Growth media composition and heavy metal tolerance behaviour of bacteria characterized from the sub-surface soil of uranium rich ore bearing site of Domiasiat in Meghalaya

Abstract

Enrichment based cultivation method was utilised to isolate uranium (U)-tolerant bacteria from the sub-surface soil of U-rich ore bearing site of Domiasiat in Meghalaya, India. Two isolates with distinct colony morphology and pigmentation were closely matched as <i style="mso-bidi-font-style:normal">Serratia marcescens</i> PKRS1 and <i style="mso-bidi-font-style:normal">Pseudomonas ficuserectae </i>PKRS11 based on 16S rRNA gene sequence similarity analysis and phylogenetic clustering approach. Mueller-Hinton (MH) and Low phosphate (LP) medium were used for comparative determination of the minimum inhibitory concentration (MIC) of U and other metals against the identified bacteria. The wild isolates tolerated higher amount of U and other metals when compared to the type strain <i style="mso-bidi-font-style:normal">S.</i> <i style="mso-bidi-font-style: normal">marcescens</i> ATCC13880. Higher MIC was observed in MH than LP medium. The present study reveals that the metal-microbe interaction, such as, uptake and precipitation, are highly influenced by growth media composition. LP medium as the basal medium offers more authentic results due to low carbon source and negligible phosphates, which provides lower precipitation affinity to metals making it uniformly available to the isolates during growth as compared to complex MH medium.