Question

1. List and explain one beneficial effect and one detrimental effect of bacteria.

Answer 1

Answer:- Bacteria are both our friend as well as foes.

Beneficial effect of bacteria:-

(1) Bacteria are the source of many antibiotics and serum . For example : Pencillium was isolated from Penicillium notatum, Streptomyces, and Bacillus are some important bacteria.

(2) Many bacterium ,such as Pseudomonas , Micrococcus and Candida are capable of degrading petroleum hydrocarbons both in marine and fresh water habitats.

(3) Bacteria are natural scavengers . They break down organic matter into inorganic constituents . The inorganic substances are used by plants as nutrients.

(4) Plants do not use atmospheric nitrogen directly .Many symbiotic as well as free living can fix molecular nitrogen into nitrogenous compounds.

(5) Bacteria also use in dairy industry for manufacture of milk products like butter, cheese, yoghurt etc.

Lactobacillus bulgaricus , Lactobacillus acidophilus, Streptococcus lactis are common bacteria used in dairy industry

(6) Bacteria also use to degrade pollutants from soil , underground water, chemical spills, etc .., and this process is known as bioremediation.

Two bacterial genera - Pseudomonas and Bacillus are commonly used bioremedial microbes.

Detrimental effect of bacteria:-

(1) Bacteria grow on food materials very luxuriantly when temperature and humidity are favourable.Bacteria change the flavour ,smell and appearance of food materials thus affecting it's quality.

Lactobacillus, Streptococcus, Micrococcus are responsible for spoilage of milk and milk products.

(2) Bacteria multiply in water and makes it unpotable. Bacteria causing typhoid fever ( Salmonella typhi) , Cholera ( Vibrio cholerae).

(3) Bacteria also causes disease in plants.

Blight of potato :- Xanthomanas oryzae.