Seasonal variations in culturable archaea and their plant growth promoting attributes to predict their role in establishment of vegetation in Rann of Kutch

Abstract

Archaea are unique microorganisms that are present in ecological niches of high temperature, pH and high salinity. Archaea may be present freely or associated with plant rhizosphere. The plant-microbe interactions may be implicit to plants adaptation to abiotic stress of hypersalinity. With an aim to look for population dynamics of archaea at different seasons of the year in hypersaline environments of Rann of Kutch, the rhizospheric, non-rhizospheric, water and sediment samples were collected during autumn, winter and summer. Sampling sites were selected on the basis of topography and vegetation which included barren land, salt pan and rhizosphere of monocot and dicot plants. Soil pH and salinity (mS cm−1) varied from 7.4–10.15 and 1.19–106.7 respectively. A total of 157 halophilic archaea were isolated using seven different selective media. The isolated archaeal were screened for abiotic stress and it has been found they show the wide range of in the tolerance to temperatures (25–65 °C), NaCl concentrations (0.86–5.48 M), water stresses (upto −0.75Mpa) and pH (4–10). The profiling of archaeal community using 16S rRNA gene sequencing and phylogenetic analysis revealed that all archaeal isolates belonged to a family halobacteriaceae of phylum euryarchaeota. Based on 16S rRNA gene sequencing the cultures were identified and belonged to twenty eight distinct species of 16 genera namely Haladaptatus, Haloarcula, Halobacterium, Halococcus, Haloferax, Halogeometricum, Halolamina, Halopenitus, Halorubrum, Halosarcina, Halostagnicola, Haloterrigena, Natrialba, Natrinema, Natronoarchaeum and Natronomonas. In the present study, seasonal and niche-specific archaea were reported and characterized from hypersaline environments. The haloarchaea with multifunctional plant growth promoting attributes, prevalent in the hypersaline environments must be colonizing the rhizosphere of plants and contributing to the growth and sustenance of plants.