Screening the growth of the cyanobacteria Aphanothece under photoautotrophic and Photoheterotrophic conditions

Abstract

Screening the Growth of Cyanobacteria Aphanothece under Photoautotrophic and Photoheterotrophic Conditions Ifti Ahmed1,2, Ali Parsaeimehr1, Ph.D., and Bertand Hankoua1, Ph.D. 1Department of Agriculture and Natural Resources Delaware State University, Dover, DE 19901 2Middletown High School, Middletown, DE 19709. Microalgae are used in different industrial sectors including, the biopharmaceutical and nutraceutical industries. The main objective of this study was to identify a high yield photoheterotrophic condition for the Cyanobacteria Aphanothece in aim to produce phycocyanin, and allophycocyanin metabolites with pharmaceutical values. In this study, a BG11 based media was used. To establish a photoheterotrophic conditions a ratio of glucose (0, 025, 0.5, 2, and 4%) as a carbon source was applied. Our results demonstrated, a higher yield of biomass under the photoheterotrophic conditions containing 2 % glucose (3.11 ± 0.35 g/L fresh weight, OD750=1.08 ±0.14 7th day; relative growth rate: OD750= 0.120 ± 0.2 day, 74.22 ±3.2%, an increase of 74.22 ±3.2% compared to photoautotrophic growth). A negative influence was observed at higher concentration of carbon source (4% of glucose) on the biomass production (52.82 ±2.7 % decrease). Considerably, the production of phycocyanin (6.72 ± 0.42 mg/g fresh weight), and allophycocyanin (0.132 ± 0.08 mg/g fresh weight) were recorded higher under the photoheterotrophic condition compared to the photoautotrophic growth by 236 ± 17 % and 69.23 ± 8.3 % increase, respectively for phycocyanin and allophycocyanin. We observed increasing the carbon source to 4% had a negative impact by 128.57 ± 14 % decrease on the production of phycocyanin, while a positive influence by 145 ± 12 % increase on the allophycocyanin production (0.324 ± 0.028 mg/g fresh weight). In conclusion, we suggest a photoheterotrophic BG11 based media with 2 % glucose for the production of phycocyanin, and allophycocyanin when using Cyanobacteria Aphanothece as a platform. Keywords: Aphanothece, photoheterotrophic, phycocyanin, and allophycocyanin Funder Acknowledgments: We acknowledge USDA NIFA Capacity Building Grant Award# 2016-06642 for funding my internship and the project as part of the student experiential learning goal and the project Director, Dr. Gulnihal Ozbay for providing this internship opportunity.