Microbes in Human Welfare

Rhizobium is used as a biofertilizer for raising crop. Rhizobium japonicum forms symbiotic association in the roots of the leguminous plant, soybean.

The genus Glomus form endomycorrhiza, a symbiotic associations with plants. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development.
Nostoc is a blue green algae, Agaricus is a basidiomycetes, Rhizobium is a eubacteria.

Azospirillum is an anaerobic nitrogen fixing bacteria which forms loose association with roots of some plants. Inoculation of paddy fields with these bacteria helps in increasing yield and saving of nitrogen fertilizers.

The natural method of pest and pathogen control involving use of viruses, bacteria and other insects (which are their natural predators and pests) is called biocontrol or biological control. For example, free living fungus Trichoderma exerts biocontrol over several plant pathogens for the control of plant diseases. Baculoviruses (mostly of genus Nucleopolyhedrovirus) are also used as biocontrol agents but they are used for the control of insects and arthropods. Bacillus thuringiensis is a soil bacterium which is used as biopesticide. Glomus species are the most common fungal partners of mycorrhiza residing in the roots of higher plants.

Organic farming involves use of organic wastes and other biological material along with beneficial microbes to release nutrients to crop to increase the soil fertility in an ecofriendly, and pollution tree environment. Glomus, earthworm and Oscillatoria can be used in organic farming while snail cannot.

Activated sludge is a process for treating sewage and industrial wastewaters using air and a biological floc composed of bacteria and protozoans. During the process, the primary effluent is taken to aeration tank that contain large number of aerobic heterotrophic microbes. They form flocs that digest a lot of organic matter. As the biological oxygen demand of waste water is reduced, it is passed into settling tank to undergo sedimentation. The sediment of the settling tank is called activated sludge that is a rich source of aerobic bacteria. Hence, the statement (b) is correct.
Biogas is produced by anaerobic breakdown of biomass with the help of methanogenic bacteria. It is made up of methane, carbon dioxide with traces of nitrogen, hydrogen sulphide and hydrogen.
Methanobacterium is an anaerobic bacterium that is found in rumen of cattle and is helpful in the breakdown of cellulose.

Alcohol and nitrogenase pair is wrongly matched. Ethanol produces alcohol.

Xanthomonas campestris is not used as a biopesticide. Xanthomonas campestris is a plant pathogen that causes black rot in cotton plants.

Trichoderma harzianum has proved a useful microorganism for biological control of soil borne plant pathogens. Trichoderma harzianum is a fungus that is also used as a fungicide. It is used for foliar application, seed treatment and soil treatment for suppression of various disease causing fungal pathogens. Commercial biotechnological products such as 3 Tac have been useful for treatment of Botrytis, Fusarium, Penicillium sp. It is also used for manufacturing enzymes.

The most common symbiotic association of legume and bacteria on roots is as nodules, which are small outgrowth on the roots. The microbe Frankia is symbiont in root nodules of several non-legume plants like Casurina and Alnus. Both Rhizobium and Frankia are free living in soil but as symbiont can fix atmospheric nitrogen.

Paecilomyces lilacinus proved effective for biological control of nematodal diseases in plant.

Probiotics are defined as live microorganisms, including Lactobacillus species, Bifidobacterium species and yeasts, that may beneficially affect the host upon ingestion by improving the balance of the intestinal microflora. The dietary use of live microorganisms has a long history.

Coliforms are a broad class of bacteria found in our environment, including the feces of man and other warm-blooded animals. The presence of coliform bacteria in drinking water may indicate a possible presence of harmful, disease-causing organisms.

Methane forms a major part of gobargas. Ammonia is toxic. Ethane and butane are not major components of gobar gas.

Serratia marcescens is considered a harmful human pathogen which has been known to cause urinary tract infections, wound infections and pneumonia. Serratia bacteria also have many antibiotic resistance properties which may become important if the incidence of Serratia infections dramatically increases.

Cohesion is the force of attraction between similar molecules. Osmosis is the movement of solvent molecules from a region of low solute concentration to a region of high solute concentration through a semipermeable membrane.

Agrobacterium tumefaciens is the causative agent of crown gall, an important disease of many commercial crops. This disease has come to be recognized in recent years as being caused by a DNA plasmid (Ti plasmid) carried by bacterium and transferred to the plant cells.

Lignin is a complex polymer of phenylpropane units, which are cross-linked to each other with a variety of different chemical bonds.

Maximum application of animal cell culture technology is in the production of vaccines. Vaccines are chemical substances prepared from the proteins of other animals which confer immunity to a particular virus. Some of the vaccines synthesized biologically through genetic engineering are vaccines for hepatitis-B virus, vaccines for rabies virus, vaccines for poliovirus and vaccines for small pox virus, etc.

Yeast carry out fermentation, releasing CO₂ making bread soft and porous. Hence, Saccharomyces is referred to as baker’s yeast.

Methanobacillus (methanogen) occurs in marshes and also in dung. It produces CH₄ gas under anaerobic condition and is utilized in gobar gas plant.

Azolla and blue green algae- Anabaena form biofertilizer in rice fields.

Erucic acid is a monounsaturated omega-9 fatty acid, denoted 22 : 1 $\omega $-9. It is prevalent in rapeseed, wallflower seed, and mustard seed, making up 40 to 50 percent of their oils. Erucic acid is also known as cis13-docosenoic acid and the trans isomer is known as brassidic acid.

Azolla plays a very important role in rice production. Azolla and its nitrogen-fixing partner, Anabaena, have been used as green manure to fertilise rice paddies and increase production. With the help of Azolla, rice can be grown year after year, several crops a year, with little or no decline in productivity; hence no rotation of crops is necessary. So, Azolla is an excellent biofertilizer.

Yeast helps in ethyl alcohol formation. Lactobacillus is the milk bacteria while is the free living nitrogen fixing bacteria and Penicillium is the source of Penicillin.