Introduction To Microbiology - Bacteria #1 PDF

Introduction to Microbiology BY451 Learning Outcomes (this class links directly to next week’s one as well) Understand the scope of microbiology Understand what the following terms mean: Eukaryote, prokaryote, akaryote Understand the following terms: Mutualism, predation, nutrien...

Introduction to Microbiology BY451 Learning Outcomes (this class links directly to next week’s one as well) Understand the scope of microbiology Understand what the following terms mean: Eukaryote, prokaryote, akaryote Understand the following terms: Mutualism, predation, nutrient cycling, microbial transfer/ transmission routes Understand key points of the biology of bacterial cells What is microbiology? Microbiology is the study of a diverse range of organisms. These include bacteria, archaea, viruses, protists & akaryotes. These organisms can occur in an incredibly large number of natural habitats, such as soil, water, in association with plants, and inside animal intestines. They can also be harnessed for the benefit of society by such processes as food production, vaccine development, and antibiotic production. Image: B&H  2079-004-e5dc978e Antonie Van Leewenhoek Van Leeuwenhoek´s famous description of microbes in tooth plaque in 1683 was the first observation of bacteria. Van Leeuwenhoek´s drawing of sort rods or bacilli and bacteria, the spheres of micrococci, and the Corkscrew-shaped spirillum. Important historical names in Microbiology http://www.nobelprize.org/nobel_prizes/medicine/laureates/1945 Louis Pasteur Dr Edward Jenner Prof Frederick Sir Alexander - - Griffith Fleming promoted started the first - - vaccination, vaccination discovered the discovered penicillin promoted germ programmes in phenomenon of theory; developed England transformation Pasteurisation in bacteria What is a eukaryote? Eukaryotes possess a cell nucleus containing multiple chromosomes, a nuclear envelope, and membrane-bound internal cell bodies (e.g. Golgi apparatus). Eukaryotes encompass animal, plant and fungal cells. NB – the image shows an animal cell. Plants and fungi have some key differences in their cellular structure, but they are very similar. Image: Britannica  Example eukaryote: Penicillium roqueforti P. roqueforti is used to make blue cheese. It is a fungus, and therefore a eukaryote. It produces proteases which breakdown casein, and lipases that breakdown triglycerides to give the cheese the unique texture & flavour. It is also related to Penicillium chrysogenum, which produces penicillin. www.rrnursingschool.biz http://www.cheesemaking.com/shop/roqueforti-blue-mold-powder-1-4-oz.html What is a prokaryote? Prokaryotes are members of the Bacteria or Archaea Domains of Life. Prokaryotes are single-celled organisms. They contain a single chromosome, but do not possess a nucleus or other membrane bound organelles. Bacteria & Archaea are approximately the same size & shape, but have a very different biology to that of eukaryotes. They are adapted to very different environments, and have unique cellular functions that are different to each other, and different to eukaryotes.  Example prokaryote: Escherichia coli E. coli is a bacterium, and as such a prokaryote. It exists within the intestines of humans & animals. The bacterium is also associated with diarrhoea & severe diseases. It is related to organisms such as Salmonella sp, and Yersinia pestis. studyblue Food poison journal What is an akaryote? An akaryote is an organism without a nucleus. This term is not to be confused with prokaryotes. Akaryotes are not capable of independent replication, while eukaryotes & prokaryotes are. An example would be a prion, or a virus. Nature.com Microbiology & immunology online  What is mutualism? This is a close & permanent association between two populations of organism, where both benefit from the interaction. An example would be Rhizobium sp. These are bacteria that live in association with certain plant species, and allow for nitrogen fixation. The bacteria benefit by gaining a favourable environment to reside within the plant. The plant benefits by gaining nitrogen, and therefore increasing growth rate. http://bio1903.nicerweb.com/Locked/media/ch27/rhizobium.html Rhizobium sp. https://www.quora.com/Can-leguminous-plants-absorb-ammonia What is predation? In microbiology, predation is where one microorganism feeds on another. The majority of predators share similar cell features… e.g. active motility, an ability to secrete compounds capable of degrading cell contents. This is a type of antagonistic species interaction. The end point is the death of one organism, benefitting the second by providing food. Examples of bacterial predation Bacterial predation: 75 years and counting! Environmental Microbiology Volume 18, Issue 3, pages 766-779, 21 JAN 2016 DOI: 10.1111/1462-2920.13171 http://onlinelibrary.wiley.com/doi/10.1111/1462-2920.13171/full#emi13171-fig-0001 Key Learning Points Every organism exists in association with other organisms. These associations can be beneficial to both partners in the association (e.g. nitrogen fixation), or harmful to one partner (e.g. predation) It is important to note that certain species (but not all) of bacteria, virus, & fungi can be linked to human infectious disease. Archaea are not associated with human disease, BUT several species have been isolated from gastro-intestinal tracts, possibly suggesting a type of mutualism. Microorganisms For the next couple of minutes, think about the names of as many microorganisms as you can. Think of those that cause any infectious diseases you can think of, and then… Think of those that are involved in useful processes… Organism Infectious disease Useful process So, how do micro-organisms move between locations? Movement between locations/ habitats can be by… 1) Natural movements (e.g. air, water flow) 2) Personal contact (e.g. skin-to-skin, sexual, coughing/sneezing, blood, saliva) 3) Contact with animals (e.g. food consumption, occupation & lifestyle) 4) Human-associated processes (e.g. manure on fields, transport of foods, transport of animals)  Water The movement of water is of critical importance to microbial movement. An example organism would be Vibrio cholerae. This is a bacterium which is associated with gastro-intestinal disease in humans. Faecal contamination of water sources can lead to the bacterium being consumed by humans drinking the water. The bacterium can be killed by boiling the water, or by sanitation processes. But, in communities without access to such infrastructure, disease can result in otherwise healthy humans. Kenyoncollege Person-to-person contact Some microorganisms can be spread by skin to skin contact, or by the inhalation of aerosols (airborne particles containing viable microorganisms). Examples: Inhalation - influenza (a virus), or Skin-to-skin contact - Staphylococcus aureus (a bacterium); or Ebola (a virus) Staphylococcus aureus – direct contact Staphylococcus aureus is a bacterial member of the normal microbiota of humans. The bacterium resides on mucous membranes and skin of humans. The structure of the cell wall makes this bacterium resistant to desiccation, and can survive on fomites for long periods of time. Gram stain of Staphylococcus aureus It is an important nosocomial & community pathogen. Ebola – spread by direct contact The Ebola virus is one of two Filoviruses, the second being the Marburg virus. They are approximately 80 nm in diameter, and generally between 650 and 1,400 nm in length. The viruses can be spread by zoonotic, or person-to- Ebola virus, a member of person means. Means of host recovery are as yet the Filoviridae family unclear; infection is usually fatal. Damage to the liver, kidneys and vascular system are known, but the exact pathogenic process is unclear. Contact with animals Contact with animals can come in many forms. 1. Food consumption 2. Occupation 3. Lifestyle  Animal Husbandry As well as changes in the type of animals being kept, changes have also come in terms of the number of animals and in the ways in which they are kept (housing & husbandry) – e.g. hens http://www.aact.org.au/images/battery_hens/Pitts%20Farm.JPG Escherichia coli (E. coli) The most important point to remember is that this is not just a food poisoning bacterium. The bacterium is transmitted via faecal contamination of soil and ground water, and also through surface waters, such as rivers and the sea through run-off. For example, animals defecating onto fields leads to the contamination of the soil, and rain can wash the bacterium into the water, therefore contaminating the river and then in to the sea (e.g. sewage leaks on to the beach!). Useful Processes Finally, microbes can be utilised for beneficial processes. Examples include: 1. Vaccine production (e.g. Polio, MMR) 2. Food production (e.g. bread, alcohol, cheese) 3. Pharmaceuticals (e.g. antibiotics, insulin) Examples of vaccines and sites of vaccination Intramuscular Influenza, hepatitis A & B, Polio (Salk) Sub-cutaneous MMR, meningitis Oral Polio (Sabin) Microbially derived foods Pediococcus species can be used on an industrial scale to produce soy sauce Lactobacillus, Bifidobacterium species are used to produce cheeses and yoghurts Lactobacillus species are used to produce sauerkraut Summary & advice Understanding the cell biology & biochemistry of microbes can enable us to learn how diseases can spread, and how microbes can be harnessed for beneficial purposes, such as food production. Learn the key transmission routes, and example organisms for each route. As we move through the next few weeks of lectures & labs, remember to build on each by linking topics throughout the series of classes. Bacteria #1 Link this lecture to content covered in next week’s session. Beneficial uses Recycling of elements Sewage treatment Bioremediation Pest control (e.g. caterpillar control) Biotechnology/genetic engineering Chemical production Food production (e.g. pro- biotics) Normal microbiota of the body Infections Leprosy Mycobacterium leprae Source: Independent Dental decay  Strep throat http://bioweb.uwlax.edu/bio203/s2007/falk_pete/Gram%20Positive.jpg Streptococcus pyogenes Basic bacterial shapes: Cocci, bacilli, curved bacilli & spirals Cocci (singular = coccus) Meaning a spherical cell Examples: Staphylococcus aureus, Streptococcus sp. https://www.ncbi.nlm.nih.gov/ Bacilli (singular = bacillus) Meaning oblong shaped cell E.g. Pseudomonas aeruginosa, Escherichia coli Vibrio Meaning a curved bacillus E.g. Vibrio cholerae microbeonline Spirochaete meaning corkscrew shape Example: Treponema pallidum CDC Staphylococcus aureus: clusters of cocci CDC Streptococcus sp.: Chains of cocci (streptococci) Sciencephotolibrary Neisseria gonorrhoeae: pairs of cocci (diplococci) Sciencephotolibrary Lactobacillus sake: Chains of bacilli  How big are bacteria? Red blood cells are approximately 7.5 m in diameter Bacteria generally range from 0.2 – 2.0 m diameter and 2-8 m length Viruses range from 20 -14 000 nm Key Learning Points 1. Bacteria exist in a variety of forms, with typical sizes being 0.2 -2.0µm diameter, and 2-8µm length, but exceptions exist. 2. Shapes include cocci, bacilli & spirochaetes. They may be arranged in a variety of formations, such as pairs, chains, clusters, or individually. 3. Cell morphology & arrangement can be used for identification purposes, sometimes enabling identification to genus level The bacterial cell Key cell features and their function Structural features of a bacterial cell Fimbria (pl. Flagellum (pl. fimbriae) flagella) Cytoplasm Storage granule (or other inclusion body) Pilus (pl. pili) Cell wall Chromosome Ribosomes Plasmid Capsule Plasma (nucleoid) membrane Bacterial packaging The cell membrane and the cell wall. The cell (plasma) membrane External environment Glycolipid Glycoprotein Non-polar tails: fatty acids Lipid bilayer Integral protein: Polar head: may form a pore phosphate group & Peripheral protein glycerol Cytoplasm Functions of the cell membrane (outermost, in contact with the external environment) Selectively permeable barrier Enzymes for metabolism Respiration and energy generation (ATP) DNA replication Synthesis of cell wall components Protein secretion Photosynthesis in some bacteria Movement across the membrane Simple diffusion Passive Facilitated transport diffusion Osmosis Passage of molecules Active Group transport translocation A comparison of Gram positive and Gram negative cell walls The Gram positive cell wall Wall teichoic acid Peptidoglycan Lipoteichoic acid Periplasm Plasma membrane Peptidoglycan structure  (1-4) glycosidic bond N-acetylglucosamine N-acetylmuramicacid Tetrapeptide chain Peptide cross-bridge Cross-linking of peptidoglycan E. coli Staph. aureus NAM NAG NAM NAG L-alanine L-ala D-glutamine D-alanine D-gluNH2 D-ala Diaminopimelic Diaminopimelic L-lysine L-lysine acid acid D-alanine D-glutamine D-ala D-gluNH2 L-alanine L-ala Direct peptide NAM NAG Penta-glycine NAM NAG link link Examples of common Gram positive organisms Staphylococcus aureus causative agent of many skin infections & food poisoning Bacillus cereus causative agent of food poisoning Streptococcus pyogenes causative agent of sore throats, scarlet fever and skin & soft tissue infections  The Gram negative cell wall Lipopoly- saccharide P P P Protein O LP Lipoprotein LP PO Porin Peptidoglycan Periplasmic space Plasma membrane  Lipopolysaccharide (LPS) Core polysaccharide Lipid A n O-specific polysaccharide The O specific region is antigenic. Lipid A is responsible for the toxic effects of contact with the Gram negative cell membrane  Examples of common Gram negative organisms Escherichia coli causative agent of gastrointestinal infections, traveller’s diarrhoea Salmonella spp. causative agent of food poisoning, gastrointestinal infections Pseudomonas aeruginosa opportunistic pathogen, wound & burn infections, urinary tract infections, complications of cystic fibrosis KEY LEARNING POINTS Component Gram positive Gram negative cells cells Cell (plasma) membrane Peptidoglycan Teichoic acid LPS Lipid/Lipoprotein Periplasmic space Outer membrane Suggested reading- Brock Biology of Microorganisms. Chapter 2 Paper copies are available from the library, or an online version is available via the READING LIST tab for this module.