Tolerance to allelopathic inhibition by free fatty acids in five biofuel candidate microalgae strains. (February 2023) - Thomas, Patrick K.
Abstract: Contaminating organisms (grazers, pathogens, competitors) and self-inhibition by algae-produced allelopathic chemicals are two issues that may limit the productivity of algal cultivation for bioproducts. One potential solution is to identify algal strains that are not affected by allelopathic inhibition even while undesirable organisms are suppressed. Here we used two experiments to test how sensitivity to allelopathy varies across algae. In the first experiment, we tested the sensitivity of five biofuel candidate green algae strains to two allelopathic compounds (i.e., free fatty acids) and found that the degree of inhibition depends strongly on both the species and specific compound. In the second experiment, we exposed one alga ( Chlorella ) to the sterile-filtered medium of each species, and found that the concentration of free fatty acids released into the media predicted Chlorella 's growth response. This provides a better understanding of how the production of, and sensitivity to, allelopathic compounds determines algal productivity. Graphical abstract: Unlabelled Image Highlights: 5 green algae species were experimentally exposed to free fatty acids (FFAs). Estimated inhibitory FFA levels range widely from 4 to >4000 mg L −1 . Chlorella growth rate (−37 %), biomass (−26 %) reduced by Botryococcus filtrate. Chlorella growth rate (+33 %), biomass (+81 %) increased by other species' filtrate. Understanding chemical interactions among algae can help optimize algal production.