Gupta Apurva, Mohan Devendra, Saxena Rishi Kumar, Singh Surendra
Centre for Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
Department of Civil Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, 221005, India.
J Phycol. 2018 Feb;54(1):44-55. doi: 10.1111/jpy.12597. Epub 2017 Nov 15.
Commercial cultivation of Spirulina sp. is highly popular due to the presence of high amount of C-phycocyanin (C-PC) and other valuable chemicals like carotenoids and γ-linolenic acid. In this study, the pH and the concentrations of nitrogen and carbon source were manipulated to achieve improved cell growth and C-PC production in NaCl-tolerant mutant of Spirulina platensis. In this study, highest C-PC (147 mg · L ) and biomass (2.83 g · L ) production was achieved when a NaCl-tolerant mutant of S. platensis was cultivated in a nitrate and bicarbonate sufficient medium (40 and 60 mM, respectively) at pH 9.0 under phototrophic conditions. Kinetic study of wildtype S. platensis and its NaCl-tolerant mutant was also done to determine optimum nitrate concentrations for maximum growth and C-PC production. Kinetic parameter of inhibition (Haldane model) was fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Results showed that the maximum specific growth rate (μ ) for NaCl-tolerant mutant increased by 17.94% as compared to its wildtype counterpart, with a slight increase in half-saturation constant (K ), indicating that this strain could grow well at high concentration of NaNO . C-PC production rate (C ) in mutant cells increased by 12.2% at almost half the value of K as compared to its wildtype counterpart. Moreover, the inhibition constant (K ) value was 207.85% higher in NaCl-tolerant mutant as compared to its wildtype strain, suggesting its ability to produce C-PC even at high concentrations of NaNO .
钝顶螺旋藻的商业种植非常受欢迎，因为其含有大量的C-藻蓝蛋白（C-PC）以及其他有价值的化学物质，如类胡萝卜素和γ-亚麻酸。在本研究中，通过调控pH值以及氮源和碳源的浓度，以提高钝顶螺旋藻耐盐突变体的细胞生长和C-PC产量。在本研究中，当钝顶螺旋藻耐盐突变体在光养条件下，于pH 9.0的硝酸盐和碳酸氢盐充足的培养基（分别为40 mM和60 mM）中培养时，实现了最高的C-PC产量（147 mg·L）和生物量（2.83 g·L）。还对野生型钝顶螺旋藻及其耐盐突变体进行了动力学研究，以确定最大生长和C-PC产量所需的最佳硝酸盐浓度。将抑制动力学参数（哈代模型）拟合到从生长曲线获得的比生长速率与底物浓度之间的关系。结果表明，耐盐突变体的最大比生长速率（μ）比其野生型对应物提高了17.94%，半饱和常数（K）略有增加，表明该菌株在高浓度NaNO₃下能良好生长。与野生型对应物相比，突变体细胞中的C-PC生产率（C）在K值几乎减半时提高了12.2%。此外，耐盐突变体的抑制常数（K）值比其野生型菌株高207.85%，表明其即使在高浓度NaNO₃下也能产生C-PC。
