Unraveling the Algae Potential: Methane Production, Cosmeceuticals, and CO2 Capture

Microalgae for Methane Production

Microalgae, specifically cyanobacteria such as Pseudanabaena sp. CY14-1, are recognized for their proficiency in methane production. Their cell walls are less rigid than those of eukaryotic microalgae, which facilitates higher methane yields during anaerobic digestion. Pre-treatment techniques like enzymatic and thermo-alkaline methods can further enhance methane yields, with enzymatic pre-treatment showing a 162% increase for Chlorella vulgaris. Additionally, co-digestion of macroalgae like Rugulopteryx okamurae with carbon-rich substrates, such as olive mill solid waste, can improve methane generation, offering a strategy for biomass valorization and energy production.

Cosmeceutical Applications of Microalgae

In the cosmeceutical industry, microalgae species including Trachydiscus minutus and Chlorella vulgaris, alongside red marine macroalgae such as Phycocalidia acanthophora and Porphyra linearis, have demonstrated remarkable properties. These species are treasure troves of antioxidants, anti-aging, anti-inflammatory, and photoprotective compounds, which are beneficial for skincare. Algae-derived bioactive compounds present an eco-friendly alternative to synthetic chemicals, and their metabolites are noted for their skincare benefits, making them ideal for modern cosmeceutical formulations.

Algae in CO2 Capture

Certain algae species, including Chlorella sp., Hydrodictyon, Spirogyra, Oscillatoria, and Oedogonium, have been studied for their CO2 capture capabilities in industrial applications. Selected for their rapid growth, high photosynthesis rates, and tolerance to various gases, these strains can utilize captured CO2 as a nutrient, which can then be harnessed to produce valuable products like amino acid-rich feed and algal oil. Cultivation methods such as vertical tubular bioreactors and flat panel photobioreactors are employed for CO2 capture. The advantages of using microalgae for CO2 capture include emission risk mitigation and the absence of a need for fertile soil. However, challenges related to temperature management, CO2 storage, and scalability must be addressed for broader industrial application.

Natural Peel Extracts as Algal Inhibitors

A variety of peel extracts, including those from watermelon, mandarin, shaddock, and pomegranate, as well as extracts from Melastoma malabathricum, Cosmos caudatus, Pistia stratiotes, Etlingera elatior, and Cinnamomum cassia, have been studied for their ability to inhibit algal growth. Fresh and dried watermelon peels have shown high effectiveness, with an inhibiting rate of 99.2% three days post-treatment. Mandarin skin extract outperforms banana peel extract in anti-algal activity. Ethyl acetate extracts from shaddock peel, pomegranate peel, and seed have been identified as allelochemicals with inhibitory effects on algae. Melastoma malabathricum extract is particularly potent, suppressing up to 50% of algae growth.

Optimal Strain for Lipid Extraction from Microalgae

Chlorella sp. is identified as the optimal strain for lipid extraction from microalgae. The Bligh and Dyer method using a chloroform-methanol mixture has yielded the highest extraction rates for Chlorella sp. Microwave-assisted extraction with the same solvent combination also resulted in a high lipid yield, indicating Chlorella sp.'s rich lipid content among the studied microalgal strains.