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.
Wild cassava (Manihot glaziovii Muell. Arg) is one of the varieties of cassava that contains toxic compounds cyanogenic glucosides, which cause unmarketable food products more suitable to be processed into bioethanol. This wild cassava plant produces tubers four times in weight compared to that of ordinary cassava, and the flesh contains about 40–70% starch by dry weight. This study aimed to determine the effect of the microbial types and fermentation times on bioethanol production from M. glaziovii Muell. Arg crude starch and to determine the type of microbes and fermentation time that can produce the highest bioethanol product from M. glaziovii Muell. Arg crude starch. This study consists of two factors using a factorial randomized block design (RBD). The first factor was the type of microbe which consists of 2 different microbes, namely R5I3 isolates and Saccharomyces cerevisiae ATCC 9763. The second factor was the fermentation time which consists of 4 levels, namely 3, 4, 5 and 6 days. The observed parameters were total dissolved solids value, pH value, reducing sugar content, and ethanol content. The data obtained were analyzed using analysis of variance (ANOVA) and continued with Tukey’s HSD post hoc tests. The results showed that fermentation using R5I3 isolates with a fermentation time of 5 days was the best treatment to obtain a maximum ethanol of 21.64±3.03 g/L, with a final pH value of 4.70±0.14, total dissolved solids 4.10±0.14°Brix and reducing sugar content of 0.91±0.02 g/L. Therefore, the new isolate R513 was highly potential for producing bioethanol from wild cassava crude starch.
Bioactive peptides fermented milk is very potential as functional food products for health. The aim of this study is to analyze the inhibition activity of Angiotensin Converting Enzyme and kefir whey amino acid profile and IC50. The design being applied is a comprehensive random design with five treatments (fermentation time 0, 3, 6, 9 and 12 days) and 3 replications. ACE inhibition indicators include ACE inhibition with IC50, protein, peptide concentration, total proteolytic, and amino acid profiles. The results show that ACE inhibition activity ranges from 35.94 -66.67% with peptide levels of 872.80 -1084.74 mg/mL and IC50 of 65.48 µg/mL, and contained hydrophobic amino acids which functioned for ACE inhibition. The conclusion of this study that the highest ACE inhibition is obtained at 0 day of fermentation with inhibition ability (IC50) of 65.48 µg/mL and functioning as nutraceuticals food.
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