Efficient Lignin Decomposing Microbial Consortium to Hasten Rice-Straw Composting with Moderate GHGs Fluxes

Pradeep Kumar Dash,Pratap Bhattacharyya,Ankita Pattanayak,Amaresh Kumar Nayak,Periyasamy Panneerselvam,Soumya Ranjan Padhy,Soumya Routray,Himanshu Pathak

doi:10.1007/s12649-021-01508-9

Pradeep Kumar Dash, Pratap Bhattacharyya + Show 6 more

Open Access

https://doi.org/10.1007/s12649-021-01508-9

Copy DOI

Abstract

We hypothesized that lignin decomposition microbial consortium would make rice-straw decomposition faster as straw contain around 15–24% lignin. In this study, we isolated aerobic lignin degrading microbes from four natural sources and based on their ability towards lignin degradation four microbial strains and their combination (2 bacteria (LB 8, LB 18) and 2 fungi (LF 3, LF 9) were selected for rice straw decomposition. The greenhouse gases emission, enzymatic activities (β-glucosidase, cellulase, laccase), reduction in lignin content, weight loss and carbon nitrogen ratio (C:N) were quantified during the process of decomposition. The β-glucosidase, cellulase and laccase activities were higher in compost where LB 18 + LF 3 consortium was applied as compared to others. The lignin content was also decreased (8.9–9.5 to 6.6–7.9%) gradually from initial to 28th days of composting under LB 18 + LF 3. We found the microbial consortium LB 18 + LF 3 decomposed the rice straw relatively faster than other strains/consortium tested as indicated by lowering of C:N ratio and reduction of lignin, hemicellulose, and cellulose contents of 60, 19.2, 41.5 and 10.3%, respectively at 28th day of composting compared to initial values. However, higher, methane and carbon dioxide fluxes were also observed at 28th days of composting (1.36 and 200.7 mg m−2 h−1) with no significant trend in nitrous oxide fluxes. Further, the consortium identified could be tested for in-situ straw decomposition with proper moisture management to evaluate its potential in field condition. Therefore, we conclude that use of lignin decomposing microbial consortium has the potential to hasten the composting of rice straw in large scale.Graphic abstract

Highlights

India is the global prime producer of rice (Oryza sativa) accounting for about 20% of world rice production
We found the microbial consortium LB 18 + LF 3 decomposed the rice straw faster as indicated by reduction of C:N ratio and reduction of lignin, hemicellulose and cellulose contents of 60, 19.2, 41.5 and 10.3%, respectively at 28th day from initial compare to other strains/consortium
We conclude that use of lignin decomposing microbial consortium has the potential to hasten the composting of rice straw in large scale, so viable option to reduce the menace of straw burning

Summary

Introduction

India is the global prime producer of rice (Oryza sativa) accounting for about 20% of world rice production. 760 million tons of rice straw produced per year globally which is the 1.5 times greater than per ton of rice-grain production (FAO 2017; Satlewal et al 2018). The disposal of this surplus straw creates a major concern a day in all the rice growing areas (Borah et al 2016). Since last two decades farmers prefer to burn this straw to clear the field for the timely sowing of wheat in northern and north-western parts of India. Burning of rice straw emits 0.7- 4.1g of CH4 and 0.019- 0.057g of N2O per kg of dry rice straw and other gaseous pollutants such as SO2, NOx, HCl, and to some extent, dioxins and furans (Oanh et al 2011)

Methods

Results

Discussion

Conclusion