RESUMEN
Glycerol is a main co-product of biodiesel production. Crude glycerol may serve as a cheap and attractive substrate in biotechnological applications, e.g. for the production of valuable chemicals or as an electron donor for reduction processes. In this work, sulfate reduction with glycerol was studied at neutral and acidic pH using bioreactor sludge samples and Tinto River sediments as a source of inoculum, respectively. Communities of sulfate-reducing bacteria (SRB) and fermentative bacteria were co-enriched at both pH values. Molecular analyses revealed that sequences belonging to Desulfomicrobium genus were dominant in the cultures enriched at pH 7, while Desulfosporosinus sequences dominated in the culture enriched at pH 4. Glycerol conversion was coupled to sulfate reduction, but the substrate was incompletely oxidized to acetate in the neutrophilic enrichments, and acetate, lactate, and 1,3-propanediol under low pH conditions. Two strains belonging to Desulfomicrobium and Proteiniphilum genera were isolated from the neutrophilic enrichments, but the first isolate was not able to use glycerol, which suggests a syntrophic relationship between glycerol-degrading fermentative bacteria and SRB. A Clostridium strain able to grow with glycerol was isolated from the low pH enrichment. Our data indicate that glycerol promotes the growth of sulfate-reducing communities to form sulfide, which can be used to precipitate and recover heavy metals.
Asunto(s)
Bacterias/metabolismo , Glicerol/metabolismo , Concentración de Iones de Hidrógeno , Sulfatos/metabolismo , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Reactores Biológicos/microbiología , ADN Bacteriano , Sedimentos Geológicos/microbiología , Oxidación-Reducción , Filogenia , ARN Ribosómico 16S , Ríos/microbiología , Aguas del Alcantarillado/microbiologíaRESUMEN
A flora tem sido uma fonte valiosa de constituintes bioativos para manutenção da saúde humana. Tal fato tem reforçado a crescente investigação do potencial terapêutico das plantas medicinais. Neste contexto, o presente trabalho teve como objetivo avaliar o potencial antibacteriano dos extratos hidro-alcoólicos da casca, folha, e raiz de Avicennia schaueriana Stapf & Leechm. ex Moldenke, Verbenaceae. As partes vegetais foram coletadas no povoado pesqueiro de Siribinha, Bahia e os extratos vegetais foram preparados pelo método de maceração. Todos os testes de sensibilidade dos extratos vegetais foram avaliados por meio de testes não-paramétricos. O extrato da raiz de A. schaueriana apresentou uma atividade inibitória do crescimento superior aos extratos da folha e casca, com halos de inibição que variaram entre 7 a 18 mm de acordo com as concentrações e as cepas bacterianas testadas. Já a concentração inibitória mínima dos extratos hidro-alcoólicos de A. schaueriana apresentaram uma média de valores entre 0,62 a 10,00 mg/mL para as bactérias analisadas. Os resultados estatísticos confirmaram a diferença de sensibilidade dos microrganismos estudados frente aos extratos de A. schaueriana.
Natural products have been a valuable bioactives constituent source for maintenance of the health human being. Such fact has strengthened the increasing inquiry of the therapeutical potential of medicinal plants. This work had as objective evaluate the antibacterial potential from leaf, root and bark hydro-alcoholics extracts of Avicennia schaueriana Stapf & Leechm. ex Moldenke, Verbenaceae. The plant parts had been collected in the fishing town of Siribinha, Bahia and the plant extracts had been prepared by the method of maceration. All the tests of sensitivity of plant extracts had been evaluated by means of notparametric tests. The results of the test of diffusion in disk showed that the extract of the root of the A. schaueriana had been higher to extracts of the leaf and bark, with inhibition rings from growth varying of 7 to 18 mm; in accordance with the tested concentrations. Already the minimum inhibitory concentration of hydro-alcoholic extracts of A. schaueriana had presented an average of values between 0,62 to 10,00 mg/mL for the analyzed bacteria. The statistical results had confirmed the difference of sensitivity of the studied microorganisms front to extracts of the A. schaueriana.
RESUMEN
O presente trabalho objetivou avaliar o potencial antimicrobiano in vitro do extrato hidro-alcoólico da casca de Abarema cochliocarpos (Gomes) Barneby & Grimes, conhecido como barbatimão, nas cepas de Staphylococcus aureus (ATCC 6538), Micrococcus luteus (ATCC 9341), Escherichia coli (ATCC 10536), Pseudomonas aeruginosa (ATCC 15442) e Staphylococcus aureus isolado de amostra clínica (SAIACLIN). Coletaram-se cascas de um espécime de barbatimão no Parque Ecológico INDES, localizado em Vila de Sauípe, Bahia, para preparação do extrato hidro-alcoólico. Os testes de susceptibilidade bacteriana foram realizados através do método de difusão em disco e da concentração inibitória mínima (CIM). O extrato hidro-alcoólico de A. cochliocarpos inibiu o crescimento somente das bactérias Gram-positivas. S. aureus (ATCC 6538), SAIACLIN e M. luteus apresentaram halos crescentes de inibição bacteriana de acordo com o aumento da concentração do extrato (1, 2 e 3 mg/disco), que variaram entre 8 a 15 mm, de 8 a 16 mm e de 13 a 22 mm para os respectivos microrganismos. Os resultados confirmaram a capacidade de inibição do crescimento bacteriano in vitro pelo extrato da casca de A. cochliocarpos, corroborando os relatos populares.
The present study aimed at evaluating the in vitro antimicrobial potential of the hydroalcoholic extract from the bark of Abarema cochliocarpos (Gomes) Barneby & Grimes, known as 'barbatimão', over the strains of Staphylococcus aureus (ATCC 6538), Micrococcus luteus (ATCC 9341), Escherichia coli (ATCC 6538), Pseudomonas aeruginosa (ATCC 15442) and over a Clinical Sample isolated from Staphylococcus aureus (SAIACLIN). Samples of 'barbatimão' bark were collected from a specimen at the INDES Ecological Park, located at Vila de Sauípe, Bahia to prepare the hydroalcoholic extract. The bacterial susceptibility tests were carried through the disk diffusion method and through the minimum inhibitory concentration (MIC). The hydroalcoholic extract of A. cochliocarpos only inhibited the growth of the Gram-positive bacteria. S. aureus (ATCC 6538), SAIACLIN and M. luteus had presented increasing zones of bacterial inhibition in accordance with the increase of the extract concentration (1, 2 and 3 mg/disco), that had varied between 8 to 15 mm, from 8 to 16 mm and from 13 to 22 mm for the respective microorganisms. The results had confirmed the capacity of inhibition of the in vitro bacterial growth for the extract of the bark of A. cochliocarpos, corroborating the popular stories.