Microorganism | biology | Britannica (original) (raw)
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cheese making
In dairy product: Inoculation and curdling …is then inoculated with fermenting microorganisms and usually with rennet, which promote curdling. The fermenting microorganisms carry out the anaerobic conversion of lactose to lactic acid. The type of organisms used depends on the variety of cheese and on the production process. Rennet is an enzymatic preparation that contains a… Read More
In soil: Pathways of detoxification Soil microorganisms, particularly bacteria, have developed diverse means to use readily available substances as sources of carbon or energy. Microorganisms obtain their energy by transferring electrons biochemically from organic matter (or from certain inorganic compounds) to electron acceptors such as oxygen (O2) and other inorganic compounds.… Read More
microbiology
In microbiology The word microbe was coined in the last quarter of the 19th century to describe these organisms, all of which were thought to be related. As microbiology eventually developed into a specialized science, it was found that microbes are a very large group of extremely diverse organisms. Read More
occurrence in hot springs
In hot spring …are caused by thermophilic (heat-loving) microorganisms, which include certain types of bacteria, such as cyanobacteria, and species of archaea and algae. Many thermophilic organisms grow in huge colonies called mats that form the colourful scums and slimes on the sides of hot springs. The microorganisms that grow in hot springs… Read More
osteomyelitis
In bone disease: Infectious diseases of bone …infection of bone tissue by microorganisms, which may gain access to bone either by spreading in the bloodstream in an infectious lesion elsewhere in the body (hematogenous osteomyelitis) or through a skin wound such as an open fracture. Read More
plankton
In marine ecosystem: Plankton …range in size from tiny microbes (1 micrometre [0.000039 inch] or less) to jellyfish whose gelatinous bell can reach up to 2 metres in width and whose tentacles can extend over 15 metres. However, most planktonic organisms, called plankters, are less than 1 millimetre (0.039 inch) long. These microbes thrive… Read More
water quality and treatment
In wastewater treatment: Removal of plant nutrients …first converted into nitrates by microorganisms. The nitrates are further metabolized by another species of bacteria, forming nitrogen gas that escapes into the air. This process requires the construction of more aeration and settling tanks and significantly increases the cost of treatment. Read More
water supply systems
In water supply system: Health concerns The most important microbiological measure of drinking-water quality is a group of bacteria called coliforms. Coliform bacteria normally are not pathogenic, but they are always present in the intestinal tract of humans and are excreted in very large numbers with human waste. Water contaminated with human waste always… Read More
food spoilage
In food preservation: Microbial contamination …are the principal types of microorganisms that cause food spoilage and food-borne illnesses. Foods may be contaminated by microorganisms at any time during harvest, storage, processing, distribution, handling, or preparation. The primary sources of microbial contamination are soil, air, animal feed, animal hides and intestines, plant surfaces, sewage, and food… Read More
baked goods
In baking: Spoilage by microbes Bakery products are subject to the microbiological spoilage problems affecting other foods. If moisture content is kept below 12 to 14 percent (depending on the composition), growth of yeast, bacteria, and molds is completely inhibited. Nearly all crackers and cookies fall below this level,… Read More
eggs
In egg: Microbiology More than 90 percent of all eggs are free of contamination at the time they are laid; contamination with Salmonella bacteria and with certain spoilage organisms occurs essentially afterward. Proper washing and sanitizing of eggs eliminates most Salmonella and spoilage organisms deposited on the… Read More
fish
In fish processing: Microbiology Because of their soft tissues and aquatic environment, fish are extremely susceptible to microbial contamination. At the time of harvest, fish carry a high microbial load on the surface of their skin, in their intestinal tract, and in their gills. Read More
fruits
In fruit processing: Storage concerns Microorganisms can also cause problems during senescence and storage. Many bacteria and fungi, for instance, are involved in decay after harvest. Typical fungi include Alternaria, Botrytis, Monilinia, Penicillium, and Rhizopus. These fungi are generally weak pathogens, in that they usually invest only weak or damaged… Read More
In poultry processing: Microbial contamination …medium for the growth of microorganisms. The principal spoilage bacteria found on poultry include Pseudomonas, Staphylococcus, Micrococcus, Acinetobacter, and Moraxella. In addition, poultry often supports the growth of certain pathogenic (disease-causing) bacteria, such as Salmonella. Read More
role in
infectious diseases
In infectious disease …agent, often a type of microorganism, that impairs a person’s health. In many cases, infectious disease can be spread from person to person, either directly (e.g., via skin contact) or indirectly (e.g., via contaminated food or water). Read More
rickettsial diseases
In human disease: Rickettsial diseases …rickettsial diseases are caused by microorganisms that fall between viruses and bacteria in size. These minute agents are barely visible under the ordinary light microscope. Like viruses, they multiply only within the cells of susceptible hosts. They are found in nature in a variety of ticks and lice and, when… Read More
