Ecological features of trace elements tolerant microbes isolated from sewage sludge of urban wastewater treatment plant

Abstract

Worldwide wastewater treatment plants generate enormous amounts of sewage sludge, and their further disposal depends on the treatment technologies applied and spontaneously occurring microbiological processes. From different ages urban sewage sludge, 12 strains of bacteria with simultaneous tolerance to two or more trace elements: Co, Ni, Cu, Zn, Cd and Pb at concentration of 3-5 mmol were isolated and identified by PCR of target genes and Sanger sequencing methods. The isloated metal(loids) tolerant strains belong to the species, i.e., Serratia fonticola, Rhodococcus qingshengii, Pseudomonas fragi, Pseudomonas extremaustralis, Pseudomonas cedrina, Stenotrophomonas maltophilia, Serratia liquefaciens and Citrobacter freundii. The ecological features of the isolated strains were studied. The optimal growth temperatures for most strains was 15–30°C at pH range of 5–9, although some strains grew at 7°C (Pseudomonas fragi SS0-4, Serratia fonticola SS0-9 and Serratia fonticola SS12-11). Satisfactory growth of two strains (Serratia fonticola SS0-1and Citrobacter freundii SS60-12) was noted in an acidic medium at pH 4. Most of the strains grew in the NaCl concentration range of 1–5%. The isolated bacteria resistant to high concentrations of trace elements can be used for the effective mineralization of sewage sludge and for the decontamination of wastewater.

Microbial Biofilms: Features of Formation and Potential for Use in Bioelectrochemical Devices

“…Biofilm-based biosensors can be used as a primary tool for assessing the overall quality of water or for finding specific pollutants (cyanides, azides, polychlorinated biphenyls, polycyclic aromatic compounds, etc.) [ 189 , 190 ]. However, they must necessarily be combined with more accurate and selective analysis methods, because for the most part, they are only able to provide an early warning about the deterioration of the quality of a particular water sample, but are not able to provide accurate information about the content of dangerous substances in it.…”