Low-temperature caproate production,microbial diversity,and metabolic pathway in xylose anaerobic fermentation

Mixed culture fermentation(MCF)is challenged by the unqualified activity of enriched bacteria and unwanted methane dissolution under low temperatures.In this work,caproate production from xylose was investigated by MCF at a low temperature(20°C).The results showed that a 9 d long hydraulic retention time(HRT)in a continuously stirred tank reactor was necessary for caproate production(~0.3 g/L,equal to 0.6 g COD/L)from xylose(10 g/L).The caproate concentration in the batch mode was further increased to 1.6 g/L.However,changing the substrate to ethanol did not promote caproate production,resulting in~1.0 g/L after 45 d of operation.Four genera,Bifidobacterium,Caproiciproducens,Actinomyces,and Clostridium_sensu_stricto_12,were identified as the enriched caproate-producing bacteria.The enzymes in the fatty acid biosynthesis(FAB)pathway for caproate production were identified via metagenomic analysis.The enzymes for the conversion of(C_(n+2))-2,3-Dehydroxyacyl-CoA to(C_(n+2))-Acyl-CoA(i.e.,EC 1.3.1.8 and EC 1.3.1.38)in the reverseβ-oxidation(RBO)pathway were not identified.These results could extend the understanding of low-temperature caproate production.

Mechanism of powdered activated carbon enhancing caproate production

Caproate, produced by microbial chain elongation process, is potential to replace the diversified fossilbased products, contributing to carbon neutrality. However, its production performance is far from industrial application, so the cost-effective enhancement measures are highly needed. This study confirmed powdered activated carbon(PAC) has a significant effect on enhancing caproate production performance.The production, yield, and selectivity of caproate were improved by more than 1-fold by the optimized PAC dosage of 15 g/L, comparing with control. Mechanism investigation from a new visual angle showed that PAC accelerated ethanol oxidation to generate acetyl-Co A, and simultaneously boosted the efficiency of reverse β oxidation(RBO) by promoting the timely reaction of butyrate and acetyl-Co A to synthesis caproate. The addition of PAC also shifted the microbial community by enriching more caproateproducing bacteria but eliminating irrelevant ones. Furthermore, metagenomic analysis revealed that PAC effectively up-regulated the functional genes encoding key enzymes responsible for ethanol oxidation and RBO pathway, which was the root cause for the improved caproate production. This study presented the intrinsic insights into the mechanism of PAC promoting caproate generation, laying a foundation to the scale production of caproate.

Isolation of aromatic yeasts(non-<i>Saccharomyces</i><i>cerevisiae</i>) from Korean traditional <i>nuruks</i>and identification of fermentation characteristics

Ethyl caproate and isoamyl alcohol are important for the quality of Yakju, one of the Korean traditional alcoholic beverages. From Korean traditional fermentation agent, Nuruk, we have isolated 8 yeasts which produced rich aromatic compounds using YEPD agar plates (1% yeast extract, 2% peptone, 2% dextrose, 2% agar) containing 50 uL cerulenin at 30℃. The isolated aromatic yeasts are identified as Pichia anomala (4 strains), Pichia fabianii (2 strains), Pichia farinose (1 strains), Geotrichum candidum (1 strains). We conducted alcohol fermentation with each of the aromatic yeasts and the compounds (ethyl caproate and isoamyl alcohol) producing range were 59.5 - 193.2 ppm and 10.8 - 91.6 ppm respectively. As a control, Fermivin&reg;, famous aromatic wine yeast, was 89.4 ppm and 16.2 ppm respectively. We also find that the isolated Pichia anomala could produce higher level ethanol (4.2% - 5.0%, v/v) than other species (0.4% - 2.2%, v/v). Using the aromatic yeasts in fermentation industries, we expect to improve the quality of traditional alcoholic beverages.

Approach of Obtaining Liquor Flavoring From Yellow Water Based on Azeotropic Distillation

In order to extract the scarce natural liquor flavoring which is the dream of many liquor factories from yellow water,this research first added a proper amount of food-grade entrainer ethanol into yellow water,to form yellow water containing high content of ethanol.Then,the yellow water was subjected to azeotropic distillation and catalytic esterification,obtaining natural acetaldehyde,ethyl formate,ethyl acetate and esterification liquid containing various compounds that can influence the flavor of liquor.In the esterification liquid,the contents of ethyl propionate,ethyl butyrate,ethyl valerate,ethyl lactate and ethyl hexanoate are as higher as 19.0,46.5,1.5,39.8 and 137.1 g/L,respectively.The esterification liquid prepared by one fraction of yellow water can blend 9.14 fractions of common liquor into top-grade Luzhou-flavor liquor.Therefore,yellow water has great recycling value.

What Prevents Eligible Patients from Receiving Progesterone Therapy to Prevent Recurrent Preterm Birth

Objective: The use of intramuscular 17-alpha-hydroxyprogesterone caproate (17-OHPC) has been shown to be beneficial for the prevention of preterm birth (PTB) in women with a prior history. Not all patients with a prior preterm birth receive 17-OHPC. The purpose of this study was to investigate potential barriers to receiving this therapy. Methods: A retrospective chart review of those patients at our institution who received the diagnosis of “previous preterm delivery” in 2010 and 2011 was performed to see whether they were offered and received 17-OHPC. Patients were considered eligible if they had a prior delivery at less than 36 weeks of gestation secondary to idiopathic preterm labor. For those patients that were deemed eligible but did not receive therapy, an explanation was sought. Results: Sixty-six charts were reviewed in detail. Forty-three patients were considered eligible to receive 17-OHPC. The remaining had medical indications for delivery including premature rupture of membranes (PROM) (15), intrauterine growth restriction (IUGR) (1), and hypertension (2). Of the 43 patients deemed eligible, 17 did not receive 17-OHPC. Of these, eight patients were not offered therapy, 2 patients declined therapy, 3 patients presented with therapy after 28 weeks (too late), and 4 received a prophylactic cerclage as their only therapy. There were no significant differences between the two groups. Conclusion: In an effort to increase 17-OHPC use among eligible patients, we must continually identify physician biases and patient barriers that prevent utilization of this intervention. In addition, patients who deliver preterm should be told the importance of presenting early in subsequent pregnancies in order to receive the full benefits of this therapy.

Risk Assessment and Prevention of Spontaneous Preterm Birth

Preterm parturition is the consequence of pathological signals that activate the common pathway of parturition and considered as a syndrome.Many risk factors for spontaneous preterm birth(sPTB)have been identified.Two significant risk factors for sPTB are history of prior sPTB and short cervical length at midtrimester.17 hydroxyprogesterone caproate,vaginal progesterone,cerclage,and pessary have all been studied for prevention of sPTB.Difference in patient populations likely contributes to the conflicting study results.Further studies are needed to establish strategies in prevention of sPTB in singleton as well as multiple pregnancies.