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 27 degrees C, 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.

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Fresh-cut tropical fruit is increasingly popular currently, stimulated by public awareness of health and practical lifestylefresh-cut fruit presenting consumers' convenience, safety, and quality. Tropical fruit contains functional components that are quite varied and good for health. Mangosteen, Mango, and Rambutan are three exotic tropical fruits that have high economic value and are liked by foreign people. They have a nonedible relatively high and potentially processed into fresh-cut fruit-the process of stripping cutting and slicer, causing wounds that spur damage. During storage, fresh-cut fruits undergo physical-chemical changes-increased respiration rate, ethylene production, oxidation, and browning processes that can shorten shelf life. The damage will be faster if stored at an improper temperature. Fresh-cut fruit is preferably stored at cold temperatures, to extend the shelf life. The research aims to determine the physicochemical characteristics of fresh-cut tropical fruits during cold storage. The research uses a pattern of random group three replicate. The first factor is fruit type (Mango, Mangosteen, Rambutan); the second factor is storage time in cold temperatures (0, 5, 10 days). The variables observed in the study included physical characteristics color (L*a*b*), weight, and texture. Observations of chemical characteristics include moisture content, pH, total acids, vitamin C levels, and total dissolved solids. Freshcut tropical fruit has different physicochemical characteristics and experiences deterioration during cold temperatures. The characteristics of tropical fruit have changed significantly on day 5. Mango shows more significant changes than others, seen from variable moisture content, vitamin C, color, and texture. Meanwhile, based on the physicochemical analysis, rigidity of fresh-cut Mango higher than Mangosteen and Rambutan.

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