Question

bacteria & its uses in food preservation

Answer 1

acetic acid which is also called as vinegar is manufactured by the fermentation process. Malted barley or grape is fermented by yeast and is converted to alcohol. The alcohol is then converted to acetic acid by further fermentation by bacteria - acetobacter aceti
BUTYRIC acid is produced by the action of bacteria , clostridium butylicum during fermentation and is responsible for the rincidity of butter 

lactic acid is produced by the fermentation of sugars by both bacteria ( streptococccus lactis and lactobacillus ) and fungi rhizopus. 
it is used in food products like pickles , juices, bakeries , canned foods, meat etc 

pectinase and proteases are the enzymes obtained from aspergillus niger and bacillus species and are used to clear bottled fruit juices 


saccharomyces cerevisiae , bakers yeast or simply called yeast  is used as a raising agent . On fermentation it produces co2 that makes bubbles in bread dough . 

in cheese making , the pasteurised milk is fermented by adding a starter culture of bacteria , usually streptococcus thermophilus and lactobacilus at40 °c

lactic acid bacteria is having an anti mircrobial action . It prevents the growth of micro organisms in the food