Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings APPLIED MICROBIOLOGY  CHAPTER 26  MICROBIOLOGY 130  ROBERTA BRASHEAR-KAULFERS

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microorganisms found in Food  Food safety is a global issue  Soil microbes can spoil food  Contamination by unsanitary handling of food  Improper storage and preparation procedures can lead to contamination by pathogens  Imports of fruits and vegetables from 3 rd World countries can bring in diseases and parasites  *Hands washed properly??

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Bread Production - Sour Dough Bread  Sourdough culture- yeast Candida milleri and Lactobacillus sanfrancisco 1:100 ratio  German sour rye bread has 4 different yeast species and 13 species of Lactobacilli  Yeast feed on the sugars except maltose, Lactobacilli need maltose, then produce ethyl alcohol and CO2  Lactobacilli produce lactic and acetic acids giving the sour flavor, pH inhibits microbial growth

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings GRAINS  Rye and wheat are harvested dry  If they get wet, molds and other microbes will grow  Insect, birds and rodent vectors also transmit microbes  Raw grain with mold Claviceps purpurea cause ergotism, mold is halucinogenic and deadly  Aspergillus produce aflatoxins  Rhizopus nigricans is most common bread mold, also Aspergillus, Penicillium and Monila (pink mold)  Rye bread likely infected by Bacillus sp (w/spores)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings FRUITS AND VEGETABLES  Pseudomonas fluorescens are found on surface of fruits and vegetables  Pathogens: Salmonella, Shigella, Entameoba, Ascaris can be transmitted on surfaces  Leafy vegetables more susceptible to rot by Erwinia carotovora, Penicillium mold on citrus fruits and apples  Fungus Phytophthora infestans caused potato blight  Now using GMO to make plants resistant  Tomato rot- Fusarium fungus, Rhizopus injected by insects. Peach rot - Monilia fruiticola

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings MEATS AND POULTRY 70 pathogens found at slaughterhouses, inspected by vet Dec st case of Mad Cow in US, stricter laws Carcasses are hung in refrigerated rooms to age, some mold: Rhizopus and Mucor, Pseudomonas release H2S and green coloration Clostridium cause bone stink deep in carcass Ground meat- may have helminths-Trichinella, lactobacilli Should be cooked to kill pathogens

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings MEATS AND POULTRY  20 bacteria found on Poultry- 1/2 of all infections caused by Salmonella, ¼ by Clostridium perfringens, ¼ Staphylococcus aureus,  Gram – Pseudomonas cause slime and odors  Eggs have a hard porous shell, and microbes can get through  Chickens laying eggs can have Salmonella,1/10000 eggs has this bacteria in side shell, it does not have to be cracked so always cook eggs; don’t eat raw eggs!

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings FISH AND SHELLFISH  Fresh fish have microbes: enteric bacteria, worms, & viruses which survive even shipped in ice  Shellfish- oysters & clams –Salmonella and Vibrio  Clams filter feeder can pick up red tides toxins, sewage  Shrimp (breaded) have high bacterial counts  Lobster and crabs - enteric pathogens  Crabs carry Clostridium, Cryptococcus and Candida

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings MILK  Breeding cattle for high milk production have large udders and easily admit bacteria- get rid of 1 st few squirts which can have 15,000 bacteria /ml  Mostly Staphylococcus, Micrococcus, Pseudomonas  Hand milking- E. coli, Acinetobacter  Diseased cattle can transmit Mycobacterium bovis Brucella, TB  Milk is Soured by Streptococcus lactis, Lactobacillus

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings OTHER EDIBLE SUBSTANCES  Sugar- raw cane supports fungi: Aspergillus, Saccharomyces, Candida. Bacteria: Bacillus and Micrococcus  Clostridium causes the bulge in cans  High sugar concentration acys as preservative  Maple trees are tapped in spring -Leuconostoc, and Enterobacter  Honey toxins for Clostridium spores-floppy baby syndrome botulism

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings OTHER EDIBLE SUBSTANCES  Spices- mask odors rather than preserve  Condiments, ketchup mustard have acids  Harvested coffee subject to molds and coffee rust  Tea leaves mold by Aspergillus and Penicillium  Microbes needed to make coffee: Erwinia needed to digest pectin on coffee bean,  Yeasts turn bean pulp into alcohol also create flavor of chocolate

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PREVENTING DISEASE TRANSMISSION AND FOOD SPOILAGE  More contamination in large processing plants  Klebsiella found in human digestive tract is also a respiratory pathogen, but can cause diarrhea  TB can be transmitted from unpasteurized milk/cheese  Virus are transferred through food  Milk is ideal medium for growth of pathogens/microbes  Crucial factor to prevent spoilage and disease is cleanliness in handling, use fresh foods, refrigerate,  Process quickly and store properly

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Are Preserved By  Drying of grain  Osmotic pressure (salt or sugar)- Dried and salted meats and other foods  Fermentation - milk allowed to sour was made into cheese  Canning - use of moist heat under pressure, used to preserve fruits, vegetables, meats in glass jars and metal cans. Destroys microbes, endospores, prevents spoilage

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings CANNING  Some thermophiles (Bacillus stearothermophilus) may remain alive even after canning, spores can germinate and grow, can will bulge in heat (thermophilic anaerobic spoilage)  Flat sour spoilage  Mesophilic spoilage- improper canning at room temp  Sugars

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Industrial Food Canning Figure 28.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Commercial Sterilization to Destroy C. botulinum Endospores  12D treatment kills endospores  Surviving endospores of thermophilic anaerobes cause spoilage with gas  Or flat-sour spoilage

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings DRYING AND LYOPHILIZATION  Drying- desication or dehydration is oldest method  Remove 90% of water  Stops growth but does not kill microbes  Can be sun dried, heated in ovens etc  Addition of slat, sugar or chemicals also used  Lyophilization- freeze drying is used for instant coffee and dry yeast for bread making

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Preservation- Irradiation  Aseptic packaging: Pre- sterilized materials assembled into packages and aseptically filled.  Gamma radiation kills bacteria, insects, and parasitic worms.  High-energy electrons Figure 28.4

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 28.3 FOOD IRRADIATION- Ionizing Radiation 2 types of Irradiation- UV and Ionizing Still new and controversial Microwaves do not kill, but the heat is microbicidal, but food must be rotated Ionizing-Gamma Rays can penetrate and are microbicidal Can be done, before or after packaging Cobalt 60 gamma and Cs 137 used in Japan and Europe, FDA has declared safe in the US USDA proposed rules for irradiation of fresh poultry.. Still a debate!

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings CHEMICAL ADDITIVES  Benzoic, sorbic and propionic acids used in margarine, juice, bread, other baked goods  Alkylating agents- ethylene oxide used on nuts/spices  Ozone used on shellfish  NaCl- salt to cure meats, dehydrates bacteria  Halogen, chloride for processing equipment  Nitrates on sausage, hot dogs  QUATS- sanitize udders, fresh vegetables, eggshell surfaces

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings ANTIBIOTICS  In US only nisin - bacteriocin produced by milk fermentation by Streptococcus lactis  Antibiotics are prohibited because: (p 790)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PASTUERIZATION OF MILK - STANDARDS  2 methods : High temp short time  Low temp long time  Ultra high temperature- UHT treatment  Some chemical additives  Milk and Food in US carefully regulated by FDA  Animals inspected and soon stricter methods by microscope  Quality control has many tests for purity and guarantees high quality milk to consumers

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings MICROORGANISMS AS FOOD AND IN FOOD PRODUCTION  Algae, Fungi, and Bacteria as Food:  Yeasts are good source of protein  1 kg yeast = 100 kg protein, but human digestive tract can only handle small amounts of it  Algal cultures: Cyanobacteria- Spirulina and red algae grown in aquaculture (in Kona)  Algae- ingredient of ice cream  Yeast, algae and bacteria could increase World Food Supply!

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings FOOD PRODUCTION: BREAD & DAIRY  BREAD- previous slide on sour dough  Yeast Saccharomyces is a leavening agent, produce gas ato make bread rise and alcohol by fermentation  Alcohol and CO 2 driven off during baking- holes  DAIRY- cultured buttermilk- Streptococcus cremoris is added to skim milk and allowed to ferment, also Leuconostoc sp  Sour cream- add one of above microbes to cream  Yogurt- Streptococcus and Lactobacillus added to milk

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings FOOD PRODUCTION: DAIRY  Fermented Milk beverages- Mongolia- Arak drink from Mare’s milk produces alcohol  Acidophilus milk- add Lactibacillus acidophilus  Bulgarian milk- add L. bulgaricus, makes it more acidic  Kefir- Balkan goats milk stored in goatskin bags  Koumiss- Russian drink from Mare’s milk  Streptococcus lactis, L. bulgaricus, and yeasts are responsible for lactic acid, alcohol and other products

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cheese  Curd: Solid casein from lactic acid bacteria and rennin  Whey: Liquid separated from curd  Hard cheeses produced by lactic acid bacteria  Semisoft cheeses ripened by Penicillium on surface Figure 28.8a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings OTHER PRODUCTS  Vinegar: ethyl alcohol by Acetobacter aceti  Sauerkraut: cabbage with salt and microbes Lactobacillus and Leuconostoc ferment under anaerobic conditions  Pickles: add brine to cucumbers and ferment  Olives: ferment in Salt and Leuconostoc  Poi: ferment taro paste, yeast adds alcohol  Soy Sauce: soybeans, salt and Aspergillus-ferment  Soy Products: Miso, Tofu soft curd  Fermented Meats: salami, bologna, summer sausage

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Alcoholic Beverages-Beer, Wine and Spirits  Distillation-  Beer and ale are fermented starch.  Malting: Germinating barley converts starch to maltose and glucose.  Yeast ferment sugars to ethyl alcohol + CO 2

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Yeast Fermentations Table 28.5

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Making Red Wine Figure 28.9

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings SugarEthyl alcohol + CO 2 Saccharomyces cerevisiae Malic acidLactic acid Lactic acid bacteria Ethyl alcoholAcetic acid Acetobacter or Gluconobacter Microbial Metabolism

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fermentation Technology Figure 28.10

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Primary Fermentation Figure 28.11a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Secondary Fermentation Figure 28.11b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Industrial Microbiology/Pharmaceutical Micro  Amino acids  Citric acid  Enzymes  Vitamins  Antibiotics :  Penicillum  Steroids UN 28.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Useful Organic Products  Simple Organic Compounds-  Antibiotics-1940’s penicillin, 2% are marketed, others are too toxic, semi-synthetic antibiotics - augmentin  Enzymes-used in industrial processes  Proteolytic enzymes in coated granules are added to detergents  Enzymes in paper production-lignin digested by fungi  Amino acids-8 of 20 essential aa not synthesized by us  Need lysine, glutamic acid etc  Bioconversion-steroids, insulin, cortisone, progesterone

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbiological Mining: Biological Leaching of Copper Ores Figure 28.14a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings BiomassMethane or ethyl alcohol Bioconversion Alternative Energy Sources Using Microorganisms Figure 28.15

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbiological Waste Disposal  Sewage treatment plants  Bioremediation- use of microbes to dispose of chemical wastes  3 strains of microbes can Deactivate Aroclor a toxic PCB  Others detoxify cyanide and dioxin  Use GMO microbes