Isolation and Characterization of Euglena gracilis-Associated Bacteria, Enterobacter sp. CA3 and Emticicia sp. CN5, Capable of Promoting the Growth and Paramylon Production of E. gracilis under Mixotrophic Cultivation

Abstract

Euglena gracilis produces paramylon, which is a feedstock for high-value functional foods and nutritional supplements. The enhancement of paramylon productivity is a critical challenge. Microalgae growth-promoting bacteria (MGPB) can improve microalgal productivity; however, the MGPB for E. gracilis remain unclear. This study isolated bacteria capable of enhancing E. gracilis growth and paramylon production under mixotrophic conditions. Enterobacter sp. CA3 and Emticicia sp. CN5 were isolated from E. gracilis grown with sewage-effluent bacteria under mixotrophic conditions at pH 4.5 or 7.5, respectively. In a 7-day E. gracilis mixotrophic culture with glucose, CA3 increased E. gracilis biomass and paramylon production 1.8-fold and 3.5-fold, respectively (at pH 4.5), or 1.9-fold and 3.5-fold, respectively (at pH 7.5). CN5 increased E. gracilis biomass and paramylon production 2.0-fold and 4.1-fold, respectively (at pH 7.5). However, the strains did not show such effects on E. gracilis under autotrophic conditions without glucose. The results suggest that CA3 and CN5 promoted both E. gracilis growth and paramylon production under mixotrophic conditions with glucose at pH 4.5 and 7.5 (CA3) or pH 7.5 (CN5). This study also provides an isolation method for E. gracilis MGPB that enables the construction of an effective E. gracilis–MGPB-association system for increasing the paramylon yield of E. gracilis.

Replacing starch with resistant starch (Laminaria japonica) improves water quality, nitrogen and phosphorus budget and microbial community in hybrid snakehead (Channa maculata ♀ × Channa argus ♂)

“…Ammonia nitrogen and nitrate nitrogen make up most of the total nitrogen among them (Lananan et al, 2014). The principal differential microbial in the control group C and FR group, Gemmobacter , Rhodobacter , Emticicia and Bosea were discovered to be Proteobacteria by subsequent identification of the experiment's differential microbial (Li, Li, et al, 2022; Rubiyatno et al, 2021; Song et al, 2020). Moreover, these microbial all have the effect of denitrification (Tan et al, 2020).…”

APPLICATION OF Euglena sp. ISOLATED FROM YOGYAKARTA, INDONESIA ON NUTRIENT REMOVAL FROM PALM OIL MILL EFFLUENT (POME)

“…E. gracilis was distinguished by its tolerance to high nutrient concentrations in water (Nezbrytska et al, 2022). Euglena can grow both autotrophic, heterotrophic, and mixotrophic (Rubiyatno et al, 2021). Besides that, Euglenoids were a group of fast-growing algae, capable of reaching very high cell densities, even in extreme environments (O'Neill, 2020).…”