Methods in Photosynthetic Physiology, Cultivation and Harvesting of Photosynthetic Microbes

The crucial aspects of cultivation of photosynthetic microbes are assessing photosynthetic physiology and optimizing bioreactors and biomass processing. Several instruments including Pulse Amplitude Modulator, Fluorometer, and Infrared Gas Analyzer measure photosynthetic dynamics. Fast kinetics of chlorophyll a fluorescence and light response curves give holistic understanding of photosystem complexes to different environmental conditions. OJIP fluorescence transients’ analysis and corresponding K, L, and P bands investigate the kinetics, regulation, and functional significance of photosystems and other photosynthetic machinery. The dissipation of excess energy occurs through passive mechanisms such as heat and fluorescence emitted by light-harvesting complexes, which play a crucial role in the production of Y(NO) and Y(NPQ). Other than photosynthetic physiology, designing of bioreactors and downstream processing are crucial elements in microbial biorefinery, impacting the acquisition, alteration, extraction, and purification of high-value compouunds. Two-stage cultivation of microalgae optimizes growth and productivity for various applications thus reducing competition for resources. Algae and bacteria symbiosis is beneficial for nutrient exchange, gene transfer, and signal transduction and highly useful in fixed bed photobioreactors, airlift reactors, and photobioreactors. Photobioreactors are artificially constructed systems that facilitate light-dependent photosynthesis, allowing for higher algal yields. Airlift reactors have a high degree of flexibility and are well-suited for integration into biorefineries and integrated power-generating systems. Horizontal tubular bioreactors are space-efficient and helical tubular bioreactors are space-efficient but require larger pipes and tubes for scaling up. Flat plate bioreactors aim to maximize efficiency from sunlight but have drawbacks like disrupted flow control and increased oxygen content. High-rate algal ponds are sustainable, cost-effective, and have applications in cattle and aquaculture feed, soil conditioner, and biofuel production. The present chapter outlines the techniques involved in photosynthetic physiology, describes the instrumentation and methodology. Further, the chapter gives a detailed overview of the culturing and processing techniques of photosynthetic microbes.