Study of Algal Species Isolated From River Ginzo in Katsina State, as a Potential Source for Biodiesel Production

An ecological study of algae at River Ginzo in Katsina town was carried out for six weeks at three different sites. In this study, various strains of native microalgae were identified and isolated. The water's physicochemical properties were analyzed at Kofar Marusa, Kofar Sauri, and Kofar Durbi of River Ginzo in Katsina State. The physicochemical parameters studied showed temperature and pH range of 28oC to 31oC and 6.42 to 7.36. A total of eighteen (18) algal species were identified, out of which Ten (10) species belong to the Class Chlorophyceae with Spirogyra species having the highest cell counts, five (5) species belong to the Class Cyanophyceae with Oscillatoria species having the highest cell count and three (3) species belong to the Class Bacillariophyceae with Nitzchia spp having the highest cell counts. Among the isolates, Chlorella species showed an increased growth rate with higher biomass productivity of (88.67±2.57) X 104 (cell/ml) after six days of incubation. The results showed that Chlorella, Spirogyra, and Oocystis species could be a possible candidate species for producing oils for sustainable biodiesel production, based on their high growth rate and presence in all the locations.

STANDARDIZATION AND APPLICATION OF PCR TARGETING CHLORELLA SPECIES ISOLATED FROM ENVIRONMENTAL SAMPLES

Objective: Identification of Chlorella species from the environment through 18s ribosomal RNA sequencing. This study was aimed to design primer targeting Chlorella and other closely related algal species targeting 18s ribosomal RNA, ITS1 region. Methods: Sanger sequencing was carried out for the identification of algae up to the genus and species level using an in-house designed primer and optimized PCR conditions. Results: Out of 2 algae samples identified phenotypically, one isolate identified as Chlorella vulgaris and other one identified as Chlorella sorokiniana based on the results of Basic Alignment Search Tool (BLAST). Conclusion: To conclude, this study provided primers with PCR conditions to characterize algal samples through molecular identification with 100% accuracy than the phenotypic method.

Strain-Specific Biostimulant Effects of Chlorella and Chlamydomonas Green Microalgae on Medicago truncatula

Microalgae have been identified to produce a plethora of bioactive compounds exerting growth stimulating effects on plants. The objective of this study was to investigate the plant-growth-promoting effects of three selected strains of eukaryotic green microalgae. The biostimulatory effects of two Chlorella species (MACC-360 and MACC-38) and a Chlamydomonas reinhardtii strain (cc124) were investigated in a Medicago truncatula model plant grown under controlled greenhouse conditions. The physiological responses of the M. truncatula A17 ecotype to algal biomass addition were characterized thoroughly. The plants were cultivated in pots containing a mixture of vermiculite and soil (1:3) layered with clay at the bottom. The application of live algae cells using the soil drench method significantly increased the plants’ shoot length, leaf size, fresh weight, number of flowers and pigment content. For most of the parameters analyzed, the effects of treatment proved to be specific for the applied algae strains. Overall, Chlorella application led to more robust plants with increased fresh biomass, bigger leaves and more flowers/pods compared to the control and Chlamydomonas-treated samples receiving identical total nutrients.

Toxicity response of Chlorella microalgae to glyphosate herbicide exposure based on biomass, pigment contents and photosynthetic efficiency

The extensive use of glyphosate (N-(phosphonomethyl) glycine) herbicide in agriculture is accompanied by the risk of environmental contamination of aquatic ecosystems. In this study, the effects of glyphosate at different concentrations (50–500 µg ml-1) on three Chlorella species including Chlorella ellipsoidea, Chlorella sorokiniana and Chlorella vulgaris especially in relation to the biomass, pigment contents and photosynthetic efficiency were assessed. After treatment for 24 hr, the acute toxicity results showed that C. vulgaris (IC50 = 449.34 ± 6.20 µg ml-1) was more tolerant to glyphosate than C. ellipsoidea (IC50 = 288.23 ± 23.53 µg ml-1) and C. sorokiniana (IC50 = 174.28 ± 0.50 µg ml-1). After a 72-hr chronic toxicity treatment with glyphosate, glyphosate concentrations decreased to 400–500 µg ml-1 in C. ellipsoidea, 200–300 µg ml-1 in C. sorokiniana and 200–500 µg ml-1 in C. vulgaris respectively. During 24-hr acute toxicity exposure to glyphosate, the pigment contents and maximum quantum efficiency of photosystem II (Fv/Fm) decreased as the concentration of glyphosate increased. Overall, the biomass, pigment contents and photosynthetic efficiency presented a high positive correlation. It is worthwhile to mention that our study provides detailed information on the toxicity and sensitivity of these Chlorella species to glyphosate.

CO2 supply modulates lipid remodelling, photosynthetic and respiratory activities in Chlorella species

ABSTRACTMicroalgae represent potential solutions to reduce the atmospheric CO2 level through photosynthesis. To boost CO2 fixation by microalgae it is essential to understand physiologic and metabolic responses at the base of CO2 assimilation and carbon flow. In this work two Trebouxiophyceae species, Chlorella sorokiniana and Chlorella vulgaris, were investigated for their metabolic responses to high and low CO2 (air level) availability. High CO2 availability resulted in an increase in biomass accumulation in both species but with a different chloroplast and mitochondrial responses. In C. sorokiniana we observed increased polar lipids and protein amount and a balanced NADPH redox state and a similar total respiration in the two conditions analysed. In contrast, in C. vulgaris high CO2 level caused an increase in TAG accumulation and a higher NADPH consumption suggesting a CO2 dependent increase of reducing power consumption in the chloroplast, which in turn influences the redox state of the mitochondria by lowering total dark respiration. Several rearrangements of the photosynthetic machinery were observed in both species, which differ from those described for the model organism Chlamydomonas reinhardtii. In the case of C. reinhardtii, adaptation of the photosynthetic apparatus to different CO2 availability relies on the translational repressor NAB1. NAB1 homologous protein could be identified only in C. vulgaris but lacked the regulation mechanisms previously described in C. reinhardtii. These findings highlight that the acclimation strategies to cope with a fluctuating inorganic carbon supply are diverse among green microalgae and point to new biotechnological strategies to boost CO2 fixation.One sentence summaryHigh/low CO2 availability induces cell responses as lipids remodelling, adaptations of the photosynthetic apparatus and modulation of mitochondrial respiration not conserved among green algae