TITLE:
Phylogenetic Characterization of BKH3 Bacterium Isolated from a Hot Spring Consortium of Bakreshwar (India) and Its Application
AUTHORS:
Biswadeep Chaudhuri, Nurul Alam, Manas Sarkar, Trinath Chowdhury, Brajadulal Chattopadhyay
KEYWORDS:
Bioconcrete, Compressive Strength, Hot Spring, 16S rRNA, Phylogenetic Analysis
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.6,
May
18,
2016
ABSTRACT: Background: The silica leaching
attribute of some of the mystifying bacteria
present in the cluster of hot springs (temperatures range 35°C - 80°C) at Bakreshwar (West Bengal, India, 23°52'48"N; 87°22'40") has provided some significant advancements
in construction technology when incorporated to the concrete/mortar specimens. The
present investigation was designed to isolate other novel bacterial strains from
65°C hot spring that could have similar or better performance
in construction technology. Methods: Soil sample collected from the 65°C hot spring was inoculated
to the culture vials (incubated at 65°C) containing a specific
synthetic growth medium (pH 8.0) to grow the bacterial population anaerobically
by degassing the medium with CO2 gas. Subsequent serial dilution techniques
were employed to isolate pure culture of a specific bacterial strain. 16S rRNA gene sequence and phylogenetic analysis
was carried out to identify the novelty of the isolated bacterial strain. The isolated
bacteria were incorporated to the cement sand mixture at various cell concentrations
to evaluate the efficacy of the strain in construction technology. Results: The work revealed
the presence of a novel bacterial strain (BKH3; GenBank Accession No.: KP 890928)
within the same hot spring consortium whose 16S rRNA gene sequence data showed 96% identity
with Citrobacter freundii bacterial species. The newly isolated bacteria
when incorporated at different cell concentration to the cement/cement-sand mixture
were found to possess the similar compressive strength increment property, the cracks
repairing ability and the water ingression resistivity. It also reduced the permeability
of sulphate ions to the cementitious matrix reflecting the increment of durability
of the incorporated material. Conclusions: The enhancement of compressive strength
and durability of the as prepared bio-concrete material by using the isolated bacterial
strain (BKH3) was due to the silica leaching activity of the bioremediase like protein
secreted by the bacterium. This may open up another vista of utilization of hot
spring bacterium for beneficial purposes in construction technology.