MICR20010G (1).pptx

MICR20010 Agricultural Microbiology Dr. Tadhg Ó Cróinín Note E-mail on Exams • Practical Online MCQ exam is on this Friday Nov 24th from 2-3pm • Please try the sample questions under quiz tab in brightspace and note instructions in e-mail. • Sample MCQ questions for final exam in RDS also availab...

MICR20010 Agricultural Microbiology Dr. Tadhg Ó Cróinín Note E-mail on Exams • Practical Online MCQ exam is on this Friday Nov 24th from 2-3pm • Please try the sample questions under quiz tab in brightspace and note instructions in e-mail. • Sample MCQ questions for final exam in RDS also available on Brightspace. MICR20010 - remaining lectures • • • • • • • • • Lecture 11 – Microorganisms and Disease Lecture 12 – The Immune System Lecture 13 - Pathogenic Bacteria Lecture 14 – Pathogenic Fungi and Viruses Lecture 15 – Antibiotic Resistant Microorganisms Lecture 16 – Identification of Microorganisms Lecture 17 – Microbiology in the Food Industry – The Fungi Lecture 18 – Microbiology in the Food Industry - Fermentations Lecture 19 – The Nitrogen Cycle Indirect Fermentations Alcoholic drinks Beer starch  sugars + M/O Wine Must (juices + indigenous m/o if non controlled) +/- M/O Vinegar's Milk Wine + M/O Yoghurt Symbiotic M/O association Cheese- ripening with M/O Meat Jerky, Salami Meat + indigenous m/o or controlled Single cell protein + Microbial Biomass Single Cell Protein • Began in WW2 to produce protein cheaply - S. cerevisiae and Candida utilis. • Rapid development in 1960s and 1970s with emergence of phrase SCP. • Most used as animal feed rather than human consumption • Production of yeast from whey or Quorn production Protein increase in global population…search for alternative protein source • Single cell protein (SCP) – SCP= microbial cells grown and harvested for animal/ human food WHY SCP? Choice of m/os due to • rapid growth • high protein content • use cheap organic substrates to grow Protein production by cattle + yeast bullock.. Wt 500Kg..yields 0.4kg protein/24h Yeast.. Wt 500kg..yields> 50,000kg/24h The Fermentor Applications for Yeast in the Food Industry Production of Yeast Biomass • Key to high yield is aeration – avoid fermentation • Cheap media –historically media from cereal grains, now predominantly molasses. • Gradual scale up of culture from bench-top to fermentor! • Special feeding regime to avoid fermentation (fed batch) Production of Yeast Biomass • Ripening stage to encourage production of trehalose and reduce protein production • Centrifugal separators before washing, drying and packing • Maximising Biomass is the key aim Yeast Production What makes a good Bakers Yeast? • High growth rates • Good storage characteristics including cryotolerance • Osmotolerance – to function within dough • Rapid utilization of maltose – main sugar of dough • High Glycolytic activity and “gassing power” SCP-can be produced from – Algae..spirulina – fungi… – bacteria Biomass can be produced by – submerged fermentation – solid state fermentation – After fermentation: biomass is harvested, washed, disrupted, and protein extracted Substrates for micro-organism production: Algae: use CO2 + sunlight Fungi: cheap wastes supply C + N source Bacteria: wastes or by-products of industrial processes Substrates for micro-organism production: • molasses from sugar manufacture/ starch hydrolysis • spent sulphite liquor • acid hydrolysates of wood • Agricultural wastes • methane • methanol +ethanol • gas oil Nutritive value of micro-organism Algae: • rich in proteins, fats + vitamins A,B,C,D +E • 40-60% protein • 7% mineral Fungi: • B-complex group of vit. • aa content of A.niger: well balanced • Yeast: have thiamine, riboflavin, biotin Bacterial SCP: • high in protein + certain essential aa • methionine: 2.2-3% > algal (1.4-2.6%) and fungi (2.5-1.8%) SCP: limitations for use Algal SCP • cell wall- cellulytic component cannot be digested by humans • ..walls must be pre-digested (not for cattle feed) • production is weather dependent Fungal SCP: • Aspergillus parasiticus, A.flavous:.. Mycotoxins Bacterial SCP • use is limited to cost • harvesting can be expensive • bacterial cells have high nucleic acid content (uric acid accumulates in body..kidney stones + gout) SCP in solving protein malnutrition • source of human + animal feeds • m/o’s accepted for human consumption: – Saccharmyces cerevisiae – Candida utilis – Chlorella spp. SCP example: Quornmyco-protein Fusarium graminearum Schwabe A3/5-used in UK • Quornmyco-protein for humans • meat alternative: – taste,textures of meat products (vegi alternative) myco-protein: • cells grown on glucose • harvested • High nutritional value • once produced it is mixed with a binder to give desired shape + flavour Indirect Fermentations M/O in food production direct Single cell protein direct Mushrooms Mushrooms Mushrooms: • Filamentous fungi that form fruiting bodies known as mushrooms • ~12,000 fungal species (~2000 have some edibility) – Agaricus bisporus (button mushroom) – Lentinus edodes – Pleurotus spp (oyster mushroom) Mushrooms • A long tradition of use of mushrooms as a food source (or narcotic) • Very cheap to produce and can readily be grown on plant waste • Excellent source of protein • Easy to harvest the fruiting bodies Agaricus Bisporis Mushroom production • Preparation of inoculum in liquid culture • Preparation of beds - composting • Inoculation into compost and mycelial growth at 25oC for 2-3 weeks • Application of casing of peat (covering layer) • Fruiting body production in about four flushes (successive crops) over a period of 4-6 weeks. Lentinus edulus Other benefits of mushrooms: Medicinal mushrooms Extracts of species from genera: • Auricularia • Flammulina, • Ganoderma, • Hericium And more Employed medicinally In medicine: • Immunomodulators – Some have anti-cancer action • Source of rare minerals and amino acids – Copper, zinc, selenium, iron. Problems of fungi: Mycotoxins Mycotoxins secondary metabolite of fungi: – mycotoxicoses in animals + humans – some linked with certain types of cancer – present in mycelium and in some cases in the spores of filamentous fungi – not all are harmful In human food chain problems with – Aspergillus, Penicillium: contaminate foods during drying and storage – Fusarium: plant pathogen- produces mycotoxin before/ immediately after harvesting Alflatoxins: first discovered in 1960 – 100,000 turkey poults died suddenly in England – 14,000 ducklings – 9 out breaks in calves – common factor: Brazilian peanut meal in animal feed. • Produced mainly by: Aspergillus flavus, A.parasiticus Alflatoxins: • 4 main alflatoxins: B1,B2,G1, G2 (&M1) • difuranocoumarin derivatives-B &G = Blue (B) & green (G) fluorescent colours produced under UV light Aflatoxins found in: maize, animal products, peanuts. • M1= hydroxylated derivative of B1 • M2= .. .. of B2 – M1 & 2 – formed + excreted in milk of lactating animals – less toxic than B1 or 2 – BUT M1= toxic & carcinogenic Next Monday on MICR20010 Microbiology in the Food Industry – Alcohol, Dairy Industry and Vinegar Dr. Tadhg Ó Cróinín Remember Online Practical MCQ exam on Friday at 2pm!