<i>Candida albicans</i> biofilm inhibition by synergistic action of terpenes and fluconazole

1032-1037The current treatment options for Candida albicans biofilm-device related infections are very scarce due to their intrinsic increased tolerance to antimycotics. The aim of this work was to study synergistic action of terpenes (eugenol, menthol and thymol) with fluconazole (FLA) on C. albicans biofilm inhibition. The minimum inhibitory concentration (MIC) assayed using CLSI M27-A3 broth micro-dilution method showed antifungal activity against C. albicans MTCC 227 at a concentration of 0.12 % (v/v) for both thymol and eugenol as compared to 0.25 % (v/v) for menthol. FLA was taken as positive control. The effect of these terpenes on metabolic activity of preformed C. albicans biofilm cells was evaluated using 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay in 96-well polystyrene microtiter plate. Thymol and eugenol were more effective at lower concentrations of ≥ 1.0 % (v/v) than menthol. Synergistic studies using checkerboard micro-dilution assay showed fractional inhibitory concentration index (Σ FIC=0.31) between thymol/FLA followed by eugenol/FLA (Σ FIC=0.37) and menthol/FLA (Σ FIC&lt;0.5) against pre-formed C. albicans biofilms. Thymol with fluconazole showed highest synergy in reduction of biofilm formation than eugenol and menthol which was not observed when their activities were observed independently. Adherence assay showed 30% viability of C. albicans cells after 2 h of treatment with 0.05 % (v/v) thymol/FLA. Effect of thymol/FLA on C. albicans adhesion visualized by SEM micrographs showed disruption in number of candidal cells and alteration in structural design of C. albicans. Thus, the study demonstrated synergistic effect of terpenes with fluconazole on C. albicans biofilm, which could be future medications for biofilm infections. </span

Assessment of fuel properties on the basis of fatty acid profiles of oleaginous yeast for potential biodiesel production

Over the last decade, there has been a huge upsurge of interest in sustainable production of biomass-based biofuels to fulfill the existing energy demand and simultaneously reducing the environmental deterioration. Earlier, vegetable oils and animal fats were utilized for biodiesel production, but due to food crisis and environmental sustainability, renewable sources such as neutral lipid derived from microbes are gaining much attention for budding biodiesel industries. Among various types of microorganisms, oleaginous yeasts are more promising feedstock to accomplish the current demand of biodiesel production and utilize a large number of cost-effective renewable substrates for their growth and lipid accumulation. However, biodiesel obtained from oleaginous yeasts have certain restrictions regarding their commercial utilization due to their unstable fuel properties such as oxidative stability, cetane number, viscosity and low-temperature performance etc. Numerous articles have been published in the public domain describing the fatty acid profiles of oleaginous yeast as feedstock for biodiesel production. However, the evaluation of quality parameters of biodiesel obtained from oleaginous yeasts is still in infancy. Although there is a huge disparity in a number of papers published for biodiesel production yet the reporting performance on diesel engines need to be verified in details. In this review article, attempt has been made to assess the important biofuel properties on the basis of the fatty acid profile of oleaginous yeast. Thus this evaluation would provide a guideline to the biodiesel producer to improve the production plans related to feedstocks for oleaginous yeast, culture conditions and biodiesel blending

Delineating the molecular responses of a halotolerant microalga using integrated omics approach to identify genetic engineering targets for enhanced TAG production

Abstract Background Harnessing the halotolerant characteristics of microalgae provides a viable alternative for sustainable biomass and triacylglyceride (TAG) production. Scenedesmus sp. IITRIND2 is a fast growing fresh water microalga that has the capability to thrive in high saline environments. To understand the microalga’s adaptability, we studied its physiological and metabolic flexibility by studying differential protein, metabolite and lipid expression profiles using metabolomics, proteomics, real-time polymerase chain reaction, and lipidomics under high salinity conditions. Results On exposure to salinity, the microalga rewired its cellular reserves and ultrastructure, restricted the ions channels, and modulated its surface potential along with secretion of extrapolysaccharide to maintain homeostasis and resolve the cellular damage. The algal-omics studies suggested a well-organized salinity-driven metabolic adjustment by the microalga starting from increasing the negatively charged lipids, up regulation of proline and sugars accumulation, followed by direction of carbon and energy flux towards TAG synthesis. Furthermore, the omics studies indicated both de-novo and lipid cycling pathways at work for increasing the overall TAG accumulation inside the microalgal cells. Conclusion The salt response observed here is unique and is different from the well-known halotolerant microalga; Dunaliella salina, implying diversity in algal response with species. Based on the integrated algal-omics studies, four potential genetic targets belonging to two different metabolic pathways (salt tolerance and lipid production) were identified, which can be further tested in non-halotolerant algal strains

Insights into the Enhanced Lipid Production Characteristics of a Fresh Water Microalga under High Salinity Conditions

Bioprospecting of microalgae capable of growing and accumulating high amounts of lipids in high salinity conditions such as seawater can substantially improve the economic vaibaility of algal biodiesel production. In view of this, a fresh water microalga, <i>Scenedesmus</i> sp. IITRIND2, was cultivated under saline conditions to assess its halotolerant behavior and potential as biodiesel feedstock. The microalga efficiently adapted to 100% seawater salinity, enhanced its lipid content by 52%, thus yielded ∼3.2 fold higher lipid productivity as compared to the Bold’s basal media (BBM). The increase in the lipid content was balanced by a sharp decrease in its protein and carbohydrate content. Biochemical analysis evidenced that salinity induced oxidative stress resulted in reduced levels of photosynthetic pigments, elevated levels of reactive oxygen species (H₂O₂, thiobarbituric acid reactive substances), osmolytes (proline, glycine betaine), and activity of antioxidant enzymes (catalase, ascorbate peroxidase). These studies suggested that microalga efficiently modulated its metabolic flexibility in order to acclatamize the salanity induced stress. Further, the FAME analysis revealed the dominance of C14:0, C16:0, C18:0, C18:1, and C18:2 fatty acids under halotolerant conditions, and the properties of the resulting biodiesel were in compliance with ASTM (American Society for Testing Materials) D6751 and EN 14214 (European) fuel standards. These results consolidate that the lipid augmented halotolerant algal strains capable of growing in saline/seawater can be formulated as environmental sustainable and economic viable sources for biodiesel production