Crescimento e sobrevivência do recombinante Rhodococcus sp. isolado RHA1 (fcb) em turfa comercial e solo contaminado com PCB / Growth and survival of recombinant Rhodococcus sp. isolate RHA1 (fcb) in commercial peat and in PCB contaminated soil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The group of organochlorates Biphenyl Polychlorates (PCBs) is of difficult degradation and persistent in the environment, being associated to several problems in the organisms due to its toxicological potential. The isolate RHA1 (fcb) from Rhodococcus sp. was genetically built with the introduction of the operon of hydrolytic degradation 4-chlorobenzoate (fcb) to avoid the formation of toxic products during the degradation of chlorobenzoic acids. In order to obtain information about the adaptative process of the recombinant Rhodococcus sp. isolate RHA1 (fcb) in substrates containing PCBs, two essays were made evaluating the survival and growth of this isolate. Rhodococcus sp. isolate RHA1 (fcb) was inoculated (104 cells.g-1) in peat substrate previously irradiated with 50 kGy, with and without 200 mg.kg-1 of biphenyl. In another essay, besides of the recombinant, the bacteria Escherichia coli and Arthrobacter sp. were inoculated in soil, also irradiated (50 kGy), from the Estuário de Santos region containing PHAs and PCBs. The growth of the bacteria in both substrates was monitorated counting the Colony Forming Units (CFUs). Some colonies were selected randomly for DNA extraction, fcb operon detection through PCR, and sequencing of the 16S rRNA gene. Rising in the number of CFUs in the recombinant inoculated treatments was observed until 150 days in the essay with peat substrate, and until 70 days in the environmental sample. Nonetheless, there was a reduction in the number of CFUs after 10 days in the treatment inoculated with E. coli and Arthrobacter sp. The genes fcbA and fcbB from the operon fcb were detected in the isolated colonies of the treatments inoculated with the isolate RHA1 (fcb) in both substrates. The analysis of the sequences belonging to the colonies isolated from the treatment inoculated with the isolate RHA1 (fcb) through BLAST in the NCBI and Ribosomal Database Project sites showed 99% identity with the sequence of the gene 16S ribosomal from Rhodococcus sp. isolate ZC-3 (AM076672.1). Only the sequences referring to the treatment inoculated with E. coli were analyzed, which showed 99% identity with the sequence of the 16S ribosomal gene from E. coli isolate K-12 MG 1655 (U00096.2). These results suggest that Rhodococcus sp. isolate RHA1 (fcb) grows in the peat irradiated (until 150 days), in the presence and absence of PCB and in this irradiated sediment sample (until 70 days), with apparent stability of the fcb operon during this period and in these conditions. The possible presence of the fcbA and fcbB genes in native bacteria grown in K1 medium with 4-chlorobenzoate acid isolated from sediment before irradiation suggests the presence of native bacteria with biodegradation potential of this compound.

ASSUNTO(S)

polychlorinated biphenyl toxicologia ambiental peat turfa bactéria recombinante bifenil policlorado biodegradação sediment sedimento recombinant bacteria biodegradation seqüênciamento genético environmental toxicology genetic sequence

ACESSO AO ARTIGO

Documentos Relacionados