Microbial roles and food preservation

Decomposer microorganisms break down dead matter and wastes, returning nutrients to the non-living environment. Photosynthetic phytoplankton contribute to primary production and oxygen release. Some digestive microorganisms help process food. Humans also use microbes in bread, yoghurt and other fermented foods. Genetically modified microorganisms can produce proteins such as human insulin when given appropriate genetic instructions.

Spoilage occurs when microbial activity changes food quality. Refrigeration commonly slows growth; heating can destroy susceptible microbes; drying reduces available water. Salt or concentrated sugar lowers water availability and can draw water from microbial cells. Acids inhibit organisms outside their suitable pH range. Preventing recontamination also matters: slowing growth is different from making a product sterile.

Watch out: It generally slows microbial growth and does not necessarily kill all microorganisms.