Search

Oleaginous microalgae with high biomass productivity, lipid content, and lipid productivity are desirable for sustainable biofuel production. Rapid and accurate quantification of lipid content facilitates the identification of promising microalgae candidates. In the present study, 23 freshwater microalgae species from river Noyyal were isolated and identified based on their morphological and molecular (18S rRNA) features and recorded as Karunya Algae Culture Collection (KACC). Their biomass and lipid content were characterized and screened using FT-IR, Nile red staining, and gravimetric method. Results generated from FT-IR spectra differentiated KACC microalgae based on their biochemical contents with Scenedesmus rubescens KACC 2 and Chlorococcum sp. KACC 13 possessed high total protein and lipid content, respectively. Nile red fluorescence at 530/575 nm showed the yellow fluorescence under a fluorescent microscope giving the evidence of high neutral lipids in 10 KACC microalgae isolates. Total lipid content showed prominent variation between the KACC isolates and found in the range of 4 to 32% of DW. Lipid productivity and biomass productivity showed a similar pattern among KACC strains. Thus, our findings serve as a baseline data on the bioprospecting potential of KACC isolates from river Noyyal, an unexplored area of Western Ghats. [ABSTRACT FROM AUTHOR]

The approach of combining the microalgae cultivation with wastewater provides a cost-effective and eco-friendly perspective in the production of microalgae-based bio-products. In the present investigation, microalgae Scenedesmus rubescens KACC 2 isolated from catchment region of River Noyyal was found to be efficient in removing nitrogen, phosphorus, and heavy metals from industrial and domestic effluents, which was optimized through central composite design matrix for higher biomass generation. Nutrient requirements for the growth were optimized and evaluated using Plackett–Burman design to check the effect of variables. Three variables, viz., nitrate, phosphate, and inoculums, were found to be significant among the 11 variables tested, and the interaction between these variables and its optimum concentrations were statistically studied using central composite design matrix. The optimized growth conditions of this strain were found to be as nitrate (0.2%), phosphate (0.018%), and inoculums (7.5%). These conditions yielded a higher biomass of 0.73 g/L from the optimized media which was 5.4 times higher than the regular growth media. FT-IR analysis showed the variations in the spectra and also in biomolecular composition with 2-fold increase in the lipid and protein region when grown in optimized culture conditions. Lipid profile showed the presence of saturated and monounsaturated fatty acids in the biomass accepting it as a source of energy feedstock. This study concludes that nitrate, phosphate, and inoculums play a significant role in biomass production of S. rubescens with phycoremediation potential that can be exploited for simultaneous wastewater treatment–coupled biomass production. [ABSTRACT FROM AUTHOR]

Research on bioremediation of polycyclic aromatic hydrocarbons (PAHs) has established that several remediating microbial species are capable of degrading only low molecular weight (LMW)-PAHs, whereas high molecular weight (HMW)-PAHs are hardly degradable. In the present study, the efficiency of degradation of both LMW and HMW-PAHs by cytochrome P450 monooxygenase (CYP) of microalgae was studied. CYP have a key role in the detoxification of xenobiotics. So far, the structure of CYP in microalgae is not predicted; the protein structure was constructed by molecular modelling in the current study using the available template of microalgal CYP. Modelled microalgae 3D structures were docked against 38 different PAH compounds, and the information regarding the interaction between protein and PAHs viz. binding sites along with mode of interactions was investigated. We report that CYP from the microalgae Haematococcus pluvialis and Parachlorella kessleri was found to possess broad oxidising capability towards both LMW and HMW-PAHs. P. kessleri showed a least value with extra precision glide score of − 10.23 and glide energy of − 23.48 kcal/mol. PAHs bind to CYP active sites at Lys 69, Trp 96, Gln 397 and Arg 398 through intermolecular hydrogen bonding. Also, study revealed that PAHs interacted with CYP active sites through intermolecular hydrogen bonding, hydrophobic bonding, π-π interactions and van der waals interactions. Thus, structural elucidation study confirms that microalgae Parachlorella kessleri have the capacity to remediate HMW more efficiently than other microorganisms. Our results provide a framework in understanding the structure and the possible binding sites of CYP protein for degradation of PAH and that could be a screening tool in identifying the phycoremediation potential. [ABSTRACT FROM AUTHOR]