BIOCHEMICAL CHARACTERIZATION OF BACTERIA ISOLATED FROM DIFFERENT COMPOST SAMPLES AND GUT OF EARTHWORM USED IN VERMICOMPOSTING
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Date
2021
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DRPCAU, PUSA
Abstract
Composting and vermicomposting are two examples of biological waste disposal systems that are generally regarded as environment friendly and long-term solutions for managing organic waste. Composting mechanism is regulated by complex community of microbes dominated by various bacteria. Earthworms are the driving force behind vermicomposting as the gut of an earthworm is a factory to manufacture the beneficial microbial density and their products to excrete thousand times more to enrich the surrounding soil. Proper understanding of microbiology and biochemistry should be deciphered. Therefore, in present study, bacteria were isolated from three different samples viz., mushroom compost, vermicompost and earthworm gut, which were collected from AICRP on Mushroom, Vermicomposting unit of Dr. Rajendra Prasad Central Agricultural University, Pusa on different media - Nutrient Agar, Trypticase soya agar, Ken knight agar, CMC agar and Kings B media. 20 isolates were obtained from compost, 40 isolates from vermicompost and 20 from earthworm gut. These isolates were checked for their staining ability viz., gram and endospore staining and found that 26 were gram positive, 54 gram negative and 11 were endospore formers. These isolates were further screened for cellulose and hemicellulose degradation activity and found that 10 isolates from mushroom compost, 19 from vermicompost and 8 isolates from earth worm gut were able to perform cellulose degradation activity whereas 8 from compost, 25 vermicompost isolates and 14 isolates from earthworm gut were able to degrade hemicellulose. These isolates were subjected to nutrient solubilization activities like phosphorous, potassium, zinc and siderophore production. 5 from compost, 17 from vermicompost and 10 isolates of earthworm gut respectively showed phosphorous solubilisation whereas 5 from compost, 16 from vermicompost and 11 isolates from earthworm gut showed potassium solubilization. In case of zinc solubilisation 10 from compost, 18 from vermicompost and 14 isolates from earthworm gut. 8 from compost, 21 from vermicompost and 12 from earthworm gut showed siderophore production. One isolate (MC-10) from mushroom compost and seven isolates from vermicompost showed all the six activities whereas none of the isolates from earthworm gut showed all activities together. However, some isolates showed a minimum of three activities and maximum four activities. In term of solubility indices, it was observed that earthworm gut isolates showed the highest Phosphorous, potassium and zinc solubility indices when compared to compost and vermicompost isolates. Those isolates which showed either of cellulose or hemicellulose activity and any three nutrient solubilization activities were further checked for biochemical reactions i.e., IMViC test. A total of 31 promising isolates were subjected to IMViC test in which 15 isolates showed positive for indole test. 16 showed MR test and 24 isolates showed VP test. 14 isolates were able to use citrate as a source of energy. Therefore, the promising bacterial isolates which showed cellulose and hemicellulose degradation activity and other nutrient solubilizing properties can be utilized in composting which will help in better and faster decomposition of waste and reduces the composting time period.