Deciphering the seasonal dynamics of microplastic morphotypes and associated co-contaminants along the northwest coast of India

In the present study, the northwest coast of India, bordering the Arabian Sea, was selected to evaluate the microplastic (MP) abundance. This is the first study to emphasize the effects of different seasons on MP distribution. The collected MPs were dried, segregated, and evaluated based on their morphotype, size, color, and polymer type. A total of 1756.6, 7326.6, and 202 particles/kg of sand were estimated in the pre-monsoon, monsoon and post-monsoon seasons, respectively, with a dominance of polypropylene (PP) type of plastic in the pre-monsoon and high-density polyethylene (HDPE) in monsoon and post-monsoon seasons. HDPE and PP collected MPs during the monsoon season were further characterized for associated contaminants. Metal absorbance was detected using SEM-EDX mapping and ICP-MS. The presence of organic compounds (OCs) was analyzed using GC-MS. MPs exhibit distinct associations with metals, among which the HDPE pellet morphotype exhibits a higher range of metal adsorption. Total 61 different OCs were associated with MPs. The HDPE pellets contained the highest amounts of hydrophobic organic compounds. PP pellets were found to contain triglycerides, fatty aldehydes, and alkaloids, along with HOCs. Among morphotypes, pellet forms of MPs were found to adsorb more contaminants. These co-contaminants infiltrate the study area through sewage runoff and shoreline debris deposition, subsequently interacting with MPs. Furthermore, the MP diversity was studied by employing the MP diversity integrated index, which suggests that most of the MP diversity was observed in the pre-monsoon period. The pollution load index employed an MP risk assessment, which presented a low degree of MP contamination. In contrast, the polymer hazard index was calculated as 21650.3 in post-monsoon, placing the area under the extreme danger category. It is evident from the data that the types of MP is more important than their number. Thus, MP morphotypes have importance in the adsorption of co-contaminants.

Monitoring the lipid oxidation and fatty acid profile of oil using algorithm-assisted surface-enhanced Raman spectroscopy

Deep-fat frying of food develops lipid oxidation products that deteriorate oil and pose a health risk. This necessitates the development of a rapid and accurate oil quality and safety detection technique. Herein, surface-enhanced Raman spectroscopy (SERS) and sophisticated chemometric techniques were used for rapid and label-free determination of peroxide value (PV) and fatty acid composition of oil in-situ. In the study, plasmon-tuned and biocompatible Ag@Au core-shell nanoparticle-based SERS substrates were used to obtain optimum enhancement despite matrix interference to efficiently detect the oil components. The potent combination of SERS and the Artificial Neural Network (ANN) method could determine the fatty acid profile and PV with upto 99% accuracy. Moreover, the SERS-ANN method could quantify the low level of trans fats, i.e., < 2%, with 97% accuracy. Therefore, the developed algorithm-assisted SERS system enabled the sleek and rapid monitoring and on-site detection of oil oxidation.

Molecular and structural insights of β-boswellic acid and glycyrrhizic acid as potent SARS-CoV-2 Envelope protein inhibitors

BACKGROUND

Over million people have been infected with SARS-CoV-2 virus worldwide, with around 3% reported deaths till date. A few conventional antiviral treatments have been tried to mitigate the coronavirus. However, many alternative therapeutics are being evaluated worldwide. In the present study, we investigated traditional Indian medicinal compounds antiviral potencies as an effective drug for targeting SARS-CoV-2E. SARS-CoV-2 E protein plays a key role in coronavirus life cycle and is an interesting target for the development of anti-SARS-CoV-2 E drugs.

METHODS

Molecular docking studies of medicinal compounds possessing wide range of pharmacological and antiviral activities against enveloped viruses were evaluated with the computer-aided drug design screening software; PyRx. Twelve medicinal compounds isolated from plants were screened and visualized on Biovia Discovery-Studio. Moreover, SARS-CoV-2 E protein's secondary structural insights were deciphered using Swiss Model and ProFunc web server.

RESULTS

Glycyrrhizic acid, triterpene glycoside isolated from plants of Glycyrrhiza (licorice) showed interactions with envelope protein at chain A: Arg 61, chain B: Phe 23, chain B: Tyr 57, and chain C: Val 25. β- boswellic acid, an ayurvedic herb (pentacyclic terpenoid are produced by Boswellia) represented direct interactions and indirect binding with chain C. Their pharmacological aspects and drug-likeness properties were deduced by DruLiTo. Toxicological assessment, along with their ADME profiling, was validated using vNNADMET. The findings showed that ligands, β-boswellic acid, and glycyrrhizic acid possessed the best bindings, with the target having binding affinity (-9.1 kcal/mol) amongst compounds tested against SARS-CoV-2 E. In-vitro studies reveals the promising effect as potent SARS-CoV-2 E inhibitors. Functionality loss and structural disruptions with ∼90% were observed by UV-spectra and fluorescent based analyses.

CONCLUSION

The study demonstrated that β-boswellic acid, and glycyrrhizic acid are strong SARS-CoV-2 E protein inhibitors. In addition, the work linked GA antiviral activity to its effect on SARS-CoV- 2 E protein that can pave the way for designing antiviral therapeutics.

Effect of Psidium guajava leaves extracts on thermo-lipid oxidation and Maillard pathway born food toxicant acrylamide in Indian staple food

Deep frying of food is a common practice that leads to the formation of lipid oxidation products. These lipid oxidation products have a role in the Maillard reaction, which ultimately leads to the formation of cancer-causing and neurotoxic substance acrylamide. In this regard, the Psidium guajava leaves extract-treated sunflower oil on oxidative stability and acrylamide content in pooris a popular deep-fried staple food in India were studied and compared with synthetic antioxidant butylated hydroxytoluene (BHT) till four frying cycles. P. guajava leaves contain 173.33 ± 1.95 mg GAE/g extract total phenolic content and 20.43 ± 0.25 mg RUE/g extract total flavonoid content. Some of the phytochemicals in the extract were identified and quantified by HPTLC. P. guajava leaves extract (1 g) contained 0.039 mg gallic acid, 0.196 mg rutin, 0.021 mg naringenin, 0.059 mg ferulic acid. The IC50 values for guava leaves extract, BHT, and ascorbic acid were 61.4, 30.4, 26.6 µg/mL, respectively. The peroxide and p-anisidine values indicated that P. guajava leaves extract inhibited lipid oxidation and provided oxidative stability. Pooris fried in P. guajava leaves extract-treated, BHT treated sunflower oil contained a lower acrylamide than pooris fried in control sunflower oil.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at (10.1007/s13197-021-04984-y).

Benefits and challenges of antibody drug conjugates as novel form of chemotherapy

Antibody drug conjugates (ADCs) are an emerging therapeutic modality for targeted cancer treatment. They represent the unique amalgamation of chemotherapy and immunotherapy. ADCs comprise of monoclonal antibodies linked with drugs (payloads) through a chemical linker designed to deliver the cytotoxic moiety to the cancer cells. The present paper is a review of recent clinical advances of each component of ADCs (antibody/linker/payload) and how the individual component influences the activity of ADCs. The review discusses opportunities for improving ADCs efficiency and ways to have a better antibody-based molecular platform, which could substantially increase chemotherapy outcomes. This review casts an outlook on how ADCs enhancement in terms of their pharmacokinetics, therapeutic indexes and safety profiles can overcome the prevailing challenges like drug resistance in cancer treatment. A novel strategy of augmenting antibodies with nanoparticles anticipates a huge success in terms of targeted delivery of drugs in several diseases. Antibody conjugated nanoparticles (ACNPs) are a very promising strategy for the cutting-edge development of chemo/immunotherapies for efficient delivery of payloads at the targeted cancer cells. The avenues of a high drug to antibody ratio (DAR) owing to the selection of broad chemotherapy payloads, regulating drug release eliciting higher avidity of ACNPs over ADCs will be the modern immunotherapeutics. ACNPs carry immense potential to mark a paradigm shift in cancer chemotherapy that may be a substitute for ADCs.

Trans fatty acids in food: A review on dietary intake, health impact, regulations and alternatives

Trans fats are desired by the edible oil industry as they impart firmness, plasticity, and oxidative stability to oil. However, clinical trials have demonstrated the adverse effects of trans fats in food on human health and nutrition. Regulatory actions have been taken up by government and non-government bodies worldwide to eliminate the presence of trans fats in the food supply. The World Health Organization (WHO) has launched a "REPLACE" action plan to eliminate trans-fat from the global food industry by 2023. A few enabling technologies are developed to mitigate trans fats namely, trait-enhanced oils, modification in the hydrogenation process, interesterification, fractionation, blending, and oleogelation. Some of them have the drawback of replacing trans-fat with saturated fats. Interesterification and oleogelation are in-trend techniques with excellent potential in replacing trans fats without compromising the desired functionality and nutritional quality attributes. This review presents an overview of trans fatty acid for example, its dietary intake in food products, possible adverse health impact, regulations, and approaches to reduce the usage of trans fats for food application. PRACTICAL APPLICATION: The requirement for the replacement of trans fatty acids (TFAs) in food supply globally has challenged the food industry to find a novel substitute for trans fats without compromising the desired functionality and nutritional property. This review presents detailed background on trans fats, their health impacts and current trends of reformulation of oils and fats to mitigate their presence in food supply chains. Information compiled in this paper will help food scientists and technologists, chemists, food processors, and retailers as there is an urgent need to find novel technologies and substitutes to replace trans fats in processed foods.

Effect of key regulators in augmenting transcriptional expression of Transglutaminase in Streptomyces mobaraensis

Transglutaminase forms isopeptide bonds in proteins which are helpful in various industrial applications. However, low productivity and high cost are the major bottlenecks for industrial Transglutaminase production. The present study describes the regulatory mechanism of microbial Transglutaminase (MTGase) biosynthesis from Streptomyces mobaraensis and the effect of key regulators to maximize production. The transcriptional responses under the effect of various key modulators of MTGasebiosynthesis were evaluated. Productivity of MTGase with novel biosynthesis approach by regulators augmentation was correlated by transcriptional profiling. The optimization by key modulators by combinational supplementation led to 2-fold rise in activity. The functional attributes, the copy number of MTGase gene and relative changes were assessed by Real-Time quantitative PCR. Protease, MgCl₂, CTAB induced upregulation, whereas PMSF, NaF and bleomycin sulphate showed inhibitory action on MTGase production and activity. The optimization by combinational supplementation of key modulators led to 4.27-fold increase (6.11 IU/mL) in production.

Microbial transglutaminase nanoflowers as an alternative nanomedicine for breast cancer theranostics

Breast cancer is the most common malignancy among women. With the aim of decreasing the toxicity of conventional breast cancer treatments, an alternative that could provide appropriate and effective drug utilization was envisioned. Thus, we contemplated and compared the in vitro effects of microbial transglutaminase nanoflowers (MTGase NFs) on breast cancer cells (MCF-7). Transglutaminase is an important regulatory enzyme acting as a site-specific cross-linker for proteins. With the versatility of MTGase facilitating the nanoflower formation by acting as molecular glue, it was demonstrated to have anti-cancer properties. The rational drug design based on a transglutaminase enzyme-assisted approach led to the uniform shape of petals in these nanoflowers, which had the capacity to act directly as an anti-cancer drug. Herein, we report the anti-cancer characteristics portrayed by enzymatic MTGase NFs, which are biocompatible in nature. This study demonstrated the prognostic and therapeutic significance of MTGase NFs as a nano-drug in breast cancer treatment. The results on MCF-7 cells showed a significantly improved in vitro therapeutic efficacy. MTGase NFs were able to exhibit inhibitory effects on cell viability (IC₅₀-8.23 μg ml⁻¹) within 24 h of dosage. To further substantiate its superior anti-proliferative role, the clonogenic potential was measured to be 62.8%, along with migratory inhibition of cells (3.76-fold change). Drastic perturbations were induced (4.61-fold increase in G0/G1 phase arrest), pointed towards apoptotic induction with a 58.9% effect. These results validated the role of MTGase NFs possessing a cytotoxic nature in mitigating breast cancer. Thus, MTGase bestows distinct functionality towards therapeutic nano-modality, i.e., nanoflowers, which shows promise in cancer treatment.

Development of a novel therapeutic nano-modality in the form of enzymatic transglutaminase nanoflowers; endowed with anti-cancerous action against breast cancers.

A Chemosensor Based on Gold Nanoparticles and Dithiothreitol (DTT) for Acrylamide Electroanalysis

Rapid and simple electroanalysis of acrylamide (ACR) was feasible by a gold electrode modified with gold nanoparticles (AuNPs) and dithiothreitol (DTT) with enhanced detection sensitivity and selectivity. The roughness of bare gold (Au) increased from 0.03 μm to 0.04 μm when it was decorated with AuNPs. The self-assembly between DTT and AuNPs resulted in a surface roughness of 0.09 μm. The DTT oxidation occurred at +0.92 V. The Au/AuNPs/DTT surface exhibited a surface roughness of 0.24 μm after its exposure to ACR with repeated analysis. SEM imaging illustrated the formation of a polymer layer on the Au/AuNPs/DTT surface. Surface plasmon resonance analysis confirmed the presence of AuNPs and DTT on the gold electrode and the binding of ACR to the electrode's active surface area. The peak area obtained by differential pulse voltammetry was inversely proportional to the ACR concentrations. The limit of detection (LOD) and the limit of quantitation (LOQ) were estimated to be 3.11 × 10-9 M and 1 × 10-8 M, respectively, with wide linearity ranging from 1 × 10-8 M to 1 × 10-3 M. The estimated levels of ACR in potato chips and coffee samples by the sensor were in agreement with those of high-performance liquid chromatography.

Antimicrobial resistance in biofilms: Exploring marine actinobacteria as a potential source of antibiotics and biofilm inhibitors

Antimicrobial resistance (AMR) is one of the serious global public health threats that require immediate action. With the emergence of new resistance mechanisms in infection-causing microorganisms such as bacteria, fungi, and viruses, AMR threatens the effective prevention and treatment of diseases caused by them. This has resulted in prolonged illness, disability, and death. It has been predicted that AMR will lead to over ten million deaths by 2050. The rapid spread of multidrug-resistant bacteria is also causing old antibiotics to become ineffective. Among the diverse factors contributing to AMR, intrinsic biofilm development has been highlighted as an essential contributing facet. Moreover, biofilm-derived antibiotic tolerance leads to serious recurrent chronic infections. Therefore, the discovery of novel bioactive molecules is a potential solution that can help combat AMR. To achieve this, sustained mining of novel antimicrobial leads from actinobacteria, particularly marine actinobacteria, can be a promising strategy. Given their vast diversity and different habitats, the extraordinary capacity of actinobacteria can be tapped to synthesize new antibiotics or bioactive molecules for biofilm inhibition. Advanced screening strategies and novel approaches in the field of modern biochemical and molecular biology can be used to detect such new compounds. In view of this, the present review focuses on understanding some of the recent strategies to inhibit biofilm formation and explores the potential role of marine actinobacteria as sources of novel antibiotics and biofilm inhibitor molecules.

One-pot production of lactic acid from rice straw pretreated with ionic liquid

Production of platform chemicals has been advocated as a sustainable option to tackle the problems associated with agro-waste management. In this report, for the first time, efforts were made to effectively produce second-generation lactic acid from rice straw pretreated with imidazolium ionic liquid [EMIM][OAc] and subsequently fermented with a promising Lactobacillus plantarum SKL-22 strain saccharified with a commercial cellulase enzyme. Medium optimization was carried out to enhance the lactic acid (LA) yield by response surface methodology. In a 5 L bioreactor, the process was further upscale, and a yield increment of 1.11% was observed. The process using rice straw as substrate led to a LA yield of 36.75 g/L from L. plantarum SKL-22 in a single pot bioprocess. Overall, the above finding has shown the ability of L. plantarum SKL-22 to produce LA from the hydrolysate of rice straw. This study presented a novel environmental-friendly method for LA production.

Overexpression and repression of key rate-limiting enzymes (acetyl CoA carboxylase and HMG reductase) to enhance fatty acid production from Rhodotorula mucilaginosa

Implementing two-way strategies to enhance the lipid production in Rhodotorula mucilaginosa with the help of metabolic engineering was focused on the overexpression of acetyl coenzyme A carboxylase (ACC1 carboxylase) gene and repression of 3-hydroxy 3-methylglutaryl reductase (HMG-CoA reductase). Using an inducer (sodium citrate) and inhibitor (rosuvastatin), the amounts of biomass, lipid, and carotenoid were estimated. In the presence of inhibitor (200 mM), 62% higher lipid concentration was observed, while 44% enhancement was recorded when inducer (3 mM) was used. A combination of both inhibitor and inducer resulted in a 57% increase in lipid concentration by the oleaginous yeast. These results were again confirmed by real-time polymerase chain reaction by targeting the expression of the genes coding for ACC1 carboxylase and 13-fold increase was recorded in the presence of inducer as compared with control. This combined strategy (inducer and inhibitor use) has been reported for the first time as far as the best of our knowledge. The metabolic engineering strategies reported here will be a powerful approach for the enhanced commercial production of lipids.

Ecological and toxicological manifestations of microplastics: current scenario, research gaps, and possible alleviation measures

Microplastics (MPs) and associated contaminants have become a major environmental concern. From available literature, their ubiquitous presence is now well established. However, the kind and level of toxicological impacts these MPs accomplish on various life forms are not well understood. Nevertheless, the environmental toxicity of MP is now being revealed gradually with supporting studies involving groups of lower organisms. Additionally, the presence of microplastics also disturbs the functions of ecosystem through affecting the vulnerable life forms, thus ecological manifestations of MPs also need to be analyzed. The present review encompasses an overview of toxicological effects mediated by various types of MPs present in the environment; it covers the types of toxicity they may cause and other effects on humans and other species. In this review, aquatic systems are used as primary models to describe various eco-toxicological effects of MPs. Various research gaps as well as methods to alleviate the level of MPs, and future strategies are also comprehensively highlighted in the review.

Utilization of agro-industrial waste for production of Transglutaminase from Streptomyces mobaraensis

This work studied the production of Transglutaminase (TGase) using wheat bran as carbon source. The medium components and culture conditions were optimized by statistical Box-Behnken response surface methodology. The release of active Transglutaminase was enhanced by adding (i) protease to remove pro-region to make inactive enzyme to active form, (ii) Cetyl trimethyl ammonium bromide (CTAB) which facilitated more secretion. Under finally optimized conditions viz. 5 g wheat bran, protease: 39.14 U, magnesium chloride (MgCl₂): 0.10 M, CTAB: 0.08% and inoculation size: 2% led to 4-fold (12.949 ± 0.061 IU/g) increased TGase production over that of un-optimized conditions. The application of TGase was shown to be useful in effective casein cross-linking.

Statistical and sequential (fill-and-draw) approach to enhance rhamnolipid production using industrial lignocellulosic hydrolysate C6 stream from Achromobacter sp. (PS1)

Statistical optimization using industrial rice-straw hydrolysate (C₆ stream) containing 5.0% total sugars was carried out for enhancing the rhamnolipid production from Achromobacter sp. (PS1) with subsequent adoption of a sequential fermentation approach with fill-and-draw operation for further increment. The interactive effects of six influential variables obtained from one-factor-at-a-time approach as sodium nitrate, yeast extract, ferrous sulphate, phosphate concentrations and agitation in presence of lignocellulosic hydrolyzed sugars as a basal medium using central composite design revealed the experimental rhamnolipid yield of 5.46 g/L at optimum conditions of total sugars 40 g/L (w/v), sodium nitrate 6.0 (g/L), yeast extract 2 (g/L), ferrous sulphate 0.2 (mg/L) and phosphate 1000 mM at 100 rpm at 30 °C in 8 days. The sequential approach further resulted in an overall yield of 19.35 g/L of rhamnolpid in five sequential-cycles with an increase of 258% over the batch process on account of nutrients replenishment and dilution of toxic by-products.

Refolding of thermally denatured cholesterol oxidases by magnetic nanoparticles

Proteins are prone to unfolding and subsequent denaturation by changes in temperature, pH and other harsh conditions. Nanoparticles act as artificial 'chaperones' due to favourable orientation of the proteins on their scaffold which prevents aggregation and reconfigures denatured proteins into their native functional state. In the present study, thermal denaturation of Cholesterol oxidases from Pseudomonas aeruginosa PseA, Rhodococcus erythropolis MTCC 3951 and Streptomyces sp. were studied at temperatures 50-70 °C. Further, these thermally denatured proteins were refolded using functionalized Magnetic Iron (II, III) oxide nanoparticles which was confirmed using DLS, Zeta Potential Measurements, fluorescence and CD spectroscopy. The refolded proteins were found to regain their secondary structure and activity to a great extent.

Proteomic profiling of Sporotrichum thermophile under the effect of ionic liquids: manifestation of an oxidative stress response

Sporotrichum thermophile, a known producer of industrial enzymes exhibited stability in the presence of ionic liquids (ILs).The study reports, for the first time, the stress response of S. thermophile upon exposure to ILs. In vitro assay showed increased anti-oxidative enzyme levels indicating ROS-mediated oxidative stress by ILs. The proteomic profile and identification of differential proteins confirmed the fungal adaptations by (i) increased expression of glycolytic enzymes and ATP synthases (ii) downregulation of TCA cycle and protein synthesis machinery components (iii) expression of HSP70 and catalase/peroxidase. These changes are indicative of metabolic regulation of many important pathways and how ILs can be used to manipulate protein behavior.

Thermozymes: Adaptive strategies and tools for their biotechnological applications

In today's scenario of global climate change, there is a colossal demand for sustainable industrial processes and enzymes from thermophiles. Plausibly, thermozymes are an important toolkit, as they are known to be polyextremophilic in nature. Small genome size and diverse molecular conformational modifications have been implicated in devising adaptive strategies. Besides, the utilization of chemical technology and gene editing attributions according to mechanical necessities are the additional key factor for efficacious bioprocess development. Microbial thermozymes have been extensively used in waste management, biofuel, food, paper, detergent, medicinal and pharmaceutical industries. To understand the strength of enzymes at higher temperatures different models utilize X-ray structures of thermostable proteins, machine learning calculations, neural networks, but unified adaptive measures are yet to be totally comprehended. The present review provides a recent updates on thermozymes and various interdisciplinary applications including the aspects of thermophiles bioengineering utilizing synthetic biology and gene editing tools.

Efficacy of ureolytic Enterobacter cloacae EMB19 mediated calcite precipitation in remediation of Zn (II)

In this study, urease mediated calcite precipitation technique was used for remediation of Zn (II). A urease positive Enterobacter cloacae EMB19 was used to produce calcite impregnated with Zn ions. In co-presence of Ca (II), Zn (II) concentrations of 10 and 20 mg L^-1 were completely remediated by the bacterium from the media at 72 and 96 h of incubation, respectively. Co-precipitation of Ca (II) and Zn (II) to form calcite-Zn precipitate is one of the major mechanisms of Zn remediation in the present study. Role of urease in calcite-Zn precipitation was substantiated by using urease/carbonate and ammonium enriched cell free culture supernatant (CFS) obtained after sufficient microbial growth. Using CFS, 68% removal of initial 50 mg L^-1 Zn (II) was detected. Energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction pattern (XRD) of the precipitate supports calcite mediated remediation of Zn. Remediation of multiple metals viz. Cd, Zn, Cu was also analyzed using CFS laden with urease. The preparation showed 40% Cd, 23% Zn, and 8% Cu reduction from the solution containing initial 25 mg L^-1 of each metal. Overall, it can be concluded that, the E. cloacae mediated calcite precipitation technique could effectively be used for alleviation of Zn (II) and other heavy metals from the contaminated environment.

Role of Musa paradisiaca ascorbate peroxidase in the transformation of methyl phenyl sulfide to its sulfoxide

An ascorbate peroxidase from a new source Musa paradisiaca leaf juice has been purified to homogeneity using a simple procedure involving concentration by ultra filtration and anion exchange chromatography on diethyl amino ethyl [DEAE] cellulose column. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis [SDS-PAGE] analysis of the purified enzyme has shown a single protein band of molecular mass 208.9 kDa which has been confirmed by native-PAGE and intact mass analysis by mass spectrometry. The Km and k_cat values of the enzyme using ascorbate and H₂O₂ as the variable substrates were 0.13 m mol L^-1, 40.42 s^-1 and 0.23 m mol L^-1, 27.24 s^-1, respectively. The pH and temperature optima of the enzyme were 7.0 and 298 K, respectively. The enzyme transformed approximately 97% methyl phenyl sulfide to its sulfoxide. The product was racemic mixture.

Stability and structure of Penicillium chrysogenum lipase in the presence of organic solvents

The present work describes the enzymatic properties of Penicillium chrysogenum lipase and its behavior in the presence of organic solvents. The temperature and pH optima of the purified lipase was found to be 55 °C and pH 8.0 respectively. The lipase displayed remarkable stability in both polar and non-polar solvents upto 50% (v/v) concentrations for 72 h. A structural perspective of the purified lipase in different organic solvents was gained by using circular dichroism and intrinsic fluorescence spectroscopy. The native lipase consisted of a predominant α-helix structure which was maintained in both polar and non-polar solvents with the exception of ethyl butyrate where the activity was decreased and the structure was disrupted. The quenching of fluorescence intensity in the presence of organic solvents indicated the transformation of the lipase microenviroment P. chrysogenum lipase offers an interesting system for understanding the solvent stability mechanisms which could be used for rationale designing of engineered lipase biocatalysts for application in organic synthesis in non-aqueous media.

Current insight and futuristic vistas of microbial transglutaminase in nutraceutical industry

Microbial transglutaminase (MTGase) has become a driving force in the food industry cross-linking the food proteins. MTGase-the nature's molecular glue is recognized to reorient food protein's functional properties without affecting its nutritive value. The scope and approach of this review is to have insight on the action mechanism of MTGase and impact of molecular linkage on functional proteins in various protein moieties in development of innovative features in food production for better consumer's choice and satisfaction. The study covers a wide range of published work across food industries involving innovative use of MTGase, an environment friendly production approach for commercial utilization to get better outcome in terms of culinary delight. The intrinsic biochemical properties and structural information by sequence analysis and clustering validates the mode of reaction mechanism of the biological glue enzyme. The review singles out how the MTGase emerged as a prime choice in ever evolving food industry.

Harnessing the bio-mineralization ability of urease producing Serratia marcescens and Enterobacter cloacae EMB19 for remediation of heavy metal cadmium (II)

In the present study, urease positive Serratia marcescens (NCIM2919) and Enterobacter cloacae EMB19 (MTCC10649) were individually evaluated for remediation of cadmium (II) using ureolysis-induced calcium carbonate precipitation. Both the cultures were observed to efficiently remove cadmium from the media through co-precipitation of Cd (II) and Ca (II). S. marcescens and E. cloacae EMB19, respectively showed 96 and 98% removal of initial 5.0 mg L^-1 soluble Cd (II) from the urea and CaCl₂ laden media at 96 h of incubation period. At higher Cd (II) concentrations of 10 and 15 mg L^-1, cadmium removal efficiency was much higher in case of E. cloacae EMB19 compared to S. marcescens. In-vitro cadmium (II) remediation study using urease containing cell-free culture supernatant of S. marcescens and E. cloacae EMB19 showed respective 98 and 53% removal of initial 50 mg L^-1 Cd (II) from the reaction mixtures in co-presence of Ca (II). While in sole presence of Cd (II), only 16 and 8% removal of Cd (II) were detected for S. marcescens and E. cloacae EMB19, respectively. The elemental analysis of the co-precipitated mineral products using Energy Dispersive X-ray spectroscopy (EDX) clearly showed the prevalence of Ca and Cd ions. The morphology Cd-Ca composites formed with respect to both the cultures were observed to be of different shape and size as revealed through Scanning Electron Microscopy (SEM). Entire study hence comes out with a sustainable bioremediation option which could be effectively used to tackle Cd (II) or other heavy metal pollution.

One-pot bioprocess for lactic acid production from lignocellulosic agro-wastes by using ionic liquid stable Lactobacillus brevis

The lignocellulosic agro-wastes are an attractive renewable resource in biorefinery for production of value-added platform chemicals and biofuels. The study describes use of different agro-wastes as substrate for production of lactic acid, a C3-platform chemical and high demand industrial product by Lactobacillus brevis in a one-pot bioprocess. The simultaneous saccharification and co-fermentation (SSCF) process was achieved by L. brevis governed fermentation of sugars, derived from saccharification of ionic liquid pretreated feedstocks by nanoimmobilized cellulase, which was further recovered and used for consecutive cycle. The lactic acid yields of 0.22, 0.49, 0.52 g/g were obtained from cottonseed cake, wheat straw and sugarcane bagasse, respectively. The ionic liquid-tolerant L. brevis, cellulolytic reusable nanoimmobilized enzyme coupled with valorization of renewable feedstocks points towards a holistic approach for future biorefineries with sustainable production of bioproducts.

Potential of ionic liquids for inhibiting the growth and β-lactamase production by Bacillus cereus EMB20

Present work reports the inhibition of Bacillus cereus EMB20 β-lactamase by a deep eutectic solvent, maline in an uncompetitive manner. Far-UV CD and intrinsic fluorescence spectroscopy revealed a disrupted secondary as well as tertiary structure as a function of maline concentration. The effect of individual components of maline on β-lactamase inhibition showed that malonic acid was mainly responsible for inhibiting the β-lactamase. Structural and docking studies found that malonic acid led to major perturbations in the secondary and tertiary structure of the enzyme while H-bonding with the active site residues. Further the antibacterial and cytotoxic studies also confirmed the potential of maline as a potent growth inhibitor of β-lactamase producing B. cereus EMB20.

Three phase partitioning and spectroscopic characterization of bioactive constituent from halophilic Bacillus subtilis EMB M15

In the present study, a halophilic Bacillus subtilis subsp. spizizenii (NCBI GenBank accession number KX109607) was isolated from the Sambhar Salt Lake, Rajasthan India. This organism exhibited significance antibacterial and antifungal activity against Proteus vulgaris, Bacillus subtilis, Aspergillus niger, Rhizopus oligosporus and Penicillium chrysogenum respectively. The bioactive constituent responsible for it was extracted by three phase partitioning and purified by column chromatography. The purified compound was further characterized by FTIR-ATR, NMR and Mass spectrometry. The mass spectra show a molecular ion of m/z 301.14. The compound has very high antimicrobial activity showing 35mm zone of inhibition against Bacillus subtilis.

Development of cellulase-nanoconjugates with enhanced ionic liquid and thermal stability for in situ lignocellulose saccharification

The present work aimed to improve catalytic efficiency of Trichoderma reesei cellulase for enhanced saccharification. The cellulase was immobilized on two nanomatrices i.e. magnetic and silica nanoparticles with immobilization efficiency of 85% and 76% respectively. The nanobioconjugates exhibited increase in V_max, temperature optimum, pH and thermal stability as compared with free enzyme. These could be efficiently reused for five repeated cycles and were stable in 1-ethyl-3-methylimidazoliumacetate [EMIM][Ac], an ionic liquid. Ionic liquids (IL) are used as green solvents to dissolve lignocellulosic biomass and facilitate better saccharification. The cellulase immobilized on magnetic nanoparticles was used for in situ saccharification of [EMIM][Ac] pretreated sugarcane bagasse and wheat straw for two cycles. The structural deconstruction and decrease in biomass crystallinity was confirmed by SEM, XRD and FTIR. The high hydrolysis yields (∼89%) obtained in this one-pot process coupled with IL stability and recycled use of immobilized cellulase, potentiates its usefulness in biorefineries.

Structure and Functional Characterisation of a Distinctive β-Lactamase from an Environmental Strain EMB20 of Bacillus cereus

The rampant use and misuse of antibiotics in human medicine, agriculture and veterinary have become the key contributors to global antimicrobial resistance. One of the significant resistance mechanisms that inactivates antibiotics and impedes treatment of bacterial infections is the expression of β-lactamases. Rising evidence of newer variants of β-lactamases in the environment is therefore a serious threat to the presently available antibiotic armoury. The present work describes the purification of a variant β-lactamase isolated from a soil strain EMB20 of Bacillus cereus. The lactamase was purified using three-phase partitioning and gel filtration chromatography to a 30-fold purification and 15% recovery yield. Contrary to the general trend, the lactamase was not a metalloenzyme, but its activity was enhanced in the presence of Mg²⁺ and Mn²⁺. The EMB20 lactamase exhibited improved stability against inhibitors and denaturing agents such as urea and GdmCl as compared to its commercial analogue. The improved stability of EMB20 lactamase was further validated by circular dichroism and fluorescence spectroscopy. This study reemphasizes the rising prevalence of environmental lactamase variants. Decoding the structure-function correlation of such lactamases in the presence of inhibitors will provide insights into the response of this enzyme towards inhibitors as well as its substrates.

Biodegradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) by using Serratia marcescens NCIM 2919

A solvent tolerant bacterium Serratia marcescens NCIM 2919 has been evaluated for degradation of DDT (1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane). The bacterium was able to degrade up to 42% of initial 50 mg L^-1 of DDT within 10 days of incubation. The highlight of the work was the elucidation of DDT degradation pathway in S. marcescens. A total of four intermediates metabolites viz. 2,2-bis (chlorophenyl)-1,1-dichloroethane (DDD), 2,2-bis (chlorophenyl)-1,1-dichloroethylene (DDE), 2,2-bis (chlorophenyl)-1-chloroethylene (DDMU), and 4-chlorobenzoic acid (4-CBA) were identified by GC-Mass and FTIR. 4-CBA was found to be the stable product of DDT degradation. Metabolites preceding 4-CBA were not toxic to strain as reveled through luxuriant growth in presence of varying concentrations of exogenous DDD and DDE. However, 4-CBA was observed to inhibit the growth of bacterium. The DDT degrading efficiency of S. marcescens NCIM 2919 hence could be used in combination with 4-CBA utilizing strains either as binary culture or consortia for mineralization of DDT. Application of S. marcescens NCIM 2919 to DDT contaminated soil, showed 74.7% reduction of initial 12.0 mg kg^-1 of DDT after 18-days of treatment.

Biodegradation of cytotoxic 7-Ketocholesterol by Pseudomonas aeruginosa PseA

The present study aims to degrade 7-Ketocholesterol (7KC), a major oxysterol implicated in many age-related disorders, through microbial means and find candidate enzymes involved for further application in food systems and as a therapeutic. During initial screening of previously isolated bacteria from our laboratory, Pseudomonas aeruginosa PseA was found to be a potential degrader strain using 7KC as a sole carbon source. Under optimized conditions, it is able to degrade 88% of an initial concentration of 1000ppm (1g/l) 7KC. Preliminary in vitro studies with extra-cellular extract has shown degradation of the compound, thus reinforcing the occurrence of suitable enzymatic systems involved in the process. We have been able to identify cholesterol oxidase as one such potential enzyme. Some intermediate products of degradation have also been identified. This is the first detailed report of 7KC degradation by a P. aeruginosa strain.

Effect of organic solvents on the structure and activity of moderately halophilic Bacillus sp. EMB9 protease

Halophilic enzymes have been manifested for their stability and catalytic abilities under harsh operational conditions. These have been documented to withstand denaturation in presence of high temperature, pH, presence of organic solvents and chaotropic agents. The present study aims at understanding the stability and activity of a halophilic Bacillus sp. EMB9 protease in organic solvents. The protease was uniquely stable in polar solvents. A clear correlation was evident between the protease function and conformational transitions, validated by CD and fluorescence spectral studies. The study affirms that preservation of protein structure, possibly due to charge screening of the protein surface by Ca(2+) and Na(+) ions provides stability against organic solvents and averts denaturation. Salt was also found to exert a protective effect on dialyzed protease against chaotropism of solvents. Presence of 1 % (w/v) NaCl restored the activity in the dialyzed protease and prevented denaturation in methanol, toluene and n-decane. The work will have further implication on discerning protein folding in saline as well as non-aqueous environments.

Protective role of salt in catalysis and maintaining structure of halophilic proteins against denaturation

Search for new industrial enzymes having novel properties continues to be a desirable pursuit in enzyme research. The halophilic organisms inhabiting under saline/ hypersaline conditions are considered as promising source of useful enzymes. Their enzymes are structurally adapted to perform efficient catalysis under saline environment wherein n0n-halophilic enzymes often lose their structure and activity. Haloenzymes have been documented to be polyextremophilic and withstand high temperature, pH, organic solvents, and chaotropic agents. However, this stability is modulated by salt. Although vast amount of information have been generated on salt mediated protection and structure function relationship in halophilic proteins, their clear understanding and correct perspective still remain incoherent. Furthermore, understanding their protein architecture may give better clue for engineering stable enzymes which can withstand harsh industrial conditions. The article encompasses the current level of understanding about haloadaptations and analyzes structural basis of their enzyme stability against classical denaturants.

Production of Sporotrichum thermophile xylanase by solid state fermentation utilizing deoiled Jatropha curcas seed cake and its application in xylooligosachharide synthesis

De-oiled Jatropha curcas seed cake, a plentiful by-product of biodiesel industry was used as substrate for the production of a useful xylanase from Sporotrichum thermophile in solid state fermentation. Under the optimized conditions, 1025U xylanase/g (deoiled seed cake) was produced. The xylanase exhibited half life of 4h at 45°C and 71.44min at 50°C respectively. It was stable in a broad pH range of 7.0-11.0. Km and Vmax were 12.54mg/ml and 454.5U/ml/min respectively. S. thermophile xylanase is an endoxylanase free of exoxylanase activity, hence advantageous for xylan hydrolysis to produce xylooligosachharides. Hydrolysis of oat spelt xylan by S. thermophile xylanase yielded 73% xylotetraose, 15.4% xylotriose and 10% xylobiose. The S. thermophile endoxylanase thus seem potentially useful in the food industries.

Characterization of detergent compatible protease of a halophilic Bacillus sp. EMB9: differential role of metal ions in stability and activity

A moderately halophilic protease producer, Bacillus sp. strain isolated from sea water is described. The protease is purified to homogeneity by ammonium sulphate precipitation and CM cellulose chromatography. The serine protease has a molecular mass of 29 kDa. Enzymatic characterization of protease revealed K(m) 2.22 mg mL(-1), Vmax 1111.11 U mL(-1), pH optimum 9.0, t1/2 190 min at 60°C and salt optima 1% (w/v) NaCl. The protease is remarkably stable in hydrophilic and hydrophobic solvents at high concentrations. The purified preparation is unstable at room temperature. Ca(2+) ions are required for preventing this loss of activity. Interestingly, the activity and stability are modulated differentially. Whereas, divalent cation Ca(2+) are involved in maintaining stability in solution at room temperature by preventing unfolding, monovalent Na(+) and K(+) ions participate in regulating the activity and assist in refolding of the enzyme. Application of the protease is shown in efficient removal of blood stain.

Purification and characterization of maltooligosaccharide-forming α-amylase from moderately halophilic Marinobacter sp. EMB8

Maltooligosaccharides especially maltotriose and maltotetraose producing amylases are highly desirable for application in bread making and other food industries. A maltotriose and maltotetraose producing amylase from moderately halophilic Marinobacter sp. EMB8 is described. Under optimized culture conditions, 48.0 IU/mL amylase was obtained. The enzyme was purified to homogeneity by ultrafiltration, DEAE cellulose and Sephadex G-75 column chromatography with 52% yield and 76-fold purification. It was a monomeric protein of 72 kDa. The amylase had many novel features viz. stability up to 20% NaCl, 80 °C temperature, pH 6.0-11.0 and in wide range of organic solvents at high concentrations. The enzyme efficiently hydrolyzed starch into maltooligosaccharides rich in maltotriose and maltotetraose. These novel properties make the Marinobacter sp. amylase a potentially useful enzyme.

Comparative one-factor-at-a-time, response surface (statistical) and bench-scale bioreactor level optimization of thermoalkaline protease production from a psychrotrophic Pseudomonas putida SKG-1 isolate

BACKGROUND

Production of alkaline protease from various bacterial strains using statistical methods is customary now-a-days. The present work is first attempt for the production optimization of a solvent stable thermoalkaline protease by a psychrotrophic Pseudomonas putida isolate using conventional, response surface methods, and fermentor level optimization.

RESULTS

The pre-screening medium amended with optimized (w/v) 1.0% glucose, 2.0% gelatin and 0.5% yeast extract, produced 278 U protease ml(-1) at 72 h incubation. Enzyme production increased to 431 Uml(-1) when Mg2+ (0.01%, w/v) was supplemented. Optimization of physical factors further enhanced protease to 514 Uml(-1) at pH 9.0, 25°C and 200 rpm within 60 h. The combined effect of conventionally optimized variables (glucose, yeast extract, MgSO4 and pH), thereafter predicted by response surface methodology yielded 617 U protease ml(-1) at glucose 1.25% (w/v), yeast extract 0.5% (w/v), MgSO4 0.01% (w/v) and pH 8.8. Bench-scale bioreactor level optimization resulted in enhanced production of 882 U protease ml(-1) at 0.8 vvm aeration and 150 rpm agitation during only 48 h incubation.

CONCLUSIONS

The optimization of fermentation variables using conventional, statistical approaches and aeration/agitation at fermentor level resulted in ~13.5 folds increase (882 Uml(-1)) in protease production compared to un-optimized conditions (65 Uml(-1)). This is the highest level of thermoalkaline protease reported so far by any psychrotrophic bacterium.

Stability of haloalkaliphilic Geomicrobium sp. protease modulated by salt

A novel protease from the halophilic bacterium Geomicrobium sp. EMB2 (MTCC 10310) is described. The activity of the protease was modulated by salt, and it exhibited remarkable stability in organic solvents, at alkaline pH, and in other denaturing conditions. The structural changes under various denaturing conditions were analyzed by measurements of intrinsic fluorescence and circular dichroism spectroscopy. Circular dichroism showed that the secondary structure of the protease was predominantly α-helical but unfolded in salt-free medium. The structure is regained by inclusion of NaCl in the range of 2-5%. The presence of NaCl exerted a protective effect against thermal, organic solvent, and guanidine hydrochloride denaturation by preventing unfolding.

Degradation of phorbol esters by Pseudomonas aeruginosa PseA during solid-state fermentation of deoiled Jatropha curcas seed cake

Large amount of seed cake is generated as by-product during biodiesel production from Jatropha seeds. Presence of toxic phorbol esters restricts its utilization as livestock feed. Safe disposal or meaningful utilization of this major by-product necessitates the degradation of these phorbol esters. The present study describes the complete degradation of phorbol esters by Pseudomonas aeruginosa PseA strain during solid state fermentation (SSF) of deoiled Jatropha curcas seed cake. Phorbol esters were completely degraded in nine days under the optimized SSF conditions viz. deoiled cake 5.0 g; moistened with 5.0 ml distilled water; inoculum 1.5 ml of overnight grown P. aeruginosa; incubation at temperature 30 °C, pH 7.0 and RH 65%. SSF of deoiled cake seems a potentially viable approach towards the complete degradation of the toxic phorbol esters.

Mercury bioaccumulation and simultaneous nanoparticle synthesis by Enterobacter sp. cells

A mercury resistant strain of Enterobacter sp. is reported. The strain exhibited a novel property of mercury bioaccumulation with simultaneous synthesis of mercury nanoparticles. The culture conditions viz. pH 8.0 and lower concentration of mercury promotes synthesis of uniform sized 2-5 nm, spherical and monodispersed intracellular mercury nanoparticles. The remediated mercury trapped in the form of nanoparticles is unable to vaporize back into the environment thus, overcoming the major drawback of mercury remediation process. The mercury nanoparticles were recoverable. The nanoparticles have been characterized by high resolution transmission electron microscopy, energy dispersive X-ray analysis, powder X-ray diffraction and atomic force microscopy. The strain can be exploited for metal bioaccumulation from environmental effluent and developing a green process for nanoparticles biosynthesis.

Utilization of deoiled Jatropha curcas seed cake for production of xylanase from thermophilic Scytalidium thermophilum

Jatropha curcas is a major biodiesel crop. Large amount of deoiled cake is generated as by-product during biodiesel production from its seeds. Deoiled J. curcas seed cake was assessed as substrate for the production of xylanase from thermophilic fungus Scytalidium thermophilum by solid-state fermentation. The seed cake was efficiently utilized by S. thermophilum for its growth during which it produced good amount of heat stable extracellular xylanase. The solid-state fermentation conditions were optimized for maximum xylanase production. Under the optimized conditions viz. deoiled seed cake supplemented with 1% oat-spelt xylan, adjusted to pH 9.0, moisture content 1:3 w/v, inoculated with 1×10(6) spores per 5 g cake and incubated at 45 °C, 1455 U xylanase/g deoiled seed cake was obtained. The xylanase was useful in biobleaching of paper pulp. Solid-state fermentation of deoiled cake appears a potentially viable approach for its effective utilization.