Dose-response effect of crude extracts produced by actinobacteria on in vitro rumen fermentation / Padrão dose-resposta de extratos brutos produzidos por actinobactérias sobre a fermentação ruminal in vitro

Actinobacteria have been researched as a source that produces crude extracts, which contain bioactive compounds able to act as antimicrobial agents. The present investigation evaluated the dose-response effect of two crude extracts, obtained at Caatinga rhizosphere (Caat) and Rhizophora mangle (AMC), on in vitro ruminal fermentation by:cumulative gas production, digestibility of dry (IVDMD) and organic matter (IVOMD), and short-chain fatty acids concentration (SCFA). Three multiparous Holstein dairy cows with ruminal fistula were used as the inoculum donors and fed a basal diet consisting of corn silage, soybean meal, urea, ground corn and mineral supplement. Ruminal fluid samples were incubated in glass bottles with 1 g of the dried and milled diet, a buffer solution, and the crude extracts evaluated in four doses (0.3, 0.6, 0.9 and 1.20 mg/10 mL inoculum) in a randomized block design, and the donators were considered as blocks with random effects. Additionally, negative controls were used. The results were expressed as average values based on triplicate analyses. Decreased cumulative gas production was observed according to linear dose response at 24, 48 and 72 h of incubation with the addition of Caat extract. The IVOMD showed a linear decrease at 72 h of incubation with dose Caat inclusion. Furthermore, the inclusion of Caat extract linearly reduced butyric and isovaleric acid concentrations, as well as acetate:propionate ratio. Finally, the Caat inclusion increased the propionic acid concentration in comparison to AMC extract. However, the inclusion of AMC extract did not affect any of the analyzed variables at the used doses. The Caat extract could be used as a modulator of in vitro ruminal fermentation, since it reduced acetate:propionate ratio and cumulative gas production.(AU)

As actinobactérias têm sido pesquisadas como fonte produtoras de extratos brutos que contêm compostos bioativos capazes de atuar como agentes antimicrobianos. O presente trabalho investigou o efeito dose-resposta de dois extratos brutos, AMC e Caat, na fermentação ruminal in vitro por: produção cumulativa de gás, digestibilidade in vitro da matéria seca (IVDMD) e matéria orgânica (IVOMD) e concentração de ácidos graxos de cadeia curta (SCFA). Três vacas leiteiras da raça Holandesa, multíparas e portadoras de fístula ruminal foram utilizadas como doadoras de inóculo ruminal e foram alimentadas com uma dieta basal composta por silagem de milho, farelo de soja, ureia, milho moído e suplemento mineral. As amostras de inóculo ruminal foram incubadas em garrafas de vidro com 1 g da dieta seca e moída, solução tampão e os extratos brutos avaliados em quatro doses (0,3, 0,6, 0,9 e 1,20 mg/10 mL de inóculo) em delineamento em blocos casualizados, sendo as doadoras consideradas os blocos como efeito aleatório. Além disso, foram utilizados controles negativos para a correção da produção de gás. Os resultados foram expressos como valores médios com base em análises triplicadas. A diminuição da produção cumulativa de gás foi observada de acordo com a dose em resposta linear às 24, 48 e 72 h de incubação com a adição de extrato de Caat. A IVOMD mostrou uma diminuição linear com 72 h de incubação com inclusão de Caat. Além disso, a inclusão do Caat reduziu linearmente as concentrações de ácido butírico e isovalérico, bem como a proporção de acetato/propionato. Diferentemente, a inclusão do extrato de AMC não afetou nenhuma das variáveis analisadas nas doses utilizadas. O extrato de Caat pode ser usado como um modulador da fermentação ruminal in vitro, uma vez que reduziu a proporção de acetato/propionato e a produção de gás acumulada. (AU)

Biomineralization of a calcifying ureolytic bacterium Microbacterium sp. GM-1

Background: Biomineralization is a significant process performed by living organisms in which minerals are produced through the hardening of biological tissues. Herein, we focus on calcium carbonate precipitation, as part of biomineralization, to be used in applications for environmental protection, material technology, and other fields. A strain GM-1, Microbacterium sp. GM-1, isolated from active sludge, was investigated for its ability to produce urease and induce calcium carbonate precipitation in a metabolic process. Results: It was discovered that Microbacterium sp. GM-1 resisted high concentrations of urea up to 60 g/L. In order to optimize the calcification process of Microbacterium sp. GM-1, the concentrations of Ni2+ and urea, pH value, and culture time were analyzed through orthogonal tests. The favored calcite precipitation culture conditions were as follows: the concentration of Ni2+ and urea were 50 µM and 60 g/L, respectively, pH of 10, and culture time of 96 h. Using X-ray diffraction analysis, the calcium carbonate polymorphs produced by Microbacterium sp. GM-1 were proven to be mainly calcite. Conclusions: The results of this research provide evidence that Microbacterium sp. GM-1 can biologically induce calcification and suggest that strain GM-1 may play a potential role in the synthesis of new biominerals and in bioremediation or biorecovery.

Carbazole degradation in the soil microcosm by tropical bacterial strains

In a previous study, three bacterial strains isolated from tropical hydrocarbon-contaminated soils and phylogenetically identified as Achromobacter sp. strain SL1, Pseudomonas sp. strain SL4 and Microbacterium esteraromaticum strain SL6 displayed angular dioxygenation and mineralization of carbazole in batch cultures. In this study, the ability of these isolates to survive and enhance carbazole degradation in soil were tested in field-moist microcosms. Strain SL4 had the highest survival rate (1.8 x 107 cfu/g) after 30 days of incubation in sterilized soil, while there was a decrease in population density in native (unsterilized) soil when compared with the initial population. Gas chromatographic analysis after 30 days of incubation showed that in sterilized soil amended with carbazole (100 mg/kg), 66.96, 82.15 and 68.54% were degraded by strains SL1, SL4 and SL6, respectively, with rates of degradation of 0.093, 0.114 and 0.095 mg kg−1 h−1. The combination of the three isolates as inoculum in sterilized soil degraded 87.13% carbazole at a rate of 0.121 mg kg−1 h−1. In native soil amended with carbazole (100 mg/kg), 91.64, 87.29 and 89.13% were degraded by strains SL1, SL4 and SL6 after 30 days of incubation, with rates of degradation of 0.127, 0.121 and 0.124 mg kg−1 h−1, respectively. This study successfully established the survivability (> 106 cfu/g detected after 30 days) and carbazole-degrading ability of these bacterial strains in soil, and highlights the potential of these isolates as seed for the bioremediation of carbazole-impacted environments.

Preliminary Study on Some Actinomycetes and Evaluation of Their Potential Antagonism against Fungal Pathogens.

Aims: Control of microbial pathogens by using antagonistic microorganisms is a promising alternative to chemical fungicides. The objective of the present study was to isolate and characterize soil actinomycetes and to their inhibitory activity against some fungal plant pathogens. Place and Duration of Study: National Park “El Chico”, Hidalgo State, and Laboratory of the Southeast Unit of CIATEJ, Yucatán, México, between June 2010 and May 2011. Methodology: Actinomycete species were isolated from six composite soil samples using microbiological standard procedures. All isolates were phenotypically characterized. Antagonistic isolates were selected according to the inhibitory growing of Fusarium sp. and Candida albicans. Afterwards, a new evaluation for the isolates selected was done against Helminthosporium sp., Curvularia sp., and Aspergillus niger. Actinomycetes were identified performing an analysis of the 16S rDNA gene sequence. Results: 164 actinomycete strains were characterized by morphological and biochemical features. Six of them, inhibited the growth of Fusarium sp. and C. albicans from 5 to 10 mm distance in between the actinomycete´s colony growth border of fungal or yeast. A growing reduction from 50 to 83 % in the in vitro antagonism assays was observed for Helminthosporium sp., Curvularia sp., and Aspergillus niger. Results in disc diffusion assays suggested an inhibitory growing capacity of CACIA-1.46HGO for P. capsici, this behavior could be due to the production of diffusible compounds related to secondary metabolism, hydrolytic enzymes, or both of them. Four antagonistic isolates were identified into Streptomyces genus and one as Microbacterium sp. through 16S rDNA gene sequence. Conclusion: Actinomycetes could be potentially a control tool to prevent several fungal commercial plants diseases. However, in situ isolate evaluations are suggested to be investigated.

In vivo metabolism of Talosin A, new isoflavonol glycoside from Kitasatospora kifunensis, in rats

The isoflavonol glycoside Talosin A, genistein (GT)-7-alpha-L-6-deoxy talopyranose (GT-Tal), was first isolated from the culture broth of Kitasatospora kifunensis MJM341. The aim of the present study was to evaluate the oral absorption and metabolism of the newly isolated isoflavonol glycoside, GT-Tal compared to genistin (GT-7-O-beta-D-glucopyranoside; GT-Glu). Free GT-Glu and GT-Tal could not be detected prior to enzymatic hydrolysis of the corresponding conjugates in rat plasma. Following oral administration of GT-Tal (15 min), GT-Tal was rapidly absorbed through the gastrointestinal tract and metabolized into GT-Tal conjugates with a mean Cmax of 2.74 microg/mL. GT-Tal was further metabolized to its aglycone, free GT and conjugated GT. After oral administration, GT-Glu was absorbed after being convereted to its aglycone and then further metabolized into its conjugate metabolites (free GT with a mean Cmax of 0.24 mg/mL at 1.25 h; conjugated GT with a mean Cmax of 1.31 mg/mL at 2.00 h). Significant differences in absorption and metabolism of GT-Tal and GT-Glu were observed. GT-Tal was metabolized into its corresponding conjugates or underwent deglycosylation to form GT, whereas GT-Glu was metabolized into its aglycone, GT.

Production of industrially important enzymes by some actinomycetes producing antifungal compounds.

Seventeen strains of actinomycetes antagonistic to yeast and moulds have been tested for their ability to produce amylase, lipase, gelatinase and caseinase using solid media containing starch, Tween-20, gelatin and skimmed milk, respectively, Enzyme producing potential of test strains is expressed in ternis of relative enzyme activity (REA). Actinomycetes strain Streptomyces somaliensis GS 1242 and Streptomyces sampsonii GS 1322 showed higher amylase production (REA 6.5) while maximum lipase activity was noted in Streptomyces strain SAP 1089 (REA 7.0). Gelatinase activity was noted higher is S. sampsonii GS 1322 (REA 9.6) and S. somaliensis GS 1242 (REA 8.8). Enzyme producing potential of these strains has been discussed in terms of their industrial significance.

Antifungal activity of some actinomycetes isolated from various habitats.

A total of 287 actinomycetes were isolated from 79 samples collected from five different habitats i.e., cultivated field soil (CFS), garden soil (GS), compost (CM), decaying organic matter (DOM) and stored agricultural products (SAP) of different localities of Sagar, Madhya Pradesh (23 degrees 50 degrees N latitude and 78 degrees 40 degrees E longitude). These were screened for antagonistic activity against Candida albicans, Aspergillus niger, Microsporum gypseun and Trichophyton sp. using 'Cross streak method'. Out of these, a total of 166 isolates were found antagonistic to Candida albicans, while 164, 134 and 132 actinomycetes showed antagonistic properties against A. niger, M. gypseum and Trichophyton sp., repectively. A total of 17 isolates showed very strong anticandidal activity causing total inhibition in the growth of C. albicans and hence, distribution of isolated test actinomycetes in different habitats and the cultural and antagonistic properties of selected 17 promising strains are reported here.

Characterisation of a new bioactive actinomycete AUB N5/8 from marine sediments.

Actinomycetes were isolated from marine sediments off Machilipatnam coast of Andhra Paradesh by plating on Starch-Casein Agar medium. From which one isolate AUB N5/8 was selected for detailed morphological, cultural, physiological and biochemical studies. The genera encountered were, Streptomycetes. Studies were compared with known strain S. baarinenisis (ISP 5232). It showed enough significant difference to create the status of a separate species for our isolate AUB N5/8. Hence it was designated as Streptomyces kavutarensis Sp.nov.

Screening of actinomycetes isolated from soil samples of Ajmer, Rajasthan for antimicrobial activity.

Several strains of actinomycetes were isolated from soil samples collected from various localities ofAjmer district. These isolates were tested for their antagonistic proerties against few test organisms viz. Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus sp., Saccharomyces cerevisiae and Aspergillus niger. Some of these actinomycete strains exhibited antimicrobial activity against bacteria, no antifungal activity was observed. Six such isolates were selected for detailed morphological, cultural, physiological and biochemical studies for identification. Five of these were identified as members beloging to the genus Streptomyces and the remaining one belonging to the genus Actinoplanes.