Culturable diversity and functional annotation of psychrotrophic bacteria from cold desert of Leh Ladakh (India)

Abstract

o study culturable bacterial diversity undersubzero temperature conditions and their possible functionalannotation, soil and water samples from Leh Ladakh regionwere analysed. Ten different nutrient combinations wereused to isolate the maximum possible culturable morpho-types. A total of 325 bacterial isolates were characterizedemploying 16S rDNA-Amplified Ribosomal DNA Restric-tion Analysis with three restriction endonucleasesAluI,MspI andHaeIII, which led to formation of 23–40 groups forthe different sites at 75 % similarity index, adding up to 175groups. Phylogenetic analysis based on 16S rRNA genesequencing led to the identification of 175 bacteria, groupedin four phyla, Firmicutes (54 %), Proteobacteria (28 %),Actinobacteria (16 %) and Bacteroidetes (3 %), and inclu-ded 29 different genera with 57 distinct species. Overall39 % of the total morphotypes belonged to theBacillusandBacillusderived genera (BBDG) followed byPseudomonas(14 %),Arthrobacter(9 %),Exiguobacterium(8 %),Ali-shewanella(4 %),Brachybacterium, Providencia, Plano-coccus(3 %),Janthinobacterium,Sphingobacterium,Kocuria(2 %) andAurantimonas, Citricoccus, Cellulosi-microbium, Brevundimonas, Desemzia, Flavobacterium,Klebsiella, Paracoccus, Psychrobacter, Sporosarcina,Staphylococcus, Sinobaca, Stenotrophomonas, Sanguib-acter, Vibrio(1 %). The representative isolates from eachcluster were screened for their plant growth promotingcharacteristics at low temperature (5–15°C). Variationswere observed among strains for production of ammonia,hydrogen cyanide, indole-3-acetic acid and siderophore,solubilisation of phosphate, 1-aminocyclopropane-1-car-boxylate deaminase activity and biocontrol activity againstRhizoctonia solaniandMacrophomina phaseolina.Coldadapted microbes may have application as inoculants andbiocontrol agents in crops growing at high altitudes undercold climate condition.