BACKGROUND:Excessive accumulation of microplastics (MPs) inside the body can induce serious diseases, and the potential pathological mechanism was related to endoplasmic reticulum (ER) stress induced by the surge of intracellular reactive oxygen species (ROS). However, until now, the invasion of MPs triggering this unique process remains elusive. RESULTS:Herein, peroxynitrite (ONOO-), was selected as the model target, and an ER-targeted fluorogenic probe (ER-NA-PB) was constructed for real-time visualizing the fluctuation of ONOO- during cellular ER stimulated by MPs. ER-NA-PB exhibited excellent sensitivity (15.2 nM) and selectivity toward ONOO- in aqueous solution, and the exogenous and endogenous ONOO- fluctuation in ER also can be visualized by this potently fluorescent tracing tool. In addition, ER-NA-PB revealed that the content of ONOO- in ER during stimulation of MPs was elevated with increase of MPs concentration and prolongation of stimulation time. SIGNIFICANCE:For the first time, the fluctuation of active molecule in embryonic tissue was revealed by fluorescence probe, and this research provides a promising tool for deeper studying the pathological mechanisms underlying relevant diseases caused by MPs pollution inducing ER stress.

Abstract To understand the ecology of species and promote biotechnology through beneficial strain selection for improving starch yield in maize wet-milling steeping, bacterial diversity and community structure during the counter-current steeping process in a commercial steeping system were characterized and investigated in this study. Microbial diversity in the steeping liquor, which consisted of 16 phyla, 131 families, and 290 genera, was more abundant compared to those present on the surface of unsteeped maize. As the process of counter-current steeping progressed, with the newest maize being exposed to the oldest steepwater, Lactobacillus became the primary family, replacing Rahnella, Pseudomonas, Pantoea, and Serratia. The thermophilic and acidophilic microbial consortia were enriched through adaptive evolution engineering and employed to improve starch yield. Several steeping strategies were evaluased, including water alone, SO2 alone, mono-culture of B. coagulans, microbial consortia, and a combination of consortium and SO2. The combination of microbial consortium and SO2 resulted in a significant increase in starch yield, reaching approximately 66.4±0.5%, which was an increase of 22% and 46% compared to SO2 alone and microbial consortium alone, respectively. Additionally, protein solubilization was enhanced. Scanning electron microscope (SEM) of steeped maize structure indicated that the combination of consortium and SO2 disrupted the protein matrix and increased the gap between starch granules in maize endosperm. This led to the release of protein into the steepwater and the presence of starch granules in the aleurone layer. The steeping strategy of thermophilic and acidophilic microbial consortium as additives shows potential application as an environmentally friendly alternative for conventional procedures of maize steeping.

AbstractTo understand the ecology of species and promote biotechnology through beneficial strain selection for improving starch yield in maize wet-milling steeping, bacterial diversity and community structure during the counter-current steeping process in a commercial steeping system were characterized and investigated. The microbial diversity in the steeping liquor, which consisted of 16 phyla, 131 families, and 290 genera, was more abundant compared to those present on the surface of unsteeped maize. As the counter-current steeping progressed, exposing newer maize to the older steepwater, Lactobacillus dominated, replacing Rahnella, Pseudomonas, Pantoea, and Serratia. The thermophilic and acidophilic microbial consortia were enriched through adaptive evolution engineering and employed to improve starch yield. Several steeping strategies were evaluated, including water alone, SO2 alone, mono-culture of B. coagulans, microbial consortia, and a combination of consortium and SO2. Combining the microbial consortium with SO2 significantly increased the starch yield to, about 66.4 ± 0.5%, a 22% and 46% increase over SO2 alone and the consortium alone, respectively. Scanning electron microscope (SEM) of steeped maize structure indicated that the combination of consortium and SO2 disrupted the protein matrix and widened gaps between starch granules in maize endosperm. This released proteins into the steepwater and left starch granules in the aleurone layer. The steeping strategy of using thermophilic and acidophilic microbial consortium as additives shows potential application as an environmentally friendly alternative to conventional maize steeping procedures.

In recent years, growing attention has been devoted to improving stress resistance of yeast to temperature and ethanol concentration as it affects fermentation productivity in biofuel ethanol industry. Rice husk was found to increase the resistance of yeast to high temperature and high ethanol concentration, which can be attributed to yeast cell adsorption on rice husk. Compared with no addition of rice husk, the ethanol yield of brown rice fermented at 32 degrees C and 39 degrees C with 1.0 % rice husk increased by 9.4 % and 5.1 %. The fermentation kinetics of cell growth and ethanol formation could be described by the improved Logistic model and Luedeking-Piret model, respectively. Based on the effect of rice husk, the higher ethanol concentration (106.7 g/L at 32 degrees C) and complete substrate utilization could be achieved by using a mixed substrate at dry mass ratio of whole rice to brown rice of 3:1.

Deoxynivalenol (DON) is a mycotoxin that significantly threatens the food and feed industry. Corn steep liquor (CSL) is an acidic byproduct of the corn starch industry, and DON is concentrated in CSL once the material is contaminated. In this work, a Pichia kudriavzevii strain that could remove DON from CSL was isolated and characterized. The strain P. kudriavzevii E4-205 showed detoxifying activity in a pH range of 4.0~7.0 and temperature of 25~42 °C, and 39.4% DON was reduced by incubating this strain in CSL supernatant diluted by 2-fold (5 μg/mL DON) for 48 h at pH 5.0 and 30 °C. Further mechanism studies showed that P. kudriavzevii E4-205 could adsorb DON by the cell wall and degrade DON by intracellular enzymes with NADH as a cofactor. The degradation product was identified as 3,7,8,15-tetrahydroxyscirpene by liquid chromatography-tandem mass spectrometry. DON adsorption by inactivated cells was characterized, and the adsorption followed pseudo first-order kinetics. This study revealed a novel mechanism by which microbes degrade DON and might serve as a guide for the development of DON biological detoxification methods.

Phycocyanobilin (PCB) is a linear open-chain tetrapyrrole chromophore that captures and senses light and a variety of biological activities, such as anti-oxidation, anti-cancer, and anti-inflammatory. In this paper, the biological activities of PCB are reviewed, and the related mechanism of PCB and its latest application in disease treatment are introduced. PCB can resist oxidation by scavenging free radicals, inhibiting the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and delaying the activity of antioxidant enzymes. In addition, PCB can also be used as an excellent anti-inflammatory agent to reduce the proinflammatory factors IL-6 and IFN-γ and to up-regulate the production of anti-inflammatory cytokine IL-10 by inhibiting the inflammatory signal pathways NF-κB and mitogen-activated protein kinase (MAPK). Due to the above biological activities of phycocyanobilin PCB, it is expected to become a new effective drug for treating various diseases, such as COVID-19 complications, atherosclerosis, multiple sclerosis (MS), and ischaemic stroke (IS).

Cellulose is a major component of dietary fiber and it is proved to influence starch digestibility. The effects of native cellulose (NC), microcrystalline cellulose (MC), soluble cellodextrin (SC) on starch digestion have not been clearly elucidated. In this study, three types of cellulose with representative molecular weights (NC, 422500 Da; MC, 27750 Da; SC, 2202 Da) were prepared and their effects on starch digestion, glucose diffusion, α-amylase and amyloglucosidase activity were compared. The results suggested SC inhibited starch digestibility to a greater degree than those of NC and MC. When addition of SC reached 3 %, rapidly digestible starch proportion decreased from 31.2 % to 11.3 % and resistant starch proportion increased from 15.0 % to 58.0 %. Notably, hindrance effects of SC on glucose diffusion were higher than those of NC and MC. Moreover, SC reduced activity of α-amylase and amyloglucosidase to a larger extent than those of MC and NC. With the effect of starch digestion inhibition, NC, MC and SC could be utilized as functional food ingredients. Especially, the soluble property and the highest starch digestion inhibition ability of SC favors its application in food industry.

Filamentous fungi occupy a uniquely favorable position in the bioproduction of organic acids. Intracellular stress is the main stimulator in filamentous fungi to produce and accumulate organic acids with high flux. However, stress can affect the physiological activities of filamentous fungi, thereby deteriorating their fermentation performance. Herein, we report that peptide supplementation during Rhizopus oryzae fermentation significantly improved fumaric acid production. Specifically, fumaric acid productivity was elevated by approximately 100%, fermentation duration was shortened from 72 to 36 h, while maintaining the final titer. Furthermore, transcriptome profile analysis and biochemical assays indicated that the overall capabilities of the stress defense systems (enzymatic and nonenzymatic) were significantly improved in R. oryzae. Consequently, glycolytic metabolism was distinctly enhanced, which eventually resulted in improved fumaric acid production and reduced fermentation duration. We expect our findings and efforts to provide essential insights into the optimization of the fermentation performance of filamentous fungi in industrial biotechnology and fermentation engineering.

The raw-starch glucoamylase (RSGA) digested starch at temperatures lower than the gelatinization point, resulting in lower operational costs. In this study, a RSGA from Aspergillus fumigatus A1163 was characterized after being expressed in Escherichia coli BL21(DE3) and Pichia pastoris (currently known as Komagataella phaffii) GS115, respectively. The extracellular enzyme activity of P. pastoris (pRSGA) was 20 times that of E. coli (eRSGA). The optimal temperatures of pRSGA and eRSGA were 70 degrees C and 60 degrees C, respectively. Furthermore, the half-life of pRSGA at 60 degrees C reached 97 min, which is 78 min longer than that of eRSGA. EndoH reaction and mutation analysis show that glycosylation at N422 is responsible for the differences in catalytic properties between the two recombinant enzymes. pRSGA converted 92.2 % of raw corn starch (200 g/L) into glucose after 36 h at 40 degrees C in the presence of alpha-amylase and pullulanase. Our findings show that an efficient RSGA and its producing strain can be used to degrade raw starch.

Abstract Background Lignocellulosic feedstocks have attracted much attention as a potential carbon source for lactic acid (LA) production because of their ready availability, sustainability, and renewability. However, there are at least two major technical challenges to producing LA from lignocellulose. Inhibitors derived from lignocellulose pretreatment have a negative impact on the growth of cells producing LA. Furthermore, pentose sugars produced from the pretreatment are difficultly utilized by most LA producers, which is known as the carbon catabolite repression (CCR) effect. This complex feedstock can be utilized by a robust microbial consortium with high bioconversion efficiency. Results In this study, a thermophilic consortium DUT50 producing LA was enriched and employed to improve corn stover (CS) utilization. Enterococcus was the dominant family in the consortium DUT50, accounting for 93.66% of the total abundance, with Lactobacillus, Bacillus, Lactococcus, and Trichococcus accounted for the remaining 2.68%. This consortium could be resistant to inhibitors concentration up to 9.74 g/L (2.88 g/L acetic acid, 2.46 g/L furfural, 2.20 g/L 5-HMF, and 2.20 g/L vanillin derived from pretreatment of CS), and simultaneously metabolizes hexose and pentose without CCR effect. Based on the promising consortium features, an efficient process of simultaneous saccharification and co-fermentation (SSCF) was developed to produce LA from acid pretreated corn stover, in which solid–liquid separation and detoxification were avoided. The key influencing factors were investigated and optimized, including dry biomass and cellulase loading, corn steep liquor powder concentration, and the pre-hydrolysis time. The highest LA titer of 71.04 g/L with a yield of 0.49 g/g-CS was achieved at a dry biomass loading of 20% (w/v), which is the highest LA production from non-detoxified acid pretreated corn stover via the SSCF process without wastewater generation reported to date. The simultaneous metabolism of hexose and pentose revealed collaboration between Enterococcus in the consortium, whereas xylose may be efficiently metabolized by Lactobacillus and Bacillus with low abundance via the pentose phosphate pathway. Conclusions The experimental results demonstrated the potential advantage of symbiosis in microbial consortia used for LA production from lignocellulosic biomass.

Communicated by Ramaswamy H. Sarma

聚苹果酸是一种以苹果酸为唯一单体且以酯键连接而成的高分子聚合物.因具有良好的生物特性,被广泛用于医药材料、药物载体、化妆品、食品包装材料、表面活性剂及香精香料等领域.聚苹果酸的生产途径有化学合成途径和微生物合成途径,其中通过微生物合成途径制备的聚苹果酸具有分子量高、产物纯等特点.同时,该途径主要使用可再生资源,对环境污染较小.本文系统综述了出芽短梗霉发酵制备聚苹果酸所涉及的发酵工程策略,包括高产菌株的选育、培养基优化、发酵条件等对聚苹果酸的微生物发酵合成研究.