Rice straw hydrolysis using in-situ produced enzymes: Feedstock influences fungal enzyme composition and hydrolytic efficiency.

Trichoderma reesei RUT-C30 was cultivated on differentially pretreated rice straw and pure cellulose as a carbon source/inducer for cellulase production, and the enzymes were evaluated for hydrolysis of sequential acid and alkali pretreated rice straw. Growth on pretreated rice straw enhanced protein secretion and cellulase activities compared to pure cellulose as a carbon source. The yield of cellulolytic enzymes was higher for alkali pretreated rice straw (ALP-RS), while H2O2-treated (HP-RS) could not induce cellulases to a larger level compared to pure cellulose. Protein concentration was 3.5-fold higher on ALP-RS as compared to pure cellulose, with a maximum filter-paper cellulase (FPase) activity of 1.76 IU/ml and carboxy-methyl cellulase (CMCase) activity of 40.16 IU/ml (2.18 fold higher). Beta-glucosidase (BGL) activity was more or less the same with the different substrates and supplementation of heterologous BGL could result in a quantum jump in hydrolytic efficiencies, which in the case of ALP-RS induced enzymes was 34% (increased from 69.26% to 92.51%). The use of lignocellulosic biomass (LCB) itself as a substrate for the production of cellulase is advantageous not only in terms of raw material costs but also for obtaining a more suitable enzyme profile for biomass hydrolysis.

Recent advances in biodiesel production: Challenges and solutions.

Mono alkyl fatty acid ester or methyl ethyl esters (biodiesel) are the promising alternative for fossil fuel or petroleum derived diesel with similar properties and could reduce the carbon foot print and the greenhouse gas emissions. Biodiesel can be produced from renewable and sustainable feedstocks like plant derived oils, and it is biodegradable and non-toxic to the ecosystem. The process for the biodiesel production is either through traditional chemical catalysts (Acid or Alkali Transesterification) or enzyme mediated transesterification, but as enzymes are natural catalysts with environmentally friendly working conditions, the process with enzymes are proposed to overcome the drawbacks of chemical synthesis. At present 95% of the biodiesel production is contributed by edible oils worldwide whereas recycled oils and animal fats contribute 10% and 6% respectively. Although every process has its own limitations, the enzyme efficiency, resistance to alcohols, and recovery rate are the crucial factors to be addressed. Without any benefit of doubt, production of biodiesel using renewable feedstocks and enzymes as the catalysts could be recommended for the commercial purpose, but further research on improving the efficiency could be an advantage.

Enzymatic approaches in the bioprocessing of shellfish wastes.

Several tonnes of shellfish wastes are generated globally due to the mass consumption of shellfish meat from crustaceans like prawn, shrimp, lobster, crab, Antarctic krill, etc. These shellfish wastes are a reservoir of valuable by-products like chitin, protein, calcium carbonate, and pigments. In the present scenario, these wastes are treated chemically to recover chitin by the chitin and chitosan industries, using hazardous chemicals like HCl and NaOH. Although this process is efficient in removing proteins and minerals, the unscientific dumping of harmful effluents is hazardous to the ecosystem. Stringent environmental laws and regulations on waste disposal have encouraged researchers to look for alternate strategies to produce near-zero wastes on shellfish degradation. The role of enzymes in degrading shellfish wastes is advantageous yet has not been explored much, although it produces bioactive rich protein hydrolysates with good quality chitin. The main objective of the review is to discuss the potential of various enzymes involved in shellfish degradation and their opportunities and challenges over chemical processes in chitin recovery.

Sustainable and eco-friendly strategies for shrimp shell valorization.

Among the seafood used globally, shellfish consumption is in great demand. The utilization of these shellfish such as prawn/shrimp has opened a new market for the utilization of the shellfish wastes. Considering the trends on the production of wealth from wastes, shrimp shell wastes seem an important resource for the generation of high value products when processed on the principles of a biorefinery. In recent years, various chemical strategies have been tried to valorize the shrimp shell wastes, which required harsh chemicals such as HCl and NaOH for demineralization (DM) and deproteination (DP) of the shrimp wastes. Disposal of chemicals by the chitin and chitosan industries into the aquatic bodies pose harm to the aquatic flora and fauna. Thus, there has been intensive efforts to develop safe and sustainable technologies for the management of shrimp shell wastes. This review provides an insight about environmentally-friendly methods along with biological methods to valorize the shrimp waste compared to the strategies employing concentrated chemicals. The main objective of this review article is to explain the utilization shrimp shell wastes in a productive manner such that it would be offer environment and economic sustainability. The application of valorized by-products developed from the shrimp shell wastes and physical methods to improve the pretreatment process of shellfish wastes for valorization are also highlighted in this paper.

Biogenic Ag Nanoparticles from Neem Extract: Their Structural Evaluation and Antimicrobial Effects against Pseudomonas nitroreducens and Aspergillus unguis (NII 08123).

Silver nanocrystals have been successfully fabricated by the bioreduction route using the ethanolic extract of Azadirachta indica (neem) leaves as the reducing and capping agent without solvent interference. The silver nanocrystals were grown in a single-step method, without the influence of external energy or surfactants, and at room temperature. The nanoparticles were prepared from different ratios of silver ions to reducing agent molecules and were characterized by UV-vis spectroscopy and transmission electron microscopy (TEM). The nanoparticles were roughly spherical and polydispersed with diameters of less than 40 nm, as determined with high-resolution transmission electron microscopy (HRTEM). Fast Fourier transform (FFT) analysis and X-ray diffraction (XRD) analysis elucidated the crystalline nature of the nanoparticles. The presence of participating functional groups was determined with Fourier transform infrared (FTIR) spectroscopy. The synthesized silver nanoparticles were analyzed as a potential surface-enhanced Raman spectroscopy (SERS) substrate by incorporating rhodamine B as the Raman reporter molecule. The bioreduction process was monitored through SERS fingerprint, which was evaluated by the change in vibrational energies of metal-ligand bonds. It was possible to detect the SERS spectral pattern of the probe molecules on the Ag nanoparticles without the use of any aggregating agent. Thus, the formation of probable intra- and interparticle hot spots was attributed to evaporation-induced aggregation. Furthermore, stirring and precursor salt concentration influenced the kinetics involved in the fabrication process. The thermal stability of the lyophilized nanoparticles prepared from 0.1 M AgNO3 was evaluated with thermogravimetric analysis (TGA) and had a residual mass of 60% at 600 °C. X-ray photoelectron spectroscopy (XPS) studies were used to validate the compositional and chemical-state information. The biomass-capped silver nanoparticles provided antimicrobial activity by inhibiting the growth of Pseudomonas nitroreducens, a biofilm-forming bacterium, and the fungus, Aspergillus unguis (NII 08123).

Genomic sequence analysis of a plant-associated Photobacterium halotolerans MELD1: from marine to terrestrial environment?

Mercury impacts the function and development of the central nervous system in both humans and wildlife by being a potent neurotoxin. Microbial bioremediation is an important means of remediation of mercury-contaminated soil. The rhizospheric Photobacterium halotolerans strain MELD1 was isolated from mercury and dioxin contaminated site from Tainan, Taiwan. It has been shown to reduce Hg(2+) to Hg(0). The 4,758,027 bp genome of P. halotolerans MELD1 has a G + C content of 50.88 % and contains 4198 protein-coding and 106 RNA genes. Genomic analysis revealed the presence of a number of interesting gene cluster that maybe involved in heavy metal resistance, rhizosphere competence and colonization of the host plant.

Genome Sequence of Photobacterium halotolerans MELD1, with Mercury Reductase (merA), Isolated from Phragmites australis.

Here, we present the whole-genome sequence of Photobacterium halotolerans strain, MELD1, isolated from the roots of a terrestrial plant Phragmites australis grown in soil heavily contaminated with mercury and dioxin. The genome provides further insight into the adaptation of bacteria to the toxic environment from where it was isolated.

A rhizosphere-associated symbiont, Photobacterium spp. strain MELD1, and its targeted synergistic activity for phytoprotection against mercury.

Though heavy metal such as mercury is toxic to plants and microorganisms, the synergistic activity between them may offer benefit for surviving. In this study, a mercury-reducing bacterium, Photobacterium spp. strain MELD1, with an MIC of 33 mg x kg(-1) mercury was isolated from a severely mercury and dioxin contaminated rhizosphere soil of reed (Phragmites australis). While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer. The efficiency of MELD1 to vaporize mercury (25 mg x kg(-1), 24 h) and its tolerance to toxic metals and xenobiotics such as lead, cadmium, pentachlorophenol, pentachloroethylene, 3-chlorobenzoic acid, 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin is promising. Combination of a long yard bean (Vigna unguiculata ssp. Sesquipedalis) and strain MELD1 proved beneficial in the phytoprotection of mercury in vivo. The effect of mercury (Hg) on growth, distribution and tolerance was examined in root, shoot, leaves and pod of yard long bean with and without the inoculation of strain MELD1. The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots. Biolog plate assay were used to assess the sole-carbon source utilization pattern of the isolate and Indole-3-acetic acid (IAA) productivity was analyzed to examine if the strain could contribute to plant growth. The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.

Highly glucose tolerant ß-glucosidase from Aspergillus unguis: NII 08123 for enhanced hydrolysis of biomass.

Aspergillus unguis NII-08123, a filamentous fungus isolated from soil, was found to produce ß-glucosidase (BGL) activity with high glucose tolerance. Cultivation of the fungus in different carbon sources resulted in the secretion of different isoforms of the enzyme. A low molecular weight isoform, which retained ~60 % activity in the presence of 1.5 M glucose, was purified to homogeneity and the purified enzyme exhibited a temperature and pH optima of 60 °C and 6, respectively. The K(m) and V(max) of the enzyme were 4.85 mM and 2.95 U/mg, respectively, for 4-nitrophenyl ß-D-glucopyranoside. The glucose inhibition constant of the enzyme was 0.8 M, indicating high glucose tolerance, and this is the second-highest glucose tolerance ever reported from the Aspergillus nidulans group. The glucose-tolerant BGL from A. unguis, when supplemented to cellulase preparation from Penicillium, could improve biomass hydrolysis efficiency by 20 % in 12 h compared to the enzyme without additional beta glucosidase supplementation. The beta glucosidase from A. unguis is proposed as a highly potent "blend-in" for biomass saccharifying enzyme preparations.

Synergistic collaboration of gut symbionts in Odontotermes formosanus for lignocellulosic degradation and bio-hydrogen production.

In this work, gut microbes from the macrotermitine termite Odontotermes formosanus the cellulolytic Bacillus and fermentative Clostridium were studied in batch experiments using different carbon substrates to bio-mimic the termite gut for hydrogen production. Their fungus comb aging and the in vitro lignocellulosic degradation of the mango tree substrates by the synergistic interaction of Bacillus, Clostridium and Termitomyces were detected by Solid-state NMR. From the results, Bacillus species acted as a mutualist, by initiating an anaerobic environment for the growth of Clostridium, for bio-hydrogen production and the presence of Termitomyces enhanced the lignocellulosic degradation of substrates in vitro and in vivo. Thus, the synergistic collaboration of these three microbes can be used for termite-derived bio-fuel processing technology.

Microbial community analysis in the termite gut and fungus comb of Odontotermes formosanus: the implication of Bacillus as mutualists.

The microbial communities harbored in the gut and fungus comb of the fungus-growing termite Odontotermes formosanus were analyzed by both culture-dependent and culture-independent methods to better understand the community structure of their microflora. The microorganisms detected by denaturing gradient gel electrophoresis (DGGE), clonal selection, and culture-dependent methods were hypothesized to contribute to cellulose-hemicellulose hydrolysis, gut fermentation, nutrient production, the breakdown of the fungus comb and the initiation of the growth of the symbiotic fungus Termitomyces. The predominant bacterial cultivars isolated by the cultural approach belonged to the genus Bacillus (Phylum Firmicutes). Apart from their function in lignocellulosic degradation, the Bacillus isolates suppressed the growth of the microfungus Trichoderma harzianum (genus Hypocrea), which grew voraciously on the fungus comb in the absence of termites but grew in harmony with the symbiotic fungus Termitomyces. The in vitro studies suggested that the Bacillus sp. may function as mutualists in the termite-gut-fungus-comb microbial ecosystem.