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Volume 45, Number 4, August 2012

 Study of the cultivable microflora of the large intestine of the rat under varied environmental hyperbaric pressures

Chiranjit Maity, Atanu Adak, Tarun Kumar Pathak, Bikas Ranjan Pati, Keshab Chandra Mondal

Received: December 13, 2010    Revised: July 1, 2011    Accepted: August 19, 2011   


Corresponding author:

Keshab Chandra Mondal, Department of Microbiology, Vidyasagar University, Midnapore 721102, West Bengal, India. E-mail address: (K. Chandra Mondal).


Background and purpose: 

 We conducted an in vivo experiment to investigate the effect of hyperbarometric air pressure on the quantity and composition of the cultivable microflora of the large intestine.



 Using selective culture-based methods, we enumerated from the large intestine total aerobes and total anaerobes, and indicator bacteria such as Escherichia coli, other Enterobacteriaceae, Bifidobacterium spp., Lactobacillus spp. and Clostridium perfringens, and studied their quantitative variation



 Total aerobes and facultative anaerobes (E. coli and other Enterobacteriaceae) were increased with an increase in air pressure, whereas the increase caused a drastic reduction in the numbers of total anaerobes and Clostridium perfringens. Bifidobacterium spp. and Lactobacillus spp. were affected slightly by the altered air pressures. Variation in the numbers of these groups of bacteria was correlated to dose and duration of hyperbaric treatment.



 We conclude from our results that air pressure is an important exogenous factor that strongly modulates bacterial colonization of the large intestine and the composition of the intestinal microflora, and that the occurrence of gastrointestinal disorders during hyperbarism is a result of alteration in the indigenous microflora. 


Key words:

 Altitude; Gastrointestinal tract; Hyperbaric pressure; Large intestinal microflora