Abstract
In an attempt to cultivate and identify oligophilic bacteria, 295 bacterial strains were isolated from 8 different fresh water samples collected from different water bodies, located in Burdwan, Jhargram, Bankura and Purulia (in West Bengal, India). Among these 58 strains were oligophilic and could only grow on nutritionally poor media (TSBA/100 and R2A Agar), while, the rest belonged to facultatively oligophilic category and could grow on both nutritionally poor and rich (TSBA) media. Among 58 oligophilic strains, 6 were lost during sub-culturing process. These oligophilic strains do not grow on most of the conventional culture media like Nutrient Agar (NA), Luria Bertani agar (LB agar), Mueller Hinton agar (MHA), MacConkey Agar (MAC) and on media recommended for phenotypic characterization. Preliminary identification of 32 oligophilic strains (out of 58) was carried out by using 16S rRNA gene based molecular phylogenetic approach. Their closest phylogenetic relatives were recorded to belong to 25 different genera and 32 different species. On the basis of recent cut off limit, 10 strains were concluded as possible putative novel taxa and were recorded to possess identity value less than 98.65-99% (current threshold limit for delineation of prokaryotic species) to their nearest 16S rRNA gene sequence of representative type strains. Oligophilic bacteria represent component of aboriginal microflora and their study is important from ecological aspects. Although, the present study was executed with a small sample size and less number of isolates, nevertheless, presence of high beta diversity indicated that study of oligophilic bacteria from aquatic habitats provides an opportunity to isolate possible putative novel taxa which may be further taken up for detailed taxonomic, genomics and function based biotechnological studies. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-026-04780-5.