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Applied and Industrial Microbiology

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1 Applied and Industrial Microbiology
Chapter 28 Applied and Industrial Microbiology Lectures prepared by Christine L. Case © 2013 Pearson Education, Inc.


3 Food Microbiology 28-1 Describe thermophilic anaerobic spoilage and flat sour spoilage by mesophilic bacteria. 28-2 Compare and contrast food preservation by industrial food canning, aseptic packaging, radiation, and high pressure. 28-3 Name four beneficial activities of microorganisms.

4 Historically… Drying Osmotic pressure (salt or sugar) Fermentation

5 Foods and Disease Hazard Analysis and Critical Control Point (HACCP)

6 Washing, sorting, blanching
Figure 28.1 The commercial sterilization process in industrial canning. Blanching in hot water or steam softens the product to easily fill the can. Washing, sorting, blanching Steam box This treatment lowers the microbial population and destroys enzymes that might alter color, flavor, or texture. Cans are filled to capacity, leaving minimal dead space. Steam is used to exhaust, or drive out, dissolved air. The cans are sealed. Cans are sterilized by pressurized steam in a retort, similar to an autoclave. Cans are then cooled by submersion in a water bath or by spraying them with water. Cans are labeled, stored, and delivered for sale.

7 Figure 28.2 Commercial canning retorts.

8 Formation of a double seam for top or bottom
Figure 28.3 The construction of a metal can. Sealing compound Formation of a side seam Formation of a double seam for top or bottom

9 Commercial Sterilization
Destroys C. botulinum endospores 12D treatment kills 1012 endospores Thermophilic anaerobic spoilage: surviving endospores multiply, causing the can to swell from gas Or flat sour spoilage

10 Low-acid canned food spoilage
Flat sour Geobacillus stearothermophilus Can is not swollen Thermophilic anaerobic Thermoanaerobacterium thermosaccharolyticum Swollen can Putrefactive anaerobic Clostridium sporogenes, C. botulinum

11 Food Preservation Aseptic packaging: presterilized materials assembled into packages and aseptically filled

12 Figure 28.5 Irradiation logo.

13 Table 28.2 Approximate Doses Of Radiation Needed To Kill Various Organisms (Prions Are Not Affected)

14 Ionizing Radiation Low dose 1 kGy Killing insects Pasteurizing dose
Meats and poultry High dose >10 kGy Sterilizing spices

15 Irradiation sources lifted from storage pool for processing period
Figure 28.6 A gamma-ray irradiation facility. Irradiation sources lifted from storage pool for processing period Shielding Material to be irradiated Shielding Conveyors to move material in and out of processing position The irradiation source is submerged in the storage pool. The blue glow is Cerenkov radiation caused by charged particles exceeding the speed of light in water. An irradiation facility, showing the path of the material to be irradiated

16 Figure 28.7 Electron-beam accelerator.
Bending magnet Electron gun

17 High Pressure Prewrapped, precooked foods 87,000 psi
Kills Salmonella, Listeria, E. coli Preserves color and flavor well

18 Cheese Curd: solid casein from lactic acid bacteria and rennin
Whey: liquid separated from curd Hard cheeses are produced by lactic acid bacteria Semisoft cheeses are ripened by Penicillium on surface

19 Figure 28.8 Making cheddar cheese.
The milk has been coagulated by the action of rennin (forming curd) and is inoculated with ripening bacteria for flavor and acidity. Here the workers are cutting the curd into slabs. The curd is chopped into small cubes to facilitate efficient draining of whey. The curd is milled to allow even more drainage of whey and is compressed into blocks for extended ripening. The longer the ripening, the more acidic (sharper) the cheese.

20 Figure 28.9 The basic steps in making red wine.
Grapes are tested and picked. Sulfite is added to kill undesirable yeasts and bacteria. Yeast inoculum is added. Result is pressed to separate solids from wine. Wine is clarified in settling vats. Fermentation occurs. Grapes are crushed and destemmed. Wine is filtered. Wine is aged. Wine is bottled.

21 Alcoholic Beverages and Vinegar
Beer and ale are fermented starch Malting: germinating barley converts starch to maltose and glucose For sake, rice starch is converted to sugar by Aspergillus Wine is fermented plant sugars Yeast ferment sugars to ethanol and CO2 Grape wine requires bacterial malolactic fermentation Acetobacter and Gluconobacter convert ethanol to acetic acid

22 Microbial Metabolism Sugar Ethanol + CO2 Malic acid Lactic acid
Saccharomyces cerevisiae Malic acid Lactic acid Lactic acid bacteria Ethanol Acetic acid Acetobacter or Gluconobacter

23 Is botulism a greater danger in spoilage of canned goods under thermophilic or under mesophilic conditions? 28-1 Canned foods are usually in metal cans. What sorts of containers are used for aseptically packaged foods? 28-2 Roquefort and blue cheeses are characterized by blue-green clumps. What are these? 28-3

24 Industrial Microbiology
28-4 Define industrial fermentation and bioreactor. 28-5 Differentiate primary from secondary metabolites. 28-6 Describe the role of microorganisms in the production of industrial chemicals and pharmaceuticals. 28-7 Define bioconversion, and list its advantages. 28-8 List biofuels that can be made by microorganisms.

25 Biotechnology Use of microorganisms, cells, or cell components to make a product Classical: fermentation Recombinant DNA

26 Section of a continuously stirred bioreactor
Figure 28.10a Bioreactors for industrial fermentations. Acid/base for pH control Motor Steam for sterilization Foam breaker Liquid level Flat-bladed impeller Culture broth Baffle Cooling jacket Diffuser Sterile air Harvesting drain Section of a continuously stirred bioreactor

27 Bioreactor tank, at left
Figure 28.10b Bioreactors for industrial fermentations. Bioreactor tank, at left

28 Cells Ethanol produced Cell weight or numbers Time
Figure 28.11a Primary and secondary fermentation. Cells Ethanol produced Cell weight or numbers Time (a) A primary metabolite, such as ethanol from yeast, has a production curve that lags only slightly behind the line showing cell growth.

29 Tropophase Idiophase Cells Cell weight or numbers Penicillin produced
Figure 28.11b Primary and secondary fermentation. Tropophase Idiophase Cells Cell weight or numbers Penicillin produced Time (b) A secondary metabolite, such as penicillin from mold, begins to be produced only after the logarithmic growth phase of the cell (tropophase) is completed. The main production of the secondary metabolite occurs during the stationary phase of cell growth (idiophase).

30 Figure 28.12 Immobilized cells.
Bacteria Silk fibers

31 Industrial Products Xanthan Amino acids Citric acid Enzymes Vitamins
Antibiotics Steroids

32 Xanthan Applications of Microbiology, unnumbered figure, page 808.
Xanthomonas campestris producing gooey xanthan.

33 Figure 28.14 Biological leaching of copper ores.
Leaching: Fe3+ in acidic leaching solution oxidizes insoluble copper sulfide (Cu+) to soluble CuSO4 (Cu2+). Pregnant (metal-bearing) solution, CuSO4 Copper for industrial uses Leach dump of copper sulfide ore Fe0 (metallic scrap iron) Pump Oxygen in aerated pond Oxidation pond: T.Ferrooxidans oxidizes FeSO4 to Fe3+ + H2SO4 (acidic leaching solution). Barren solution, no copper, iron as FeSO4 CuSO4 precipitates as copper (Cu0); Fe3+ is changed to FeSO4 (Fe2+).

34 Alternative Energy Sources Using Microbes
Cellulose digested by cellulase Sugars fermented to ethanol or higher alcohols or hydrogen Algal oils Biomass Methane Ethanol Hydrogen Bioconversion

35 Microturbines produce electricity from methane
Figure Methane production from solid wastes in landfills. Gas flaring stacks Microturbines produce electricity from methane

36 Industrial Microbiology and the Future
Food processing Pharmaceuticals from rDNA technology Ethanol and hydrogen And more

37 Are bioreactors designed to operate aerobically or anaerobically? 28-4
Penicillin is produced in its greatest quantities during the trophophase of fermentation. Does that make it a primary or secondary metabolite? 28-5 At one time, citric acid was extracted on an industrial scale from lemons and other citrus fruits. What organism is used to produce it today? 28-6

38 Landfills are the site of a major form of bioconversion—what is the product? 28-7
How can microbes provide fuels for cars and electricity? 28-8

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