Nandan Singh Darmwal

Bio: Nandan Singh Darmwal is an academic researcher from Dr. Ram Manohar Lohia Avadh University. The author has contributed to research in topics: Lipase & Protease. The author has an hindex of 12, co-authored 14 publications receiving 314 citations.

Xanthomonas campestris , a novel stress tolerant, phosphate-solubilizing bacterial strain from saline–alkali soils

Abstract: A total of 198 bacterial strains were isolated from various niches of saline–alkali soils, out of which 85 strains were able to solubilize phosphate on plates at 30 °C. The strain RMLU-26, identified as Xanthomonas campestris, was the most efficient with its ability to solubilize P, subjected to N-methyl-N′-nitro-N-nitrosoguanidine (NTG) for development of mutants. The P solubilizing ability of X. campestris is reported for the first time. The wild type and mutant strains of X. campestris revealed a differential response to various stress factors (high pH, temperature, and salt concentration). The mutant strain revealed maximum P solubilization (67.1%) at 30 °C and pH 8.0 while the wild type strain showed maximum solubilization (41.9%) at 35 °C and pH 7.0. Percent P2O5 solubilization by both strains revealed a steep decline in tricalcium phosphate solubilization with an increase in NaCl concentration from 0.5 to 10% along with a concomitant drop in pH of the medium from 8.0 to 4.5 in wild type and 4.0 in mutant strain. However, a 1.5- to 2-fold increase in ‘P’ solubilization was observed in the mutant strain when compared to the wild type strain in the presence of NaCl. The overall improved tolerance of the strains to alkalinity and salinity could be due to accumulation and/or secretion of specific solute (xanthan).

Enhanced Production of Extracellular Alkaline Lipase by an Improved Strain of Pseudomonas aeruginosa MTCC 10,055

Abstract: Problem statement: Lipases are industrially important enzymes having applications in numerous industries. For easy commercialization it is necessary to produce lipases at industrial level which could be achieved by strain improvement and medium formulation. Approach: In the present study strain improvement of Pseudomonas aeruginosa MTCC 10,055 was done by chemical mutagenesis using mutagen 4-nitroquinoline1-oxide for alkaline lipase production. Different fermentation parameters affecting lipase production were optimized using one-variable-at-a-time approach. Results: The selected mutant (M-05) exhibited 3.6-fold high er productivity over wild type. Maximum alkaline lipase was produced when culture was incubated at 35°C with initial medium pH 9.0 in 28 h with inoculum density 0.5% (v/v) (Abs 610 -1.0). Supplementation of production medium with combination of castor oil and starch as carbon source and Triton-X-100 as surfactant significantl y influenced the alkaline lipase production. The comp osition of fully optimized medium was determined to be (g L -1 ): (NH 4)2SO 4, 1.0; KH 2PO 4, 0.6; MgSO 4, 0.4; yeast extract, 0.2; castor oil, 2.0; starch 20.0; gum arabic, 5.0; Triton-X-100, 1.0. An overall 14-f old enhanced production was achieved after complete medium optimization. Conclusion/Recommendations: The improved strain was capable to produce high titer of alkaline lipase at flask leve l, which can be examined at fermentor level to obta in sufficient enzyme yield to meet the world wide indu strial demand.

Lipase catalysis in organic solvents: advantages and applications

Abstract: Lipases are industrial biocatalysts, which are involved in several novel reactions, occurring in aqueous medium as well as non-aqueous medium. Furthermore, they are well-known for their remarkable ability to carry out a wide variety of chemo-, regio- and enantio-selective transformations. Lipases have been gained attention worldwide by organic chemists due to their general ease of handling, broad substrate tolerance, high stability towards temperatures and solvents and convenient commercial availability. Most of the synthetic reactions on industrial scale are carried out in organic solvents because of the easy solubility of non-polar compounds. The effect of organic system on their stability and activity may determine the biocatalysis pace. Because of worldwide use of lipases, there is a need to understand the mechanisms behind the lipase-catalyzed reactions in organic solvents. The unique interfacial activation of lipases has always fascinated enzymologists and recently, biophysicists and crystallographers have made progress in understanding the structure-function relationships of these enzymes. The present review describes the advantages of lipase-catalyzed reactions in organic solvents and various effects of organic solvents on their activity.

Microbial Proteases Applications.

Abstract: The use of chemicals around the globe in different industries has increased tremendously, affecting the health of people. The modern world intends to replace these noxious chemicals with environmental friendly products for the betterment of life on the planet. Establishing enzymatic processes in spite of chemical processes has been a prime objective of scientists. Various enzymes, specifically microbial proteases, are the most essentially used in different corporate sectors, such as textile, detergent, leather, feed, waste, and others. Proteases with respect to physiological and commercial roles hold a pivotal position. As they are performing synthetic and degradative functions, proteases are found ubiquitously, such as in plants, animals, and microbes. Among different producers of proteases, Bacillus sp. are mostly commercially exploited microbes for proteases. Proteases are successfully considered as an alternative to chemicals and an eco-friendly indicator for nature or the surroundings. The evolutionary relationship among acidic, neutral, and alkaline proteases has been analyzed based on their protein sequences, but there remains a lack of information that regulates the diversity in their specificity. Researchers are looking for microbial proteases as they can tolerate harsh conditions, ways to prevent autoproteolytic activity, stability in optimum pH, and substrate specificity. The current review focuses on the comparison among different proteases and the current problems faced during production and application at the industrial level. Deciphering these issues would enable us to promote microbial proteases economically and commercially around the world.

Genetic diversity of plant growth promoting rhizobacteria isolated from rhizospheric soil of wheat under saline condition.

Abstract: In this study, a total of 130 rhizobacteria was isolated from a saline infested zone of wheat rhizosphere, and screened for plant growth promoting (PGP) traits at higher salt (NaCl) concentrations (2, 4, 6, and 8%). The results revealed that 24 rhizobacterial isolates were tolerant at 8% NaCl. Although all the 24 salt tolerable isolates produced indole-3-acetic acid (IAA), while 10 isolates solubilized phosphorus, eight produced siderophore, and six produced gibberellin. However, only three isolates showed the production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Diversity was analyzed through 16S rDNA-RFLP, and of these isolates with three tetra cutter restriction enzymes (HaeIII, AluI, and MspI), the representative cluster groups were identified by 16S rDNA sequencing. Bacillus and Bacillus-derived genera were dominant which showed PGP attributes at 8% NaCl concentration. Out of 24 isolates, nitrogen fixing ability (nif H gene) was detected in the two isolates, SU18 (Arthrobacter sp.) and SU48.

Solubilization of Phosphorus by Soil Microorganisms

Abstract: Non-mycorrhizal microbial inoculants (biofertilizers) can potentially stimulate soil P cycling by solubilizing organic- and mineral-bound P. These P-solubilizing microorganisms (PSM) include a wide range of bacteria, fungi and actinomycetes, many of which are common in the rhizosphere. There appears to be two main PSM strategies for enhancing soil P availability, namely (1) the enhanced dissolution of P-containing minerals through a combination of soil acidification and the release of metal complexing agents (predominantly organic acid anions) and (2) the enzymatic breakdown of organic P. In terms of P cycling in natural environments, it is likely that strategy (2) is most important in terms of the annual flux of P through the plant–soil system. However, in highly P-limiting environments it is likely that strategy (1) becomes more important for mobilizing highly insoluble mineral-bound P. Field application of PSM have shown highly variable responses due to the fact that most PSM are not selected for their rhizosphere competence or for their ability to survive in different soil types.

An overview of Bacillus proteases: from production to application.

Abstract: Proteases have a broad range of applications in industrial processes and products and are representative of most worldwide enzyme sales. The genus Bacillus is probably the most important bacterial source of proteases and is capable of producing high yields of neutral and alkaline proteolytic enzymes with remarkable properties, such as high stability towards extreme temperatures, pH, organic solvents, detergents and oxidizing compounds. Therefore, several strategies have been developed for the cost-effective production of Bacillus proteases, including optimization of the fermentation parameters. Moreover, there are many studies on the use of low-cost substrates for submerged and solid state fermentation. Other alternatives include genetic tools such as protein engineering in order to obtain more active and stable proteases and strain engineering to better secrete recombinant proteases from Bacillus through homologous and heterologous protein expression. There has been extensive research on proteases because of the broad number of applications for these enzymes, such as in detergent formulations for the removal of blood stains from fabrics, production of bioactive peptides, food processing, enantioselective reactions, and dehairing of skins. Moreover, many commercial proteases have been characterized and purified from different Bacillus species. Therefore, this review highlights the production, purification, characterization, and application of proteases from a number of Bacillus species.