i) Bacteria cause damage of food, clothes and other things in decaying
process.
ii) Denitrifying bacteria damage the soil fertility.
iii) Bacteria cause many diseases in plants.
iv) Bacteria cause many diseases in cattle e.g. T.B and anthrax.
v) Bacteria cause many diseased in man e.g. T.B whooping cough,
diphtheria, typhoid, tetanus, cholera etc.