Publications by authors named "Karlos H M Kalks"

Excessive use of herbicides decreases soil biodiversity and fertility. The literature on the xenobiotic response by microorganisms is focused on herbicide biodegradation as a selective event. Non-degradation systems independent of selection could allow the survival of tolerant bacteria in contaminated environments, impacting xenobiotic turnover and, consequently, bioremediation strategies.

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Controversy surrounding bacterial phylogenies has become one of the most important challenges for microbial ecology. Comparative analyses with nucleotide databases and phylogenetic reconstruction of the amplified 16S rRNA genes from DGGE (Denaturing Gradient Gel Electrophoresis) excised bands have been used by several researchers for the identification of organisms in complex samples. Here, we individually analyzed DGGE-excised 16S rRNA gene bands from 10 certified bacterial strains of different species, and demonstrated that this kind of approach can deliver erroneous outcomes to researchers, besides causing/emphasizing errors in public databases.

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This study analyzed the microbial diversity colonizing the surface of an oil sample during its contact with water, off the Trindade Island coast and simulated the efficiency of eight different bioremediation strategies for this environment. The diversity analysis was performed using acrylic coupons that served as the support for an oil inclusion at sea. The coupons were sampled over 30 days, and T-RFLP multiplex was employed to access the diversity of fungi, Bacteria and Archaea present on the oil surface.

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In the present study, acrylic coupons with a thin layer of oil on the surface were incubated in the coastal water of Trindade Island, Brazil, for 60 days. The microorganisms adhered to the coupons were isolated using enrichment medium with hexadecane and naphthalene as the sole carbon and energy source. A total of 15 bacterial isolates were obtained, and the ability of these isolates to use different hydrocarbons as the source of carbon and energy was investigated.

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We aimed to isolate biosurfactant-producing bacteria in high salt conditions from uncontaminated soils on the Brazilian oceanic island, Trindade. Blood agar medium was used for the isolation of presumptive biosurfactant-producing bacteria. Confirmation and measurements of biosurfactant production were made using an oil-spreading method.

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