INVESTIGADORES
POLTI Marta Alejandra
congresos y reuniones científicas
Título:
Cr(VI) bioremediation by Streptomyces sp. MC1: Effect on Zea mays
Autor/es:
ATJIÁN, MARIANA CRISTINA; POLTI, MARTA ALEJANDRA; AMOROSO, MARÍA JULIA; ABATE; CARLOS MAURICIO
Lugar:
Tucumán
Reunión:
Congreso; VII Congreso Argentino de Microbiología General SAMIGE del Bicentenario"; 2011
Institución organizadora:
Sociedad Argentina de Microbiología General
Resumen:
In natural water and subsurface
soils, chromium (Cr) occurs in two major oxidation states: III and VI.
Cr(VI) is the major chromium species used in industry and is the
common pollutant in soil and waste water, while Cr(III) is a
relatively insoluble and non-toxic. Cr(VI) produce toxicity acute and
chronic, neurotoxicity, dermatotoxicity, genotoxicity,
carcinogenicity and immunotoxicity. Cr(VI) compounds are 1,000 fold
more toxics than Cr(III) compounds. Biological transformation of
Cr(VI) to Cr(III) by enzymatic reduction is a means of
decontamination. This biological reduction may provide a less costly
and environmentally friendly approach to remediation. On the other
hand, vegetables can be used as contamination level markers because
they can accumulate these compounds. A Cr(VI) resistant
actinobacteria strain, Streptomyces sp. MC1, previously isolated, in
our lab, from sugar cane, has the ability of reducing Cr(VI) in
sterile soil samples.
The
aim of this work was to evaluate the ability of this strain to
bioremediate non sterile soil samples contaminated with Cr(VI), using
Zea mays as bioindicator. Streptomyces sp. MC1 was grown in Tryptic
Soy Broth (g L-1: Tryptone 15, Soy Peptone 3, NaCl 5, K2HPO4 2.5 and
glucose 2.5) during 3 days at 30 ºC. Glass pots were filled with 200
g of soil and kept at 20% humidity with distilled water. K2Cr2O7
solution was added at final Cr(VI) concentration of 200 mg kg -1 of
soil. Later these soil samples were inoculated with pre-cultured
Streptomyces sp. MC1.
Zea
mays seeds were sterilized and sown on plates with agar. Maize young
plants were potted at the same time of Streptomyces inoculation
(t0), 14 days (t14) and 28 days (t28) after the inoculation, and
cultivated during 14 days. Chromium bioavailability was measured by
atomic absorption spectrophotometry (AAS) after centrifugation 1 g of
soil at 5540 g. Maize biomass was estimated as dry weight. Chromium
accumulate by plants was measured by AAS after plant treatment with
concentrated H2SO4. Streptomyces sp. MC1 was able to reduce Cr(VI)
bioavailability up to 73% after 42 days.
Similarly, Zea mays reduced up to 70% of chromium bioavailability, in absence of Streptomyces sp. MC1.
On
the other hand, Zea mays biomass decreased up to 88% with Cr(VI) and
without Streptomyces sp. MC1. However, Zea mays biomass decreased
only 32% in presence of Cr(VI) and Streptomyces sp. MC1, when the sow
was made after 28 days of inoculation, and Cr(VI) bioavailability
was reduced up to 97%. This is the first report where Streptomyces sp.
MC1 and Zea mays show a synergic effect that could be useful to
bioremediate Cr in soil samples.