Hrudayanath Thatoi

Reduction of selenite to red elemental selenium by moderately halotolerant Bacillus megaterium strains isolated from Bhitarkanika mangrove soil and characterization of reduced product.

Two Gram (+) bacterial strains, BSB6 and BSB12, showing resistance and potential for Se(IV) reduction among 26 moderately halotolerant isolates from the Bhitarkanika mangrove soil were characterized by biochemical and 16S rDNA sequence analyses. Both of them were strictly aerobic and able to grow in a wide range of pH (4-11), temperature (4-40°C) and salt concentration (4-12%) having an optimum growth at 37°C, pH ∼7.5 and 7% salt (NaCl). The biochemical characteristics and 16S rDNA sequence analysis of BSB6 and BSB12 showed the closest phylogenetic similarity with the species Bacillus megaterium. Both the strains effectively reduced Se(IV) and complete reduction of selenite (up to 0.25 mM) was achieved within 40 h. SEM with energy dispersive X-ray and TEM analyses revealed the formation of nano size spherical selenium particles in and around the bacterial cells which were also supported by the confocal micrograph study. The UV-Vis diffuse reflectance spectra and XRD of selenium precipitates revealed that the selenium particles are in the nanometric range and crystalline in nature. These bacterial strains may be exploited further for bioremediation process of Se(IV) at relatively high salt concentrations and green synthesis of selenium nanoparticles.

Investigation on mechanism of Cr(VI) reduction and removal by Bacillus amyloliquefaciens, a novel chromate tolerant bacterium isolated from chromite mine soil

A strain CSB 9 isolated from chromite mine soil of Sukinda, India was identified as Bacillus amyloliquefaciens based on biochemical and 16S rRNA gene sequencing. The strain exhibited relatively high tolerance to Cr(VI) (⩽900mgL(-1)) and fast reduction rate of 2.22mg Cr(VI) L(-1)h(-1), under optimized conditions of 100mgL(-1) Cr(VI), pH 7 and temperature 35°C within 45h. Mechanism of Cr(VI) reduction as well as nature and fate of the reduced product were studied to determine the scope of removal of reduced Cr(III) end product. AAS analyses of the culture products treated with Cr(VI) for 45h showed the distribution of Cr(III) in pellet and culture supernatant to be 37.4±1.7 and 62.6±3.4mgL(-1), respectively. In SEM images, the bacterial pellets with Cr(VI) treatment appeared coagulated, rough and porous whereas the pellets without Cr(VI) treatment appeared regular, smooth and non-porous in structure. SEM-EDX of the bacterial precipitates under Cr(VI) treatment revealed immobilization of Cr(III) species on the bacterial cell surface. Further Raman spectroscopy analysis confirmed the presence of Cr(III) species, with characteristic peak at around 600cm(-1). TEM-EDX study of the bacterial precipitates under Cr(VI) treatment showed intracellular deposition of Cr(III) which are in nanometric range. Further characterization of reduced product by XRD, FT-IR and SAED analyses suggested the formation of poorly crystalline end products. A Cr(VI) removal mechanism considering both the surface immobilization and intracellular accumulation of Cr(III) along with the formation of coagulated cell precipitate by living B. amyloliquefaciens was suggested.

In vitro bioactivity and phytochemical screening of Suaeda maritima (Dumort): a mangrove associate from Bhitarkanika, India.

OBJECTIVE To investigate the in vitro antioxidant and antimicrobial activities along with phytochemical screening of organic and aqueous extracts of leaf and stem of Suaeda maritima (Dumort), a mangrove associate from Bhitarkanika of Odisha, India. METHODS Antioxidant activity of the crude extracts was evaluated in terms of total antioxidant capacity, total phenol content, ascorbic acid content, DPPH radical scavenging, metal chelating, nitric oxide scavenging, and reducing power etc. The antimicrobial activity of the plant was determined by agar well diffusion method along with MIC and MBC carried out by microdilution techniques against 10 gram positive and gram negative human pathogenic bacteria. The qualitative and quantative phytochemical screening were carried out by standard biochemical assays. RESULTS Out of the seven antioxidant bioassays, both the leaf and stem extracts were found to posses strong antioxidant properties of 70 % to 92 % for phenol, total antioxidant capacity, DPPH free radical scavenging activity and fairly good ascorbic acid content, metal chelating (1.33 %-22.55 %), reducing power (0.01-0.12) and nitric oxide scavenging (0.84 %-66.99 %) activities. Out of the four extracts evaluated for antimicrobial activity, two leaf extracts such as acetone and ethanol showed promising activity against four pathogenic bacteria and one stem methanol extracts against one pathogenic bacteria when compared with amoxcycillin as standard. The MIC and MBC values of the antimicrobial extracts ranged between 2.5 to 5.0 mg/mL. Screening of phytochemicals showed presence of carbohydrates, protein, tannins, alkaloids and flavonoids in comparatively higher amount than other phytochemicals tested. CONCLUSIONS The present study reveals the presence of potential antioxidants and antimicrobial properties in the plant extract which could be exploited for pharmaceutical application.

Heavy metal contamination, physico-chemical and microbial evaluation of water samples collected from chromite mine environment of Sukinda, India

Water samples from chromite mine quarry of Sukinda and its adjacent areas were analyzed for their heavy metal contamination along with physico-chemical and microbial contents. The chromite mine water samples possessed high concentrations of heavy metals in the order of Cr>Fe>Zn>Ni>Co>Mn while ground water did not show any heavy metal contamination except Fe. Physico-chemical parameters of mine water samples showed deviation from those of normal water. Mine water harboured low microbial populations of bacteria, fungi and actinomycetes in comparison with mine adjacent water samples. The correlation of data between metals with physico-chemical parameters showed both positive and negative responses while that of metal and microbial population exhibited negative correlation. Bacterial strains isolated from chromite mine water exhibited high tolerance towards chromium and other heavy metals as well as antibiotics which could be used as an indicator of heavy metal pollution.

Free radical scavenging and antioxidant potential of mangrove plants: a review

Free radicals derived from reactive oxygen species and reactive nitrogen species are generated in our body by normal cellular metabolism which is enhanced under stress conditions. The most vulnerable biological targets of free radicals are cell structures including proteins, lipids and nucleic acids. Since antioxidants synthesized in the body are not sufficient under oxidative stress, their exogenous supply is important to prevent the body from free radical-induced injury. Recent researches have shown that antioxidants of plant origin with free radical scavenging property could have great importance as therapeutic agents in management of oxidative stress. Mangrove plants growing in inhospitable environment of the intertidal regions of land and sea in tropics and sub-tropics are equipped with very efficient free radical scavenging system to withstand the variety of stress conditions. These mangrove plants possess variety of phytochemical and are rich in phenolic compounds such as flavonoids, isoflavones, flavones, anthocyanins, coumarins, lignans, catechins, isocatechins, etc., which served as source of antioxidants. Isolation and identification of these antioxidant compounds offer great potential for their pharmaceutical exploitations. However, no comprehensive literature is available on antioxidants’ studies in mangrove plants in particular. Hence, the present review discusses the antioxidant potential of mangrove plants with its specific role under salt stress as well as the progress made so far in evaluation of antioxidant activities of different mangrove species.

Ecological role and biotechnological potential of mangrove fungi: a review.

Mangroves are inhabited by large number of fungal communities, known as manglicolous fungi. They include mostly marine fungi and small group of terrestrial fungi and can be categorized into saprophytic, parasitic, and symbiotic fungi. Fungi in mangrove environment play an important ecological role in decomposition of organic matter by production of variety of extracellular degradative enzymes such as cellulase, xylanase, pectinase, amylase, and so on. Such enzymes can be isolated from the mangrove fungi and harnessed for several biotechnological applications. Several bioactive metabolites are derived from mangrove fungi, specially from mangrove endophytic fungi, which are used in pharmaceutical and nutraceutical industries to produce antimicrobial, anticancer, antioxidant, antidiabetic, and other therapeutic agents. Besides, certain mangrove fungi also contribute toward production of biopesticides useful in control of plant diseases, while others produce microbial lipids used as potential feed stock for biodiesel production. In spite of immense ecological role and biotechnological potentials, mangrove fungi are not extensively studied. The present review provides information on diversity and ecological role of mangrove fungi along with their biotechnological potentials as source of novel drugs, enzymes, biodiesel, biopesticides, and many other applications.

Nutritional and bioactive potential of two wild edible mushrooms ( Lentinus sajor-caju and Lentinus torulosus ) from Similipal Biosphere Reserve, India

The nutritional and medicinal potential (antioxidant and antibacterial activities) of 2 wild edible mushroom species (Lentinus sajor-caju and Lentinus torulosus) of Similipal Biosphere Reserve were determined. The macronutrient profile of these mushrooms in general revealed high source of protein (27.31–28.36 g/100 g), carbohydrate (64.95–68.24 g/100 g), and low amounts of fat (1.36–2.42 g/100 g) and possessed good quantities of micronutrients (vitamins and carotenoids) and minerals (P, K, Mn, Ni, and Fe). The solvent extracts (ethanol, methanol, and water) of the mushrooms exhibited strong antioxidant properties (ABTS, DPPH, H2O2, and metal chelating activities) with scavenging activity upto 70.54% along with phenol, flavonoid, and total antioxidant capacity. Both the mushrooms showed moderate antibacterial activity (11.0–18.33 mm inhibition zones) against Streptococcus aureus and Vibrio cholerae. Being a rich source of nutritional and medicinal potential, these 2 studied mushrooms can be used in human diet as nutraceuticals and functional foods.

Bioethanol production from sweet potato (Ipomoea batatas L.) flour using co-culture of Trichoderma sp. and Saccharomyces cerevisiae in solid-state fermentation

The aim of this work was to study the optimiation of co-culturing of Trichoderma sp. and Saccharomyces cerevisiae (1:4 ratio) on sweet potato (Ipomoea batatas L.) flour (SPF) for the production of bio-ethanol in solid-state fermentation (SSF). Maximum ethanol (172 g/kg substrate) was produced in a medium containing 80% moisture, ammonium sulphate 0.2%, pH 5.0, inoculuted with 10% inoculum size and fermented at 30oC for 72h. .Concomitant with highest ethanol concentration, maximum ethanol productivity (2.8 g/kg substrate/h), microbial biomass (23×108 CFU/ g substrate), ethanol yield (47 g/100g sugar consumed) and fermentation efficiency (72%) were also obtained under these conditions. Cell interaction was observed familiar between the viable cells of Trichoderma sp. and S. cerevisiae when co-cultured. Ethanol production ability by the co-culture was 65 % higher than the single culture of S. cerevisiae from un-saccharified SPF.

Impact of heavy metals on bacterial communities from mangrove soils of the Mahanadi Delta (India)

This study aimed to assess soil nutrient status and heavy metal content and their impact on the predominant soil bacterial communities of mangroves of the Mahanadi Delta. Mangrove soil of the Mahanadi Delta is slightly acidic and the levels of soil nutrients such as carbon, nitrogen, phosphorous and potash vary with season and site. The seasonal average concentrations (μg/g) of various heavy metals were in the range: 14 810–63 370 (Fe), 2.8–32.6 (Cu), 13.4–55.7 (Ni), 1.8–7.9 (Cd), 16.6–54.7 (Pb), 24.4–132.5 (Zn) and 13.3–48.2 (Co). Among the different heavy metals analysed, Co, Cu and Cd were above their permissible limits, as prescribed by Indian Standards (Co=17 μg/g, Cu=30 μ g/g, Cd=3–6 μ g/g), indicating pollution in the mangrove soil. A viable plate count revealed the presence of different groups of bacteria in the mangrove soil, i.e. heterotrophs, free-living N2 fixers, nitrifyers, denitrifyers, phosphate solubilisers, cellulose degraders and sulfur oxidisers. Principal component analysis performed using multivariate statistical methods showed a positive relationship between soil nutrients and microbial load. Whereas metal content such as Cu, Co and Ni showed a negative impact on some of the studied soil bacteria.

Phytochemical profiling and bioactivity of a mangrove plant, Sonneratia apetala, from Odisha Coast of India.

ObjectiveTo test the antioxidant, antidiabetic, anticancer and antibacterial activities along with phytochemicals of Sonneratia apetala Buch.-Ham.MethodsThe antibacterial activity was determined by agar well diffusion method. The antioxidant activity was determined by standard assay. The antidiabetic activity was evaluated by α-glucosidase inhibition assay and in vivo anticancer property was determined against Ehrlich ascites carcinoma (EAC) cells in Swiss Albino mice. Further partial characterization of the methanol extracts was carried out by thin layer chromatography, high performance liquid chromatography, 1H nuclear magnetic resonance spectroscopy and Fourier transform-infra red spectrum spectral analysis.ResultsFour solvent extracts (acetone, ethanol, methanol and aqueous) of leaf and bark possess strong antioxidant properties. In vivo anticancer activity of methanol extract leaf indicated positive activity showing 34% inhibition against EAC cells in Swiss Albino mice. All extracts exhibited α-glucosidase inhibitory activity in a dose-dependent manner indicating presence of promising antidiabetic properties. The extracts possess strong antibacterial activity against the selected pathogenic bacteria (minimal inhibitory concentration ranging from 1.25–5.00 mg/mL). The partial characterization of the methanol extracts of leaf and bark revealed the presence of phenolics as the lead compound responsible for studied bioactivities of the plant extracts.ConclusionSonneratia apetala extracts have potent antibacterial, antioxidant, antidiabetic and anticancer properties which can be further exploited for its pharmaceutical applications.