Aquatic environments have changed considerably during recent decades due to many influences, including: climate change, altered nutrient inputs, land-use modification, and invasive species. Algae are fundamental members in aquatic ecosystems, composed of microscopic photosynthetic organisms and macroscopic seaweeds. As one of the oldest organisms on the planet, their high adaptability has allowed them to thrive in a variety of aquatic habitats, such as lakes, rivers, oceans, or anthropogenic niches. The success and resilience of algae significantly impacts the environment as they are responsible for converting atmospheric CO 2 into oxygen and high carbon compounds. Moreover, as the foundation of both freshwater and marine food chains, algae and their natural products have a huge range of current and potential applications for humans. This session focuses on algal cultivation and algal biotechnology, including valuable compounds as well as biomass produced by microalgae and macroalgae. Algal Biotechnology is a rapidly expanding discipline that seeks to understand and harness the resources from some of the most diverse groups of organisms on the planet. For example, developing applications include pharmaceuticals, pigments and fluorescent molecules, nutraceuticals, feed for aquaculture, feed supplement for cattle to improve weight gain while reducing enteric methane emissions, biofuels, food variations and food supplement, enzymes, wastewater treatment, fertilizers and plant biostimulant applications, bioremediation materials on earth, and even for outer space applications. The session will also focus on macroalgal farming which is contributing to energy security by reducing greenhouse gas emissions via biofuel production as well as production of various products such as textiles, bioplastics, and fertilizers. As macroalgae farming is expanding rapidly worldwide, we aim to discuss how to develop a sustainable aquaculture industry that keeps healthy and diverse aquatic environments. The session will cover (i) algal cultivation methods, including designing of photobioreactors to optimize the growth regimes for specific purposes, (ii) production of algal biomass, (iii) production of valuable compounds by algae, and (iv) genetic engineering of algae for microalgal industry. We hope the topic will attract the attention of top scientists who will be able to present their latest studies focused on algal biotechnology.
Lead Organizer: Brittany Sprecher, University of California San Diego (brittany.sprecher@uconn.edu)
Co-organizers:
Soo Hyun Im, University of Konstanz (soo-hyun.im@uni-konstanz.de)
Tomáš Grivalský, Laboratory of Algal Biotechnology, Institute of Microbiology - Centre Algatech (grivalsky@alga.cz)
Presentations
05:00 PM
Isolating microalgae for carbon sequestration and their molecular responses to high CO2 exposure (5593)
Primary Presenter: Feng Chen, University of Maryland Center for Environmental Science (chenf@umces.edu)
Certain microalgal species can grow under high CO2 conditions and they hold the potential for tackling climate change by sequestering CO2 produced by power plants and other industries. Here we show how to select suitable algal species or strains for carbon sequestration and understand their responses to the high CO2 level (10%) at the molecular level. A community-based approach was used to enrich CO2-tolerant microalgae from a local water source. During the incubation process, changes in bacterio- and phytoplankton communities were monitored. At the end of CO2 enrichment, green algae Scenedesmus species dominated the algal community. Isolated Scenedesmus strains are able to grow rapidly with high CO2, wastewater, chicken manure nutrient, etc. The growth of algae also increased alkalinity and pH in the culture which can lead to additional carbon sequestration via the formation of CaCO3 precipitate. To understand how Scenedesmus obliquus responds to 10% CO2 exposure at the molecular level, we applied time-resolved transcriptomics (2, 12, 24 and 72 hrs) to investigate differential gene expression of the alga. Certain genes responsible for light-harvesting, chlorophyll synthesis, and carbon fixation (i.e. rbcS) were up-regulated at 10% CO2, and these functional responses are consistent with the increased photosynthesis efficiency and algal biomass under 10% CO2. Key genes like RuBisCO (rbcL) and carbonic anhydrase in carboxysomes did not respond actively to 10% CO2. S. obliquus responded quickly (2 hr) and became adaptive within 12 h when exposed to 10% CO2.
05:15 PM
A BIO-OPTICAL APPROACH TO OPTIMIZING THE COUPLING BETWEEN WASTE REMEDIATION AND PRODUCTION OF ALGAL BIOMASS AND BIOPRODUCTS (6966)
Primary Presenter: Hugh MacIntyre, Dalhousie University (hugh.macintyre@dal.ca)
Use of microalgal or cyanobacterial culture to remediate waste-streams and produce biomass or bioproducts at minimal cost requires selecting an appropriate strain/strains and optimizing growth conditions. However, there is no widely used metric that allows comparison of the responses of different organisms or the variation in response of a single organism to different growth conditions. Optimal candidate organisms and conditions can be assessed explicitly by comparisons of the quantum yields of production. In the simple case of optically-thin, photosynthetic cultures, this is derived from spectral light absorption and attenuation and the specific growth rate. In the case of metabolic products with significant commercial value (protein, omega-3 fatty acids, carotenoids, anti-microbials etc.), it also requires specification of the biomass quota of the target constituent. The approach can be expanded to mixotrophic growth by considering the effects of mixotrophy on light absorption, growth rate, and internal resource partitioning. We illustrate the combined lab and modelling approach with examples of biomass and high-value compounds from organisms in photoautotrophic vs mixotrophic culture. The mixotrophic cultures were grown on media amended with high-nutrient wastes from food industries (whey permeate from cheese production; processing waste from fisheries; and vinasse from distillation).
05:30 PM
Engineered cyanobacteria as promising platform for sustainable 2-phenylethanol production (5754)
Primary Presenter: Barbara Menin, National Research Council of Italy (barbara.menin@ibba.cnr.it)
The resilience and recovery strategies implemented by European Union countries have as key pillars the reduction of environmental impacts and waste valorisation. In this context, biotechnological approaches based on cyanobacteria offer great potential as biocatalyst for CO<sub>2</sub> conversion into a plethora of added-value compounds. By a combined approach of metabolite doping and metabolic engineering, we developed and optimized an efficient microbial platform based on engineered <em>Synechococcus elongatus</em> PCC 7942 for the production of 2-phenilethanol (2-PE), a high-value aromatic rose-scented compound, exploitable in the food, fragrance and flavour industries. The success of our strategy lies on the compensation of the metabolic burden by implementing a BG11 medium doped with L-phenylalanine and on the overexpression of a key endogenous gene (i.e. shikimate synthase) of the shikimate pathway involved in the synthesis of 2-PE precursors. Thus, we obtained a maximum 2-PE titer of 285 mg/L, the highest recorded so far for photosynthetic microorganisms in autotrophic condition. Moreover, in order to make the process sustainable, we essayed the exploitation of wastewater (WW) as growth substrate. We screened several WWs from the dairy manufacturing, a major industrial contributor to water pollution due to the large volume and high nutrient load of its effluents. Our trials showed the possibility of fully support the growth of engineered strain by balancing dairy washing water and digestate, confirming the potential of cyanobacteria as sustainable green factories.
05:45 PM
SUNFISH AS BIOLOGICAL CONTROL AGENTS FOR WASTEWATER-CLEANING ALGAE (5211)
Primary Presenter: Chase Rakowski, University of Texas at Austin (chaserak@gmail.com)
Wastewater-algal cultivation systems are a promising way to simultaneously combat multiple environmental problems. In these systems algae use polluting nutrients to grow, thereby cleaning wastewater while producing biomass to be used for biofuel or fertilizer. However, wastewater-algal cultivation has not yet been widely adopted, one reason being that herbivorous zooplankton often proliferate and reduce algal yields. Biological control is a promising solution to this problem, but few studies have tested methods of biological control to improve algal yields. To test whether bluegill sunfish can improve the performance of wastewater-algal cultivation systems, we built 18 225-L raceway ponds with continuous circulation. We filled the ponds with ammonium-rich hypereutrophic media intended to imitate wastewater, inoculated them with local phytoplankton and zooplankton, and performed 12.5% media exchanges every two days to imitate a continuous culturing system. We placed one juvenile bluegill (Lepomis macrochirus) in each of 12 ponds, half inside a 0.1-m2 cage meant to reduce predation rates on more mobile prey and half outside the cage. The remaining six ponds served as fishless controls. While placement of fish inside or outside the cage had little effect, after just 18 days the fish had decreased zooplankton mass by 89% and increased dry algal mass by 45%. Our findings demonstrate the potential for hardy zooplanktivorous fish to improve the efficiency of wastewater-algal cultivation, suggesting a strategy for facilitating wider adoption of environmental algal technologies.
06:00 PM
OPTIMIZING THE CHEMICAL ECOLOGY OF ALGAL CONSORTIA TO ENHANCE THE SUSTAINABILITY AND ECONOMIC VIABILITY OF INDUSTRIAL CULTIVATION FOR BIOPRODUCTS (7033)
Primary Presenter: Patrick Thomas, Eawag (pkthomas88@gmail.com)
Domesticated microalgae have the potential to significantly enhance the efficiency, sustainability, and resilience of global food and fuel production. However, large scale cultivation in open ponds is challenged by problems related to both the ecology of complex aquatic systems (e.g. grazers, competitors, and pathogens) and engineering (e.g. energy-intensive harvesting practices). One proposed solution to these problems is to use synthetic algal communities that are more robust to invasion and also possess traits that facilitate more streamlined and efficient methods for the extraction of bioproducts. Specifically, optimizing the chemical ecology of algal consortia by strategically employing strains that excrete useful extracellular metabolites has the potential to inhibit pests while also simplifying the harvesting process. Here we present recent results from multiple lines of research that provide insights into the role of chemically-mediated interactions in shaping algal productivity. Specifically, we show that green algae species vary in their sensitivity to allelopathic inhibition; that green algae excrete inhibitory fatty acids in species-specific quantities; that algal exudates can have effects ranging from inhibition to facilitation; and that the growth phase determines allelopathic effects. We also outline preliminary and ongoing work aimed at characterizing metabolites secreted by algae and their effects on productivity, as well as efforts to apply selective pressures to both increase extracellular lipid production and increase tolerance to these secreted lipids.
06:15 PM
EFFECTS OF REPLACING DIETARY FISH OIL AND FISHMEAL WITH ALGAL BIOMASS AND MICROBIAL OIL ON FATTY ACID AND STEROL COMPOSITION OF ATLANTIC SALMON TISSUES (6505)
Primary Presenter: Chris Parrish, Memorial University of Newfoundland (cparrish@mun.ca)
The continuous growth of aquaculture places a growing demand on alternative sources for fish oil (FO) and fishmeal (FM) in aquafeeds. Certain microorganisms provide a potential sustainable replacement for FO and FM due to their content of omega-3 long-chain polyunsaturated fatty acids, which are essential for fish health. Salmon feeding trials were conducted to determine the effects of replacing FO and FM with oil and biomass from different microorganisms. The first trial replaced FO with a microbial oil (MO) derived from Schizochytrium. The second reduced FO and replaced FM with algal biomass (AB) derived from Pavlova. Growth was unaffected when microbial products replaced dietary fish oil and fishmeal; however, lipid profiles were altered. With MO, linoleic acid and α-linolenic acid were present in low proportions, and DHA was present in very high proportions in the cellular membrane, especially in muscle tissue. In addition to cholesterol in muscle tissue, cholestanol, campesterol, stigmasterol, dinosterol and 24-methylpavlovol were detected in salmon. With AB, DHA was present in high proportions in tissues of all dietary treatments, especially in cellular membranes. Stable isotope data indicated a direct integration of EPA and DHA and not biosynthesis from its precursor ALA. Growth performance, lipid class composition, phospholipid fatty acid composition, and compound specific stable isotope analysis all suggest that salmon grown on microbial-based diets digested and utilized nutrients well, and directly incorporated critically important fatty acids into their tissues.
SS048 Algal Industry for the Greener Future: Algal Cultivation, Biotechnology, Algal Compounds, and Biomass
Description
Time: 5:00 PM
Date: 5/6/2023
Room: Auditorium Illes Balears