Microalgal competence in urban wastewater management: phycoremediation and lipid production

The present study was conducted to assess the strain aptness, phycoremediation potential and lipid yield in microalgae <i>Chloroccocum humicola</i> and <i>Oscillatoria</i> sp. Results revealed that microalgae treated with different concentration of wastewater (25%, 50%, 75% and 100%) recovered nutrients (Nitrogen: 50.55–85.90%, Phosphorus: 69.98–93.72%) and removed heavy metals (24.17–88.10%) from wastewater. Microalgae <i>C. humicola</i> showed significant reduction in physico-chemical parameters of wastewater at 25% and 50% respectively with considerable increase in lipid production (1.61 folds) at 50% wastewater concentration. In order to counterbalance the wastewater induced toxicity, both microalgae exhibited stimulated antioxidants viz., proline (1.26–4.04 folds), ascorbic acid (1.01–9.21 folds), cysteine (1.44–4.92 folds), catalase (0.99–3.63 folds), superoxide dismutase (1.15–1.43 folds) and glutathione reductase (1.43–6.67 folds) at different wastewater concentrations. Further, Fourier transforms infrared spectroscopy spectral elucidation of <i>Chloroccocum humicola</i> at 50% reflected high lipid peak in the regions 3000–2800<b> </b>cm⁻¹ as compared to <i>Oscillatoria</i> sp. Thus, growth characteristics, biochemical responses and lipid yield presented the suitability of the <i>Chloroccocum humicola</i> to be used in phycoremedation, resource recovery as well as lipid production, which may be further utilized as potent feedstock for third generation energy demand.

本研究旨在评估微藻土生绿球菌（Chloroccocum humicola）与颤藻（Oscillatoria）sp.的菌株适应性、藻类修复（phycoremediation）潜力及脂质产率（lipid yield）。结果表明，经不同浓度废水（25%、50%、75%及100%）处理的微藻可回收废水中的营养物质（氮：50.55%~85.90%，磷：69.98%~93.72%），并去除废水中24.17%~88.10%的重金属。土生绿球菌（Chloroccocum humicola）在25%与50%废水浓度下可显著降低废水的理化参数，且在50%废水浓度下脂质产量提升1.61倍，增幅显著。为抵消废水诱导的毒性，两种微藻在不同废水浓度下均激活了抗氧化系统，具体包括脯氨酸（proline，1.26~4.04倍）、抗坏血酸（ascorbic acid，1.01~9.21倍）、半胱氨酸（cysteine，1.44~4.92倍）、过氧化氢酶（catalase，0.99~3.63倍）、超氧化物歧化酶（superoxide dismutase，1.15~1.43倍）及谷胱甘肽还原酶（glutathione reductase，1.43~6.67倍）。进一步通过傅里叶变换红外光谱（Fourier transforms infrared spectroscopy, FTIR）对50%废水浓度处理下的土生绿球菌进行光谱解析，发现其在3000~2800 cm⁻¹区域的脂质特征峰强度高于颤藻（Oscillatoria）sp.。综上，生长特性、生化响应与脂质产率均证实土生绿球菌（Chloroccocum humicola）适用于藻类修复、资源回收及脂质生产，可进一步作为第三代能源需求的优质原料。