Journal of microbiology and biotechnology最新文献

There is growing interest in pentose-based prebiotic oligosaccharides as alternatives to traditional hexose-based prebiotics. Among these, arabino-oligosaccharides (AOS), derived from the enzymatic hydrolysis of arabinan polymers, have gained significant attention. AOS can selectively stimulate the growth of beneficial gut bacteria, including Bifidobacterium and Bacteroides species, and contribute to health-benefit functions such as blood sugar control, positioning AOS as a promising synbiotic candidate. For the industrial production of AOS, the development of efficient enzymatic processes is essential, with exo- and endo-1,5-α-L-arabinanases (exo- and endo-ABNs) playing a crucial catalytic role. Most ABNs belong to the glycoside hydrolase (GH) family 43, characterized by a five-bladed β-propeller fold structure. These enzymes hydrolyze internal α-1,5-L-arabinofuranosidic linkages, producing AOS with varying degrees of polymerization. Some ABNs GH43 were known to exhibit exo-type hydrolytic modes of action, producing specific AOS products such as arabinotriose. Additionally, exo-ABNs from GH93, which feature a six-bladed β-propeller fold, exclusively release arabinobiose through their exo-type catalytic mechanism. This review represents the first comprehensive analysis of exo- and endo-ABNs, offering scientific insights into their biotechnological potential for AOS production. It systematically compares enzyme classification, structural differences, catalytic mechanisms, paving the way for innovative applications in health, food, and pharmaceutical industries.

Leuconostoc mesenteroides is a lactic acid bacteria found in fermented products. In our previous study, L. mesenteroides was isolated from Camellia japonica flowers, and its acid tolerance and antibacterial properties were thoroughly investigated. This study focuses on the inhibition of melanin synthesis and inflammation of exosomes derived from L. mesenteroides. Moreover, L. mesenteroides exosomes (DB-14 exosome) exhibited significant inhibitory effects on inflammation and melanogenesis. At concentrations of 4.44 × 10⁸, 8.88 × 10⁸, and 1.78 × 10⁹ particles/ml, the exosomes reduced nitric oxide and prostaglandin E2 activity while maintaining the growth of RAW 264.7 macrophages. In addition, proinflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha, were rarely expressed, and western blot revealed that L. mesenteroides DB-14 derived exosomes inhibited inducible nitric oxide synthase and cyclooxygenase-2 expression. Moreover, the exosomes had no toxic effects on B16F10 melanoma cells at concentrations of 1.78 × 10⁹, 3.55 × 10⁹, and 7.10 × 10⁹ particles/ml, and they suppressed melanogenesis by reducing tyrosinase activity. Furthermore, western blot analysis demonstrated that microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase related protein (TRP)-1, and TRP-2 were evidently reduced, ultimately repressing melanin production. Moreover, MITF expression was inhibited by reduced mitogen-activated protein kinase and protein kinase B phosphorylation levels. Overall, this study proves the efficacy of the novel DB-14 exosome as a strong lightening and anti-inflammatory agent.

The intracellular pathogen Chlamydia trachomatis can inflict substantial damage on the host. Notably, Chlamydia infection is acknowledged for its precise modulation of diverse host signaling pathways to ensure cell survival, a phenomenon intricately connected to genetic regulatory changes in host cells. To monitor shifts in gene regulation within Chlamydia-infected cells, we employed mesenchymal stem cells (MSCs) as a naïve, primary cell model. Utilizing biochemical methods and imaging, our study discloses that acute Chlamydia infection in human MSCs leads to the downregulation of transcription factors Oct4, Sox2, and Nanog, suggesting a loss of pluripotency markers. Conversely, pluripotency markers in MSCs were sustained through treatment with conditioned medium from infected MSCs. Additionally, there is an augmentation in alkaline phosphatase activity, along with elevated Sox9 and CD44 mRNA expression levels observed during acute infection. A comprehensive screening for specific cell markers using touchdown PCR indicates an upregulation of mRNA for the early chondrogenesis gene Sox9 and a decrease in mRNA for the MSC marker vimentin. Real-time PCR quantification further corroborates alterations in gene expression, encompassing increased Sox9 and CD44 mRNA levels, alongside heightened alkaline phosphatase activity. In summary, the infection of MSCs with C. trachomatis induces numerous genetic deregulations, implying a potential trend towards differentiation into chondrocytes. These findings collectively underscore a targeted impact of Chlamydia on the gene regulations of host cells, carrying significant implications for the final fate and differentiation of these cells.

Staphylococcus aureus (S. aureus, SA) is one of the most common bacteria in nosocomial infections. Sensitive and efficient analysis of methicillin-resistance of SA is crucial for improving the nursing performance of pneumonia. However, methicillin-resistance analysis with favorable sensitivity and specificity in an enzyme-free manner remains a huge challenge. This paper presents the development of a new fluorescent biosensor for detecting mecA gene using a triple-branch catalytic hairpin assembly (CHA) triggered DNAzyme switch-based DNA tweezer. The SA from the samples are immobilized on the plate's surface using the protein A antibody. The biosensor possesses several key features. Firstly, it utilizes dual signal amplification processes, specifically the triple-branch CHA and DNAzyme controlled DNA tweezer-based signal recycling, to enable mecA detection on the plate. This design enhances the method's sensitivity, resulting in a low limit of detection of 1.5 fM. Secondly, the biosensor does not rely on enzymes for mecA analysis, ensuring a high level of stability during target analysis. Lastly, the method demonstrates a remarkable selectivity by accurately distinguishing target sequences from non-target sequences. The proposed biosensor, which does not require enzymes and has a high level of sensitivity, offers a viable platform for the rapid and simple quantification of mecA in SA.

In this study, icariside II was prepared from icariin by a special enzyme. The yield of the substrate icariin from a powdered extract of the popular herb Epimedium was 16.9%. The enzyme, which was produced from Aspergillus sp.y48 fermentation, hydrolyzes icariin to icariside II and was characterized. The molecular weight was 75 kDa, while the optimum temperature and pH were 45°C and 5.0. The purified enzyme hydrolyzed the 7-O-glucoside of icariin or epimedin A, B, and C to icariside II, or sagittatoside A, B, and C, respectively, and further hydrolyzed the terminal 3-O-xyloside of sagittatoside B to icariside II. The enzyme is a special icariin glycosidase that hydrolyzed icariin to icariside II at low cost. Based on the crude enzyme's reaction dynamics, the optimal conditions for icariside II preparation showed that 2% icariin reacted at 45°C for 6 to 9 h. Here, we obtained 13.3 g icariside II and 0.45 g of the by-product icaritin from 20 g icariin. The icariside II molar yield was 87.4%, the by-product icaritin yield was 4.1%, and the total molar yield was 91.5%. Therefore, icariside II was resoundingly prepared from an icariin glycosidase of an Epimedium extract using a non-GMO, crude enzyme from Aspergillus sp.y48. The obtained icariside II and the by-product icaritin can be directly applied in the production of cosmetics and pharmaceuticals.

Acetaminophen (APAP) is a well-known analgesic used globally. Generally, APAP has been proven to be safe and effective at therapeutic doses; however, it can cause serious liver damage when administered at high levels. We prepared Codium fragile extract (CFE) using the seaweed C. fragile and confirmed that the CFE contains a substance called Loliolide with antioxidant activity. We performed the present study to determine whether CFE protects HEPG2 cells and BALB/c mice from oxidative stress-induced liver damage. We confirmed that CFE and Loliolide were non-cytotoxic and protected against liver damage by reducing the activities of ALT and AST, which were increased by APAP treatment, and that CFE reduced the mRNA expression of inflammatory cytokines TNF-α and IL-6 and inhibited the phosphorylation of ERK and p38 in HEPG2 cells as determined by RT-PCR and Western blot analyses. Furthermore, the TNF-α and IL-6 levels, which were increased after APAP treatment in BALB/c mice, decreased after CFE treatment. Therefore, we demonstrated that CFE exerts a protective effect against APAP-induced liver injury by suppressing the inflammatory response through anti-inflammatory activity. Our findings provide new perspectives for developing functional foods that utilize seaweeds to improve liver function.

Antiviral agents that target the viral envelope surface glycoproteins can disrupt the interactions between the viral glycoproteins and host cell receptors, thereby preventing viral entry into host cells. However, the mechanisms underlying glycoprotein processing and cellular trafficking have not been fully elucidated. In this study, we aimed to investigate the mechanism of action of cryptotanshinone (CTN) and dihydrotanshinone I (DTN) as inhibitors of viral glycoprotein trafficking, by assessing their inhibitory action on syncytium formation and cytopathic effects. CTN and DTN were isolated and characterized from Salvia miltiorrhiza; they effectively inhibited syncytium formation in Newcastle disease virus-infected baby hamster kidney cells. Both compounds inhibited the transport of viral G-proteins to the cell surface, resulting in intracellular accumulation. These results suggest that CTN and DTN are potential glycoprotein trafficking inhibitors that function at the Golgi apparatus. Overall, our results indicate that CTN and DTN suppress intracellular glycosylation by competing as inhibitors of glycosylation trafficking.

Organic fertilizer application in agricultural land is known to improve soil microbial processes, fertility, and yield. In particular, the changes in soil chemical composition due to multi-year application of organic fertilizers are thought to alter the microbial community. Here, the effects of organic fertilization with oil-cake amendments (OC) on soil bacterial diversity, community profile, and enzyme activity were evaluated and compared to those amended with chemical fertilizer (NPK). Diversity indices show that the application of organic fertilizer potentially increases microbial diversity as well as the number of different microbial groups. The ordination plot distinguished and clustered both treatments, showing the differential effects of soil chemical factors on the microbial communities in each treatment. Proteobacteria, Verrucomicrobia, and Bacteriodetes were significantly more abundant in OC-amended soil than in the NPK soil, indicating alterations in community structure, composition, and diversity, concurrent to the changes in the pH, Ca, and Mg contents of the soil. These shifts in bacterial community structure and composition, partially explained by differences in soil chemical factors, could be observed from the phylum to the genus level in NPK- and OC-amended soils. The OC soil contained a significantly higher abundance of predicted genes corresponding to enzymes related to biogeochemical cycling, decomposition, and plant growth promotion. Collectively, these results support the use of an unconventional organic fertilizer positively altering bacterial populations in jujube orchards. The application of an unconventional organic fertilizer improved microbial diversity and enhanced ecosystem functions related to biogeochemical cycles, mineralization, and plant growth promotion.

Succinic acid is an industrially important component that plays a key role in food additives, dietary supplements, and precursors for biodegradable polymers. Due to environmental and economic issues, succinic acid production has become increasingly attractive. This work aimed to improve succinic acid production from lignocellulosic biomass in Actinobacillus succinogenes through genetic modifications and fermentation strategies. Firstly, the effects on succinic acid production by overexpressing genes encoding phosphoenol carboxylase, malate dehydrogenase, and fumarase were evaluated in batch fermentations of engineered A. succinogenes strains. The engineered A. succinogenes expressing PCK, MDH, and FUM (AS-PMF) showed a 1.3-fold increase in succinic acid production compared to the wild-type strain. Subsequently, the fed-batch fermentation with MgCO₃ was carried out using AS-PMF, which led to producing 50 g/l of succinic acid with 0.79 g/g of yield. Finally, 22.2 g/l of succinic acid with 0.64 g/g of yield was achieved in batch fermentation from lignocellulosic hydrolysate of barley straw. These results support that sustainable succinic acid from agricultural wastes might be a promising strategy for industrial applications.

This study was performed to investigate the use of plant-based lactic acid bacteria (LAB) to reduce microbiological hazards in kimchi. Cell-free supernatants (CFS) from four LAB strains isolated from kimchi were tested for antimicrobial activity against five foodborne pathogens and two soft-rot pathogens. Each CFS showed antimicrobial activity against both foodborne and soft-rot pathogens. Washing salted kimchi cabbages inoculated with B. cereus with 5% CFS inhibited B. cereus to a greater extent than NaClO. The CFS from WiKim 83 and WiKim 87 exhibits inhibition rates of 25.09% and 24.21%, respectively, compared to the 19.19% rate of NaClO. Additionally, the CFS from WiKim 116 and WiKim 117 showed inhibition rates of 18.74% and 20.03%, respectively. Direct treatment of kimchi cabbage with soft-rot pathogens and CFS for five days inhibited the pathogens with similar efficacy to that of NaClO. To elucidate the antimicrobial activity mechanisms, pH neutralization, heat treatment, and organic acid analyses were performed. pH neutralization reduced the antimicrobial activity, whereas heat treatment did not, indicating that lactic, acetic, citric, and phenyllactic acids contribute to the thermal stability and antimicrobial properties of CFS. This study suggests that the four kimchi-derived LAB, which maintain a low pH through organic acid production, could be viable food preservatives capable of reducing biological hazards in kimchi.