MICROBIAL BIOCONVERSION OF AGRI-WASTE INTO COMPOST: AN ECO-ENTERPRISING MODEL
Loading...
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
DRPCAU, PUSA
Abstract
Bacterial isolates were collected from Department of Microbiology, Dr. Rajendra Prasad Central Agricultural University, Pusa. Total 28 isolates were collected and then subculturing were done in different media and broth. Based on 16S rDNA sequence analysis VC2, VC4, VC6, VC7, VC12, C10 and CC6 were identified as Bacillus sonorensis, Bacillus subtilis, Bacillus inaquosorum, Bacillus cabrialesii, Bacillus subtilis, Bacillus paramycoides and Bacillus stercoris. Out of 28 isolates, 27 isolates showed cellulose hydrolysing ability indicated by the formation of clearance zone in the range of 12.62 mm to 32.05 mm and the highest activity was shown by VC2 (32.05 mm). In the case of hemicellulose, 18 isolates showed positive results with hydrolysing zone formation in the range of 12.4 mm to 33.5 mm and the highest activity was shown by M18 (33.51 mm). As the enzyme activity concerned, cellulase production ability was reported by 16 isolates. Among them isolate VC2 had highest enzyme activity of 0.5428 U/ml with specific activity of 0.0037 U/mg and the lowest activity was indicated by C10 was 0.0668 U/ml with specific activity 0.0009 U/mg. Xylanase production ability was reported by 10 isolates, isolate VC7 showed highest enzyme activity 8.2479 U/ml with specific activity 0.0341 U/mg and the lowest activity was reported by C8 was 0.0368 U/ml. Bacterial strains that were observed with high enzymatic activity further tested for antagonistic activity. All the isolates were compatible with each other without showing any antagonistic behaviour.
Compatible cultures were grown separately in enrichment media then they were mixed to produce bacterial consortia which was used for preparation of formulations. Formulations of different concentrations were prepared using various substrates like wheat straw (2g), glucose (6g), lime (3%), Urea (2%), microbial consortia and distilled water of varying quantities but final volume was made to 200 ml. 18 formulations were prepared with 3 replications. Further analysis of wheat straw for degradation was done using different formulations. There was observed that the pH of the formulations varies related to various concentrations of different substrates. Highest pH was observed in formulation containing lime and glucose it is because lime increases pH of the solution. A15 formulation showed showed highest pH (11.13) followed by A3 (10.67) then the lowest pH was shown by A16 (2.54). It was observed that all the formulations at the initial showed decreased pH until 14 days then increased upto 42 days then decreased to attain pH constant (56 days). pH at the initial stage was high (>7.5) found to have less amount of nitrogen. At the next stage (i.e., after 20- 24 days) there occurs sharp increase in nitrogen content due to reduced pH (<6.5) causes increased accumulation of N and at the end of composting, pH again starts increasing slightly to maintain optimum level (i.e.,6.5 - 7) but N content slightly decreased or increased based on nutrient availability and decomposition rate. High N content was reported in formulation containing microbial consortia with pH in optimum level (i.e., 6.5-8). Formulations maintaining pH range 6.5 to 8 were observed to produce optimum N content and the formulations containing pH in the too acidic or alkaline range leads to contain very less or no N content.