Biology subjects

Karitani, Y.

Publications and source records attributed to Karitani, Y..

2 recordsLinked to original sources

bioRxiv2024

Co-utilization of microalgae and heterotrophic microorganisms improves wastewater treatment efficiency

Wastewater treatment using co-culture systems of microalgae and heterotrophic microorganisms is expected to be useful under atmospheric dilute carbon dioxide conditions. In this study, we investigated the combination of microalgae and heterotrophic microorganisms to improve the efficiency of wastewater treatment. Furthermore, to elucidate the cause of the changes in wastewater treatment efficiency in the co-culture system, changes in gene expression were revealed through transcriptome analysis. Three types of microalgae and five heterotrophic microorganisms were used in combination for wastewater treatment. The combination of Chlamydomonas reinhardtii NIES-2238 and Saccharomyces cerevisiae SH-4 showed the highest wastewater treatment efficiency. Using this combination for artificial wastewater treatment, the removal rates of TOC (Total organic carbon), PO43-, and NH4+ reached 80%, 93%, and 63%, respectively, after 18 h of treatment. Transcriptome analysis revealed that the combined wastewater treatment altered the expression of 1371 and 692 genes in C. reinhardtii and S. cerevisiae, respectively. The genes upregulated in C. reinhardtii included those related to molecular and ion transport. Genes upregulated in S. cerevisiae included those related to cell protection from various types of damage and stress. To the best of our knowledge, this is the first study to show that a combination of green algae and yeast improves the efficiency of wastewater treatment. As both the green alga C. reinhardtii and the yeast S. cerevisiae are highly safe microorganisms, the establishment of their effective combination for wastewater treatment is highly significant.

bioengineering↗

bioRxiv2023

Improvement of cell growth in green algae Chlamydomonas reinhardtii through co-cultivation with yeast Saccharomyces cerevisiae

Biological fixation methods have attracted considerable attention because they can be applied for the fixation of dilute CO2 in the atmosphere. Co-cultivation of certain microalgae with heterotrophic microorganisms can increase the growth potential of microalgae under dilute CO2 conditions. The objective of this study was to determine the culture conditions under which the growth potential of green algae Chlamydomonas reinhardtii is enhanced by co-culturing with the yeast Saccharomyces cerevisiae, and to identify the cause of the enhanced growth potential using transcriptome analysis. When C. reinhardtii and S. cerevisiae were co-cultured with an initial green algae to yeast inoculum ratio of 1:3, the cell concentration of C. reinhardtii reached 133 x 105 cells/mL on day 18 of culture, which was 1.5 times higher than that of the monoculture. Transcriptome analysis revealed that the expression levels of 363 green algae and 815 yeast genes were altered through co-cultivation. These include genes responsible for ammonium transport and CO2 enrichment mechanism in green algae and the genes responsible for glycolysis and stress responses in yeast. In conclusion, we identified the culture condition suitable for the co-cultivation of C. reinhardtii and S. cerevisiae. In addition, we discuss the cause of the increased growth potential of C. reinhardtii based on transcriptome analysis data. Although further studies are needed to elucidate the full impact of microbial interactions in C. reinhardtii and S. cerevisiae co-cultures, the findings of this study represent an important first step toward achieving this goal.

bioengineering↗