Tag: microbes in human welfare

Myxomycetes, also called as mycetozoa, phylum of fungus-like organisms within the kingdom protista, commonly known as true slime molds. They exhibit characteristics of both protozoans (one-celled microorganisms) and fungi. Myxomycetes is a class of slime molds, formerly regarded as animals (Mycetozoa), but now generally thought to be plants and often separated as a distinct phylum (Myxophyta); equivalent to the division Myxomycota. They are found on damp earth and decaying vegetable matter and consist of naked masses of protoplasm, which creep very slowly over the surface and ingest solid food.

Biofertilizers are the suspension of microorganism which mainly increases the growth of the plants. These secrete the growth promoting substances. The microorganisms in bio-fertilizers restore the soil's natural nutrient cycle and build soil organic matter. Bio-fertilizers such as Rhizobium, Azotobacter, Azospirilium and blue-green algae (BGA) are used. Anabaena in association with water fern Azolla contributes nitrogen up to 60 kg/ha/season and also enriches soils with organic matter.

Mycorrhiza is the symbiotic relationship between fungi and plant roots in which both gets benefit from each other. Fungus acts as the plant's root hairs and acts as an extension of the root system for more absorption of nutrients and in turn receives carbohydrates (sugars) and growth factors from the plant, Plants with thick roots, poorly branched and with few root hairs, are usually more dependent on mycorrhizae for normal growth and development. Thus, the correct answer is option C.

Blue Green Algae (BGA) is a good alternative source of nitrogen in rice fields to increase the soil fertility. Various BGA like Nostoc, Anabaena, Aulosira Scytonema are used to increase rice production. Out of all these, Aulosira fertilissima are most commonly used in rice fields.

Rhizobium is an important symbiont for legumes but it plays an important role with nonlegumes by producing growth hormones. When wheat is inoculated with Rhizobium, no effects are observed in terms of growth and yield, which indicates that uptake of soil nitrogen is not seen as in legumes.

Heterocyst is a specialized nitrogen=fixing cell found in some filamentous cyanobacteria like Nostoc, Anabaena. It has cell wall which is made up of three layers. It carries carries out nitrogen fixation. It is formed due to lack of fixed nitrogen. It fixes nitrogen under aerobic conditions. It contains nif gens and synthesize nitrogenase enzyme. Apart from nitrogenase enzymes, it also contains other enzymes required for nitrogen fixation. It promotes vegetative reproduction by filament fragmentation. It does not possesses PS II and hence cannot produce oxygen.