Geobacter sp. SD‐1 with enhanced electrochemical activity in high‐salt concentration solutions

Abstract

An isolate, designated strain SD-1, was obtained from a biofilm dominated by Geobacter sulfurreducens in a microbial fuel cell. The electrochemical activity of strain SD-1 was compared with type strains, G. sulfurreducens PCA and Geobacter metallireducens GS-15, and a mixed culture in microbial electrolysis cells. SD-1 produced a maximum current density of 290 ± 29 A m−3 in a high-concentration phosphate buffer solution (PBS-H, 200 mM). This current density was significantly higher than that produced by the mixed culture (189 ± 44 A m−3) or the type strains (< 70 A m−3). In a highly saline water (SW; 50 mM PBS and 650 mM NaCl), current by SD-1 (158 ± 4 A m−3) was reduced by 28% compared with 50 mM PBS (220 ± 4 A m−3), but it was still higher than that of the mixed culture (147 ± 19 A m−3), and strains PCA and GS-15 did not produce any current. Electrochemical tests showed that the improved performance of SD-1 was due to its lower charge transfer resistance and more negative potentials produced at higher current densities. These results show that the electrochemical activity of SD-1 was significantly different than other Geobacter strains and mixed cultures in terms of its salt tolerance.

Microbial Electrochemical Sensors for Anaerobic Digestion Process Control – Performance of Electroactive Biofilms under Real Conditions

“…shows a slight increase of the current density. This behavior is in line with the results that can be found in the literature , , , . Sodium chloride was used to generically simulate all other salts in the AD process that have no further inhibitory effects in contrast to, e.g., ammonium, sulfates, and sulfides , .…”

“…Especially Geobacter sp. SD 1 was shown to be very tolerant of high salinity levels [12]. Later, the same authors classified Geobacter sp.…”

“…The neutral pH (7.5-8) and the temperature range of psychrophilic (< 25°C) and mesophilic (37-42°C) conditions would provide highly suitable conditions for growth and activity of Geobacter sp.-dominated biofilms [10]. However, in AD fermenters, other parameters like high salinity or high ammonium concentrations and a multitude of biological and chemical compounds with already known [10][11][12][13][14][15][16][17][18] or even unknown effects on the electroactive biofilms are present.…”

Effects of NaCl concentration on anode microbes in microbial fuel cells

“…This clearly demonstrates that a certain level of the ionic strength (corresponding to the solution conductivity) is required for anode respiration by exoelectrogens. Although a salt-tolerant strain of Geobacter that can generate electricity in an MFC at 0.65 M NaCl was recently isolated and characterized (Sun et al 2014), this strain also preferentially generates electricity at ionic strengths corresponding to 0.1 M NaCl or lower. These observations suggest that the optimum NaCl concentration (0.1 M NaCl in the present study) is determined by the balance of the two factors, namely, the solution conductivity and salt tolerance of exoelectrogens.…”

Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

“…Geobacter metallireducen familiar for their electrochemical activity in MFCs have been found enriched in the 'hybrid-H', recent report also coherence with activity in high salt concentrations [53]. Indeed, in extreme haloalkalophile Desulfurivibrio alkaliphilus, which is a sulfate reducing bacteria commonly found in soda lakes [54], Interestingly, Desulfurivibrio alkaliphilus is also found in long rang electron transfer through filaments, in which its activity might be employed to form an electrochemical activity in MFC [55].…”