Cyanobacterial photosynthetic activity can be electrochemically detected on stainless steel

L. H. ORFEI; S. SIMISON; J.P. BUSALMEN.

Mar del Plata, Bs.As.,Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.

Aiming to get insight on microbial corrosion mechanisms of stainless steel (SS) in seawater, we investigated the influence of photosynthetic microorganisms (PMO) on the electrochemical behavior of this material. Coupons of UNS30403 SS were exposed to pure cultures of Synechococcus sp. (PCC 7002) in the logarithmic phase of growth. Cultures were maintained at 30ºC ± 1ºC under a 16/8 h light/dark photoperiod. Chlorophyll content, photosynthetic activity and pH were periodically determined. The open circuit potential (OCP) of samples was continuously registered, while cathodic polarization curves were performed at each sampling time to evaluate changes in the concentration of dissolved oxygen.  Results indicate that the interface of SS is highly sensitive to chemical changes introduced by the photosynthetic process. OCP rises were consistently observed during light hours in spite of the alkalinization produced by photosynthesis. A possible explanation is the depolarization of the cathodic reaction by the increment of dissolved oxygen. OCP ennoblement is the main cause of microbiologically induced corrosion failures of SS. Results reported here provide new evidences about the participation of photosynthetic microorganisms in the process. Besides this, the interface sensitivity clearly show the possibility for the development of whole cell PMO-based biosensors of environmental use.