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Retting of bast fibres requires removal of pectin, hemicellulose and other non-cellulosic materials from plant stem tissues by a complex microbial community. A microbial retting consortium with high-efficiency pectinolytic bacterial strains is effective in reducing retting-time and enhancing fibre quality. We report comprehensive genomic analyses of three bacterial strains (PJRB 1, 2 and 3) of the consortium and resolve their taxonomic status, genomic features, variations, and pan-genome dynamics. The genome sizes of the strains are ~3.8 Mb with 3729 to 4002 protein-coding genes. Detailed annotations of the protein-coding genes revealed different carbohydrate-degrading CAZy classes viz. PL1, PL9, GH28, CE8, and CE12. Phylogeny and structural features of pectate lyase proteins of PJRB strains divulge their functional uniqueness and evolutionary convergence with closely related Bacillus strains. Genome-wide prediction of genomic variations revealed 12461 to 67381 SNPs, and notably many unique SNPs were localized within the important pectin metabolism genes. The variations in the pectate lyase genes possibly contribute to their specialized pectinolytic function during the retting process. These findings encompass a strong foundation for fundamental and evolutionary studies on this unique microbial degradation of decaying plant material with immense industrial significance. These have preponderant implications in plant biomass research and food industry, and also posit application in the reclamation of water pollution from plant materials.

Jute (Corchorus spp. L.), the second most important fibre crop next to cotton, is a biodegradable and eco-friendly crop and one of the main cash crops of eastern India. India is the largest producer of raw jute in the world earning about `2200 crores per annum through export of diversified jute goods for which quality jute fibre is needed. The jute fibre quality depends directly on retting process. In India, more than 90% jute farmers do not have the access to free flowing water, so they carry out jute retting in stagnant water. The quality of jute fibre is deteriorated in stagnant water retting because of several factors like less rainfall, repeated retting, absence of efficient retting microbes, direct use of mud, soil etc. In this review paper we have discussed the views of various research workers about the efficient retting microbes, their utilization as microbial consortium for faster retting and quality jute fibre production even in stagnant water retting. Latest molecular approaches for identification of retting microbes including whole genome sequencing of retting microbes and their utilization as talc based formulation, spore based liquid formulation, use of immobilized strain of efficient retting microbes for faster environment friendly jute retting towards quality jute fibre production under farmers’ field conditions have also been discussed in detail.

Aim: To study the dynamics of enzymes involved in biochemical process of jute (Corchorus spp.) retting with and without microbial retting consortium. Methodology: Two large scale retting trials were conducted with and without microbial retting consortium in triplicate. The retting water samples were collected every day at 24 hrs interval from both the trials. Polygalcturonase (PG), pectin lyase (PNL) and xylanase activities along with the pH were measured from the collected retting water samples following standard procedure. Fibre quality parameters were also studied from the resultant fibre obtained from both the retting trials. Results: There was a sharp decrease in pH of retting liquor by 1.35 units and that of pectin lyase activity by 97.9 Uml-1 within 24 hrs of inoculation of microbial retting consortium. Thereafter, higher pectin lyase (123.1 Uml-1), polygalacturonase (3.56 Iuml-1) and xylanase (0.818 IUml-1) activities were recorded during middle stage of retting. The enzyme activities were lower and non-significant at last stage of retting (11-14 days). The completion of retting without microbial consortium took longer time due to lower enzymatic activities as compared to microbial consortium mediated retting. Interpretation: The PG, PNL and xylanase enzymes released by the microbial consortium during retting of jute helped in faster biodegradation of pectin and xylan compared to control retting. Hence, the pre retting treatment of jute with microbial consortium is suggested for quick retting.

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