| Summary: | 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. 4C 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.
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