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[Display omitted] • C. sorokiniana showed superior tolerance capacity on high acetate dosage up to 30 g/L. • Heterotrophy benefits to algal growth and lipogenesis when supplying 20 g/L acetate. • Inhibition of photosynthesis led to poor mixotrophic growth under 20 g/L acetate. • Heterotrophy produced superior amino acid profiling and more linoleic acid (50%). • Heterotrophic repeat fed-batch mode resulted in 23.4 g/L biomass and 7.0 g/L lipid. The low-cost carbon source, acetate, was utilized to feed a linoleic acid-rich Chlorella sorokiniana for microalgal biomass and lipid accumulation. Remarkably high tolerance capability to high acetate dosage up to 30 g/L was observed, with heterotrophy being the preferred trophic mode for algal growth and lipogenesis when supplemented 20 g/L acetate. Transcriptome analysis revealed a marked activation of pathways involved in acetate bioconversion and lipogenesis upon exposure to high-level of acetate. However, the enhancement of photorespiration inhibited photosynthesis, which ultimately led to a decrease in biomass and lipid under mixotrophy. Heterotrophic acetate-feeding generated more superior amino acid profiling of algal biomass and a predominant linoleic acid content (50 %). Heterotrophic repeat fed-batch strategy in 5 L fermenter significantly increased the growth performance and lipid titer, with the highest levels achieved being 23.4 g/L and 7.0 g/L, respectively. This work provides a viable approach for bio-products production through acetate-based heterotrophic algal cultivation. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the feasibility of using lipid-accumulating microalgae to remove cephalosporin antibiotics 7-amino cephalosporanic acid (7-ACA) from wastewater with the additional benefit of biofuels production. Three isolated microalgal strains (namely, Chlorella sp. Cha-01, Chlamydomonas sp. Tai-03 and Mychonastes sp. YL-02) were cultivated under 7-ACA stress and their biomass productivity, lipid production and N-NO 3 − consumption were monitored. It was found that 7-ACA had slight inhibition effects on the microalgal growth at the ratio of 12.0% (Cha-01), 9.6% (YL-02), 11.7% (Tai-03). However, lipid accumulation in the three microalgae was not influenced by the presence of 7-ACA. The investigation on the 7-ACA removal mechanisms during microalgal growth shows that 7-ACA was mainly removed by microalgae adsorption as well as hydrolysis and photolysis reactions. This study demonstrates that using microalgae to treat antibiotic-containing wastewater is promising due to the potential of simultaneous antibiotic removal and biofuel production. [ABSTRACT FROM AUTHOR]

Harvest water recycling for Chlorella zofingiensis re-cultivation under nutrient limitation was investigated. Using 100% harvest water, four cultures were prepared: Full medium, P-limited medium, N-limited medium and N- and P-limited medium, while another full medium was also prepared using 50% harvest water. The results showed that the specific growth rate and biomass productivity ranged from 0.289 to 0.403 day −1 and 86.30 to 266.66 mg L −1 day −1 , respectively. Nutrient-limited cultures witnessed much higher lipid content (41.21–46.21% of dry weight) than nutrient-full cultures (26% of dry weight). The N- and P-limited medium observed the highest FAME yield at 10.95% of dry weight, while the N-limited culture and P-limited culture shared the highest biodiesel productivity at 20.66 and 19.91 mg L −1 day −1 , respectively. The experiment on harvest water recycling times demonstrated that 100% of the harvest water could be recycled twice with the addition of sufficient nutrients. [ABSTRACT FROM AUTHOR]

Abstract: A green microalgae, named as Ettlia texensis was obtained from local freshwater in Turkey. The effects of autotrophic, photoheterotrophic and heterotrophic cultivations on biomass and lipid production were studied. Searching the preferences of the carbon and nitrogen source revealed that this strain could grow photoheterotrophically well with glucose and yeast extract. In the optimized medium, the highest biomass productivity and total lipid content achieved were 0.97g/Ld and 26% of dry weight basis, respectively. Moreover, the major fatty acid methyl esters were C16:0; C18:1; C18:2 and C18:3. In a scale-up attempt, productions were accomplished in a 3L stirred tank bioreactor. The final biomass and lipid productivities obtained in bioreactor with 250rpm agitation rate were 0.92g/Ld and 322mg/Ld, respectively. The biochemical compositions were monitored simultaneously by the FTIR spectroscopy during the production in bioreactor. E. texensis could be potent candidate for commercial production in the bioreactor photoheterotrophically. [Copyright &y& Elsevier]

Abstract: Over 100 green-colored colonies were isolated from environmental samples when cultivating on a BG11 agar medium, and 4 strains showing different morphologies were selected based on light microscopic observation. Among these strains, the microalgal species with the highest growth rate under 10% CO2 was identified as Ettlia sp. YC001 using an 18S rDNA-based phylogenetic analysis and morphological comparison. The highest cell density of 3.10g/L (based on dry cell weight) and biomass productivity of 0.19g/L/d were obtained under 5% CO2 after 16days. The lipid content and productivity were also up to 42% of the dry cell weight and 80.0mg/L/d, respectively. The color of the Ettlia sp. YC001 culture changed from green to red after a month due to the accumulation of certain carotenoids. Therefore, it would seem that Ettlia sp. YC001 is appropriate for mitigating CO2 due to its high biomass productivity, and a suitable candidate for producing biodiesel and high-value products. [Copyright &y& Elsevier]

Abstract: The fresh water microalga Neochloris oleoabundans was investigated for its ability to accumulate lipids and especially triacylglycerols (TAG). A systematic study was conducted, from the determination of the growth medium to its characterization in an airlift photobioreactor. Without nutrient limitation, a maximal biomass areal productivity of 16.5gm−2 day−1 was found. Effects of nitrogen starvation to induce lipids accumulation was next investigated. Due to initial N. oleoabundans total lipids high content (23% of dry weight), highest productivity was obtained without mineral limitation with a maximal total lipids productivity of 3.8gm−2 day−1. Regarding TAG, an almost similar productivity was found whatever the protocol was: continuous production without mineral limitation (0.5gm−2 day−1) or batch production with either sudden or progressive nitrogen deprivation (0.7gm−2 day−1). The decrease in growth rate reduces the benefit of the important lipids and TAG accumulation as obtained in nitrogen starvation (37% and 18% of dry weight, respectively). [Copyright &y& Elsevier]