Comparative Genomics and Physiological Investigation Supported Safety, Cold Adaptation, Efficient Hydrolytic and Plant Growth-promoting Potential of Psychrotrophic Glutamicibacter Arilaitensis LJH19, Isolated from Night-Soil Compost

Background: Night-soil compost (NSC) has traditionally been conserving water and a source of organic manure in northwestern Himalaya. Lately, this traditional method is declining due to modernization, its unhygienic conditions, and social apprehensions. Reduction in the age-old traditional practice has led to excessive chemical fertilizers and water shortage in the eco-sensitive region. In the current study, a bacterium has been analysed for its safety, cold-adaptation, efficient degradation, and plant growth potential attributes for its possible application as a safe bioinoculant in psychrotrophic bacterial consortia for improved night-soil composting. Results: : Glutamicibacter arilaitensis LJH19, a psychrotrophic bacterium, was isolated from the night-soil compost of Lahaul valley in northwestern Himalaya. The strain exhibited amylase (186.76 ± 19.28 U/mg), cellulase (21.85 ± 0.7 U/mg) and xylanase (11.31± 0.51 U/mg) activities at 10°C. Possessing efficient hydrolytic activities at low-temperature garners the capability of efficient composting to LJH19. Additionally, the strain possessed multiple plant growth-promoting (PGP) traits such as indole acetic acid production (166.11 ± 5.7 µg/ml), siderophore production (85.72 ±1.06 % psu), and phosphate solubilization (44.76 ± 1.5 µg/ml). Enhanced germination index and germination rate of pea seeds under the LJH19 inoculation further supported the bacterium's PGP potential. Whole-genome sequencing (3,602,821 bps) and genome mining endorsed the cold adaptation, degradation of polysaccharides and, plant growth-promoting traits of LJH19. Biosynthetic gene clusters for type III polyketide synthase (PKS), terpene, and siderophore supplemented the endorsement of LJH19 as a potential PGP bacterium. Comparative genomics within the genus revealed 217 unique genes specific to hydrolytic and PGP activity. Conclusion: The physiological and genomic evidence promotes LJH19 as a potentially safe bio-inoculant to formulate psychrotrophic bacterial consortia for accelerated degradation and improved night-soil compost.