Increased Diversity of Predacious Bdellovibrio-Like Organisms (BLOs) as a Function of Eutrophication in Kumaon Lakes of India

Abstract

Predation by Bdellovibrio-like organisms (BLOs) results in bacterial community succession in aquatic ecosystems. The effects of nutrient loading on the distribution and phylogeny of BLOs remain largely unknown. To this end, we present our findings on BLO diversity from four north-Indian lakes that are variable in their trophic status; Nainital is eutrophic, both, Bhimtal and Naukuchiatal are mesotrophic and Sattal remains oligotrophic, respectively. Initially, total heterotrophic bacteria and BLOs were quantified by most probable number (MPN) analyses using Pseudomonas putida and Escherichia coli as prey bacteria. Total bacterial numbers were at least two-logs higher in the eutrophic lake samples compared with oligotrophic lake. Similarly, BLO numbers were approximately 39-fold higher using Pseudomonas sp., which is likely the preferred prey within these lakes. Conversely, significant differences were not observed between mesotrophic and oligotrophic BLO numbers when E. coli was used as the prey. PCR-RFLP of small subunit rDNA (SSU rDNA) of BLOs, followed by cloning, sequencing, and taxonomic categorization revealed distinct differences such that, eutrophic lake consisted of higher BLO diversity compared with mesotrophic and oligotrophic lake, most likely due to both, higher numbers and availability of a diverse population of prey bacteria resulting from nutrient loading in this ecosystem.

Diversity, Dynamics, and Distribution of Bdellovibrio and Like Organisms in Perialpine Lakes

“…Excluding temperature and salinity, BALOs may not be directly correlated to conductivity, pH, oxygen, ammonium, chlorophyll, or other measurements but might be dependent on the presence of prey bacteria. This is what Chauhan et al (50) found with clear positive correlations between BALOs and allochthonous prey bacterial abundances. Van Essche et al (25) suggested that BALOs can prey in microaerophilic or anaerobic habitats.…”

A comparative analysis of the bacterial community structure of freshwater lakes located in the outer Himalayan Region of India

“…The Shannon alpha diversity index calculated in the present study was maximum for NT, followed by the NKT, BT, GT and ST. It was established by the previous workers that trophic status of these lakes vary from each other i.e NT was evaluated as eutrophic with high percentage of carbonate, nitrogen, phosphorous [70][71]. The status of BT, NKT and ST cames under mesotrophic level whereas GT can be considered as the oligotrophic one.…”

Natural Water Treatment Systems for Safe and Sustainable Water Supply in the Indian Context: Saph Pani

“…The Macrobenthic community in the lake has almost completely disappeared below a depth of 7 m (Gupta & Pant, 1983). Studies have been conducted on its water quality (Purohit and Singh, 1981), phytoplankton community (Sharma et al, 1982), macrophytes (Purohit et al, 1986), protozoa (Shukla & Gupta, 2001), predacious Bdellovibrio-like Organisms (Chauhan et al, 2009), water and sediment geochemistry (Das et al, 1995;Chakrapani, 2002;Purushothaman et al, 2012), morphology and morphometry (Rawat, 1987), sediment accumulation (Das et al, 1994), water balance , pesticides (Dua et al, 1998), and heavy metal concentrations . Since 2007, several measures have been taken to conserve the lake and control its eutrophication.…”