Alok Patel

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.

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.

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.

Antibiofilm activity of quercetin- encapsulated cytocompatible nanofibers against Candida albicans

In this study, nanofibers against pro dimorphic fungal sessile growth were developed. Quercetin was successfully encapsulated within poly(d,l-lactide-co-glycolide)–poly(ε-caprolactone) nanofibers using an electrospinning technique. Field emission scanning electron microscopy, fluorescent microscopy, and Fourier-transformed infrared spectrometer were used to confirm the formation as well as encapsulation of quercetin within the nanofibers. These fabricated nanofibers were further evaluated to determine the effectiveness of the antibiofilm activity against Candida albicans. The cytocompatibility of quercetin-encapsulated nanofibers was found to be similar to control and pure polymeric nanofibers based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay against human embryonic kidney (HEK-293) cell lines. These fabricated nanofibers potentially could be used as coatings on biomedical devices to inhibit microbial contaminations.

Synergistic effect of fermentable and non-fermentable carbon sources enhances TAG accumulation in oleaginous yeast Rhodosporidium kratochvilovae HIMPA1

Novel strategy for enhancing TAG accumulation by simultaneous utilization of fermentable and non-fermentable carbon sources as substrate for cultivation of oleaginous yeast Rhodosporidium kratochvilovae HIMPA1 were undertaken in this investigation. The yeast strain showed direct correlation between the size of lipid bodies, visualized by BODIPY stain (493-515 nm) and TAG accumulation when examined on individual fermenting and non-fermenting carbon sources and their mixtures. Maximum TAG accumulation (μm) in glucose (2.38 ± 0.52), fructose (4.03 ± 0.38), sucrose (4.24 ± 0.45), glycerol (4.35 ± 0.54), xylulose (3.94 ± 0.12), and arabinose (2.98 ± 0.43) were observed. Synergistic effect of the above carbon sources (fermentable and non-fermentable) in equimolar concentration revealed maximum lipid droplet size of 5.35 ± 0.76 μm and cell size of 6.89 ± 0.97 μm. Total lipid content observed in mixed carbon sources was 9.26 g/l compared to glucose (6.2g/l). FAME profile revealed enhanced longer chain (C14:0-C24:0) fatty acids in mix carbon sources.

Impact of various media and organic carbon sources on biofuel production potential from Chlorella spp.

In this study, five Chlorella species (Chlorella vulgaris, Chlorella minutissima, Chlorella pyrenoidosa, Chlorella sp.1 and Chlorella sp.2) were grown in various nutrient medium including BG-11, BBM, Fog’s medium and M4N medium for the evolution of biomass and lipid production potential. Among the tested medium, BG-11 was found most economical and efficient medium for all Chlorella species. To see the impact of organic carbon sources on lipid production potential, all microalgae species were also cultured in selected medium (BG-11) with different organic carbon sources like glucose, glycerol, sodium acetate, and sucrose under mixotrophic condition. The results showed that all Chlorella species performs better under mixotrophic condition, but Chlorella vulgaris achieved maximum lipid productivity (3.5 folds higher) in glycerol supplemented culture medium than control medium among all species.

Microwave-assisted expeditious and efficient synthesis of novel quinolin-4-ylmethoxychromen-2- and -4-ones catalyzed by YbCl3 under a solvent free one-pot three component domino reaction and their antimicrobial activity

An efficient and highly eco-friendly synthesis of diverse and functionalized quinolin-4-ylmethoxychromen-2- and -4-ones via a one-pot three-component domino reaction of propargylated-flavone or -coumarin with aldehydes and anilines under solvent-free and microwave conditions is described using YbCl3 as catalyst. The reaction took 4 min to give the desired products in excellent yields (80–95%) at 100 °C. This approach has advantages such as high yields, solvent-free mild reaction conditions, functional group tolerance, 95% atom-economy and recyclability of catalyst. The synthesized compounds were examined for their antimicrobial activity. Among the tested compounds, compounds 4n, 5f, 5g and 5h showed excellent antimicrobial activity.

Augmented lipid accumulation in ethyl methyl sulphonate mutants of oleaginous microalga for biodiesel production

The aim of this work was to generate high lipid accumulating mutants of Chlorella minutissima (CM) using ethyl methyl sulphonate (EMS) as a random chemical mutagen. Amid the 5% surviving cells after exposure to EMS (2M), three fast growing mutants (CM2, CM5, CM7) were selected and compared with wild type for lipid productivity and biochemical composition. Among these mutants, CM7 showed the maximum biomass (2.4g/L) and lipid content (42%) as compared to wild type (1.5g/L; 27%). Further, the mutant showed high photosynthetic pigments with low starch content signifying the re-allocation of carbon flux to lipid. The obtained mutant showed no visible morphological changes in comparison to its WT. The fatty acid profile showed increase in monounsaturated fatty acids while decreased saturated and polyunsaturated fatty acids signifying good quality biodiesel. The mutant strain thus obtained can be optimized further and applied for enhanced biodiesel production.

A novel rapid ultrasonication-microwave treatment for total lipid extraction from wet oleaginous yeast biomass for sustainable biodiesel production

Oleaginous yeasts have emerged as a sustainable source of renewable oils for liquid biofuels. However, biodiesel production from them has a few constraints with respect to their cell disruption and lipid extraction techniques. The lipid extraction from oleaginous yeasts commonly includes dewatering and drying of cell biomass, which requires energy and time. The aim of this work was to establish a process for the lipid extraction from wet biomass applying acid catalyzed hot water, as well as microwave, and rapid ultrasonication-microwave treatment together with the conventional Bligh and Dyer method. In the wake of testing all procedures, it was revealed that rapid ultrasonication-microwave treatment has great potential to give high lipid content (70.86% w/w) on the cell dry weight basis. The lipid profile after treatment showed the presence of appropriate quantities of saturated (10.39 ± 0.15%), monounsaturated (76.55 ± 0.19%) and polyunsaturated fatty acids (11.49 ± 0.23%) which further improves biodiesel quality compared to the other methods. To the best of our knowledge, this is the first report of using rapid ultrasonication-microwave treatment for the lipid extraction from wet oleaginous yeast biomass in the literature.

Biodegradation of phenol via meta cleavage pathway triggers de novo TAG biosynthesis pathway in oleaginous yeast

Phenol is reported to be one of the most toxic environmental pollutants present in the discharge of various industrial effluents causing a serious threat to the existing biome. Biodegradation of phenol by oleaginous yeast Rhodosporidium kratochvilovae HIMPA1 was found to degrade 1000mg/l phenol. The pathways for phenol degradation by both ortho and meta-cleavage were proposed by the identification of metabolites and enzymatic assays of ring cleavage enzymes in the cell extracts. Results suggest that this oleaginous yeast degrade phenol via meta-cleavage pathway and accumulates a high quantity of lipid content (64.92%; wt/wt) as compared to control glucose synthetic medium (GSM). Meta-cleavage pathway of phenol degradation leads to formation of pyruvate and acetaldehyde. Both these end products feed as precursors for de novo triacylglycerols (TAG) biosynthesis pathway which causes accumulation of TAG in the lipid droplets (LD) of 6.12±0.78μm grown on phenol while 2.38±0.52μm observed on GSM. This was confirmed by fluorescence microscopic images of BODIPY505-515nm stained live yeast cells. GC-MS analysis of extracted total lipid showed enhanced amount of monounsaturated fatty acid (MUFA) which was as 51.87%, 58.33% and 62.98% in presence of 0.5, 0.75 and 1g/l of phenol.