Influence of high salinities on the degradation of diesel fuel by bacterial consortia

Abstract

Microbial communities from three Argentinean saline soils were extracted and tested for their ability to degrade diesel fuel in liquid culture at salinities between 0% and 25%. In each case, the degradation process was continuously monitored by measuring oxygen consumption. Two communities (CR1 and CR2) showed nearly equal degrees of degradation across a salinity range of 0%-10% (the former degrading about 63% of the diesel fuel and the latter about 70% after 53 and 80 d, respectively). Furthermore, the degree of degradation was not significantly lower in the presence of 17.5% salt (58% and 65% degraded, respectively). A third community (El Zorro) showed a maximum turnover at 5% salt (79% diesel fuel degraded) and significant degradation (66%) at a salinity of 10%. However, the degree of degradation by this community clearly dropped at 0% and 15% salt. None of the communities were able to degrade diesel fuel in the presence of 25% salt, but the living cell counts showed that components of the microbial population survived the long-term exposure. The surviving portion is obviously sufficient to allow substantial restoration of the original community, as verified by the BIOLOG method. Isolates of the CR1 community were identified as members of the genera Cellulomonas, Bacillus, Dietzia, and Halomonas. In light of our investigations, the bioremediation of contaminated saline soils should be quite possible if the salinity of the soil water is lower than 15% or if it is reduced below this limit by the addition of water.

Electrobioremediation of an unsaturated soil contaminated with hydrocarbon after landfarming treatment

“…Esto generará que la electroósmosis en el suelo siga una dirección desde al ánodo hacia el cátodo. Los valores del análisis químico realizado (Tabla 1) fueron congruentes con lo observado en suelos patagónicos estudiados anteriormente [4,23,24]. La función del amonio y del nitrato en los sistemas de biorremediación es de nutriente.…”

“…El número de bacterias heterótrofas y de BDH se corresponde con los valores obtenidos para suelos patagónicos estudiados anteriormente por este grupo. El voltaje y las modificaciones de pH no presentaron impacto en los recuentos bacterianos manteniéndose en los valores iniciales y en un valor aceptable para la degradación bacteriana de hidrocarburos [2,4,23]. Los cambios de pH de los suelos generan carga en la membrana de las bacterias que, de esta manera, migran hacia uno de los electrodos dependiendo del valor de pH [29].…”

Population Dynamics within a Microbial Consortium during Growth on Diesel Fuel in Saline Environments

“…Ralstonia and Dietzia species are known to degrade various hydrocarbons (13,14,54,64,72,76), and a halotolerant Dietzia sp. has been isolated from a similar diesel fuel-degrading consortium (59). A highly uniform, proliferating subcommunity of minor abundance present in gates 7 and 8 (Fig.…”

“…An extremely halophilic archaeon from a salt marsh degraded various saturated and aromatic hydrocarbons at salinities of up to 31% and grew optimally at 22% NaCl (10). In our own laboratory, microbial communities from saline soils in Patagonia degraded diesel fuel up to a salinity of 17.5% (59). Although some members of the communities were identified, their contributions to the diesel fuel biodegradation remained obscure.…”

Microbial degradation of palm (Elaeis guineensis) biodiesel

“…Indeed, biodegradation of petroleum derivatives has been observed for pure cultures of all the bacterial genera contained in the microbial material used in this study (Maachi et al 2001, Marchal et al 2003, Obire and Nwaubeta 2002, Riis et al 2003, Williams et al 1998). …”