PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Chromate reduction by Cr(VI)-resistant yeasts isolated from textile effluents in Tucumán, Argentina
Autor/es:
FERNÁNDEZ, PABLO M; VIÑARTA, SILVANA C.; FARIÑA, JULIA I; LUCÍA IC FIGUEROA
Lugar:
Kiyv, Ukraine
Reunión:
Congreso; 12th International Congress on Yeats; 2008
Resumen:
Manufacturing of metallic alloys and dyes, and tanning of leathers represent the main industrial uses of chromium. Chromium is usually found in nature in its trivalent state, but hexavalent chromate is generally found as a result of anthropogenic activities. Chromium(VI) compounds are known to be extremely toxic to living organisms due to their strong oxidizing nature. Its reduction to less toxic Cr(III) is an important step in the remediation of Cr(VI)-contaminated environments. Microbial metal-processing capacity can be used to concentrate, remove, and recover metals from streams and to enhance the efficiency of wastewater treatment processes. In this work, two yeasts arbitrarily named as PAM 9 and PAM 10 isolated from a textile dying factory effluent were tested on their Cr(VI) removal efficiency. Yeast Nitrogen Base (YNB) (w/o AA and ammonium sulfate) culture medium was supplemented with sucrose as C-source and ammonium sulfate as N-source (pH 5), plus 1mM Cr(VI) as K2Cr2O7. Cultures were incubated at 25ºC, 250 rpm, during 5 days. Culture broth samples were analyzed for pH, biomass dry weight (BDW), glucose and ammonium following conventional protocols. Cr(VI) was measured by the diphenylcarbazide (DPC) method. Growth, pH and ammonium kinetics were similar for both yeasts, though PAM 10 reached higher BDW values. Conversely, glucose consumption profiles showed differences between yeasts. PAM 10 was able to remove 100% of the initial Cr(VI) concentration at 24 h of cultivation, whereas PAM 9 only removed a 70% in the same time. Total chromium content was measured by atomic absorption spectroscopy (AAS) both in digested washed pellets and cell-free supernatants. Total chromium bioaccumulated and/or bioadsorbed in yeast cells between 0 and 120 h ranged from 1,196 to 0,786 mg Cr/g BD and from 0,817 to 0,260 mg Cr/g BD for PAM 9 and PAM 10, respectively. Most of the total chromium was detected in the supernatants, which might be ascribed to the trivalent state. Accordingly, bioreduction may be suggested as the main mechanism implicated in the removal of Cr(VI) from cultures. In addition, electron microscopic images showed that the Cr(VI) concentration used did not affect the general appearance and shape of cells. The results herein presented put in evidence the capability of the selected yeasts for Cr(VI) removal by biospeciation, a strategy potentially useful at the moment of developing metal bioremediation processes.