Enhancement of Lipid Productivity and Self-flocculation by Cocultivating Monoraphidium sp. FXY-10 and Heveochlorella sp. Yu Under Mixotrophic Mode

Recent advances in microalgal production, harvesting, prediction, optimization, and control strategies

The market value of microalgae has grown exponentially over the past two decades, due to their use in the pharmaceutical, nutraceutical, cosmetic, and aquatic/animal feed industries. In particular, high-value products such as omega-3 fatty acids, proteins, and pigments derived from microalgae have high demand. However, the supply of these high-value microalgal bioproducts is hampered by several critical factors, including low biomass and bioproduct yields, inefficiencies in monitoring microalgal growth, and costly harvesting methods. To overcome these constraints, strategies such as synthetic biology, bubble generation, photobioreactor designs, electro-/magnetic-/bioflocculation, and artificial intelligence integration in microalgal production are being explored. These strategies have significant promise in improving the production of microalgae, which will further boost market availability of algal-derived bioproducts. This review focuses on the recent advances in these technologies. Furthermore, this review aims to provide a critical analysis of the challenges in existing algae bioprocessing methods, and highlights future research directions.

Development of Microalgae Biodiesel: Current Status and Perspectives

Microalgae are regarded as a promising source of biodiesel. In contrast with conventional crops currently used to produce commercial biodiesel, microalgae can be cultivated on non-arable land, besides having a higher growth rate and productivity. However, microalgal biodiesel is not yet regarded as economically competitive, compared to fossil fuels and crop-based biodiesel; therefore, it is not commercially produced. This review provides an overall perspective on technologies with the potential to increase efficiency and reduce the general costs of biodiesel production from microalgae. Opportunities and challenges for large-scale production are discussed. We present the current scenario of Brazilian research in the field and show a successful case in the research and development of microalgal biodiesel in open ponds by Petrobras. This publicly held Brazilian corporation has been investing in research in this sector for over a decade.

Coculturing of Mucor plumbeus and Bacillus subtilis bacterium as an efficient fermentation strategy to enhance fungal lipid and gamma-linolenic acid (GLA) production

This study aimed to improve lipid and gamma-linolenic acid (GLA) production of an oleaginous fungus, Mucor plumbeus, through coculturing with Bacillus subtilis bacteria, optimising the environmental and nutritional culture conditions, and scaling them for batch fermentation. The maximum levels of biomass, lipid, fatty acid, and GLA in a 5 L bioreactor containing cellobiose and ammonium sulfate as the optimal carbon and nitrogen sources, respectively, achieved during the coculturing processes were 14.5 ± 0.4 g/L, 41.5 ± 1.3, 24 ± 0.8, and 20 ± 0.5%, respectively. This strategy uses cellobiose in place of glucose, decreasing production costs. The nutritional and abiotic factor results suggest that the highest production efficiency is achieved at 6.5 pH, 30 °C temperature, 10% (v/v) inoculum composition, 200 rpm agitation speed, and a 5-day incubation period. Interestingly, the GLA concentration of cocultures (20.0 ± 0.5%) was twofold higher than that of monocultures (8.27 ± 0.11%). More importantly, the GC chromatograms of cocultures indicated the presence of one additional peak corresponding to decanoic acid (5.32 ± 0.20%) that is absent in monocultures, indicating activation of silent gene clusters via cocultivation with bacteria. This study is the first to show that coculturing of Mucor plumbeus with Bacillus subtilis is a promising strategy with industrialisation potential for the production of GLA-rich microbial lipids and prospective biosynthesis of new products.