Exploration of Actinobacteria from Mangrove Ecosystems of Nizampatnam and Coringa for Antimicrobial Compounds and Industrial Enzymes.

Aim: A study was made to examine the kinship between the seasonal distribution of actinobacteria and the physico-chemical properties of the mangrove sediments of Nizampatnam and Coringa located along the South East coast of Andhra Pradesh, India. Place and Duration of Study: Department of Botany and Microbiology, between April 2010 to February 2011. Methodology: Seasonal enumeration of actinobacteria from two different stations 1 (Nizampatnam) and 2 (Coringa) accorded by four different pre-treatments of soil sediments followed by plating onto three different media showed high incidence of actinobacteria in the month of February and least in December. Pretreatment with calcium carbonate and plating on starch casein agar yielded maximum number of actinobacteria. The strains were identified based on the morphological characteristics such as aerial mycelium, substrate mycelium, diffusible pigments and micro morphological features. Results: The present investigation revealed that majority of the mangrove actinobacteria 69%) belongs to Streptomyces spp. Among the 55 isolates screened for antimicrobial compounds, 28 were found to be potential producers. The isolates could also produce commercially important enzymes such as L-asparaginase, cellulase and amylase. In addition the statistical study also revealed that positive correlation between the distribution of the actinomycetes and influence of physico-chemical parameters and the organic matter of the soil. Conclusion: Our study revealed that the unexplored regions like Nizampatnam and Coringa mangrove ecosystems are proved as potential sites for antimicrobial and industrial enzyme producing actinobacteria.

Diversity and seasonal fluctuation of predominant microbial communities in Bhitarkanika, a tropical mangrove ecosystem in India

Different groups of microorganisms are present in mangrove areas, and they perform complex interactions for nutrient and ecological balances. Since little is known about microbial populations in mangroves, this study analyzed the microbial community structure and function in relation to soil physico-chemical properties in Bhitarkanika, a tropical mangrove ecosystem in India. Spatial and seasonal fluctuations of thirteen important groups of microorganisms were evaluated from the mangrove forest sediments during different seasons, along with soil physico-chemical parameters. The overall microbial load (x10(5)cfu/g soil) in soil declined in the order of heterotrophic, free living N2 fixing, Gram-negative nitrifying, sulphur oxidizing, Gram-positive, spore forming, denitrifying, anaerobic, phosphate solubilizing, cellulose degrading bacteria, fungi and actinomycetes. Populations of the heterotrophic, phosphate solubilizing, sulphur oxidizing bacteria and fungi were more represented in the rainy season, while, Gram-negative, Gram-positive, nitrifying, denitrifying, cellulose decomposing bacteria and actinomycetes in the winter season. The pool size of most of other microbes either declined or maintained throughout the season. Soil nutrients such as N, P, K (Kg/ha) and total C (%) contents were higher in the rainy season and they did not follow any common trend of changes throughout the study period. Soil pH and salinity (mS/cm) varied from 6-8 and 6.4-19.5, respectively, and they normally affected the microbial population dynamics. Determination of bacterial diversity in Bhitarkanika mangrove soil by culture method showed the predominance of bacterial genera such as Bacillus, Pseudomonas, Desulfotomaculum, Desulfovibrio, Desulfomonas, Methylococcus, Vibrio, Micrococcus, Klebsiella and Azotobacter. Principal component analysis (PCA) revealed a correlation among local environmental variables with the sampling locations on the microbial community in the mangrove soil. Rev. Biol. Trop. 60 (2): 909-924. Epub 2012 June 01.

En las zonas de manglares están presentes diferentes grupos de microorganismos, los cuales presentan complejas interacciones que afectan los balances ecológicos y de nutrientes. Debido a que se sabe poco sobre las poblaciones microbianas en los manglares, este estudio analiza la estructura y función de la comunidad microbiana según las propiedades físico-químicas del suelo en Bhitarkanika, un ecosistema de manglares tropicales en la India. Se evaluaron las fluctuaciones espaciales y temporales de 13 grupos de microorganismos importantes en el sedimento de los manglares durante diferentes temporadas y parámetros físico-químicos del suelo. La carga microbiana total (x10(5)cfu/g de suelo) en el suelo se redujo en la categoría de las heterotróficas, de las bacterias libres fijadoras de N2, Gram-negativas nitrificantes, oxidativas de azufre, Gram-positivas, formadoras de esporas, desnitrificantes, anaeróbicas, las solubilizadoras de fosfato, bacterias degradadoras de celulosa, hongos y actinomicetos. Las poblaciones de heterótrofos, solubilizadoras de fosfato, oxidativas de azufre y los hongos estuvieron más representadas en la temporada lluviosa, mientras que, las Gram-negativas y Gram-positivas, nitrificantes, desnitrificantes, descomponedoras de celulosa y los actinomicetos, en la temporada de invierno. El tamaño poblacional de otros microorganismos disminuyó o se mantuvo durante toda la temporada. Los nutrientes del suelo, tales como N, P, K (Kg/ha) y el contenido total de C (%) fueron mayores en la temporada de lluvias, y no siguieron ninguna tendencia común de cambio a través del período de estudio. El pH del suelo y la salinidad (mS/cm) variaron de 6-8 y 6.4-19.5, respectivamente, lo que afectó significativamente la dinámica de la población microbiana. La determinación de la diversidad de bacterias en el suelo del manglar Bhitarkanika por el método de cultivo mostró el predominio de los géneros de bacterias como Bacillus, Pseudomonas, Desulfotomaculum, Desulfovibrio, Desulfomonas, Methylococcus, Vibrio, Micrococcus, Klebsiella y Azotobacter. El análisis de componentes principales (ACP) reveló una correlación entre las variables locales del ambiente y los sitios de muestreo en la comunidad microbiana en el suelo del manglar.

Isolation, Identification and Molecular Characterization of Rare Actinomycetes from Mangrove Ecosystem of Nizampatnam

Aims: Isolate and characterize the antimicrobial actinomycetes from sediments of Mangrove ecosystems of Nizampatnam located in the south coastal region of Andhra Pradesh, India. Methodology and Results: The Mangrove soil samples were collected, pre-treated and plated on asparagine-glucose agar medium. Identification of the strain was carried out by employing the polyphasic taxonomical studies including the 16S rRNA sequence based analysis. Phylogenetic tree was constructed using the Molecular Evolutionary Genetic Analysis (MEGA) version 5. The potent bioactive metabolite strain was isolated and designated as VUK-10. Further polyphasic studies revealed that the Isolate VUK-10 belongs to the genera Pseudonocardia. Phylogenetic analysis of 16S rRNA sequencing studies revealed that the strain is closely related to Pseudonocardia endophytica and the bioactive metabolites produced by the isolate inhibited Gram positive, Gram negative and Fungi. Conclusion, significance and impact of study: The isolation, characterization of the rare actinomycetes from the mangrove ecosystem will be useful for the discovery of the novel bioactive metabolites that are effective against wide range of pathogens.

The abundance of some pathogenic bacteria in mangrove habitats of Paraiba do Norte estuary and crabmeat contamination of mangrove crab Ucides cordatus

Study on mangrove water and sediment of Paraiba do Norte river (Northeastern Brazil) and crabmeat of Ucides cordatus was carried to investigate the relation between the abundance of bacteria in the mangrove habitat and in the crabmeat. Simultaneous collection of samples of water, sediment and crabs (U. cordatus) was done during the rainy and dry seasons at two areas of mangroves that differed in influence of tide and sewage discharge. The numbers of total heterotrophic bacteria in the mangrove water were between 0.04 and 6 log CFU 100mL-1, and in the sediment between 5 and 6 log CFU g-1. The location closer to waste discharge showed higher incidence of total heterotrophic bacteria, coliforms, Staphylococcus aureus and Salmonella spp. The counts of total heterotrophic bacteria in the crabmeat varied from 1.3 to 4.4 log CFU g-1, and did not differ significantly between the locations analysed. No crabmeat sample showed the presence of coliforms, S. aureus and Salmonella spp.

O estudo sobre água e sedimento do mangue do rio Paraíba do Norte (Nordeste do Brasil) e carne de caranguejo-uçá (Ucides cordatus) foi conduzido para investigar a relação entre a abundância de bactérias heterotróficas totais e patogênicas no ambiente e na carne de caranguejo. As amostras de água, sedimento e caranguejos U. cordatus foram coletadas simultaneamente em duas áreas do manguezal que diferiam em influencia da maré e do esgoto lançado no mangue. O número de bactérias heterotróficas totais nas amostras de água do mangue variaram de 0,04 a 6 log UFC 100mL-1, e no sedimento de 5 a 6 log UFC g-1. Em local mais próximo a desembocadura do esgoto evidenciou-se maior incidência de bactérias heterotróficas totais, coliformes, Staphylococcus aureus e Salmonella spp. As contagens de bactérias totais nas amostras da carne de caranguejo variaram de 1,3 a 4,4 log UFC g-1, não diferindo estatisticamente entre as áreas estudadas. Nenhuma amostra da carne de caranguejo apresentou coliformes, S. aureus e Salmonella spp.