VWT 272 Class 15. Quiz Number of quizzes taken 25 Min 6 Max 30 Mean 24.0 Median 26 Mode 30

Transcription

1 VWT 272 Class 15 Quiz Number of quizzes taken 25 Min 6 Max 30 Mean 24.0 Median 26 Mode 30

2 Class 15 Bacteria: the Good, the Bad, and the Ugly What you see is that the most outstanding feature of life's history is a constant domination by bacteria. Stephen Jay Gould

3 Plan of Study Bacteria as a Domain Bacterial structure Peptidoglycan Lactic Acid Bacteria Acetic Acid Bacteria Other Bacterial Products

4 Bacteria Fun Facts Bacteria Prokaryotic microorganism (no nucleus) Prokaryote Before Nucleus DNA in rings - plasmids not rod like structures - Chromosomes Have cytoplasm & ribosomes to make proteins Evolved ~ 3 Billion years ago from Archaea Tiny, often > 1μm in length Numerous 4 X 10 7 bacteria in a gram of soil 1 X 10 6 in a ml of water 1 ton of soil ~ 4 million species of bacteria (mostly unknown) There are about 10 times more bacterial cells in/on the human body than make up the human body.

5 Simple Bacteria Structure

6 Simple Bacteria Structure No Nucleus DNA floats free in loop DNA in Plasmids Ribosome Machine that makes amino acids into proteins with the help of mrna Different Forms

7 Simple Bacteria Structure Different Forms

8 Simple Bacteria Structure Different Forms

9 Not So Simple Bacteria Structure Cell Wall Two types Gram + Gram -

10 Peptidoglycan the planks of the bacterial cell wall Peptidoglycan is ONLY found in Bacteria

11 Peptidoglycan Antibiotics Lysozyme & Penicillin penicillin

12 Peptidoglycan Penicillin disrupting growth in bacteria

13 Not So Simple Bacteria Structure Cell Wall Two types Gram + Gram -

14 Not So Simple Bacteria Structure Cell Wall Two types Gram + = purple Gram - = pinkish

15 There are two kinds of people Bacterial classification Gram-positive vs. Gram-negative Thick cell wall vs. thin (double) cell wall Aerobic vs. Anaerobic Require Oxygen vs. poisoned by oxygen Catalase-positive vs. Catalase-negative If bacteria produce O 2 from H 2 O 2 they are catalase-positive Heterotrophic vs. Autotrophic Live off other organisms vs. make their own food Cyanobacteria (blue green algae) responsible for oxygen atmosphere

16 There are two kinds of people Bacterial classification Endospore forming vs. non endospore forming Endospores produced during times of stress DNA and ribosomes surrounded by a shell Resistant to UV light, gamma radiation, disinfectants, heat, freezing, high pressure, radiation, space travel(?) Remain viable for millions of years

17 There are two kinds of (wine) people Wine Bacterial classification Acetic Acid vs. Lactic Acid Bacteria

18 Acetic Acid Bacteria - AAB Taxonomy is a mess many texts disagree Gram-positive Aerobic Catalase-positive Rod shaped (?) usually single or in pairs Tiny.8 to 4 μm

19 Gluconacetobacter Gluconacetobacter europaeus Aerobe Highly resistant to acetic acid Primary energy source is Ethanol Produces acetic acid Used in Europe to produce vinegar SO 2 somewhat sensitive, EtOH tolerant Gluconacetobacter hansenii Aerobe Highly resistant to acetic acid Primary energy source is Ethanol Produces acetic acid Fast and vigorous growth Can stick yeast fermentation Can produce polysaccharides which can clog filters SO 2 highly sensitive, EtOH somewhat tolerant

20 Gluconobacter oxydans Gluconobacter Aerobe Primary energy source is Ethanol Produces acetic acid Can utilize hexoses (glucose/fructose) Produces gluconic acid Often found in high sugar environments SO 2 sensitive, EtOH slightly sensitive

21 Acetobacter aceti Acetobacter cerevisiae Acetobacter lovaniensis Acetobacter oeni Acetobacter orleanensis Acetobacter pasteurianus Acetobacter Aerobe Primary energy source is Ethanol Produces acetic acid & ethyl acetate In low oxygen environments (barrels) can produce acetaldehyde Can produce polysaccharides Scum on surface of wine clog filters SO 2 sensitive, EtOH tolerant

22 Lactic Acid Bacteria - LAB Taxonomy is a mess many texts disagree Huge group of bacteria Wine Lactobacillus Oenococcus Pediococcus Gram-positive Anaerobic (microaerobic) Catalase-negative Rod shaped (?) single, pairs and chains Vary in size from medium to large 2 to 4 μm

23 Lactobacillus brevis Lactobacillus hilgardii Lactobacillus fermentum Heterofermenters Lactobacillus I Can produce Lactic Acid and ethanol from glucose/fructose Can produce Lactic Acid from Malic Acid Can produce acetic acid (not ethyl acetate) from glucose/fructose Can produce mousiness Ethanol must be present SO 2 somewhat sensitive, EtOH tolerant

24 Lactobacillus II Lactobacillus casei Lactobacillus paracasei Lactobacillus mali Lactobacillus nagelii Facultative Heterofermenters Can produce Lactic Acid and ethanol from glucose/fructose and 5 carbon sugars Can produce Lactic Acid from Malic Acid Can produce acetic acid (not ethyl acetate) from glucose/fructose Can produce mousiness Ethanol must be present SO 2 sensitive, EtOH tolerant

25 Lactobacillus kunkeei Heterofermenter Lactobacillus III Can produce Lactic Acid and ethanol from glucose/fructose Can produce Lactic Acid from Malic Acid Can produce acetic acid (not ethyl acetate) from glucose/fructose Can grow VERY rapidly Grows primarily in juice Can stick fermentation SO 2 highly sensitive, EtOH tolerant

26 Lactobacillus plantarum Lactobacillus IV Facultative Heterofermenter Can produce Lactic Acid and ethanol from glucose/fructose and 5 carbon sugars Can produce Lactic Acid from Malic Acid Can produce biogenic amines Histamine Cadaverine Putrescine SO 2 slightly sensitive, EtOH slightly sensitive

27 Oenococcus oeni AKA Leuconostoc oenos Heterofermenters Oenococcus Can produce Lactic Acid and ethanol from glucose/fructose Can produce Lactic Acid from Malic Acid Requires many amino acids to convert Malic to Lactic Acid Found at low ( < 3.5 ph) Fast growth in wine Produce few unwanted compounds SO 2 somewhat sensitive, EtOH tolerant

28 Pediococcus damnosus Homofermer Pediococcus Can produce Lactic Acid and ethanol from glucose/fructose Can produce large amounts of diacetyl from pyruvate Can produce ropeieness from glucan systhesis SO 2 somewhat sensitive, EtOH somewhat tolerant

29 DON T PANIC! Significant populations of microbes are necessary to do something to the juice/wine. Many bacteria are present in background populations Threshold of concern 1 x 10 5 cells/ml

30 Number of cells Bacteria Growth Curve Time

31 Other (not so nice) Bacterial Products Acetoin Produced by LAB from Pyruvic Acid or Diacetyl In low concentrations has a buttery odor Precursor to other (smelly) compounds 2,3 Butantediol Produced by LAB from Acetoin Alcoholic & Bitter

32 Other (not so nice) Bacterial Products Acrolein Made by LAB from glycerol High glycerol producing yeast Reacts with anthocyanins to produce taint 10 mg/l can cause taint VERY Bitter Tourne Disease Described by Louis Pasteur Lactobacillus brevis makes Acetic Acid from Tartaric Acid Wine is cloudy, bitter and low in acidity

33 Other (not so nice) Bacterial Products 2-Ethyltetrahydropyridine (ETPY), 2-Acetyltetrahydropyridine (ACTPY), 2-Acetyl-1-pyrroline (ACPY) Made by LAB (and Brettanomyces) from amino acid Lysine Requires Ethanol, and Acetaldehyde, and Fe 2+ Smells like mouse cage Acidic structure not very aromatic Basic structure highly aromatic ACTPY 4 to 5 µg/l ETPY 2 to 18 µg/l ACPY 7 to 8 µg/l 30% of population is not sensitive

34 Next Week Practical Wine Micro - Lots of Small Issues