Molecular phylogeny of a commercially important thermophilic microalga Chlorella sorokiniana LWG002615 and associated bacterium Aquimonas sp. NBRI01 isolated from Jeori thermal spring, Shimla, India

Thermophilic eukaryotic algae are rare in nature, but quite important owing to their faster growth rate, high lipid content and ability to withstand harsh environment. While screening Jeori thermal spring at Shimla for thermophilic algae we have isolated one eukaryotic chlorophycean microalga in addition to several populations of cyanophyceae. The microalga isolated from 44 degrees C temperature was identified asChlorella sorokinianabased on morphology and 18S ribosomal RNA sequence analysis. The 18S rRNA sequence showed 100% similarity withC. sorokinianaisolate 34-2 (GenBank No. KU948991). Taxonomic analysis revealed that it belongs to phylum Chlorophyta, class Trebouxiophyceae and family Chlorellaceae. Phylogenetic reconstruction by 'Maximum Likelihood' showed that it was mostly clustered with different isolates ofC. sorokiniana.The 18S rDNA sequence was submitted to NCBI GenBank (accession number MH382824). The alga was deposited in institutional herbarium asC. sorokinianaisolate LWG002615. One associated thermophilic bacteriaAquimonassp. NBRI01 was also identified by 16S rRNA sequencing and assigned the NCBI gene bank accession number MH379673. Isolation ofC. sorokinianaLWG002615 from natural thermal spring will encourage the outdoor cultivation of this important thermophilic alga in high temperature regions and will further strengthen its commercial application.