RESUMEN

Escalating environmental concerns and petroleum demands leads into the present study. In this investigation delignification of rice straw was optimized by NaOH and H2SO4 pretreatment using L16 Taguchi orthogonal array. NaOH pretreatment revealed higher delignification as compared to H2SO4 and; further subjected to separate enzymatic hydrolysis and co-fermentation (SHCF) using RSM as the SHCF demonstrated a maximum glucose and xylose yield of 575 and 205 mg/g. Further, butanol concentration of 4.32 g/L was achieved from 20 g/L of sugar loadings by co-culture of Saccharomyces cerevisiae and Pichia sp. at 72 h of incubation time which was 79.25% higher as compared to monocultures of Pichia sp. Scale-up experiments with higher sugar loadings (90 g/L) demonstrated a butanol concentration of 13.3 g/L. The release of amino acids in co-culture and monoculture systems demonstrated that the addition of S. cerevisiae promoted the butanol synthesis pathway which led to higher butanol concentration.

Asunto(s)

RESUMEN

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.

Asunto(s)