermophiles exist - *Bacillus anthracis and Bacillus cereus* are the only two pathogens - Most strains don't cause diseases but and some causes foodborne gastroenteritis - Alicyclobacillus - Aneurinibacillus - Brevibacillus - Gracillibacillus - Paenibacillus - Virgibacillus - Salibacillus **Brevibacillus** - Soil and water, plants, air, dust - Nine species **Brochothrix** - [Gram-positive], [non-spore forming rods] - Related to *Lactobacillus* and *Listeria* - Not true coryneforms - Exponential phase are rods, other cells are coccoids - Share features with *Microbacterium* - Common on processed meats both fresh and stored in gas-impermeable packages - Only two species are recognized - *Brochothrix thermosphacta* - *Brochothrix campestris* - [Rhamnose positive] - [Hippurate positive] - Do not grow at 37C - **Mol% G+C content is 36** **Burkholderia** - [Gram-negative rods] on plants - Raw milk, and causes vegetable spoilage - In a raw cow's milk in Northern Ireland, 14 out of 26 (54%) has *Burkholderia cepacia* - Found in cystic fibrosis patients - Formerly classified in the genus *Pseudomonas* **Campylobacter** - [Gram-negative, spirally curved rods], previously classified as *Vibrio* - [Microaerophilic to anaerobic] - **Mol% G+C content is 30-35** - now under *Arcobacter* - *Campylobacter nitrofigilis* - *Campylobacter cryaerophila* - now under *Helicobacter* - *Campylobacter cinnaedi* - *Campylobacter fenneliae* - now under *Campylobacter* - *Wolinella carva* *C. curvus* - *Wolinela recta* *C.rectus* **Carnobacterium** - [Gram-positive], [catalase-negative rods] - Formed to accommodate some organisms previously classified as lactobacilli - Differ from lactobacilli in being unable to grow on acetate medium and their synethesis of oleic acid - Phylogenetically closer to Enterococci and Vagococci - Found in vacuum-packaged meats, fish, and poultry - [Heterofermentative] - Grow at 0C and none at 45C - Gas is produced from glucose - **Mol% G+C content is 33.0-37.2** **Citrobacter** - [Enteric bacteria], [slow lactose-fermenting], [gram-negative rods] - Produce [yellow colonies] on PCA - All members uses citrate as the sole carbon source - **Mol% G+C content is 50-52** - *Citrobacter freundii* - the most prevalent species I foods, not uncommon on vegetables and fresh meats **Clostridium** - [Anaerobic], [spore forming rods], widely distributed in nature - Many species, some causes disease in humans - [Mesotrophic], [psychotrophic], [thermophilic] strains - Reorganization of this genera created new ones, which are unimportant in foods - *Caloramater* - *Filifactor* - *Moorella* - *Oxobacter* - *Oxalophagus* **Corynebacterium** - True coryneform genera of [gram-positive], [rod shaped] - Involved in the spoilage of vegetable and meat products - [Mesotrophs], some are [psychrotrophs] - *Corynebacterium diphtheriae* - causes diphtheria in humans - some plant pathogenic species are transferred to the genus - *Clavibacter* - *Curtobacterium* - **Mol% G+C content is 51-63** **Enterobacter** - [Enteric gram-negative bacteria] are typical of other Enterobacteriaceae relative to growth requirements - They are not adapted to the gastrointestinal tract - *Enterobacter agglomerans* - has been transferred to *Pantoea* **Enterococcus** - Made to accommodate some of [the Lancefield serologic group D cocci] - Expanded to more than 16 species of [gram-positive ovoid cells], occur singly, pairs, or short chains - Once in the genus Streptococcus - Some species do not react with group D antisera **Erwinia** - [Gram-negative enteric rods,] associated with plants - Three species have been transferred to *Pantoea* - now on *Pectobacterium* - *Erwinia carotovora* *Pectobacterium carvovorum* - *Erwinia chrysanthemi* *Pectobacterium chrysanthemi* **Escherichia** - Most studied genus of all bacteria  **Flavobacterium** - [Gram-negative rods], yellow to red pigments on agar, association with plants - [Mesotrophs], others are [psychrotrophs] - Participate in the spoilage of refrigerated meats and vegetables - Some former flavobacterial species are in five new genera: - *Empedobacter* - *Chryseobacterium* - *Myroides* - *Sphingomonas* - *Sphingobacterium* **Hafnia** - [Gram-negative enteric rods] - Spoilage of refrigerated meat and vegetables products - [Motile,] [lysine positive], [ornithine positive] - **Mol% G+C content of 48-49** - *Hafnia alvei*, the only species **Kocuria** - Genus split off from *Micrococcus* - [Oxidase negative], and [catalase positive] - *Kocuria rosea* - *Kocuria varians* - *Kocuria kristinae* - **Mol% G+C content of 66-75** **Lactobacillus** - Taxonomic techniques widely used since the 1980s have reassigned some members of this genus, with changes reflected in the ninth edition of Bergey's Manual. - Based on 16S rRNA sequence data, three phylogenetic clusters were identified, with one cluster including *Weissella.* - genus is likely to undergo further reclassification in the future. - [Gram-positive], [catalase-negative rods] that often form [long chains.] - Food-associated strains are typically [microaerophilic], but many [anaerobic strains] exist, especially in the colon and rumen. - Commonly found on nearly all vegetables and some lactic acid bacteria-associated foods. - Frequently present in dairy products. - *Lactobacillus suebicus* - isolated from apple and pear mashes, capable of growing at pH 2.8 and in 12--16% ethanol. **Lactococcus** - [Lancefield serologic group N cocci] once in the *Streptococcus* - [Grom positive], [nonmotile], [catalase-negative], [spherica, or ovoid] - Single, pairs, or in chains - Grow at 10C but not at 45C - Most strains react with group N antisera - I-lactic acid is the predominant end-product of fermentation **Leuconostoc** - [Colorless nostoc], another genera of lactic acid bacteria - Gram-positive, catalase-negative cocci, [heterofermentative] - Now in *Oenococcus* - *Leuconostoc oenos* *Oenococcus oeni* - Now in *Weisella* - *Leuconostoc paramesenteroides* **Listeria** - Six species of [Gram-positive], [non-sporing rods] is closely related to Brochothrix - The six species show 80% similarity by taxonomic studies - Identical cell walls - Fatty acids - Cytochrome composition **Micrococcus** - [Gram-positive], and [catalase positive] cocci - Inhabitants of mammalian skin and can grow in the presence of high levels of NaCl - Reduced by the creation of new genera - *Dermacoccus* - *Kocuria* - *Kytococcus* - *Nesterenkonia* - *Stomatococcus* - *Micrococcus luteus* and *Micrococcus lylae,* the only two micrococcal species **Moraxella** - [Short gram-negative rods], sometimes classified as *Acinetobacter* - [Sensitive to penicillin] and [oxidase positive] - Present species in the genus *Psychrobacter* were once in *Moraxella* - [Metabolism is oxidative], do not form acid from glucose - **Mol% G+C content of 40-46** **Paenibacillus** - Has organisms formerly in the genera *Bacillus* and *Clostridium* - Notable for their degredation of macromolecules, production of antibacterial and antifungal agents - Has the capacity to [fix N2] - *Paenibacillus alvei* - *Paenibacillus amylolyticus* - *Paenibacillus azotofixans* - *Paenibacillus circulans* - *Paenibacillus durum* - *Paenibacillus larvae* - *Paenibacillus macerans* - *Paenibacillus macquariensis* - *Paenibacillus pubuli* - *Paenibacillus pulvifaciens* - *Paenibacillus validus* - Newly species added - *Paenibacillus lautus* - *Paenibacillus peoriae* - A newly-named species was isolated from raw and UHT-treated milk - *Paenibacillus lactis* **Pandoraea** - First isolated from sputa of cystic fibrosis patients - Organisms are related to some of the pseudomonads - *Pandoraea norimbergenesis* - isolated from powdered milk **Pantoea** - [Gram-negative], [non-capsulated], [non-sporing straight rods], [motile by peritrichous flagella] - Found in plants and in seeds, in soil, water, and human specimens - Some are plant pathogens, four recognized species were once *Enterobacters* or *Erwinia* - Now in Pantoea - *Pantoea agglomerans* - *Erwinia herbicola* - *Erwinia milletiae* - *Pantoea ananas* - *Erwinia annas* - *Erwinia uredovora* - *Pantoea stewartii* - *Erwinia stewartia* - *Pantoea dispersa* - **Mol% G+C content of 49.7 to 60.6** **Pediococcus** - [Coccus growing in one plane] - [Homofermentative cocci] are lactic acid bacteria - Exists in [pair or tetrads] resulting from cell division in two planes - Can grow in 18% NaCl - *Pediococcus acidilactici,* common starter species, caused septicemia in a 53-year-old male - *Pediococcus halophilus* *Tetragenococcus halophilus* - **Mol% G+C content of 34-44** **Proteus** - [Enteric gram-negative rods], [aerobes], [pleomorphism] - [Motile], produce [swarming growth] on the surface of moist agar plates - Typical enteric bacteria in the intestinal tract of humans and animals - Isolated from a variety of vegetables, meat products, especially those that undergo spoilage at temperature in the [mesophilic range] **Pseudomonas** - Soil and water bacteria, distributed among fresh foods, especially vegetables, meats, poultry, and seafood products - Largest genus of foodborne bacteria - Delimited by the transfer of many former species to 13 new genera - *Acidovorax* - *Aminobacter* - *Brevundimonas* - *Burkholderia* - *Comamonas* - *Delftia* - *Devosia* - *Herbaspirillum* - *Hydrogenophaga* - *Marinobacter* - *Ralstonia* - *Sphingomonas* - *Telluria* - *Wautersia* - *Pseudomonas fluorescens and Pseudomonas aeruginosa*, remain in the original genus **Psychrobacter** - This genus was created primarily to accommodate some of the [nonmotile Gram-negative rods] that were once classified in the genera *Acinetobacter* and *Moraxella* - They are [plump coccobacilli] that often occur in [pairs] - They are [aerobic, nonmotile, and catalase and oxidase positive], and generally do not ferment glucose - Growth occurs in [6.5% NaCl and at 1°C], but generally not at 35°C or 37°C - They [hydrolyze Tween 80], and most are [egg-yolk positive (lecithinase)] - They are sensitive to penicillin and utilize γ-aminovalerate, whereas the acinetobacters do not. - They are distinguished from the *Acinetobacter* by being oxidase positive and aminovalerate users and from nonmotile pseudomonads by their [inability to utilize glycerol or fructose] - Because they closely resemble the moraxellae, they have been placed in the family *Neisseriaceae* - The genus contains some of the former *Achromobacter* and *Moraxellae*, as noted - They are common on meats, poultry, and fish, and in water **Salmonella** - [Gram-negative enteric bacteria], considered to be human pathogens - The bacteria in the genus *Salmonella* are divided into two main species: - *Salmonella enterica* - *Salmonella bongori* - Among these, the majority of *Salmonella* strains that cause illness in humans belong to *Salmonella* enterica. This species includes many subspecies and serotypes that are responsible for foodborne illnesses like salmonellosis. - The serotypes (serovars) of more than 2400 are listed as follows - *Salmonella enterica* serotype Newport or *Salmonella* Newport **Serratia** - These [Gram-negative rods] that belong to the family *Enterobacteriaceae* are [aerobic] and [proteolytic], and they generally produce [red pigments] on culture media and in certain foods, although nonpigmented strains are not uncommon. - *Serratia liquefaciens* - is the most prevalent of the foodborne species; it causes spoilage of refrigerated vegetables and meat products. - *S. marcescens* subsp. sakuensis - a spore-forming *S. marcescens* isolate has been reported and named - **The mol% G + C content of DNA is 53--59\ ** **Shewanella** - The bacterium once classified as *Pseudomonas putrefaciens* *Alteromonas putrefaciens* *Shewanella putrefaciens* - [Gram-negative], [straight or curved rods], [nonpigmented], [oxidase positive], [motile by polar flagella] - All are associated with aquatic or marine habitats, and the growth *Shewanella benthica* is enhanced by hydrostatic pressure - *Shewanella hanedai* - *Shewanella benthica* - *Shewanella colwelliana* - **The mol% G + C content of DNA is 44-47** **Shigella** - All members of this genus are presumed to be human enteropathogens - [Gram-negative], [non-motile rods] - transmitted by the direct faecal--oral route - As a consequence, food has the potential to be contaminated through the soiled fingers of patients or carriers - The transfer of shigellae by flies breeding on faeces has been established as a very important transmission route during some outbreaks - found in surface waters and also within contaminated drinking water. - Shigella can be classified into four major serological groups: - Group A: *Shigella dysenteriae* - Group B: *Shigella flexneri* - Group C: Shigella boydii - Group D: *Shigella sonnei*, which includes only one serotype. - *Shigella sonnei* accounts for most cases of dysentery in the developed world. - Little is known about Shigella and its ability to f[orm and survive in biofilms,] which suggests the need for further research - Drinking water treatment that includes disinfection has been shown to be sufficient to remove Shigella - However, waterborne outbreaks have generally resulted from inadequate treatment **Sphingomonas** - At least 33 species of this genus of Gram-negative bacteria, typically [produce yellow pigment], formerly in the *Flavobacterium* - Found in water, vegetables, cause human disease **Staphylococcus** - [Gram-positive], [catalase-positive] cocci - *Staphylococcus aureus* - which causes several disease syndromes in humans, including foodborne gastroenteritis - *Staphylococcus caseolyticus* *Macrococcus caseolyticus* **Stenotrophomonas** - [Gram-negative rods], common inhabitants of plants and they have been recovered from soil, water, and milk - Growth-promoting or [symbionts in the rhizosphere] of several crop plants - *Stenotrophomonas maltophila* - regarded as the second most common nosocomial bacterium after *Pseudomonas aeruginosa* - *Stenotrophomonas rhizophila* - has been used to control fungal diseases in plants **Vagococcus** - Created to accommodate the [group N lactococci] based on 16S sequence data - [Motile by peritrichous flagella], [gram-positive], [catalase-negative], grow at 10C but not at 45C - Grow in 4% NaCl but not 6.5%, and no growth occurs at pH 9.6 - Cell wall peptidoglycan is Lys-d-Asp - At least one species produces H2S - Found on fish, in feces, and in water, other foods - **The mol% G + C content of DNA is 33.6** **Vibrio** - [Gram-negative straight, curved rods] - Members of the family *Vibrionaceae* - Former species have been transferred to genus *Listonella* - Several species can cause gastroenteritis and other human illness - **Mol% G+C content of 38-51** **Weissella** - This genus of lactic acid bacteria was established in 1993 in part to accommodate the "*Leuconostoc* branch" of the lactobacilli - The seven species are closely related to the *Leuconostoc*, and with the exception of - *Weissella paramesenteroides and Weissella hellenica* - they produce dl-lactate from glucose. - All produce gas from carbohydrates - *Weissella hellenica* - new species associated with fermented Greek sausages. - Leuconostoc paramesenteroides W. paramesenteroides - the following five species were formerly classified as Lactobacillus spp. - *Weissella confusa* - *Weissella halotolerans* - *Weissella kandleri* - *Weissella minor* - *Weissella viridescens* - **Mol% G+C content of DNA is 37--47** **Yersinia** - This genus includes the - *Yersinia pestis* - agent of human plague - *Yersinia enterocolitica* - causes foodborne gastroenteritis - *Yersinia mollaretti* - This sorbose-positive biogroup 3A strains have been elevated to species status - *Yersinia bercovieri* - and the sorbose-negative strains as Y. bercovieri. - **The mol% G + C content of DNA is 45.8--46.8.** **Foodborne Molds** **Alternaria** - [Separate mycelia with conidiophores] and [large brown conidia] are produced - Conidia have both cross and longitudinal septa and are variously shaped - They cause brown to black rots of stone fruits, apples, and figs - Stem-end rot and black rot of citrus fruits are also caused by species/strains of this genus - A field fungus that grows on wheat, red meats - Some species [produce mycotoxins] **Aspergillus** - [Chains of conidia] are produced - Where [cleistothecia with ascospores] are developed, the perfect stage of those found in foods is *Emericella, Eurotium, or Neosartory* - *Eurotium* (the former A. glaucus group) produces bright [yellow cleistothecia], and all species are [xerophilic] - *E. herbariorum* - has been found to cause spoilage of grape jams and jellies. - *Emericella* produces [white cleistothecia], and - *E. nidulans* - is the teleomorph of *Aspergillus nidulans* - *Neosartorya* produces [white cleistothecia] and [colorless ascospores] - *N. fischeri* - heat resistant, and resistance of its spores is similar to those of *Byssochlamys* - The aspergilli appear yellow to green to black on a large number of foods. - Black rot of peaches, citrus fruits, and figs is one of the fruit spoilage conditions produced. - They are found on country-cured hams and on bacon. Some species cause spoilage of oils, such as palm, peanut, and corn. - *Aspergillus oryzae* and *Aspergillus soyae* - are involved in the [shoyu fermentation] and the former in [koji]. - *Aspergillus glaucus* - produces [katsuobush]i, a fermented fish product - A. glaucus--A. restrictus group - contains storage fungi that invade seeds, soybeans, and common beans. - *Aspergillus niger* - produces β-galactosidase, glucoamylase, invertase, lipase, and pectinase - *Aspergillus oryzae* - produces α-amylase. - Several species produce [aflatoxin]s, and others produce [ochratoxin A and sterigmatocystin]. **Aureobasidium** - Yeast-like colonies produced initially, later spreads and produce black patches - *Aureobasidium pullulans (Pullularia pullulans)* - Most prevalent in foods - Found in shrimp, are involved in the "black spot" condition of long term stored beef, and are common on fruits and vegetables **Botrytis** - [Long, slender, pigmented conidiophores] are produced - [Mycelium is septate, conidia are borne on apical cells] and are gray in color, although black, [irregular sclerotia] are sometimes produced - *Botrytis cinerea* - Most common in foods - They are notable as the cause of gray mold rot of apples, pears, raspberries, strawberries, grapes, blueberries, citrus, and some stone fruits **Byssoclamys** - This genus is the teleomorph of certain species of *Paecilomyces*, but the latter does not occur in foods - The [ascomycete] *Byssochlamys* produces open clusters of asci, each of which contains [eight ascospores.] - The latter are notable for their [heat resistance,] resulting in spoilage of some high-acid canned foods. - In their growth, they can [tolerate low oxidation--reduction potentia]l (Eh) values. - Some are [pectinase producers] - *Byssoclamys fulva* and *Byssoclamys nivea* - spoil canned and bottled fruits - These organisms are almost uniquely associated with food spoilage - *Byssoclamys fulva* - possesses a thermal D value at 90°C between 1 and 12 minutes with a z value of 6--7°C. **Cladosporium** - [Septate hyphae] with dark, tree-like, budding [conidia variously branched], characterize this genus. - In culture, growth is [velvety and olive] colored to black. - Some conidia are lemon shaped - *Cladosporium herbarium* - produces "black spot" on beef and frozen mutton - Some spoil butter and margarine, and some cause restricted rot of stone fruits and black rot of grapes - They are field fungi that grow on barley and wheat grains - *Cladosporium herbarium* and *Cladosporium cladosporioides* - are the two most prevalent on fruits and vegetables. **Colletotrichum** - belong to class *Coelomycetes* and form conidia inside acervuli - simple but [elongated conidiophores] and [hyaline conidia] that re one celled, ovoid, or oblong are produced - The [acervuli] are [disc or cushion shaped], [waxy], and [dark] in color - *Colletotrichum gloeosporoides* - Species of concern in foods, it produces [anthracnose] (brown/black spots) on some fruits, especially tropical fruits such as mangoes or papayas **Fusarium** - Extensive [mycelium] is produced that is cottony with tinges of pink, red, purple, or brown. - [Septate fusiform] to [sickle-shaped conidia] (macroconidia) are produced. - They cause brown rot of citrus fruits and pineapples and soft rot of figs. - As field fungi, some grow on barley and wheat grains. - Some species produce [zearalenone, fumonisins,] and [trichothecenes.] **Geotrichum** - once known as *Oidium lactis* and *Oospora lactis* - These yeast-like fungi are usually white - The [hyphae are septate], and reproduction occurs by formation of [arthroconidia from vegetative hyphae.] - The arthroconidia have flattened ends - *Geotrichum candidum* - the anamorph of *Dipodascus geotrichum*, is the most important species in foods. - It is variously referred to as "dairy mold" because it imparts flavor and aroma to many types of cheese, and as "machinery mold" because it builds up on food-contact equipment in food-processing plants, especially tomato canning plants. - They cause sour rot of citrus fruits and peaches and the spoilage of dairy cream - They are widespread and have been found on meats and many vegetables. - Some participate in the fermentation of gari. **Monilia** - [Pink, gray, or tan conidia] are produced. - *Monilia sitophila* - is the conidial stage of *Neurospora intermedia* - *Monilia* - is the conidial state of *Monilinia fructicola* - They produce brown rot of stone fruits such as peaches. - *Monilina* sp. causes mummification of blueberries. **Mucor** - [Nonseptate hyphae] are produced that give rise to sporangiophores that bear [columella with a sporangium at the apex.] - No rhizoids or stolons are produced by members of this large genus. - Cottony colonies are often produced - The conditions described as "whiskers" of beef and "black spot" of frozen mutton are caused by some species. - *Mucor miehei* - is a lipase producer. It is found in fermented foods, bacon, and many vegetables. - One species ferments soybean whey curd. **Penicillium** - When [conidiophores and conidia are the only reproductive structures present], this genus is placed in the *Deuteromycota* - They are placed with the ascomycetes when [cleistothecia with ascospores] are formed as either *Talaromyces* or *Eupenicillium* - Of the two teleomorphic genera, *Talaromyces* is the most important in foods. - *Talaromyces flavus* - It is the teleomorph of *Penicillium dangerdii* - it has been involved in the spoilage of fruit juice concentrates. - It produces [heat-resistant spores] - When conidia are formed in the penicillus, they pinch off from phialides. - Typical colors on foods are blue to blue-green. - Blue and green mold rots of citrus fruits and blue mold rot of apples, grapes, pears, and stone fruits are caused by some species. - *Penicillium roqueforti* - produces blue cheese. - Some species produce [citrinin], [yellow rice toxin, ochratoxin A], [rubratoxin B], and other [mycotoxins]. **Rhizopus** - [Nonseptate hyphae] are produced that give rise to [stolons and rhizoids]. - Sporangiophores typically develop in clusters from ends of stolons at the point of origin of rhizoids. - *Rhizopus stolonifer* is by far the most common species in foods. - Sometimes referred to as "bread molds," they produce watery soft rot of apples, pears, stone fruits, grapes, figs, and others. - Some cause "black spot" of beef and frozen mutton - They may be found on bacon and other processed meats. - Some produce pectinases - *Rhizopus oligosporus* is important in the production of oncom, bongkrek, and tempeh. **Thamnidium** - These molds produce [small sporangia] borne on highly branched structures. - *Thamnidium elegans* - It is the only species, and it is best known for its growth on refrigerated beef hindquarters where its characteristic growth is described as \"whiskers.\" - It is less often found in decaying eggs. **Trichothecium** - [Septate hyphae] that bear [long, slender, and simple conidiophores] are produced. - *Trichothecium roseum* - is the only species, and it is pink in color and causes pink rot of fruits - It also causes soft rot of cucurbits and is common on barley, wheat, corn, and pecans. Some produce mycotoxins. **\ Wallemia** - Produces [deep-brown colonies on culture media] and on foods - *Wallemia sebi* (formerly *Sporendonema*) - Most notable species, can grow at an aw of 0.69 - Produces the 'dun' mold condition on dried and salted fish **Xeromyces** - Only has one species - Xeromyces bisporus - Produces [colorless cleistothecia] with evanescent asci that contain [two ascospores] - Organism that has the lowest aw growth of any other known organisms - Its aw high is 0.97, its optimum is 0.88, and its minimum is 0.61 - Its thermal D at 82.2C is 2.3 minutes - Causes problems in licorice, prunes, chocolate syrup, and other similar products. **Other Molds** **Cephalosporium** - *Cephalosporium* is a [deuteromycete] often found on frozen foods. **Diplodia** - *Diplodia* is [another deuteromycete] that causes stem-end rot of citrus fruits and water tan-rot of peaches. **Neurospora** - *Neurospora* is an ascomycete, and *N. intermedia* is referred to as the "red bread" mold. - *Monilia sitophila* is the anamorph of *Neurospora intermedia.* The latter is important in the oncom fermentation and has been found on meats. **Sporotrichum** - The "white spot" of beef is produced by *Sporotrichum* spp. **Gloeosporium** - Rots of various fruits are caused by *Gloeosporium* spp. **Helminthosporium** - Some *Helminthosporium* spp. are plant pathogens, and some are saprophytes. **Neosartorya** - *Neosartorya fischeri* - anamorph *Aspergillus fischerianus* - was first recognized in the early 1960s as the cause of spoilage of fruit products. - Its [ascospores are very heat resistant], being able to withstand boiling in distilled water for up to an hour. - It has a D87°C of around 11 minutes in phosphate buffer. - Interestingly, it produces several mycotoxins---[fumitremorgin A, B, and C; terrein; verruculogen;] and [fischerin.] **Fusarium** - The microspores of some *Fusarium* species are similar to those of *Cephalosporium*. **Aspergillus and Related Xerophilic Molds** - The second category consists of xerophilic molds, which are very important as spoilage organisms. - In addition to *Aspergillus* and *Eurotium*, Pitt and Hocking include six other genera among the xerophiles: - *Basipetospora* - *Chrysosporium* - *Eremascus* - *Polypaecilum* - *Wallemia* - *Xeromyces* - These molds are characterized by the [ability to grow below aw (water activity) = 0.85] - They are of significance in foods that owe their preservation to a low aw. **Foodborne Yeasts** **Brettanomyces (The perfect stage is Dekkera)** - These asporogenous yeasts form [ogival cells and terminal budding]. - They [produce acetic acid from glucose] only under aerobic conditions. - *Brettanomyces intermedius* is the most prevalent, and it can grow at a pH as low as 1.8. - They cause spoilage of beer, wine, soft drinks, and pickles. - Some are involved in [afterfermentation of some beers and ales.] - *Dekkera bruxellensis* is involved in some sourdough fermentations and contributes to biogenic amines in red wines. **Candida** - This genus was erected in 1923 by Berkhout and has since undergone many changes in definition and composition. - It is regarded as a [heterogeneous taxon] that can be divided into 40 segments comprising 3 main groups, based mainly on fatty acid composition and electrophoretic karyotyping. - The generic name means ["shining white,"] and cells contain [no carotenoid pigments.] - The [ascomycetous imperfect species] are placed here, including the former genus *Torulopsis*, as follows: - *Candida famata* (*Torulopsis candida*, *T. famata*) - *Candida kefyr* (*Candida pseudotropicalis*, *T. kefyr*, *Torula cremoris*) - *Candida stellata* (*Torulopsis stellata*) - *Candida holmii* (*Torulopsis holmii*) - Many of the anamorphic forms of *Candida* are now in the genera *Kluyveromyces* and *Pichia*. - *Candida lipolytica* - It is the anamorph of *Saccharomycopsis lipolytica*. - Members of this genus are the most common yeasts in fresh ground beef and poultry. - *Candida tropicalis* - It is the most prevalent in foods in general. - Some members are involved in the fermentation of cacao beans, as a component of kefir grains, and in many other products, including beers, ales, and fruit juices. C**ryptococcus** - This genus represents the anamorph of *Filobasidiella* and other *Basidiomycetes*. - They are [asporogenous], reproduce by [multilateral budding,] and are [nonfermenters of sugars]. - They are hyaline and red or orange and may form [arthrospores.] - They have been found on plants, in soils, on strawberries, other fruits, marine fish, shrimp, and fresh ground beef. **Debaryomyces** - These [ascosporogenous yeasts] sometimes produce [a pseudomycelium] and reproduce by [multilateral budding.] - They are one of the two most prevalent yeast genera in dairy products. - *Debaryyomyces hansenii* - represents what was once *Debaryyomyces subglobosus* and *Torulaspora hansenii* - and it is the most prevalent foodborne species. - It can grow in 24% NaCl and at an aw as low as 0.65. - It forms slime on wieners, grows in brines and on cheeses, and causes spoilage of orange juice concentrate and yogurt. **Hanseniaspora** - These are [apiculate yeasts] whose anamorphs are *Kloeckera* spp. - They exhibit [bipolar budding], and consequently, lemon-shaped cells are produced. - The asci contain two to four hat-shaped spores. - [Sugars are fermented]. - They can be found on a variety of foods, especially figs, tomatoes, strawberries, citrus fruits, and cacao bean fermentation. **Issatchenkia** - Members of this genus [produce pseudomycelia] and multiply by [multilateral budding]. - Some species once in the genus *Pichia* have been placed here. - *Issatchenkia orientalis* - The teleomorph of *Candida krusei* is - They typically [form pellicles in liquid media]. - They contain [coenzyme Q-7] and are prevalent on a wide variety of foods. **Kluyveromyces (Fabospora)** - These [ascospore-forming yeasts] reproduce by [multilateral budding], and the spores are spherical. - *Kluyveromyces marxianus* now includes the former - *Kluyveromyces fragilis* - *Kluyveromyces lactis* - *Kluyveromyces bulgaricus* - *Saccharomyces lactis* - *Saccharomyces fragilis* - It is one of the two most prevalent yeasts in dairy products. - contains coenzyme Q-6 and is involved in the fermentation of kumiss. - *Kluyveromyces* spp. - [produce β-galactosidase] and are vigorous fermenters of sugars, including lactose. - It is also used for lactase production from whey and as the organism of choice for producing yeast cells from whey. - They are found on a wide variety of fruits, and *K. marxianus* causes cheese spoilage. **Pichia** - This is the [largest genus of true yeasts] - They reproduce by multilateral budding, and the asci usually contain [four spheroidal], hat- or Saturn-shaped spores. - [Pseudomycelia and arthrospores] may be formed. - Some of the hat-shaped spore formers may be *Williopsis* spp. - Some of the former species are now classified in the genus *Debaryomyces*. - *Pichia guilliermondii* - is the perfect state of *Candida guillermondii* - *Pichia membranaefaciens* - The anamorph is *Candida valida* - *Pichia* spp. typically [form films on liquid media]. - They are known to be important in producing indigenous foods in various parts of the world. - Some have been found on fresh fish and shrimp. - They are known to grow in olive brines and cause spoilage of pickles and sauerkraut. **Rhodotorula** - These yeasts are [anamorphs of *Basidiomycetes*]. - The teliospore producers are in the genus *Rhodosporidium*. - They reproduce by multilateral budding and are nonfermenters. - *Rhodotorula glutinis* and *Rhodotorula mucilaginosa* - are the two most prevalent species in foods. - They produce [pink to red pigments], and most are [orange or salmon pink]. - The genus contains many [psychrotrophic] species/strains found on fresh poultry, shrimp, fish, and beef. - Some grow on the surface of butter. **Saccharomyces** - These [ascosporogenous yeasts] multiply by [multilateral] budding and produce [spherical spores in asci] - They are [diploid] and do not [ferment lactose]. - now on *Zygosaccharomyces* - *Saccharomyces bisporus* - *Saccharo rouxii* - now on *Torulaspora* - *Saccharomyces rosei* - All bakers', brewers', wine, and champagne yeasts are *Saccharomyces cerevisiae*. - They are found in kefir grains and can be isolated from a wide range of foods, such as dry-cured salami and numerous fruits. - *Saccharomyces cerevisiae* rarely causes spoilage. **Schizosaccharomyces** - These [ascosporogenous yeasts] divide by lateral fission of cross-wall formation. - They may produce [true hyphae and arthrospores.] - Asci contain from four to eight bean-shaped spores, and [no buds are produced]. - They are regarded as being only distantly related to the true yeasts. - *Schizosaccharomyces* *pombe* - is the most prevalent species; it is osmophilic and resistant to some chemical preservatives. **Torulaspora** - Multilateral budding is the method of reproduction with [spherical spores in asci] - Three haploid species formerly in the genus *Saccharomyces* are now in this genus. - They are strong fermenters of sugars and contain [coenzyme Q-6.] - *Torulaspora delbrueckii* - It is the most prevalent species. **Trichosporon** - These [nonascospore-forming oxidative yeasts] multiply by budding and by [arthroconidia formation.] - They produce a [true mycelium], and [sugar fermentation is absent or weak.] - They are involved in cacao bean and idli fermentations. - They have been recovered from fresh shrimp, ground beef, poultry, frozen lamb, and other foods. - *Trichosporon pullulans* - is the most prevalent species, and it produces lipase. **Yarrowia** - Formerly *Saccharomycopsis*, these yeasts belong to the order *Endomycetales*. - They are common on fruits, vegetables, meats, and poultry. - *Candida lipolytica* is the anamorph, and *Yarrowia lipolytica* is the teleomorphic (perfect) stage. **Zygosaccharomyces** - [Multilateral budding] is the method of reproduction, and the bean-shaped ascospores formed are generally free in asci. - Most are haploid, and they are strong fermenters of sugars. - *Z. rouxii* is the most prevalent species, and it can grow at an aw of 0.62, second only to *Xeromyces bisporus* in its ability to grow at a low aw. - Some are involved in shoyu and miso fermentations. - Some are common spoilers of mayonnaise and salad dressing, especially *Z. bailii*, which can grow at a pH of 1.8. ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### Foodborne Protozoa ### Cryptosporidium parvum - Causes cryptosporidiosis, leading to watery diarrhea, stomach cramps, nausea, vomiting, fever, and dehydration. - Spreads through contaminated water, raw or unpasteurized milk, fresh produce, and infected food handlers. - Highly resistant to chlorine, making it difficult to eliminate from water supplies **Cyclospora cayetanensis** - Responsible for cyclosporiasis, which causes watery diarrhea, bloating, fatigue, nausea, vomiting, and weight loss. - Infection occurs through contaminated fresh produce such as berries, lettuce, and basil, as well as through water. **Entamoeba histolytica** - Causes amoebiasis (amoebic dysentery), leading to bloody diarrhea, abdominal pain, weight loss, and, in severe cases, liver abscesses. - Spreads through contaminated food and water, especially in regions with poor sanitation. - Can invade the intestinal wall and spread to other organs, leading to serious complications. **Giardia lamblia** - Causes giardiasis, which leads to greasy, foul-smelling diarrhea, stomach cramps, bloating, nausea, and fatigue. - Infection occurs from consuming contaminated water, raw produce, or food handled by infected individuals. - *Giardia* cysts are highly resistant to disinfection and can survive in cold water for months. **Toxoplasma gondii** - Causes toxoplasmosis, often presenting with flu-like symptoms such as fever, swollen lymph nodes, and muscle aches. - Many infections remain asymptomatic, but severe cases can cause neurological complications. - Spreads through undercooked or raw meat (especially pork, lamb, and venison), unwashed vegetables, contaminated water, and exposure to infected cat feces.