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Butyl butyrate is a short-chain fatty acid ester (C8) with a fruity aroma. It has broad prospects in the fields of foods, cosmetics and biofuels. At present, butyl butyrate is produced by chemical synthesis in the industry, but it is highly dependent on petroleum-based products. The growing concerns regarding the future scarcity of fossil fuels have been strongly promoted the transition from traditional fossil fuels and products to renewable bioenergy and biochemicals. Therefore, it is necessary to develop a green biochemical technology to replace traditional petroleum-based materials. In recent years, microorganisms such as Escherichia coli and Clostridium have been engineered to serve as cell factories for the sustainable one-pot production of short-chain fatty acid esters, including butyl butyrate. This opinion highlights the recent development in the use of lipases and alcohol acyltransferases (AATs) for butyl butyrate production in microbial fermentation, as well as future perspectives., (© 2024 The Author(s). Microbial Biotechnology published by John Wiley & Sons Ltd.)

We conducted two feeding experiments to evaluate the effects of supplementation with either cellooligosaccharide or kraft pulp on growth performance in grazing beef calves (Japanese Black) from 4 weeks pre-weaning to 12 to 16 weeks post-weaning. In Experiment 1 (20-week duration), nine calves (2.9-month-old females) were assigned to either a control group (CON) or an experimental group (CEL) fed cellooligosaccharide at a rate of 10 g/day mixed with concentrate. Average daily weight gain tended to be greater in CEL than in CON, especially after 1 month of weaning. In Experiment 2 (16-week duration), 10 calves (2.0-month-old females) were assigned to either a control group or an experimental group (KRA) fed kraft pulp at a rate of 10% replacement of total digestible nutrients with concentrate. The proportion of fibrolytic bacteria increased and that of methanogenic Archaea decreased in the rumen microbial community composition of KRA calves in Experiment 2, whereas the decrease in Fibrobacter and Archaea was observed in CEL calves at first 4 weeks in Experiment 1. We conclude that beta-glucan prebiotic supplementation to grazing calves at pre-weaning would affect rumen microbial composition and modified rumen fermentation characteristics, leading to a better rumen environment via different means., (© 2019 Japanese Society of Animal Science.)

Bacterial nanocellulose (BNC), a natural origin biopolymer with multi-dimensional applications has captured a great deal of attention owing to its implausible properties. However, low yield of BNC accompanied with high production cost is challenging its usage in various technological applications. In this study, BNC production has been reported utilizing fermented black tea broth brewed from fresh tea leaves (FBTB F ) as well as from used tea leaves (FBTB U ) as a cost-effective and high-quality BNC yielding medium. The symbiotic combination of bacteria and yeasts (SCOBY) was exploited here to bring fermentation in tea broth. The production yields on dry weight basis were 13.3 g L -1 in FBTB F and 12.8 g L -1 in FBTB U , obtained with 60 g L -1 of glucose in 20 days. The conversion yields of 0.32 and 0.31 g BNC/g sugar were obtained with both the tea broths. The study of produced pellicle using ATR-FTIR, FE-SEM and XRD confirmed its structural, morphological and chemical nature similar to that of BNC. Thus, fermented black tea broth appears to be a potential medium for BNC production. The use of fermented tea broth for the industrial scale production of BNC might significantly reduce its production cost., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study aimed to examine the effects of feeding kraft pulp (KP) on the growth performance, feed digestibility, and rumen fermentation of Japanese Black fattening steers. Ten Japanese Black fattening steers (aged 26 months) were randomly divided into control and KP groups. The control group (n = 5) was fed concentrate feed without KP, and the KP group (n = 5) was fed concentrate feed containing 10% KP. Both the groups were provided rice straw as roughage. The experiment was conducted over a period of 12 weeks. There was no significant difference in dry matter intake, daily body weight gain, and nutrient digestibility between both groups. No difference was observed in the ruminal concentrations of volatile fatty acids among the groups. At weeks 8 and 12 after the onset of the experiment, the acetate-to-propionate ratio in the ruminal fluid of the KP group was significantly higher than that of the control group. The average daily pH of ruminal fluid and activity of ruminal lipopolysaccharide did not differ between the groups. Our results suggested that the growth performance and feed digestibility in the Japanese Black fattening steers were not influenced by replacing concentrate feed with KP., (© 2019 The Authors. Animal Science Journal published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Animal Science.)

The effect of wood kraft pulp (KP) feed on dietary digestibility, ruminal fluid pH, rumen fermentation characteristics, and milk production performance in lactating dairy cows was examined. Four lactating dairy cows were used for the feeding experiment by the cross-over design. The control group and KP group were set up as treatments. The control group was fed total mixed ration (TMR) (40% roughage and 60% concentrate) and the KP group was fed TMR containing 12% KP that replaced half of the rolled corn in the control diet. The dry matter intake, digestibility of the feed components, and milk yield were not significantly different between control group and KP group. The number of times that the ruminal fluid pH was below 6.1 tended to decrease in the KP group compared to the control group (p < 0.10). The acetic acid ratio in the ruminal fluid of the KP group increased compared to the control group (p < 0.05) and the propionic acid ratio in the ruminal fluid of the KP group decreased compared to the control group (p < 0.05). The acetate:propionate acid ratio was increased in the KP group compared with the control group (p < 0.05). Lipopolysaccharide levels in the ruminal fluid of the KP group tended to decrease compared to the control group (p < 0.10). Based on these results, it was indicated that the use of KP feed for lactating dairy cows induced the same rumen fermentation characteristics as those in cows given a large amount of roughage without depressing milk productivity. Therefore, KP could be a valuable feed resource substitute for grains, which would also reduce the risk for subacute rumen acidosis., (© 2018 The Authors. Animal Science Journal published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Animal Science.)

Consolidated bioprocessing (CBP) by micro-organisms is desired for efficient conversion of lignocellulosic biomass to bioethanol fuels. Potential candidates have been discovered, including cellulolytic bacteria and filamentous fungi. Genetic and metabolic manipulation of these organisms further promotes their fermentation capacities and the ethanol tolerance. In addition, Saccharomyces cerevisiae and several other yeasts were genetically modified to express recombinant cellulases in media or display them on the cell surface for CBP of cellulose. To compensate the insufficient capacity of a single strain, various microbial consortia have also been developed. In this article, we reviewed the recent advances in CBP microbes and focused on the efforts in strain improvement employing genetic engineering.

Vitamin B1 (VB1) is an essential coenzyme for carbohydrate metabolism and involved in energy generation in most organisms. In this study, we found that insufficient biosynthesis of VB1 in Clostridium acetobutylicum ATCC 824 is a major limiting factor for efficient acetone-butanol-ethanol (ABE) fermentation. In order to improve the fermentation performance of C. acetobutylicum ATCC 824, the VB1 biosynthesis pathway was strengthened by overexpressing the thiC, thiG, and thiE genes. The engineered strain 824(thiCGE) showed enhanced VB1 and energy synthesis, resulting in better growth, faster sugar consumption, higher solvents production, and lower acids formation than the wild-type strain in both VB1 free and normal P2 medium (1 mg/L). Compared with the wild-type strain, 824(thiCGE) produced 13.0 ± 0.1% or 12.7 ± 1.2% more butanol in VB1 free P2 medium when glucose or xylose was used as the substrate, respectively. When mixed sugar (glucose:xylose = 2:1) was used as the substrate in VB1 free P2 medium, the xylose consumption rate and butanol titer of 824(thiCGE) were 45.8 ± 1.9% and 20.4 ± 0.3% higher than those of the wild-type strain. All these results demonstrated that this metabolic engineering strategy could provide a new and effective way to improve the cellular performance of solventogenic clostridia. In addition, it may have some potential application value in ABE fermentation using simple medium and/or lignocellulosic biomass.

Various economic and environmental sustainability concerns as well as consumer preference for bio-based products from natural sources have paved the way for the development and expansion of biorefining technologies. These involve the conversion of renewable biomass feedstock to fuels and chemicals using biological systems as alternatives to petroleum-based products. Filamentous fungi possess an expansive portfolio of products including the multifunctional organic acids itaconic, fumaric, and malic acids that have wide-ranging current applications and potentially addressable markets as platform chemicals. However, current bioprocessing technologies for the production of these compounds are mostly based on submerged fermentation, which necessitates physicochemical pretreatment and hydrolysis of lignocellulose biomass to soluble fermentable sugars in liquid media. This review will focus on current research work on fungal production of itaconic, fumaric, and malic acids and perspectives on the potential application of solid-state fungal cultivation techniques for the consolidated hydrolysis and organic acid fermentation of lignocellulosic biomass.