Biofilm formation by sulphate-reducing bacteria on different metals and their prospective role in titanium corrosion

ABSTRACT

This study describes the biofilm formation by sulphate-reducing bacteria (SRB) on different materials, which has implications for the biomedical, pharmaceutical, food and chemical process industries. SRB was chosen as a model organism being an anaerobic bacterium. Biofilm formation on different materials and corrosion of titanium by SRB were monitored with time using confocal laser scanning microscopy and fluorescent FISH probes were used to authenticate the SRB strain. The thickness of the mono-culture SRB biofilm has ranged from 4 to 24 µm during thed 12–84 hr; however, the maximum biofilm thickness (24 µm) was recorded after 60 hr of growth. Planktonic growth of the SRB strain showed a log phase up to 48 hr and the sulphide production ranged from 2 to 14 mg l⁻¹. For a comparative account, the SRB biofilm formation on copper was chosen as a positive control. Finally, the putative role of extracellular electron transfer by SRB in the biocorrosion process and the plausible mechanism of pitting corrosion of titanium is described in detail.

GRAPHICAL ABSTRACT

KEYWORDS:

• Biofilm
• sulphate-reducing bacteria
• sulphide
• CSLM
• corrosion

Acknowledgements

The first author wishes to express his sincere thanks to Mr. P. Singh for his support in experimentation and to Mr. Atif Khan, WSCD, Kalpakkam, for the schematic illustration.

Disclosure statement

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

Data availability statement

The authors shall share the data presented in the manuscript on a reasonable request basis.