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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 analyzed for its safety, cold-adaptation, efficient degradation, and plant growth-promoting (PGP) 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 NSC 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 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 PGP 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. [ABSTRACT FROM AUTHOR]

The medicinal herb, Picrorhiza kurroa Royle ex Benth has become endangered because of indiscriminate over-harvesting. Although micropropagation has been attempted for mass propagation of the plant, survival of in vitro plantlets under green house/open field poses a major challenge. Biopriming of micropropagated plantlets with plant growth-promoting rhizobacteria (PGPR) are among the successful methods to combat this problem. Serratia quinivorans PKL:12 was the best-characterized PGPR from rhizospheric soil of P. kurroa as it increased the vegetative growth and survival of the micropropagated plantlets most effectively. Complete genome (5.29 Mb) predicted genes encoding proteins for cold adaptation and plant growth-promoting traits in PKL:12. Antibiotic and biosynthetic gene cluster prediction supported PKL:12 as a potential biocontrol agent. Comparative genomics revealed 226 unique genes with few genes associated with plant growth-promoting potential. Physiological and genomic evidence supports S. quinivorans PKL:12 as a potential agent for bio-hardening of micropropagated P. kurroa plantlets in cold regions. • Serratia quinivorans PKL:12, a cold-adapted PGPR from rhizospheric soil of Picrorhiza kurroa • Survival of PKL:12 treated biohardened in vitro plantlets increased from <50% to 86.7%. • Complete genome (5.29 Mb) revealed traits like cold-adaptation, plant growth promotion and biocontrol potential of PKL:12. • Suitable candidates as biopriming agent for biohardening of microprogated P. kurroa plantlets in cold [ABSTRACT FROM AUTHOR]