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KMID : 0545120130230040473
Journal of Microbiology and Biotechnology
2013 Volume.23 No. 4 p.473 ~ p.482
Biodesulfurization of Dibenzothiophene and Its Derivatives Using Resting and Immobilized Cells of Sphingomonas subarctica T7b
Ida Bagus Wayan Gunam

Kenta Yamamura
I Nengah Sujaya
Nyoman Semadi Antara
Wayan Redi Aryanta
Michiko Tanaka
Fusao Tomita
Teruo Sone
Kozo Asano
Abstract
The desulfurization ability of Sphingomonas subarctica T7b was evaluated using resting and immobilized cells with dibenzothiophene (DBT), alkyl DBTs, and commercial light gas oil (LGO) as the substrates. The resting cells of S. subarctica T7b degraded 239.2 mg of the initial 250 mg of DBT/l (1.36 mM) within 24 h at 27oC, while 127.5 mg of 2-hydroxybiphenyl (2-HBP)/l (0.75 mM) was formed, representing a 55% conversion of the DBT. The DBT desulfurization activity was significantly affected by the aqueous-to-oil phase ratio. In addition, the resting cells of S. subarctica T7b were able to desulfurize alkyl DBTs with long alkyl chains, although the desulfurization rate decreased with an increase in the total carbon number of the alkylated DBTs. LGO with a total sulfur content of 280 mg/l was desulfurized to 152 mg/l after 24 h of reaction. Cells immobilized by entrapment with polyvinyl alcohol (PVA) exhibited a high DBT desulfurization activity, including repeated use for more than 8 batch cycles without loss of biodesulfurization activity. The stability of the immobilized cells was better than that of the resting cells at different initial pHs, higher temperatures, and for DBT biodesulfurization in successive degradation cycles. The immobilized cells were also easily separated from the oil and water phases, giving this method great potential for oil biodesulfurization.
KEYWORD
Biodesulfurization, dibenzothiophene, resting cells, immobilized cells, Sphingomonas subarctica
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