Applied and Industrial Microbiology

Size: px
Start display at page:

Download "Applied and Industrial Microbiology"

Transcription

1 11/28/2016 PowerPoint Lecture Presentations prepared by Bradley W. Christian, McLennan Community College CHAPTER 28 Applied and Industrial Microbiology Industrial Food Canning Mesophilic bacteria can spoil food in leaking cans External bacteria introduced during the sealing process Cause putrefaction Most acidic foods can be preserved by processing at less than 100 C Heat-resistant fungi: Byssochlamys fulvus and Aspergillus 1

2 Aseptic Packaging Packages made of materials that cannot tolerate heat Paper and plastic sterilized with hot hydrogen peroxide or UV light Metal containers sterilized with super-heated steam or high-energy electron beams Radiation and Industrial Food Preservation Low doses (<1 kgy) Kill insects and inhibit sprouting Pasteurizing doses (1 10 kgy) Reduce pathogens on meat and poultry High doses (>10 kgy) Sterilize or greatly lower bacteria in spices 2

3 High-Pressure Food Preservation Pascalization Prewrapped, precooked foods submerged into pressurized water tanks (87,000 psi) Kills many pathogens and nonpathogens Preserves food color and flavor Food Technology 3

4 Cheese Curd: made of the protein casein and formed by the action of an enzyme (rennin) and lactic acid bacteria Whey: liquid separated from curd Hard cheeses are ripened by lactic acid bacteria Propionibacterium in Swiss cheese Soft cheeses are ripened by Penicillium on the surface Figure 28.5 Making cheddar cheese. 4

5 Other Dairy Products Butter Flavor and aroma are from diacetyls produced by lactic acid bacteria Yogurt Milk inoculated with Streptococcus thermophilus and Lactobacillus delbrueckii Nondairy Fermentations Bread dough and beer Saccharomyces cerevisiae produces ethanol anaerobically Sauerkraut, pickles, olives, chocolate, coffee 5

6 Alcoholic Beverages and Vinegar Beer and ale are fermented grain starches Malting: converting starch-containing grains into carbohydrates that can be fermented by yeasts Sake is made by converting rice starch to sugar by Aspergillus Wine is made from fermented plant sugars Bacteria conduct malolactic fermentation to make wine less acidic Acetobacter and Gluconobacter aerobically convert ethanol to acetic acid to make vinegar Figure 28.6 The basic steps in making red wine. 6

7 Industrial Microbiology Learning Objectives 28-4 Define industrial fermentation and bioreactor Differentiate primary from secondary metabolites Describe the role of microorganisms in the production of industrial chemicals and pharmaceuticals Define bioconversion, and list its advantages List biofuels that can be made by microorganisms. Fermentation Technology Industrial fermentation Large-scale cultivation of microbes to produce a commercial substance Uses bioreactors Primary metabolite: substance produced during the growth of new cells Secondary metabolites: substances produced when microbes have entered the stationary phase (trophophase) Immobilized enzymes and microorganisms Convert a continuous flow of substance without being lost 7

8 Figure 28.7 Section of a continuously stirred bioreactor for industrial fermentations. Acid/base for ph control Motor Steam for sterilization Foam breaker Liquid level Flat-bladed impeller Cooling jacket Culture broth - Batch - Fed-batch - Continuous Baffle Diffuser Sterile air Harvesting drain Figure 28.8 Immobilized cells. Bacteria Silk fibers 8

9 Industrial Products Amino acids Microbes make only the L-isomer Glutamic acid Lysine and methionine Phenylalanine and aspartic acid in artificial sweeteners Citric acid Produced by the Aspergillus mold (At one time, citric acid was extracted on an industrial scale from lemons and other citrus fruits) Industrial Products Enzymes Amylases from koji, a cereal plus Aspergillus Glucose isomerase, proteases Vitamins Vitamin B 12 Pseudomonas and Propionibacterium Riboflavin Ashbya gossypii fungus Vitamin C Acetobacter 9

10 Industrial Products Pharmaceuticals Antibiotics from streptomycetes Vaccines Steroids cortisone, estrogens, progesterone Figure 28.9 The production of steroids. 10

11 Industrial Products Copper extraction by leaching (huuhtoa, uuttaa) Acidithiobacillus ferrooxidans recovers copper Microorganisms as industrial products Baker's yeast S. cerevisiae Peat moss (rahkasammal) contains Rhizobium and Bradyrhizobium Insect toxin (Bt-toxin) Bacillus thuringiensis Figure Biological leaching of copper ores. Leaching: Fe 3+ in acidic leaching solution oxidizes insoluble copper sulfide (Cu + ) to soluble CuSO 4 (Cu 2+ ). Leach dump of copper sulfide ore Pregnant (metal-bearing) solution, CuSO 4 CuSO 4 precipitates as copper (Cu 0 ); Fe 3+ is changed to FeSO 4 (Fe 2+ ). Fe 0 (metallic scrap iron) Copper for industrial uses Pump Oxygen in aerated pond Oxidation pond: A. ferrooxidans oxidizes FeSO 4 to Fe 3+ + H 2SO 4 (acidic leaching solution). Barren solution, no copper, iron as FeSO 4 11

12 Alternative Energy Sources Using Microbes Biomass collective organic matter produced by living organisms Bioconversion converting biomass into alternative energy sources Methane produced from waste in landfills Figure Methane production from solid wastes in landfills. Gas flaring stacks Microturbines produce electricity from methane 12

13 Biofuels Sugars are fermented by microorganisms to ethanol Cellulose is digested by cellulase to make ethanol Bacteria can be genetically engineered to make long-chain alcohols Algae yield 20% of their weight in oil; remainder can be used to produce ethanol Industrial Microbiology and the Future Food processing technologies Recombinant DNA technology Ethanol and hydrogen as renewable energies 13