“Strategies for the efficient Cr(VI) removal by using preadapted inoculum-driven submerged fermentation”

.M. FERNÁNDEZ, M.M. MARTORELL, F. SIÑERIZ, J.I. FARIÑA, L.I. C. FIGUEROA

California, USA

Congreso; Recent Advances in Fermentation Technology, RAFTVIII; 2009

Society for Industrial Microbiology, SIM

Bioremediation of Cr(VI) is of special interest for environmental and human health protection because the release of this metal from a number of industrial applications is related to different levels of toxicity. Two chromium resistant yeast strains (P. jadinii M9 and P. anomala M10) isolated from textile-dye polluted enviroments were pre-cultured with 1 mM Cr(VI) and thereafter, batch-cultivated in a stirred-tank bioreactor (LH210, 1 L-working volume) in order to determine its capacity to remove different Cr(VI) concentrations from culture medium. Fermenter assays were carried out in a modified YNB medium supplemented with sucrose as C-source (50 g/L) and ammonium sulfate (0·6 g/L) as N-source, with an initial pH of 5·0. Bioreactor operative parameters such as pH, temperature, agitation and air flow rate were automatically monitored. Biomass dry weight (BDW), residual sugars, ammonium and remanent Cr(VI) were measured following conventional protocols. For both yeast strains, cell mass production and Cr(VI) removal efficiency achieved at 1 mM initial Cr(VI) concentration were positively affected by the higher incubation temperatures tested (30ºC), and by moderate aeration and stirring conditions (0·5 vvm / 250 rpm). Either for P. jadinii or for P. anomala, at 1 mM initial chromate concentration, full metal removal could be achieved at 24 h of cultivation. Preadapted inocula were shown to promote higher Cr(VI) removal rates. Optimization of these fermentation parameters constitutes an important contribution in order to perform a successful Cr-removal for bioremediation purposes.