Enrichment and Analysis of Anode-Respiring Bacteria from Diverse Anaerobic Inocula

Abstract

One of the limitations currently faced by microbial electrochemical cell (MXC) technologies lies in the shortage of different organisms capable of forming a biofilm and channeling electrons from substrates to the anode at high current densities. Using a poised anode (-0.30 V vs Ag/AgCl) and acetate as the electron donor in a MXC, we demonstrated the presence of highly efficient anode-respiring bacteria (ARB) able to produce high current densities (>1.5 A/m(2) anode) in seven out of thirteen environmental samples. These included marshes, lake sediments, saline microbial mats, and anaerobic soils obtained from geographically diverse locations. Our microbial ecology analysis, using pyrosequencing, shows that bacteria related to the genus Geobacter, a known and commonly found ARB, dominate only two of the biofilm communities producing high current; other biofilm communities contained different known and/or novel ARB. The presence of ARB in geographically diverse locations indicates that ARB thrive in a wide range of ecosystems. Studying ARB from different environmental conditions will allow us to better understand the ubiquity of anode respiration, compare the capabilities of different ARB consortia, and find ARB with useful metabolic capacities for future applications.

Electrochemical and microbial monitoring of multi-generational electroactive biofilms formed from mangrove sediment

“…Interestingly, in 2012, Miceli et al studied the electrical performances' evolution of 13 anaerobic inocula that went through two successive enrichments. This study showed that 4 inocula demonstrated increased performances with the second enrichment when 3 had their performance decreased [19]. Those second generations that showed lowered performances had their communities analysed and it could be noticed that they were among the most simplified, the less diverse [19].…”

“…The current density harvested with primary biofilms reached 2.50 A/m 2 after 16.7 days and the current density harvested with secondary biofilms reached 4.80 A/m 2 with a lag phase reduced to 6.25 days. Besides, in 2012, Miceli et al showed that two different inocula (from Carolina and Playa Sucia mangroves) permitted to form electroactive biofilms getting more efficient when stepping forward further generations [19]. Indeed, Carolina mangrove first enrichment (5 g inoculum) reached a 7.62 A/m 2 performance and its second enrichment (1 cm 2 scratched biofilm plus 5 mL suspension) produced 10.77 A/m 2 .…”

“…Indeed, Carolina mangrove first enrichment (5 g inoculum) reached a 7.62 A/m 2 performance and its second enrichment (1 cm 2 scratched biofilm plus 5 mL suspension) produced 10.77 A/m 2 . Playa Sucia mangrove (saltwater) inoculum formed a first enriched biofilm producing a 3.87 A/m 2 current density and a second one reaching 4.23 A/m 2 [19].…”

Arsenic modulates the composition of anode-respiring bacterial community during dry-wet cycles in paddy soils

“…Bacteria able to conduct extracellular respiration by donating electrons to an anode as terminal electron acceptor are termed anode respiring bacteria (ARB) (Miceli et al 2012;Lovley 2008;Logan and Regan 2006). Studies have shown that ARB are responsible for the reduction of iron and manganese oxides (Lovley et al 2004).…”

“…Studies on ARB will provide new perspectives for understanding iron and arsenic biogeochemical cycling in paddy soils. Previous studies on this topic have largely focused on the effect of soil organic matter on ARB communities (Miceli et al 2012;Dunaj et al 2012). However, the information is scarce on the effect of arsenic on ARB communities.…”