Isolation, Identification and High-Throughput Screening of Neutral Lipid Producing Indigenous Microalgae from South African Aquatic Habitats

Abstract

Exploring indigenous microalgae capable of producing significant amounts of neutral lipids through high-throughput screening is crucial for sustainable biodiesel production. In this study, 31 indigenous microalgal strains were isolated from diverse aquatic habitats in KwaZulu-Natal, South Africa. Eight superior lipid-producing strains were selected for further analysis, based on Nile red fluorescence microscopy screening. The microalgal isolates were identified to belong to the genera Chlorella, Neochloris and Chlamydomonas via morpho-taxonomic and molecular approach by 18S rRNA gene sequencing. Chlorella vulgaris PH2 had the highest specific growth rate (μ) and lowest doubling time of 0.24 day and 2.89 ± 0.05 day, respectively. Chlorella vulgaris T4 had the highest biomass productivity of 35.71 ± 0.03 mg Lday. Chlorella vulgaris PH2 had the highest lipid content of 34.28 ± 0.47 and 38 ± 9.2% (dcw) as determined by gravimetric analysis and the sulfo-phospho-vanillin (SPV) method, respectively. Chlorella vulgaris PH2 exhibited a high content of saturated fatty acids, while Chlorella sp. T4 exhibited a high total content of saturated and monounsaturated fatty acids with a low content of polyunsaturated fatty acids. The preponderance of neutral lipids suggests that Chlorella sp. T4 is a suitable candidate for biomass feedstock for biodiesel production.

Identification of microalgae cultured in Bold’s Basal medium from freshwater samples, from a high-rise city

“…and Lynbygia sp 47 ; studies from South Africa showed Chlorella sp., Neochloris sp. and Chlamydomonas sp 48 ; those from America showed Chlorella sp. and Chlorococcum sp.…”

Bioprospecting wild South African microalgae as a potential third-generation biofuel feedstock, biological carbon-capture agent and for nutraceutical applications

“…1a and b with some key observed features of UJEAS4 (Fig. 1a) as having spherical shaped cells with no flagella and the average sizes varied between 3 and 4 and 5 and 6 µm, which is a common feature of the genus Chlorella [4,39,40].…”

Biotechnological Applications of Microalgal Oleaginous Compounds: Current Trends on Microalgal Bioprocessing of Products

“…The success of the biorefinery process depends largely upon appropriate and careful selection of microalgal strains for the production of target compounds (Mutanda et al, 2011;Gumbi et al, 2017;Gifuni et al, 2018). According to Wilkie et al (2011), specific criteria of selection for the production of biofuels from indigenous microalgae should encompass biomass productivity, lipid productivity, harvestability of the microorganism, and oil extractability.…”

“…High-throughput screening of the microalgal strains producing large amounts of the desired metabolite e.g., neutral lipids, starch, proteins, carotenoids, etc. is mandatory (Delrue et al, 2016;Gumbi et al, 2017). Therefore, it is crucial to select superior, robust, and nonfastidious microalgal strains for specific applications for the whole process to succeed.…”