Factors affecting biohydrogen production by unicel

Authors: Samart Taikhao Suwannee Junyapoon Aran Incharoensakdi Saranya Phunpruch

Publish Date: 2012/08/31

Volume: 25, Issue: 2, Pages: 575-585

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Abstract

The effects of several physiological parameters on H2 production rate in the unicellular halotolerant cyanobacterium Aphanothece halophytica were investigated Under nitrogen deprivation the growth of cells was inhibited but H2 production rate was enhanced approximately fourfold Interestingly cells grown under sulfur deprivation exhibited a decrease in cell growth H2 production rate and bidirectional hydrogenase activity Glucose was the preferred sugar source for H2 production by A halophytica but H2 production decreased at high glucose concentrations H2 production rate was optimum when cells were grown in the presence of 075 M NaCl or 04 μM Fe3+ or 1 μM Ni2+ The optimum light intensity and temperature for H2 production were 30 μmol photons m−2 s−1 and 35 °C respectively A twostage culture of A halophytica was performed in order to overcome the reduction of cell growth in Nfree medium In the first stage cells were grown in normal medium to accumulate biomass and in the second stage H2 production by the obtained biomass was induced by growing cells in Nfree medium supplemented with various chemicals for 24 h A halophytica grown in Nfree medium containing various MgSO4 concentrations had a high H2 production rate between 11432 and 12767 μmol H2 mg chlorophyll a chl a−1 h−1 a 30fold increase compared to cells grown in normal medium The highest rate of 13804 μmol H2 mg chl a −1 h−1 was obtained when the Nfree growth medium contained 04 μM Fe3+ These results suggested the possibility of using A halophytica and some other halotolerant cyanobacteria thriving under extreme environmental conditions in the sea as potential sources for H2 production in the futureThe study was financially supported by the Commission on Higher Education CHE Thailand The university staff development consortium S Taikhao is also thankful to the Strategic Scholarships for Frontier Research Network for the PhD Program provided by CHE A Incharoensakdi thanks CHE and the Thai government for the National Research University Project FW 0659A and the Stimulus Package 2 TKK 2555 respectively The authors would like to thank Prof Peter Lindblad Uppsala Sweden for valuable comments

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