A comprehensive study on enhancement of lipid yield from Tetradesmus obliquus MT188616.1

Optimization of lipid production in Tetradesmus dimorphus using response surface methodology using tannery wastewater for biodiesel production

The management of industrial wastewaters and generation of sustainable energy resources are the two major challenges concerned with the global population and depleting fossil fuels. Tannery wastewater (TWW) is a major source of environmental pollution and human health hazardous if released without adequate treatment. The microalgal treatment of TWW among other approaches seems to be beneficial and effective as microalgae use TWW as nutrient source offering wastewater treatment while producing large biomass for biofuel production. Biomass and lipid content are the adequate criteria for higher biodiesel yield. In present study, Tetradesmus dimorphus was grown in TWW with an objective to treat TWW along with the generation of large biomass for biodiesel production and Response Surface Methodology (RSM) was used to optimize the biodiesel production taking into count the parameters such as wastewater concentrations, pH and photoperiod. Results showed that highest biomass and lipid content produced were 1.63 ± 0.02 g/L and 487 ± 11 mg/L, respectively with 213.80 ± 7 mg/L of biodiesel production. Gas Chromatography-Flame Ionization Detection (GC-FID) analysis of biodiesel obtained from Tetradesmus dimorphus lipids showed that it was made up of more than 40 % Methyl decanoate (C11:0) and Methyl erucate (C22:1). The interrelationships between selected parameters like STTWW concentrations, pH and photoperiods reflected the positive impact on lipid productivity as 3D contour depicted the maximum yield at 80 % wastewater concentration, pH 8 and 14 h of photoperiod. Study showed that microalgal treatment of TWW among the other approaches seems beneficial and effective to harness wastewater nutrients while producing valuable biomass for biodiesel production.

Structural and functional analysis of a novel galactose-binding lectin derived from Chlorella sorokiniana MW769776

A freshwater green microalgal strain was isolated and the lectin was identified in it by a strong hemagglutination activity (HA) assay. Characterization of the algal strain was found to be Chlorella sorokiniana (MW769776). A single step affinity chromatographic technique was developed to purify Chlorella sorokiniana lectin (CSL) using guar gum as the affinity matrix. The precipitate showed a single active peak with a titer value of 1024 HU, with a concentration of 1111 U, and a purification fold of 9. The purified protein exhibited a single band in SDS-PAGE with a molecular weight of 16 kDa. Analysis by liquid chromatography-electrospray ionization-quadrupole-time of flight mass spectrometry (LC-ESI-Q-TOF-MS) of tryptic-digested purified lectin showed that it was a monomeric protein. A multiple sequence alignment analysis revealed that the peptide sequences of CSL exhibited similarity with the H-type lectin domain of Micractinium conductrix. The structure of CSL was studied by FTIR and homology modeling methods, indicating the presence of α-helix as well as β-sheet in its secondary structure. Whereas the 3D structure exhibited the similarity with the core protein of light-harvesting reaction center complex of photosystem I. The significance of this study suggests that the characteristics of CSL are consistent with its identification as a hemagglutinin, a type of novel lectin, which suggests its candidature for various biological purposes.Communicated by Ramaswamy H. Sarma.

Development of Operating Process for Continuous Production of Biomass by Tetradesmus obliquus (MT188616.1) in a Hollow Fiber Membrane Photobioreactor

An effective prototype of photobioreactor namely hollow fiber membrane bioreactor is employed to produce algal biomass for biofuel production. The effect of two-stage cultivation system on the biomass productivity and lipid production is studied using freshwater green microalga Tetradesmus obliquus MT188616.1. The hybrid system combines exponential biomass production in hollow fiber membrane photobioreactor (HFMPBr) and a coordinated high-lipid stimulation phase in nitrogen-deprived medium by the shake flask method. This work is proposed to examine the usefulness of HFMPBr module to enhance the microalgal growth rate through the effective mass transfer by standardizing the culture medium re-circulation flow rates (5 - 45mL/min) through the hollow fiber membranes. Cultivation is carried out at continuous mode in HFMPBr containing polysulfone fabricated membranes at fixed light intensity of 50 µmol m^-2 s^-1 and temperature at 28°C. Biomass productivity and specific growth rate obtained are 0.44gL^-1d^-1 and 1.61µ d^-1 with a lipid yield of 0.1g/L. The key operating parameter i.e., liquid flow rate is optimized based on biomass production. The highest biomass concentration is produced at the flow rate of 45mLmin^-1. The results showed that HFMPBr module is a better choice for the algal-cultivation to obtain higher biomass yield.