Raman microscopy tracks maturity of melanin intermediates in Botrytis cinerea, a plant pathogen.

We use Raman microscopy to describe the structure and chemical composition of both conidiophore and hyphae of Botrytis cinerea, a common plant pathogen. To interpret experimental data, we use density functional theory (DFT) to compute Raman tensors specific to an important fungal glycopeptide, a segment of α-chitin, and several naphthalene-based precursors of increasing complexity, which we propose play a role in the melanin synthesis pathway. Using spectral interpretations based on quantum chemical validation, we review microscopy images reconstructed for specific Raman activities and describe differences in distributions of structural components, photo-protective secondary naphthalene-based pigments, and proteins in both spores and hyphal filaments. Comparison of our results with literature data on other fungi suggests an example of convergent evolution expressed at the level of secondary metabolites specific to plant pathogenic fungi. Our results indicate that pre-resonant Raman monitoring of melanin precursors may help assessment of local Botrytis population biology to aid agricultural production.

Production and characterization of Komagataeibacter xylinus SGP8 nanocellulose and its calcite based composite for removal of Cd ions.

In the present study, fermentative production of bacterial nanocellulose (BNC) by using Komagataeibacter xylinus strain SGP8 and characterization of nanocellulose is presented. The bacterium was able to produce 1.82 g L-1 of cellulose in the form of pellicle in standard Hestrin-Schramn (HS) medium. The morpho-structural characterization of the BNC using scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies, respectively revealed nanofibrillar structure and high crystallinity index (~86%). The thermogravimetric analysis (TGA) showed the stability of BNC up to 280 °C, further rise in temperature to 350 °C results in depolymerization of the sample. In order to show the applicability of produced BNC, it was modified first using calcite (CaCO3) and thereafter characterized using SEM, XRD, FTIR, and TGA studies. The BNC-CaCO3 composites as a sorbent resulted in >99% removal of initial 10 mg L-1 of Cd (II) at pH 5, 7 and 9 after 12 h of treatment. Moreover, the composite was also found to be competent in removing high concentrations of Cd (25 and 50 mg L-1) from the solution (69-70%). Overall, the above results suggest that cellulose produced by K. xylinus strain SGP8 showed excellent material properties, and modified BNC (BNC-CaCO3 composite) could effectively be used for remediation of toxic levels of Cd from the contaminated system.

Synthesis of cost-effective magnetic nano-biocomposites mimicking peroxidase activity for remediation of dyes.

The present study describes preparation of cellulose incorporated magnetic nano-biocomposites (CNPs) by using cellulose as base material. The prepared CNPs were characterised by SEM, EDAX, TEM, XRD, and FT-IR and found to exhibit an intrinsic peroxidase-like activity with a Km and Vmax of 550 µM and 3.8 µM/ml/min, respectively. The CNPs exhibited higher pH and thermal stability compared to commercial peroxidase. These nanocomposites were able to completely remove (i) a persistent azo dye, methyl orange at a concentration of 50 ppm, within 60 min under acidic conditions (pH 3.0) and also (ii) decolourize commercial textile dye mixture under acidic conditions within 30 min. CNP-mediated degradation of dyes into simple products was further confirmed by UV-Vis and AT-IR spectroscopy The added advantage of CNPs separation after decolourization by simple magnet due to their magnetic properties and consequent reusability makes them fairy attractive system for dye remediation from environmental samples or textile industries effluents.

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.

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.

Structure and Functional Characterisation of a Distinctive ß-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 ß-lactamases. Rising evidence of newer variants of ß-lactamases in the environment is therefore a serious threat to the presently available antibiotic armoury. The present work describes the purification of a variant ß-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.

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

Present work reports the inhibition of Bacillus cereus EMB20 ß-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 ß-lactamase inhibition showed that malonic acid was mainly responsible for inhibiting the ß-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 ß-lactamase producing B. cereus EMB20.

A structural study on the protection of glycation of superoxide dismutase by thymoquinone.

Accumulation of advanced glycation end products (AGEs) in tissues and serum plays important roles in diabetes-associated complications. Therefore, the identification of antiglycating compounds is attracting considerable interest. In this study, the structural changes associated with the glycation of superoxide dismutase (SOD) and its protection by thymoquinone (TQ) have been investigated by biophysical techniques. Incubation of SOD with glucose, methylglyoxal (MG) or both at 37̊C resulted in progressive hyperchromicity at 280nm, intrinsic fluorescence quenching at 310nm, decrease in negative ellipticity at 208nm, AGE-specific fluorescence enhancement in the wavelength range 400-480nm and Thioflavin T (ThT) fluorescence enhancement at 480nm (fibrillar state enhancement). Therefore, glycation by glucose or MG induced both tertiary and secondary structural changes in SOD and formation of AGEs and fibrils. The changes were more and faster with MG than with glucose since MG is a stronger glycating agent than glucose. TQ offered protection against glucose or MG-induced glycation of SOD as observed by a reduction in the structural changes, formation of AGEs and fibrils. Thus, TQ can be used for reducing diabetic complications many of which are due to protein glycation.

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.

Xeroderma pigmentosum with melanoma of face and its prosthetic management.

Xeroderma pigmentosum is a rare genetic disorder, characterized by cutaneous, ocular and neurological symptoms. Squamous cell carcinoma and melanoma are also its secondary characters. This case report is about maxillofacial prosthetic management of a 10 years old child presented with xeroderma pigmentosum. The nose of the patient was excised surgically due to melanoma. This case report elaborates the role of prosthodontist and the whole procedure of constructing the nasal prosthesis via conventional technique by using the patient's sibling nasal form as template. Regular follow up revealed marked improvement in esthetics, function and ultimately patient's quality of life.