Dual assistance of surfactants in glycerol organosolv pretreatment and enzymatic hydrolysis of lignocellulosic biomass for bioethanol production.

This study investigated an innovative strategy of incorporating surfactants into alkaline-catalyzed glycerol pretreatment and enzymatic hydrolysis to improve lignocellulosic biomass (LCB) conversion efficiency. Results revealed that adding 40 mg/g PEG 4000 to the pretreatment at 195 °C obtained the highest glucose yield (84.6%). This yield was comparable to that achieved without surfactants at a higher temperature (240 °C), indicating a reduction of 18.8% in the required heat input. Subsequently, Triton X-100 addition during enzymatic hydrolysis of PEG 4000-assisted pretreated substrate increased glucose yields to 92.1% at 6 FPU/g enzyme loading. High-solid fed-batch semi-simultaneous saccharification and co-fermentation using this dual surfactant strategy gave 56.4 g/L ethanol and a positive net energy gain of 1.4 MJ/kg. Significantly, dual assistance with surfactants rendered 56.3% enzyme cost savings compared to controls without surfactants. Therefore, the proposed surfactant dual-assisted promising approach opens the gateway to economically viable enzyme-mediated LCB biorefinery.

Construction of an Integrated mCherry Red Fluorescent Protein Expression System for Labeling and Tracing in Lactiplantibacillus plantarum WCFS1.

Thorough intestinal adhesion and colonization greatly promote the probiotic properties of lactic acid bacteria (LAB). Labeling and tracing with fluorescent proteins are effective and reliable for studying the in vivo physiological activities of LAB including localization, adhesion, and colonization. Lactiplantibacillus plantarum WCFS1 was successfully traced with a red fluorescent protein (RFP), which was expressed by the bacteria-carrying recombinant plasmids. In this study, we aimed to construct a stable RFP mCherry expression system, whose encoding gene was integrated into the bacterial chromosome via double-crossed homologous recombination, and use it for labeling WCFS1 with the goal of avoiding the potential loss of non-chromosomal plasmids along with intestinal growth. First, the constitutive expression of the mCherry protein was improved after adjusting the length of the spacer between the promoter and the gene start codon. Then, the optimized mCherry gene expression cassette was integrated into the chromosome of WCFS1. The resulting strain had normal unimpaired growth and strong fluorescent signals, even after 100 generations, indicating its stability. Furthermore, quantitative polymerase chain reaction (PCR) results revealed a strong positive correlation between the fluorescence intensity of the strain and the number of viable cells, demonstrating its potential usage for the quantification of in vivo WCFS1 cells. Finally, the increased adhesion ability of WCFS1 due to the recombinant expression of the bsh gene was visualized and evaluated using fluorescence intensity, the results of which were consistent with those obtained using the previously established quantification methods. These results suggest that the chromosomal-integrated mCherry labeling system can be extensively used to examine the distribution, colonization, and survival of LAB in vivo in order to determine the mechanism of its probiotic function.

Impact of molasses and microbial inoculants on fermentation quality, aerobic stability, and bacterial and fungal microbiomes of barley silage.

This study aimed to investigate the effects of microbial inoculants (L) and molasses (M) on the bacterial and fungal microbiomes of barley silage after the aerobic stage. The addition of molasses and microbial inoculants improved the aerobic stability of barley silage. The ML silage, which had a low pH value and high lactic and acetic acid contents, remained aerobically stable for more than 216 h. The ML silage exhibited low bacterial and high fungal diversities. Microbial inoculants and molasses enriched the abundance of Lactobacillus in silage after aerobic exposure. The enrichment of L. buchneri was significant in ML silage at days 5 and 7 during the aerobic stage. The abundance of harmful microorganisms, such as aerobic bacterial including Acinetobacter, Providencia, Bacillus, and yeasts including Issatchenkia, Candida, and Kazachstania, were suppressed in ML silage. M and L had an impact on bacterial and fungal microbes, resulting in the improvement of fermentation quality and reduction of aerobic spoilage in barley silage.

Interaction effect of silo density and additives on the fermentation quality, microbial counts, chemical composition and in vitro degradability of rice straw silage.

This research evaluated the effect of molasses (M), cellulosic enzymes (E) and lactic acid bacteria (LAB) alone or in combination (M + LAB and E + LAB) on the fermentation quality, microbial counts, chemical composition and in vitro degradability of rice straw silages in different silo densities (200, 300, 400 and 500 kg/m3). The M or E groups alone increased the dry matter (DM) losses at low silo densities. Acetic acid produced by LAB-related groups significantly inhibited yeast and mould at the silo density of 300 kg/m3. Under high silo densities (>400 kg/m3), LAB-related additives significantly improved the fermentation quality and reduced the DM losses. The use of E + LAB further improved the in vitro degradability of rice straw silages at high silo densities. In conclusion, higher silo density and appropriate complex additives were of great significance to improve the quality of rice straw silage.

Bile salt hydrolase can improve Lactobacillus plantarum survival in gastrointestinal tract by enhancing their adhesion ability.

Lactic acid bacteria (LAB) are major probiotics in food supplements. Survival in gastrointestinal (GI) tract is important for the effective use of LAB as probiotics. Bile salt hydrolase (BSH), which catalyzes the conversion of conjugated bile salts into free bile salts, can significantly modulate the gut microbiome. Here, we hypothesize that BSH is important for LAB survival and adhesion in the gut. The aim of this study is to investigate the effect of BSH on the survival of LAB in the GI tract. A panel of bsh genes from murine gut microbiota were amplified, cloned and expressed into Lactobacillus plantarum, which were then administered to mice by gavage. Our data indicated that the survival of BSH-positive L. plantarum was significantly prolonged in the GI tract compared with wild type L. plantarum. Furthermore, BSH-positive strains exhibited increased adhesion to Caco-2 intestinal cells than BSH-deleted L. plantarum. Enhanced adhesion to intestinal cells of BSH positive LAB can therefore be an important criterion for selecting effective probiotic strains in food industry.

Fermented feed regulates growth performance and the cecal microbiota community in geese.

This study was designed to investigate the effects of fermented feed diets on the growth performance and cecal microbial community in geese, and to examine associations between the gut microbiota and growth performance. A total of 720 healthy, 1-day-old male SanHua geese were used for the 55-D experiment. Geese were randomly divided into 4 groups, each with 6 replicates of 30 geese. Groups were fed a basal diet supplemented with 0.0, 2.5, 5.0, or 7.5% fermented feed. The results showed that 7.5% fermented feed had an increasing trend in the body weight and average daily gain of the geese; however, there was no significant response to increasing dietary fermented feed level with regards to ADFI and FCR. In addition, compared with the control group, there was a higher abundance of bacteria in the phylum Bacteroidetes in the cecal samples of geese in the 7.5% fermented feed group (53.18% vs. 41.77%, P < 0.05), whereas the abundance of Firmicutes was lower in the 7.5% fermented feed group (36.30% vs. 44.13%, P > 0.05). At the genus level, the abundance of Bacteroides was increased by adding fermented feed to geese diets, whereas the abundances of Desulfovibrio, Phascolarctobacterium, Lachnospiraceae_uncultured, Ruminiclostridium, and Oscillospira were decreased. These results indicate that fermented feeds have an important effect on the cecal microflora composition of geese, and may affect host growth, nutritional status, and intestinal health.

Dynamics of a microbial community during ensiling and upon aerobic exposure in lactic acid bacteria inoculation-treated and untreated barley silages.

This study investigated the effects of lactic acid bacteria on bacterial and fungal community during the fermentation process and aerobic exposure phase of barley ensiled with preparation of lactic acid bacteria (LAB). The inoculated silages displayed higher contents of lactic acid, acetic acid, and propionic acid as well as a greater number of lactic acid bacteria during ensiling. LAB-treated silage decreased the bacterial diversity during both ensiling and aerobic exposure but increased the fungal diversity during ensiling of barley. LAB-treated silage during ensiling increased the abundance of Lactobacillus but decreased that of Weissella. After aerobic exposure, LAB-treated silage increased the abundance of Lactobacillus but decreased that of Acinetobacter. Acinetobacter, Enterococcus, Providencia, and Empedobacter were the dominant bacteria after aerobic exposure. In conclusion, LAB-treated silage enhanced the number of desirable Lactobacillus and inhibited the growth of undesirable microorganisms, such as Acinetobacter.

Food-grade gene transformation system constructed in Lactobacillus plantarum using a GlmS-encoding selection marker.

Food-grade gene expression systems in lactic acid bacteria enable production of functional proteins or product testing without antibiotic requirement. Here, we expanded the available selection markers by developing a novel food-grade genetic transformation system for Lactobacillus plantarum WCFS1 using the glucosamine-6-phosphate synthase gene (glmS1). A glmS-vector pSIPH497 was constructed by replacing the erythromycin resistance gene (erm) with L. plantarum glmS1 under control of the PldhL promoter from WCFS1. The selection efficiency and stability of the glmS-vector were shown to be comparable to those of the erm-based plasmid. Moreover, using mCherry expression as a reporter gene, we showed the feasibility of the system for producing foreign proteins. This food-grade host/vector system will provide an effective and safe technique for the application of lactic acid bacteria in the food and medical industries. Furthermore, this study provides a useful strategy for developing food-grade selection markers in other host/vector systems.

Effects of exogenous inosine monophosphate on growth performance, flavor compounds, enzyme activity, and gene expression of muscle tissues in chicken.

The goal of this experiment was to examine effects of diets supplemented with exogenous inosine monophosphate (IMP) on the growth performance, flavor compounds, enzyme activity and gene expression of chicken. A total of 1,500 healthy, 1-day-old male 3-yellow chickens were used for a 52-d experimental period. Individuals were randomly divided into 5 groups (group I, II, III, IV, V) with 6 replicates per group, and fed a basal diet supplemented with 0.0, 0.05, 0.1, 0.2, and 0.3% IMP, respectively. There was no significant response to the increasing dietary IMP level in average daily feed intake (ADFI), average daily gain (ADG), and feed:gain ratio (F/G) (P ≥ 0.05). IMP content of the breast and thigh muscle showed an exponential and linear response to the increasing dietary IMP level (P < 0.05), the highest IMP content was obtained when the diet with 0.3% and 0.2% exogenous IMP was fed. There were significant effects of IMP level in diet on free amino acids (FAA) (exponential, linear and quadratic effect, P < 0.05) and delicious amino acids (DAA) (quadratic effect, P < 0.01) content in breast muscle. FAA and DAA content in thigh muscle showed an exponential and linear response (P < 0.05), and quadratic response (P < 0.01) to the increasing dietary IMP level, the highest FAA and DAA content was obtained when the diet with 0.2% exogenous IMP was fed. Dietary IMP supplementation had a quadratic effect on 5΄-NT and the alkaline phosphatase (ALP) enzyme activity in the breast muscle (P < 0.05), and the adenosine triphosphate (ATP) enzyme activity in the thigh muscles increased exponentially and linearly with increasing IMP level in diet (exponential effect, P = 0.061; linear effect, P = 0.059). Cyclohydrolase (ATIC) gene expression in thigh muscle had a quadratic response to the increasing dietary IMP level (P < 0.05), 0.2% exogenous IMP group had the highest (AMPD1) gene expression of the breast muscle and ATIC gene expression of the thigh muscle. These results indicate that dietary IMP did not affect the growth performance of chicken, the diet with 0.2 to 0.3% exogenous IMP is optimal to improve the meat flavor quality in chicken.

SUV39H1 mediated SIRT1 trans-repression contributes to cardiac ischemia-reperfusion injury.

Ischemic reperfusion (I/R) contributes to deleterious cardiac remodeling and heart failure. The deacetylase SIRT1 has been shown to protect the heart from I/R injury. We examined the mechanism whereby I/R injury represses SIRT1 transcription in the myocardium. There was accumulation of trimethylated histone H3K9 on the proximal SIRT1 promoter in the myocardium in mice following I/R injury and in cultured cardiomyocytes exposed to hypoxia-reoxygenation (H/R). In accordance, the H3K9 trimethyltransferase SUV39H1 bound to the SIRT1 promoter and repressed SIRT1 transcription. SUV39H1 expression was up-regulated in the myocardium in mice following I/R insults and in H/R-treated cardiomyocytes paralleling SIRT1 down-regulation. Silencing SUV39H1 expression or suppression of SUV39H1 activity erased H3K9Me3 from the SIRT1 promoter and normalized SIRT1 levels in cardiomyocytes. Meanwhile, SUV39H1 deficiency or inhibition attenuated I/R-induced infarction and improved heart function in mice likely through influencing ROS levels in a SIRT1-dependent manner. Therefore, our data uncover a novel mechanism for SIRT1 trans-repression during cardiac I/R injury and present SUV39H1 as a druggable target for the development of therapeutic strategies against ischemic heart disease.