Добірка наукової літератури з теми "Microalgal culture"

This study investigated nutrient removal from anaerobic digestion effluent by cultivating mixed-culture microalgae enriched from anaerobic sludge under different pH conditions: RUC (uncontrolled), R7–8 (maintained at 7–8), and R<8 (maintained below 8). Significant amounts of NH4+-N were lost by volatilization in RUC cultures due to increased pH values (≤8.6) during the early period of cultivation. The pH control strategies significantly affected the biological NH4+-N removal (highest in R7–8), microalgal growth (highest in R7–8), biomass settleability (highest in R<8), and microalgal growth relative to bacteria (highest in R<8) in the cultures. Parachlorella completely dominated the microalgal communities in the inoculum and all of the cultures, and grew well at highly acidic pH (<3) induced by culture acidification with microalgal growth. Microalgae-associated bacterial community structure developed very differently among the cultures. The findings call for more attention to the influence and control of pH changes during cultivation in microalgal treatment of anaerobic digestion effluent.

A biomassa de microalgas tem apresentado potencial para produção de biodiesel, contudo a viabilidade do cultivo de microalgas depende de fonte de nutrientes de baixo custo. O presente estudo objetivou utilizar o chorume como fonte de nutrientes para microalgas. Os experimentos foram conduzidos visando avaliar a obtenção da biomassa microalgal, conversão de lipídios e rendimento em ésteres metílicos de ácidos graxos, para os meios de cultivos utilizando 5%, 12% e 20% de chorume, com concentrações de 0,02, 0,05 e 0,08 g N. L-1 e para meio de controle contendo 1% de, Nitrogênio (N), Fósforo (P) e Potássio (K), na concentração de 20 g L-1, 5 g L-1 e 20 g L-1, respectivamente. A microalga utilizada neste trabalho foi a de classe Chlorophyceae e família Coccomyxaceae. Os resultados demonstraram que o meio com concentração de 12% de chorume obteve melhores resultados, possibilitando alcançar 1,19 g de biomassa, conversão de 108,15 mg g-1 de lipídios e conteúdo de ésteres de 410,77mg g-1, a microalga utilizada apresentou ainda predominância dos ácidos graxos palmítico e oleico, apresentando baixa quantidade de ácidos graxos saturados o que pode fornecer ao combustível, resistência ao frio. E tais aspectos demonstraram que o chorume pode ser uma fonte promissora de nutrientes para o cultivo das microalgas estudadas. AbstractMicroalgae biomass has presented potential for biodiesel production, however the viability of microalgae cultivation depends on low cost nutrient source. The present study aimed to use leachate as a source of nutrients for microalgae. The experiments were conducted to evaluate the microalgal biomass, lipid conversion and yield in fatty acid methyl esters, for the culture media using 5%, 12% and 20% leachate, with concentrations of 0.02, 0.05 and 0.08 g N. L-1 and for control medium containing 1% Nitrogen (N), Phosphorus (P) and Potassium (K), at a concentration of 20 g L-1, 5 g L-1 and 20 g L-1, respectively. The microalgae used in this work was Chlorophyceae class and Coccomyxaceae family. The results showed that the medium with a concentration of 12% of leachate obtained better results, allowing to reach 1.19 g of biomass, conversion of 108.15 mg g-1 of lipids and esters content of 410,77 mg g-1. The microalgae used also presented predominance of palmitic and oleic fatty acids, presenting low amount of saturated fatty acids which can provide the fuel with cold resistance. And these aspects demonstrated that the leachate can be a promising source of nutrients for the cultivation of the studied microalgae.

Harvesting of microalgae from their different cultivation media has pointed out challenges in resolving the problems of flocculation. These challenges must be faced with a suitable method for inducing flocculation that avoid or limit the microalgae’s contamination. This study developed the fundamental experiments with a support of chemicals and some bacteria strains inducing the flocculation of Chlorella vulgaris SAG 211-19. Particularly, the determination of minimum content of Mg2+, Ca2+, E. coli ATCC 85922 and Bacillus subtilis MT300405 was effectuated with co-cultivation of microalgae and set up in batch culture in Bold’s Basal Medium. As a result, the adjustment in 25 minutes of 199.2 mg/L CaCl2.2H2O, 50 mg/L KH2PO4, and of 141 mg/L MgSO4.7H2O induced a microalgal settling efficiency of 81% and 70%, respectively. Meanwhile, the perfomance of microalgal removing reached up to 83.6% and 84% by the inoculation into microalgal culture media of a minimum initial cell density of 8.1 ´ 105 CFU/mL of Bacillus subtilis MT300405 and 12 ´ 105 CFU/mL of E. coli ATCC 85922, respectively. The flocculation of microalgal cells by bacterial inoculation did not require a high pH adjustment as in the case of salt addition.

Abstract The efficiency of microalgal biomass production is a determining factor for the economic competitiveness of microalgae-based industries. N-acetylcysteine (NAC) and pluronic block polymers are two compounds of interest as novel culture media constituents because of their respective protective properties against oxidative stress and shear-stress-induced cell damage. Here we quantify the effect of NAC and two pluronic (F127 and F68) culture media additives upon the culture productivity of six marine microalgal species of relevance to the aquaculture industry (four diatoms-Chaetoceros calcitrans, Chaetoceros muelleri, Skeletonema costatum, and Thalassiosira pseudonana; two haptophytes-Tisochrysis lutea and Pavlova salina). Algal culture performance in response to the addition of NAC and pluronic, singly or combined, is dosage- and species-dependent. Combined NAC and pluronic F127 algal culture media additives resulted in specific growth rate increases of 38%, 16%, and 24% for C. calcitrans, C. muelleri, and P. salina, respectively. Enhanced culture productivity for strains belonging to the genus Chaetoceros was paired with an ~27% increase in stationary-phase cell density. For some of the species examined, culture media enrichments with NAC and pluronic resulted in increased omega-3-fatty acid content of the algal biomass. Larval development (i.e., growth and survival) of the Pacific oyster (Crassostrea gigas) was not changed when fed a mixture of microalgae grown in NAC- and F127-supplemented culture medium. Based upon these results, we propose that culture media enrichment with NAC and pluronic F127 is an effective and easily adopted approach to increase algal productivity and enhance the nutritional quality of marine microalgal strains commonly cultured for live-feed applications in aquaculture. Key points • Single and combined NAC and pluronic F127 culture media supplementation significantly enhanced the productivity of Chaetoceros calcitrans and Chaetoceros muelleri cultures. • Culture media enrichments with NAC and F127 can increase omega-3-fatty acid content of algal biomass. • Microalgae grown in NAC- and pluronic F127-supplemented culture media are suitable for live-feed applications.