The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

Establishment of cell suspension culture in Marchantia linearis Lehm & Lindenb. for the optimum production of flavonoids

Bryophytes are the second largest group in the plant kingdom, but studies conducted to better understand their chemical composition are limited and scattered. Axenically grown bryophytes expressed potential in biotechnological processes. The present study was designed to investigate the in vitro cell growth, culture parameters and their effect on flavonoid synthesis. Chlorophyll-containing callus cells of Marchantia linearis Lehm & Lindenb. is able to grow under low light in the presence of organic carbon source and retain the ability to produce flavonoids. Highest flavonoid production was achieved using 2,4-dichlorophenoxyacetic acid as growth hormone. Inoculum size, light intensity, organic carbon source and cations are the culture parameters affecting flavonoid productivity. Maximum flavonoid productivity is observed under low light intensity, with a photon flux density ca. 20 μmol/m²/s. Optimal inoculum size and glucose concentration for flavonoid production are 10–14 and 2–3 %, respectively. Cations like ferrous trigger flavonoid synthesis by increasing its intracellular concentrations. Flavonoid production in the cell culture is shown to be significantly growth related. Osmotic stress is ineffective in triggering flavonoid synthesis. Methyl jasmonate and 2-(2-fluoro-6-nitrobenzylsulfanyl) pyridine-4-carbothioamide elicitors showed positive effect on intracellular flavonoid content in cultured cells. Using the standard plot of quercetin (y = 0.0148x, R² = 0.975), the flavonoid contents of in vitro samples were found ranging from 4.0 to 17.7 mg quercetin equivalent/g tissue. Flavonoids are fractionated by HPLC-PAD revealed the presence of quercetin (182.5 μg/g), luteolin (464.5 μg/g) and apigenin (297.5 μg/g). Further studies are warranted to analyze the therapeutic potentiality of the flavonoids in the liverwort.

Protein Expression Optimization Strategies in E. coli: A Tailored Approach in Strain Selection and Parallelizing Expression Conditions

Escherichia coli remains a traditional and widely used host organism for recombinant protein production. Its well-studied genome, availability of vectors and strains, cheap and relatively straight-forward cultivation methods paired with reported high protein yields are reasons why E. coli is often the first-choice host expression system for recombinant protein production. The chapter enclosed here details protocols and design strategies in strain selection and methods on how to parallelize expression conditions to optimize for soluble target protein expression in E. coli. The methods described have been validated in a protein production research facility.