Isolation and characterization of endophytic bacteria colonizing halophyte and other salt tolerant plant species from coastal Gujarat

Abstract

Endophytic bacteria were isolated from leaves of four dominant halophyte and salt tolerant plant species of coastal Gujarat. The bacterial counts on nutrient agar were found to be maximum in Spharanthus indicus (40%) and were minimum in Salicornia brachiata (10%). Twenty (20) bacterial isolates were selected and were characterized through morphological characters and biochemical tests. Three were pigmented and 17 were non-pigmented and 50% isolates exhibited amylase activity and only 15% isolates showed urease activity. Six (30%) and two (10%) isolates showed positive results for ammonia production and phosphate solubilization activity. Salt tolerance of the endophytes was also tested. Of the 20 endophytic bacteria, seventeen (85%) isolates showed growth at 7.5% NaCl and fifteen (75%) tolerated upto 10% NaCl concentration. Overall, the growth rate of endophytes decreased with increasing concentration of NaCl in media. The endophytic bacteria were identified through 16S rRNA sequencing and mostly the isolated endophytic bacteria belong to genera Bacillus spp.