Enhancement of fermentative hydrogen production from green algal biomass of Thermotoga neapolitana by various pretreatment methods
✍ Scribed by Tam-Anh D. Nguyen; Kyoung-Rok Kim; Minh-Thu Nguyen; Mi Sun Kim; Donhue Kim; Sang Jun Sim
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 325 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0360-3199
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✦ Synopsis
Biomass of the green algae has been recently an attractive feedstock source for bio-fuel production because the algal carbohydrates can be derived from atmospheric CO 2 and their harvesting methods are simple. We utilized the accumulated starch in the green alga Chlamydomonas reinhardtii as the sole substrate for fermentative hydrogen (H 2 ) production by the hyperthermophilic eubacterium Thermotoga neapolitana. Because of possessing amylase activity, the bacterium could directly ferment H 2 from algal starch with H 2 yield of 1.8e2.2 mol H 2 /mol glucose and the total accumulated H 2 level from 43 to 49% (v/v) of the gas headspace in the closed culture bottle depending on various algal cell-wall disruption methods concluding sonication or methanol exposure. Attempting to enhance the H 2 production, two pretreatment methods using the heat-HCl treatment and enzymatic hydrolysis were applied on algal biomass before using it as substrate for H 2 fermentation.
Cultivation with starch pretreated by 1.5% HCl at 121 C for 20 min showed the total accumulative H 2 yield of 58% (v/v). In other approach, enzymatic digestion of starch by thermostable a-amylase (Termamyl) applied in the SHF process significantly enhanced the H 2 productivity of the bacterium to 64% (v/v) of total accumulated H 2 level and a H 2 yield of 2.5 mol H 2 /mol glucose. Our results demonstrated that direct H 2 fermentation from algal biomass is more desirably potential because one bacterial cultivation step was required that meets the cost-savings, environmental friendly and simplicity of H 2 production.