Unraveling the complex regulatory networks in biofilm formation in bacteria and relevance of biofilms in environmental remediation

Abstract

Biofilms are assemblages of bacteria embedded within a matrix of extracellular polymeric substances (EPS) attached to a substratum. The process of biofilm formation is a complex phenomenon regulated by the intracellular and intercellular signaling systems. Various secondary messenger molecules such as cyclic dimeric guanosine 3′,5′-monophosphate (c-di-GMP), cyclic adenosine 3′,5′-monophosphate (cAMP), and cyclic dimeric adenosine 3′,5′-monophosphate (c-di-AMP) are involved in complex signaling networks to regulate biofilm development in several bacteria. Moreover, the cell to cell communication system known as Quorum Sensing (QS) also regulates biofilm formation via diverse mechanisms in various bacterial species. Bacteria often switch to the biofilm lifestyle in the presence of toxic pollutants to improve their survivability. Bacteria within a biofilm possess several advantages with regard to the degradation of harmful pollutants, such as increased protection within the biofilm to resist the toxic pollutants, synthesis of extracellular polymeric substances (EPS) that helps in the sequestration of pollutants, elevated catabolic gene expression within the biofilm microenvironment, higher cell density possessing a large pool of genetic resources, adhesion ability to a wide range of substrata, and metabolic heterogeneity. Therefore, a comprehensive account of the various factors regulating biofilm development would provide valuable insights to modulate biofilm formation for improved bioremediation practices. This review summarizes the complex regulatory networks that influence biofilm development in bacteria, with a major focus on the applications of bacterial biofilms for environmental restoration.

Keywords:

• Biofilm
• secondary messengers
• quorum sensing
• EPS
• bioremediation

Acknowledgments

The authors are thankful to the authorities of NIT Rourkela for providing research facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work has been funded through a research grant [BT/PR/17390/BCE/8/1158/2016] on the utilization of marine bacterial biofilms for bioremediation of PAHs from the Department of Biotechnology, Ministry of Science and Technology, Government of India.