Study of stimulating strategies of electron-shuttles for microbial bioelectricity generation and dye decolorization

• Main Authors: Pei-Lin Yueh, 岳沛林
• Other Authors: Bor-Yann Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/05158621762355591472

碩士 === 國立宜蘭大學 === 化學工程與材料工程學系碩士班 === 104 === This feasibility study isolated indigenous functioning microorganisms from deep seawater (DSW)-fed Babylonia areolata for microbial fuel cell (MFC)-assisted dye decolorization (DD). Synergistic or antagonistic interactions of decolorized metabolites (DMs) on DD and bioelectricity generation (BG) in salty environment were also explored in depth. The rationale of study could be divided into three portions: (I) treatability study of microbial DD and BG was implemented by Shewanella sp. isolated from gut microbial consortia of DSW-fed B. areolata which was harvested from Hualien, Taiwan. Regarding screening protocol, as electron transfer (ET) mechanism for DD and BG were all associated, acclimation in dye-laden salty media was conducted for isolating bacteria with promising capabilities of DD and BG. The reasons why nanowire-generating Shewanella sp. WLP72 could be obtained herein were (1) specific gut microbial consortia in DSW-cultivated B. areolata provided critical selection pressure to maintain ecology likely not commonly present in wild nature; (2) low temperature at ca. 4C might exclude originally predominant bacteria in gut consortia to specifically isolate new functioning bacteria. The findings indicated that with serial acclimation under dye-bearing conditions Shewanella haliotis WLP72 expressed excellent dye-decolorizing performance, still maintaining stable azo-reducing capabilities in salt-laden cultures. Regarding portion (II), characteristics of BG and DD for DMs-supplemented cultures of WLP72 versus Exiguobacterium sp. K2 and Proteus sp. ZMd44 were significantly affected by chemical structure of DMs to be mediated. For example, -OH and -NH2 substitute-containing electron shuttles (ESs) were superior to dihydroxyl substitute-bearing ESs. Moreover, para-isomeric ES was apparently better performed than ortho-isomeric ES. Considering portion (III), to provide simple and plausible assessment to quantitatively evaluate ET efficiency in MFCs, this study also proposed “ET equivalent” concept, indicating “stoichiometric” equivalent electron number required to decolorize 1 g of azo dye in various conditions of SBG and DD. In fact, MFC-assisted DD increased overall ET efficiency more than 60%. Although the performance of SBG&DD reduced 40% in salty conditions, augmentation of DMs could overcome such hostile stress, resulting in >50% increase of overall performance. In summary, supplemented DMs could provide effective and feasible alternatives to overcome salty hostile conditions and significantly increase performance of BG and DD in MFCs for promising feasibility without dispute.