The effect of carbon source on microbial community structure and Cr(VI) reduction rate

Abstract

In the present work, the effect of the carbon source on microbial community structure in batch cultures derived from industrial sludge and hexavalent chromium reduction was studied. Experiments in aerobic batch reactors were carried out by amending industrial sludge with two different carbon sources: sodium acetate and sucrose. In each of the experiments performed, four different initial Cr(VI) concentrations of: 6, 13, 30 and 115 mg/L were tested. The change of carbon source in the batch reactor from sodium acetate to sucrose led to a 1.3-2.1 fold increase in chromium reduction rate and to a 5- to 9.5-fold increase in biomass. Analysis of the microbial structure in the batch reactor showed that the dominant communities were bacterial species (Acinetobacter lwoffii, Defluvibacter lusatiensis, Pseudoxanthomonas japonensis, Mesorhizium chacoense, and Flavobacterium suncheonense) when sodium acetate was used as carbon source and fungal strains (Trichoderma viride and Pichia jadinii), when sodium acetate was replaced by sucrose. These results indicate that the carbon source is a key parameter for microbial dynamics and enhanced chromium reduction and should be taken into account for efficient bioreactor design.

Modelling of biological Cr(VI) removal in draw-fill reactors using microorganisms in suspended and attached growth systems

“…Many factors affect the rate and the extent of microbial Cr(VI) reduction such as the initial biomass concentration, initial Cr(VI) concentration, pH, temperature, oxidation-reduction potential and metal cations (Wu et al, 2010;Ye et al, 2010). Also the presence of suitable carbon source is necessary to enhance the Cr(VI) reduction capacity (Tekerlekopoulou et al, 2010). Similar observations were also referred in previous studies by Ferro Orozco et al (2010) and Contreras et al (2001).…”

“…DNA extraction, PCR amplification, 16S rRNA and 18S rRNA gene sequencing For the isolation of total DNA the method previously described by Tekerlekopoulou et al (2010) was used. The DNA was quantified with a Qubit fluorometer (Invintrogen, USA) according to the manufacturer's instructions.…”

“…In particular, the use of microorganisms received much more attention in recent years since they carry wide range of binding sites for heavy metals ions (Goyal et al, 2003). Advances in the field of environmental microbiology and biotechnology indicate that bacteria, fungi, yeast and algae either as pure or mixed cultures, can remove Cr(VI) from aqueous solutions under aerobic and/or anaerobic conditions (Wang et al, 1989;Dmitrenko et al, 2003;Ramírez-Ramírez et al, 2004;Morales-Barrera and Cristiani-Urbina, 2006;Tekerlekopoulou et al, 2010). The bioreduction rate of Cr(VI) is more rapid in aerobic conditions than in anaerobic (Jeyasingh and Ligy, 2005).…”

Evaluation of the bioremoval of Cr(VI) and TOC in biofilters under continuous operation using response surface methodology

“…3 Response surfaces: a removal of TOC as a function of the sodium acetate and Cr(VI) concentration; b removal of TOC as a function of the concentration of sodium acetate and ammonium chloride and c removal of TOC as a function of the ammonium chloride and Cr(VI) concentration Cr(VI) was reduced completely at the reactor's effluent. Tekerlekopoulou et al (2010) found that the carbon source is a key parameter for microbial community structure and Cr(VI) reduction. A change of carbon source completely altered the structure of the microbial community from bacteria-dominated to fungus-dominated.…”

Molasses as an efficient low-cost carbon source for biological Cr(VI) removal

“…Additionally, the presence of a suitable carbon source is necessary to enhance Cr(VI) reduction [31][32][33][34][35][36][37]. As presented in Table 1, numerous different carbon sources have been tested, including glucose, fructose, sodium acetate, lactose, maltose, etc.…”