Chapter 28: Applied and Industrial Microbiology
28.1 Food Microbiology
- The Hazard Analysis and Critical Control Point (HACCP) system is designed to prevent contamination by identifying points at which foods are most likely to be contaminated with harmful microbes.
- Industrially canned goods undergo commercial sterilization by steam under pressure in a large retort, which operates on the same principle as an autoclave.
- Thermophilic anaerobic spoilage is therefore a fairly common cause of spoilage in low-acid canned foods.
- ==When thermophilic spoilage occurs but the can is not swollen by gas production, the spoilage is termed flat sour spoilage.==
- The use of aseptic packaging to preserve food has been increasing.
- This product, called malt, contains starch-degrading enzymes (amylases) that convert cereal starches into carbohydrates that can be fermented by yeasts.
- These bacteria convert the malic acid to the weaker lactic acid in a process called malolactic fermentation.
28.2 Industrial Microbiology and Biotechnology
- The word biotechnology was first used in 1918 to describe the use of living organisms to produce products—in reference to combining agriculture and technology.
- A primary metabolite is formed essentially at the same time as the new cells, and the production curve follows the cell population curve almost in parallel, with only minimal lag.
- Secondary metabolites are not produced until the microbe has largely completed its logarithmic growth phase, known as the trophophase, and has entered the stationary phase of the growth cycle.
- Prominent among these is biomass, the collective organic matter produced by living organisms, including crops, trees, and municipal wastes.
- Microbes can be used for bioconversion, the process of converting biomass into alternative energy sources.
- Biofuels are energy sources produced from living organisms, rather than from fossils of organisms that lived over 300 million years ago.
- The initial interest has focused on ethanol, which is already widely used as a supplement to gasoline, and the technology is well established.
- In microbial fuel cells, exoelectrogens are grown in a nutrient medium such as soil or wastewater.