Cultivable Bacterial Diversity of Alkaline Lonar Lake, India

Abstract

Aerobic, alkaliphilic bacteria were isolated and characterized from water and sediment samples collected in the winter season, January 2002 from alkaline Lonar lake, India, having pH 10.5. The total number of microorganisms in the sediment and water samples was found to be 10(2)-10(6) cfu g(-1) and 10(2)-10(4) cfu ml(-1), respectively. One hundred and ninety-six strains were isolated using different enrichment media. To study the bacterial diversity of Lonar lake and to select the bacterial strains for further characterization, screening was done on the basis of pH and salt tolerance of the isolates. Sixty-four isolates were subjected to phenotypic, biochemical characterization and 16S rRNA sequencing. Out of 64, 31 bacterial isolates were selected on the basis of their enzyme profile and further subjected to phylogenetic analysis. Phylogenetic analysis indicated that most of the Lonar lake isolates were related to the phylum Firmicutes, containing Low G+C, Gram-positive bacteria, with different genera: Bacillus, Paenibacillus, Alkalibacillus, Exiguobacterium, Planococcus, Enterococcus and Vagococcus. Seven strains constituted a Gram-negative bacterial group, with different genera: Halomonas, Stenotrophomonas and Providencia affiliated to gamma-Proteobacteria, Alcaligenes to beta-Proteobacteria and Paracoccus to alpha-Proteobacteria. Only five isolates were High G+C, Gram-positive bacteria associated with phylum Actinobacteria, with various genera: Cellulosimicrobium, Dietzia, Arthrobacter and Micrococcus. Despite the alkaline pH of the Lonar lake, most of the strains were alkalitolerant and only two strains were obligate alkaliphilic. Most of the isolates produced biotechnologically important enzymes at alkaline pH, while only two isolates (ARI 351 and ARI 341) showed the presence of polyhydroxyalkcanoate (PHA) and exopolysaccharide (EPS), respectively.

Phylogenetic Study of Methanol Oxidizers from Chilika-Lake Sediments Using Genomic and Metagenomic Approaches

“…Present study focused on the aerobic methylotrophs covering 1,100 km 2 of the Chilika Lake sediments through established molecular markers (such as the functional gene mxaF and phylogenetic 16S rRNA gene probes) which demonstrated the presence of phylogenetically diverse aerobic methylotrophs. The total viable counts were relatively higher in sediments near the sea mouth (S3; Panaspada) as also viewed by Joshi et al [44].…”

Planktonic bacterial community composition of an extremely shallow soda pond during a phytoplankton bloom revealed by cultivation and molecular cloning

“…Recently, the cultivation dependent and independent analyses of planktonic and sediment microbial communities include, among others, studying the soda lakes of South-East Siberia, Russia (Foti et al 2007(Foti et al , 2008, North-East Mongolia (Sorokin et al 2004), Inner Mongolia, China (Zhang et al 2001;Ma et al 2004a), Lonar Lake, India (Wani et al 2006;Joshi et al 2008), the East African Rift Valley, Kenya and Tanzania (Rees et al 2004;Mwirichia et al 2010Mwirichia et al , 2011, Wadi An Natrun, Egypt (Mesbah et al 2007), as well as Mono Lake, California, USA (Hollibaugh et al 2001;Humayoun et al 2003) and Soap Lake, Washington, USA (Dimitru et al 2008).…”

Active methylotrophs in the sediments of Lonar Lake, a saline and alkaline ecosystem formed by meteor impact

“…A saline (NaCl B0.9%) and alkaline lake (pH B10) occupies most of the crater floor . Microbiological studies using culturedependent and -independent strategies have identified and characterized both bacterial (Kanekar et al, 1999Nilegaonkar et al, 2002;Wani et al, 2006;Joshi et al, 2008) and archaeal (Thakker and Ranade, 2002;Surakasi, 2007;Surakasi et al, 2007) communities in the Lonar Lake water and sediments. A culture-independent study that assessed archaeal diversity in the sediments reported that most of the retrieved euryarchaeotal sequences were related to methanogens (Wani et al, 2006).…”