Microbiology Vi sinh trong sữa

Microbiology Technical Service Field Service Quality Assurance Microbiology Microbiology is the study of organisms which are so small that they can only be seen with the aid of a microscope Size is measured in micrometer µm µm = 0,001 mm Technical Service Field Service Quality Assurance Micro-organisms Groups Protozoa Algae Fungi - Yeast - Mould Bacteria Viruses Range of Size - 200 mm mm - a few meters - 10 mm - 10 mm by meters 0,5 - mm 0,015 - 0,2 mm Technical Service Field Service Quality Assurance Micro-organisms in the Laboratory cfu, colony forming unit Technical Service Field Service Quality Assurance Microbial Loads Locality CFU/hour and100cm Mibi Picture 16 240 40 Gram pos bacteria dominate 280 320 A lot of gram neg bacteria 150 Moulds dominate In-doors: Dry environment Office far from people Office close to people Corridor people passing In-doors: Wet environment Toilets Cleaning room Out-doors environment Lawn far from people Technical Service Field Service Quality Assurance Shapes of Bacteria Spherical Rods Curved or Spiral c ) b) a ) d ) Technical Service Field Service Quality Assurance The Bacterial Cell - Basic Structures Cell wall(1) Cell membrane(2) Chromosome(3) Cytoplasm(4) Technical Service Field Service Quality Assurance Bacterial Cell - Structures Cell wall Pili Cell membrane Cytoplasma with ribosomes Capsule Granule Mesosome Chromosome Flagellum Technical Service Field Service Quality Assurance Bacteria : Function of Cell Structures CELL WALL ◊ giving the cell its specific shape ◊ protects the cell against high pressure and mechanical forces CELL MEMBRANE ◊ acts as osmotic barrier ◊ active transport of nutrients and metabolites CYTOPLASM ◊ place of production CHROMOSOME ◊ carrier of genetic information Technical Service Field Service Quality Assurance Bacteria : Grampositive and Gramnegative mainly peptidoglycan s lipopolysaccharides cytoplasm peptidoglycans cytoplasm cellmembrane Technical Service Field Service Quality Assurance Growth factor - Temperature Growth rate Influence of Temperature on Growth Rate minimum optimum maximum Temperature Technical Service Field Service Quality Assurance Growth factor - Temperature Thermophilic Number of cell divisions per hour 3,0 Mesophilic Psycrotrophic 1,0 Psycrophilic 0,6 0,3 20 40 60 80 0,1 Temperature (oC) Technical Service Field Service Quality Assurance Growth factor - Temperature Examples of Genera with Psycrotrophic Strains Bacteria Acinetobacter Aeromonas Alcaligenes Bacillus Citrobacter Clostridium Corynebacterium Enterobacter Escherichia Klebsiella Bacteria Microbacterium Micrococcus Moraxella Proteus Pseudomonas Serratia Streptomyces Vibrio Yersinia Listeria Yeast Candida Crytococcus Rhodotorula Torulopsis Mould Aspergillus Cladiosporium Penicillium Trichothecium Technical Service Field Service Quality Assurance Growth factor - Nutrients Large amounts of: C, O, H, N, P, S Small amounts of: Na , K , Mg, Ca Technical Service Field Service Quality Assurance Quantitative composition of milk 0,8 4,8 Mean Value, % 4,3 3,9 87,5 20 40 60 80 Minerals Lactose Protein Fat Water 100 Technical Service Field Service Quality Assurance Structure of fat Technical Service Field Service Quality Assurance Protein Structure Technical Service Field Service Quality Assurance Carbohydrates Monosacharides • glucose,fructose,galactose Disacharides • sucrose,lactose Polysacharides • starch,cellulose,pectin, carrageenan Technical Service Field Service Quality Assurance Enzymes A given enzyme will only split certain molecules, and only at certain bonds Technical Service Field Service Quality Assurance Sugars Lactose and sucrose are split to galactose, glucose and fructose Technical Service Field Service Quality Assurance Microbial Degradation Products Sugar Protein Lipid ENZYMES Several incl oxidase Protease Lipase Waste Products n Organic acids (+gas) Drop in pH and Blown packs n Carbon dioxide + Ethanol Blown packs n Ketones Unpleasant odour n Peptides; Bitter taste n Ammonia; Unpleasant odour n Free fatty acid; Rancid taste Technical Service Field Service Quality Assurance Microbial Degradation Products lipase LIPID G L Y C E R O L O CH3-R-C COOH O CH3-R-C COOH O CH3-R-C COOH free fatty acids Technical Service Field Service Quality Assurance Microbial Degradation Products PROTEIN protease peptidase NH2 COOH R peptides amino acid Technical Service Field Service Quality Assurance Microbial Degradation Products CARBOHYDRATES I Prescence of oxygen: CO2 + Water + Energy II Absence of oxygen a) Alcoholic fermentation: Ethanol + CO2 b) Butyric acid fermentation: Butyric acid + etc c) Lactic acid fermentation - Homofermentative: Lactic acid - Heterofermentative: Lactic acid + Ethanol + Acetic acid + CO2 Technical Service Field Service Quality Assurance Microbial Degradation Products Breakdown of lactose by enzymatic action and formation of lactic acid Technical Service Field Service Quality Assurance [...]... sporophore mycelium budding hypha Technical Service Field Service Quality Assurance Fungal Spores Sexual Asexual chlamydospores conidiospores zygospore ascospores sporangiospores basidiospores Technical Service Field Service Quality Assurance Reproduction of Moulds Technical Service Field Service Quality Assurance Reproduction of Yeast Technical Service Field Service Quality Assurance Important Growth Factors... Service Field Service Quality Assurance Growth factor - Temperature Growth rate Influence of Temperature on Growth Rate minimum optimum maximum Temperature Technical Service Field Service Quality Assurance Growth factor - Temperature Thermophilic Number of cell divisions per hour 3,0 Mesophilic Psycrotrophic 1,0 Psycrophilic 0,6 0,3 0 20 40 60 80 0,1 Temperature (oC) Technical Service Field Service... preservation Technical Service Field Service Quality Assurance BERGEY’S MANUAL OF DETERMINATIVE BACTERIOLOGY 8th edition 1974 • 19 Parts • 48 Families • 245 Genera • 2000 Species Technical Service Field Service Quality Assurance BERGEY’S MANUAL OF DETERMINATIVE BACTERIOLOGY Ninth Edition 1994 Identification of Bacteria 35 Groups 550 Genera 4 500 Species Technical Service Field Service Quality Assurance... fermentation Others can only grow with fermentation Technical Service Field Service Quality Assurance Growth factor - Water Water activity, aw, is a measure of the water available for growth p aw = p 0 aw 0 < aw < 1 p = actual water vapor pressure p0= pure water vapor pressure Technical Service Field Service Quality Assurance Growth factor - Water Water activity = aw p 0 < aw < 1 aw = p 0 p = actual water vapor... Technical Service Field Service Quality Assurance Generation Time temp.(oC) Bacterium medium g(min) E coli E coli milk 37 glucose+minerals 37 12 90 Streptococcus lactis milk 37 26 Lactobacillus acidophilus milk 37 75 Technical Service Field Service Quality Assurance as Ph e Log Pha se Stationary Phase ath De Log No of Bacteria The Bacterial Growth Curve Time Lag Phase Technical Service Field Service Quality... Staphyllococcus aureus 0,86 Moulds Aspergillus Penicillium 0,70-0,84 0,79-0,83 Yeasts Saccharomyces cerevisiae Debaryomyces hansenii 0,90 0,83 Saccharomyces rouxii 0,62 Technical Service Field Service Quality Assurance Growth factor - pH pH pH = log(H+) High Acid Food 4,6 Low Acid Food 4,6 Technical Service Field Service Quality Assurance Growth factor - pH 4,6 No growth of pathogenes Effect of Acidity on Growth... Shigella ∗ Corynebacterium ∗ Serratia ∗ Actinomyces ∗ Yersinia ∗ Bacillus ∗ Vibrio ∗ Clostridium Technical Service Field Service Quality Assurance Bacterial Spores Vegetative cells Multiplication Sporulating cell The Dormant Spore Outgrowth Germination Mature spore Core Cortex Exosporium Membrane Coats Technical Service Field Service Quality Assurance BERGEY´S MANUAL OF Systematic Bacteriology Classification... Moraxella Proteus Pseudomonas Serratia Streptomyces Vibrio Yersinia Listeria Yeast Candida Crytococcus Rhodotorula Torulopsis Mould Aspergillus Cladiosporium Penicillium Trichothecium Technical Service Field Service Quality Assurance Growth factor - Nutrients Large amounts of: C, O, H, N, P, S Small amounts of: Na , K , Mg, Ca Technical Service Field Service Quality Assurance ... 23 27 15 48 58 66 - 9 38 49 58 Technical Service Field Service Quality Assurance Growth factor - Water Effect of aw on Growth Mould and Yeast No Spoilage a w: 0 Dried food milk egg vegetable Cocci Gram+ Gram 0,6 0,7 Meat extract Aged Ceese Jam 0,8 0,9 1,0 Milk Beverage Evaporated milk Tomato paste Sweet Condensed milk Tomato paste Technical Service Field Service Quality Assurance Growth factor - Water... Quality Assurance Important Growth Factors Oxygen Water Nutrients pH Temperature Technical Service Field Service Quality Assurance Growth factor - Oxygen Bacteria all types of relationships Moulds are strictly aerobic organisms with a few exceptions… Yeasts are facultative anaerobic organisms Technical Service Field Service Quality Assurance Growth factor - Oxygen Aerobic Demand of oxygen Can use oxygen at