Vikas Pruthi

Potential applications of ferulic acid from natural sources

Ferulic acid (FA), a ubiquitous natural phenolic phytochemical present in seeds, leaves, bothin its free form and covalently conjugated to the plant cell wall polysaccharides, glycoproteins,polyamines, lignin and hydroxy fatty acids. FA plays a vital role in providing the rigidity to the cell wall and formation of other important organic compounds like coniferyl alcohol, vanillin, sinapic, diferulic acid and curcumin. FA exhibits wide variety of biological activities such as antioxidant, antiinflammatory, antimicrobial, antiallergic, hepatoprotective, anticarcinogenic, antithrombotic, increase sperm viability, antiviral and vasodilatory actions, metal chelation, modulation of enzyme activity, activation of transcriptional factors, gene expression and signal transduction.

Rapid identification of biosurfactant-producing bacterial strains using a cell surface hydrophobicity technique

Rapid identification of biosurfactant-producing bacterial strains was achieved by assaying cell surface hydrophobicity which had a direct correlation with biosurfactant production by Serratia marcescens, Pseudomonas aeruginosa, Bacillus pumilus, B. laterosporus, Acineto- bacter calcoaceticus, Escherichia coli and Staphylococcus aureus. These properties namely, Hydrophobic Interaction Chromatography, Salt Aggregation Test, Bacterial Adherence To Hydrocarbon and adhesion to polystyrene by Replica Plate test, provide a simple means for identifying bacteria associated with the production of biosurfactants.

Rapid efficient synthesis and characterization of silver, gold, and bimetallic nanoparticles from the medicinal plant Plumbago zeylanica and their application in biofilm control

Background Nanoparticles (NPs) have gained significance in medical fields due to their high surface-area-to-volume ratio. In this study, we synthesized NPs from a medicinally important plant – Plumbago zeylanica. Materials and methods Aqueous root extract of P. zeylanica (PZRE) was analyzed for the presence of flavonoids, sugars, and organic acids using high-performance thin-layer chromatography (HPTLC), gas chromatography-time of flight-mass spectrometry (GC-TOF-MS), and biochemical methods. The silver NPs (AgNPs), gold NPs (AuNPs), and bimetallic NPs (AgAuNPs) were synthesized from root extract and characterized using ultraviolet-visible spectra, X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The effects of these NPs on Acinetobacter baumannii, Staphylococcus aureus, and Escherichia coli biofilms were studied using quantitative biofilm inhibition and disruption assays, as well as using fluorescence, scanning electron microscopy, and atomic force microscopy. Results PZRE showed the presence of phenolics, such as plumbagin, and flavonoids, in addition to citric acid, sucrose, glucose, fructose, and starch, using HPTLC, GC-TOF-MS, and quantitative analysis. Bioreduction of silver nitrate (AgNO3) and chloroauric acid (HAuCl4) were confirmed at absorbances of 440 nm (AgNPs), 570 nm (AuNPs), and 540 nm (AgAuNPs), respectively. The maximum rate of synthesis at 50°C was achieved with 5 mM AgNO3 within 4.5 hours for AgNPs; and with 0.7 mM HAuCl4 within 5 hours for AuNPs. The synthesis of AgAuNPs, which completed within 90 minutes with 0.7 mM AgNO3 and HAuCl4, was found to be the fastest. Fourier-transform infrared spectroscopy confirmed bioreduction, while EDS and XRD patterns confirmed purity and the crystalline nature of the NPs, respectively. TEM micrographs and DLS showed about 60 nm monodispersed Ag nanospheres, 20–30 nm Au nanospheres adhering to form Au nanotriangles, and about 90 nm hexagonal blunt-ended AgAuNPs. These NPs also showed antimicrobial and antibiofilm activity against E. coli, A. baumannii, S. aureus, and a mixed culture of A. baumannii and S. aureus. AgNPs inhibited biofilm in the range of 96%–99% and AgAuNPs from 93% to 98% in single-culture biofilms. AuNPs also showed biofilm inhibition, with the highest of 98% in S. aureus. AgNPs also showed good biofilm disruption, with the highest of 88% in A. baumannii. Conclusion This is the first report on rapid and efficient synthesis of AgNPs, AuNPs and AgAuNPs from P. zeylanica and their effect on quantitative inhibition and disruption of bacterial biofilms.

Exopolysaccharide analysis of biofilm-forming Candida albicans.

Aim:  The major objective of the study was to analyse exopolysaccharide produced by a biofilm forming‐clinical strain of Candida albicans.

Biodiesel production from non-edible lignocellulosic biomass of Cassia fistula L. fruit pulp using oleaginous yeast Rhodosporidium kratochvilovae HIMPA1

This study explored biodiesel production from a low cost, abundant, non-edible lignocellulosic biomass from aqueous extract of Cassia fistula L. (CAE) fruit pulp. The CAE was utilized as substrate for cultivating novel oleaginous yeast Rhodosporidium kratochvilovae HIMPA1. This oleaginous yeast accumulates high amount of triacylglycerides as large intracellular lipid droplets (4.35±0.54μm) using CAE as sole nutritional source. Total lipids (4.86±0.54g/l) with lipid content of 53.18% (w/w) were produced by R. kratochvilovae HIMPA1 on CAE. The FAME profile obtained revealed palmitic acid (C16:0) 43.06%, stearic acid (C18:0) 28.74%, and oleic acid (C18:1) 17.34% as major fatty acids. High saturated fatty acids content (72.58%) can be blended with high PUFA feedstocks to make it an industrially viable renewable energy product.

Rapid method for monitoring maximum biosurfactant production obtained by acetone precipitation

The appearance of surface active compounds in the culture broths grown on hydrocarbons can be easily monitored by measuring the surface tension of the cell free broth. Using three bacterial strains it was found that yields of the biosurfactants were maximum at the time when lowest surface tension values were recorded. Thus reduction of surface tension of the medium is a rapid method for assay of maximum biosurfactant formation prior to their actual isolation.

Boosting accumulation of neutral lipids in Rhodosporidium kratochvilovae HIMPA1 grown on hemp (Cannabis sativa Linn) seed aqueous extract as feedstock for biodiesel production

Hemp seeds aqueous extract (HSAE) was used as cheap renewable feedstocks to grow novel oleaginous yeast Rhodosporidium kratochvilovae HIMPA1 isolated from Himalayan permafrost soil. The yeast showed boosted triglyceride (TAG) accumulation in the lipid droplets (LDs) which were transesterified to biodiesel. The sonicated HSAE prepared lacked toxic inhibitors and showed enhanced total lipid content and lipid yield 55.56%, 8.39±0.57g/l in comparison to 41.92%, 6.2±0.8g/l from industrially used glucose synthetic medium, respectively. Supersized LDs (5.95±1.02μm) accumulated maximum TAG in sonicated HSAE grown cells were visualized by fluorescent BODIPY (505/515nm) stain. GC-MS analysis revealed unique longer carbon chain FAME profile containing Arachidic acid (C20:0) 5%, Behenic acid (C22:0) 9.7%, Heptacosanoic acid (C27:0) 14.98%, for the first time in this yeast when grown on industrially competent sonicated HSAE, showing more similarity to algal oils.

Effect of Plant Oils on Candida albicans

BACKGROUND/PURPOSE Candida species, notably Candida albicans, is the major fungal pathogen in humans. It is a dimorphic fungus capable of causing superficial mucosal infections, as well as systemic infections, in immunocompromised individuals. The factors responsible for its pathogenesis are still not fully understood and increasing resistance to commonly used antifungal agents necessitates the search for new formulations. METHODS The inhibitory effect of 30 different plant oils on Candida albicans isolated from clinical samples was evaluated. The antifungal agent fluconazole was used as a positive control. Plant oils were tested at concentrations from 0.03% to 3% (v/v) to determine the minimum inhibitory concentration and minimum fungicidal concentration (MFC) using agar dilution and macro broth dilution assays. RESULTS Of the 30 plant oils tested, 18 were found to be effective and 12 were ineffective. Based on their MFCs, effective oils were placed into three categories: most effective, moderately effective and least effective. Eucalyptus and peppermint oils were most effective, with MFC values of 0.12% and 0.15% (v/v), respectively. CONCLUSION The significant antifungal activity of these oils suggests that they could serve as a source of compounds with therapeutic potential against Candida-related infections.

Synergistic dynamics of nitrogen and phosphorous influences lipid productivity in Chlorella minutissima for biodiesel production.

The study synergistically optimized nitrogen and phosphorous concentrations for attainment of maximum lipid productivity in Chlorella minutissima. Nitrogen and phosphorous limited cells (N(L)P(L)) showed maximum lipid productivity (49.1±0.41mg/L/d), 1.47 folds higher than control. Nitrogen depletion resulted in reduced cell size with large sized lipid droplets encompassing most of the intracellular space while discrete lipid bodies were observed under nitrogen sufficiency. Synergistic N/P starvations showed more prominent effect on photosynthetic pigments as to individual deprivations. Phosphorous deficiency along with N starvation exhibited 17.12% decline in carbohydrate while no change in nitrogen sufficient cells were recorded. The optimum N(L)P(L) concentration showed balance between biomass and lipid by maintaining intermediate cell size, pigments, carbohydrate and proteins. FAME profile showed C14-C18 carbon chains in N(L)P(L) cells with biodiesel properties comparable to plant oil methyl esters. Hence, synergistic N/P limitation was effective for enhancing lipid productivity with reduced consumption of nutrients.

Production and properties of a biosurfactant synthesized byArthrobacter protophormiae — an antarctic strain

This study reports the production of biosurfactant by a psychrophilic strain ofArthrobacter protophormiae during growth on an immiscible carbon source, w-hexadecane. The biosurfactant reduces the surface tension of the medium from 68.0 mN/m to 30.60 mN/m and exhibits good emulsification activity. The strain could grow and produce biosurfactant in the presence of high NaCl concentrations (10.0 to 100.0 g/1). Although the biosurfactant was isolated by growing the organism under psychrophilic conditions (10‡C) it exhibited stable activity over a wide range of temperature (30‡C to 100‡C). It retained its surface-active properties at pH2 to 12. The biosurfactant was effective in recovering up to 90% of residual oil from an oil saturated sandpack column, indicating its potential value in enhanced oil recovery.