J Pure Appl Microbiol | Research Article | Volume 12, Issue 4 | Article Number: 5296

Piyawat Pongpadung1, Litao Zhang2, Ramaraj Sathasivam3, Kittisak Yokthongwattana4, Niran Juntawong5 and Jianguo Liu2*

1Department of Agricultural Science, Faculty of Agriculture Natural Resources and Environment,  Naresuan University, Mueang, Phitsanulok 65000, Thailand.
2Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, Shandong 266071, P.R. China.
3Department of Biotechnology, Sangmyung University, Seoul 03016, South Korea.
4Department of Biochemistry and Center for Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, 272 Rama 6 Road, Bangkok 10400, Thailand.
5Department of Botany, Faculty of Science, Kasetsart University, 50 Ngamwongwan Road, Bangkok 10900, Thailand.

Corresponding Author E-mail: jgliu@qdio.ac.cn
Received: 25/08/2018| Accepted: 09/11/2018 |Published: 29/12/2018
DOI: http://dx.doi.org/10.22207/JPAM.12.4.04

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Abstract

Photosynthetic hydrogen (H2) production by green algae has fascinated biologists and energy experts, due to the potential application of this process for renewable energy. In this study, H2 photoproduction and PSII photochemical activities were investigated in Chlorella sorokiniana exposed to simultaneous nitrogen limitation and sulfur (S-) and/or phosphorus (P-) deprivation. Under S-deprivation, C. sorokiniana produced about 48.2 mL L-1 of H2. Moreover, simultaneous nitrogen limitation (0.7 mM NH4Cl) and sulfur- and/or phosphorus-deprivation significantly increased H2 production of C. sorokiniana over that of S-deprivation alone. Maximum H2 outputs of 77.3, 98.1 and 125.1 mL L-1 were obtained in the N-limited cultures exposed to P-deprivation (TAP-P), S-deprivation (TAP-S) and simultaneous S- and P-deprivation (TAP-S-P), respectively. The average rate of H2 production for the N-limited culture exposed to TAP-P, TAP-S and TAP-S-P was 1.07, 1.36 and 1.50 mL L-1 h-1, respectively. Interestingly, the H2 inducement time in the culture subjected to simultaneous N-limitation and S- and/or P-deprivation was much shorter than that of traditional S-deprivation. The photosynthetic inhibitors, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropylp-benzoquinone (DBMIB) repressed H2 production in TAP-S-P (0.7 mM NH4Cl) medium by 68.04% and 98.65%, respectively. The conditions of simultaneous N-limitation, S- and P-deprivation provided another efficient method for inducing H2 production in C. sorokiniana. In addition, we also found that two-thirds of the required electrons were generated from the splitting of H2O in PSII and that the remaining one-third possibly came from some other substrate catabolism.

Keywords: Chlorella sorokiniana, Hydrogen production, Nitrogen limitation, Phosphorus & Sulfur deprivation.