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The specific effects vary with the size ratio between predator and prey. Pernthaler et al. classified susceptible bacteria into four groups by rough size. [14] Bacterial size < 0.4 μm were not grazed well; Bacterial size between 0.4 μm and 1.6 μm were "grazing vulnerable" Bacterial size between 1.6 μm and 2.4 μm were "grazing suppressed"
Food microbiology is the study of the microorganisms that inhabit, create, or contaminate food.This includes the study of microorganisms causing food spoilage; pathogens that may cause disease (especially if food is improperly cooked or stored); microbes used to produce fermented foods such as cheese, yogurt, bread, beer, and wine; and microbes with other useful roles, such as producing ...
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It is described using terms like brittle, creamy, sticky and dry. Staphylococci are considered to have a creamy consistency, [1]: 173 while some Neisseria species are sticky, and colonies of diphtheroid bacteria and beta-hemolytic streptococci are typically dry. [1]: 167–8 Bacteria that produce capsules often have a slimy (mucoid) consistency.
Perhaps the most obvious structural characteristic of bacteria is (with some exceptions) their small size. For example, Escherichia coli cells, an "average" sized bacterium, are about 2 μm ( micrometres ) long and 0.5 μm in diameter, with a cell volume of 0.6–0.7 μm 3 . [ 1 ]
Bacteria were at first classified based solely on their shape (vibrio, bacillus, coccus etc.), presence of endospores, gram stain, aerobic conditions and motility. This system changed with the study of metabolic phenotypes, where metabolic characteristics were used. [ 83 ]
Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacteria Carsonella ruddii, [127] to 12,200,000 base pairs (12.2 Mbp) in the soil-dwelling bacteria Sorangium cellulosum. [128]
Based on these experiments, he devised criteria for establishing a causal link between a microorganism and a disease and these are now known as Koch's postulates. [18] Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today.