Bacterial cross-talk with small molecules

Bacteria, the unicellular prokaryotic microorganisms are the first form of life to appear on earth that may be traced way back about 4 billion years ago. Bacteria exist in typically two life forms i.e planktonic or free-swimming microbial phase and association with a surface in a structure known as a biofilm. The significance of secretion and perception of small signalling molecules or secondary metabolites by the bacteria and their role in coordinating behaviour and survival has started getting appreciation since the last decade. In our present study, similar role of small signalling molecules were unearthed in intra-species bacterial communication among Pseudomonas sp.

Fig. 1. This figure shows Phenazine 1,6 di-carboxylic acid (PDC) produced by one Pseudomonas strain helps another Pseudomonas strain to make prominent biofilm.

Fig. 1. This figure shows Phenazine 1,6 di-carboxylic acid (PDC) produced by one Pseudomonas strain helps another Pseudomonas strain to make prominent biofilm.

Three strains of Pseudomonas sp. were isolated from water samples collected from three different sites at Ganges Delta in India and all the isolated Pseudomonas strains were found to be capable of utilising crude oil as carbon source. Interestingly among them, two strains (named as KPW.1-S1 & HRW.1-S3) were found to produce proficient biofilm on glass surface while the third (DSW.1-S4) was biofilm defective in nature. Additionally, the two biofilm forming strains of Pseudomonas sp. showed production of derivatives of small molecules of Phenazine group of organic compounds when grown on various carbon sources. Surprisingly, the biofilm defective third strain failed to produce any similar small molecule and administration of these Phenazine compounds helped the biofilm-defective strain to produce biofilm in a dose dependent manner. The thickness of the biofilm and biomass units were significantly increased in presence of the compound Phenazine 1,6-di-carboxylic acid (PDC). To the best of our knowledge, HRW.1-S3 is the first reported Pseudomonas strain which is able to produce PDC. Therefore, the present study showed how a small molecule produced by one strain of Pseudomonas cross-communicates with another strain and thereby contributes towards multicellular behaviour in the recipient bacterial strain (Fig1).

Debdeep Dasgupta1,2 and Tapas K. Sengupta1

1 Department of Biological Sciences,
Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur-741246, India.

2 Centre for Environmental Science & Engineering (CESE),
Indian Institute of Technology Bombay, Powai, Mumbai – 400076

 

Publication

Isolation of phenazine 1,6-di-carboxylic acid from Pseudomonas aeruginosa strain HRW.1-S3 and its role in biofilm-mediated crude oil degradation and cytotoxicity against bacterial and cancer cells.
Dasgupta D, Kumar A, Mukhopadhyay B, Sengupta TK
Appl Microbiol Biotechnol. 2015 Oct

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