Journal of microbiology and biotechnology最新文献

Natural and artificial endolysins exhibit bactericidal effects by destroying peptidoglycans in the cell wall of gram-positive bacteria and are usually composed of an N-terminal catalytic domain (CTD) and a C-terminal cell wall-binding domain (CBD). The structures and receptors of CBDs are variable, but bacterial Src homology 3 (SH3b) CBDs are prevalent among the natural endolysins of Staphylococcus aureus. Moreover, although recombinant endolysins with a C-terminal 6x histidine tag (His-tag) are often produced and convenient to purify, the deleterious effects of His-tags on antibacterial activity have not been evaluated thoroughly. Recently, we reported that the antibacterial activity of a commercial lysostaphin without a His-tag differed from that of cell-free lysostaphin with a C-terminal His-tag, and lysostaphin also contains a C-terminal SH3b CBD. In this study, we directly compared the effects of His-tags on the antibacterial activities of lysostaphin and several chimeric lysins possessing different SH3b CBDs. We confirmed that antibacterial activity decreased 16.0-32.0-fold after a His-tag was added to the SH3b CBD.

Cholera caused by Vibrio cholerae remains a major public health concern in many countries. The greatest obstacle to detection of V. cholerae contamination in drinking water or aquatic environments mainly relates to sample preparation steps, especially the enrichment step. In this study, immunomagnetic separation methods were developed based on sequence-defined recombinant antibodies (rAbs) against V. cholerae, then used for the specific and efficient enrichment of V. cholerae in water samples. Using the variable region genes of the anti-V. cholerae monoclonal antibodies (mAbs) 5F2, the full-length IgG rAbs (R5F2) were produced using mammalian human embryonic kidney 293T cells. Two antibodies, 5F2 and R5F2, were used to prepare immunomagnetic beads (IMBs), and their capture efficiencies (CEs) were evaluated. The results showed that 0.4 mg of 5F2-IMBs and R5F2-IMBs exhibited good CEs (96.0% and 75.9%, respectively) against V. cholerae within 40 min. The IMBs could still effectively capture V. cholerae in large-volume reaction systems (5 ml to 25 ml). The CEs of 5F2-IMBs and R5F2-IMBs ranged from 90.2% to 70.7% and 65.1% to 44.2%, respectively. Furthermore, 5F2-IMBs and R5F2-IMBs did not show significant cross-reactivity with other bacteria and exhibited high specificity. When R5F2-IMS was used in combination with quantitative real-time PCR, the detection limit was approximately 5 colony-forming units/25 ml after enrichment for 4 h. Our results suggest that the rAbs produced herein could provide useful alternatives to traditional hybridoma-based antibodies for accurate detection of V. cholerae in food safety and environmental monitoring.

This study evaluated the efficacy of various inorganic materials, biological control agents, organic agricultural materials (OAMs), and essential oils for controlling cucumber powdery mildew (CPM) under greenhouse conditions. Treatments included silicate, bicarbonate, copper sulfate, sulfur-based compounds, Bacillus subtilis KB-401, Bacillus amyloliquefaciens M27, Bordeaux mixtures, chitosan combined with oxidated copper salt, chitooligosaccharides, and essential oils such as castor and rapeseed oil with lecithin. Results demonstrated that Bordeaux mixtures, particularly Bordeaux Mixture I, and sulfur-based compounds provided the most reliable CPM control among inorganic materials. Bacillus strains KB-401 and M27 achieved sustained disease suppression, suggesting their value in integrated pest management (IPM). Chitosan combined with oxidated copper salt showed high efficacy, making it a promising candidate for long-term control. Among OAMs, loess-sulfur mixtures proved especially effective in preventive applications, achieving comparable results to resistant cultivar 'Saronsamcheok'. Essential oils, including castor and rapeseed oil, also exhibited significant CPM suppression potential, although repeated applications may be necessary for sustained control. These findings highlight the potential of these environmentally friendly treatments as viable components of an IPM strategy for managing CPM in cucumber crops. Further studies are recommended to optimize combinations and application timing for enhanced efficacy.

In vitro organoids that mimic the physiological properties of in vivo organs based on three-dimensional cell cultures overcome the limitations of two-dimensional culture systems. However, because the lumen of a typical intestinal organoid is internal, we used an apical-out intestinal organoid model in which the lumen that absorbs nutrients is outside to directly assess the function of postbiotics. A composite culture supernatant of Lactiplantibacillus plantarum KM2 and Bacillus velezensis KMU01 was used as a postbiotic treatment. Expression of COX-2 decreased in apical-out organoids co-treated with a lipopolysaccharide (LPS) and postbiotics. Expression of tight-junction markers such as ZO-1, claudin, and Occludin increased, and expression of mitochondrial homeostasis factors such as PINK1, parkin, and PGC1a also increased. As a result, small and large intestine organoids treated with postbiotics protected tight junctions from LPS-induced damage and maintained mitochondrial homeostasis through mitophagy and mitochondrial biogenesis. This suggests that an apical-out intestinal organoid model can confirm the function of food ingredients.

Peperomia pellucida (L.) Kunth has traditionally been used as a vegetable and herbal medicine in certain countries, though its safety remains uncertain. In this study, we investigated the plant's ingredients, volatile compounds, antioxidative activities, and toxicity in Drosophila and mice. The results revealed that P. pellucida contains volatile substances that give it a unique flavor, making it suitable for consumption and rich in antioxidant compounds, such as polyphenols, tannins, flavonoids, saponins, alkaloids, and terpenoids. The total phenolic content (TPC) and total flavonoid content (TFC) of the plant extract were 273.33 ± 4.91 mg gallic acid equivalents/g extract and 199.8 ± 0.346 mg quercetin equivalents/g extract, respectively. The remarkable antioxidative properties of the plant extract were demonstrated by nearly doubling the lifespan of Drosophila against oxidative stress. Moreover, the extract did not cause any acute or chronic toxicity in mice after being fed the plant, as indicated by the normal blood parameters and the absence of hepatic shape damage or impaired function. In light of these findings, P. pellucida is deemed safe for consumption and its bioactive ingredients can be extracted to create functional foods and pharmaceuticals.

The current pathological and physiological evaluation system for colorectal cancer (CRC) is limited; thus, effective biological targets to diagnose and treat this disease are urgently needed. In this study, we used qRT-PCR for detecting mRNA levels of genes. The levels of protein were identified by western blot, immunohistochemistry, and immunofluorescence assays. In addition, functional experiments were used to evaluate the role of cytoskeleton associated protein (CKAP) 2 in CRC cells and human umbilical vein endothelial cells (HUVECs). Bioinformatics analysis was employed to predict the binding relationship of CKAP2 and TFDP1, which was confirmed through dual luciferase reporter assay and immunoprecipitation assay. Furthermore, we injected human colorectal carcinoma HCT116 cells into mice flanks, and we injected Luciferase-labeled HCT116 cells into mice tail vein. HE staining was used to detect tumor nodules. As a result, high CKAP2 expression was found in CRC cells and tissues. CKAP2 silencing reduced CRC cell migration, invasion, proliferation, and epithelial-mesenchymal transition. Moreover, CKAP2 expression was positively associated with M2 macrophage levels. CKAP2 promoted protein expression of CD86, CD206, IL-1β, and CCL17. Moreover, CKAP2 promoted the proliferation of HUVECs and angiogenesis via affecting the tumor microenvironment (TME). We also found that CKAP2 could interact with TFDP1. The inhibitory impacts of TFDP1 downregulation on CRC cell' proliferation, migration, and invasion were reversed via CKAP2 overexpression. In vivo silencing of CKAP2 repressed tumor growth and metastasis. Overall, CKAP2 was positively regulated by TFDP1, which promoted tumorigenesis and metastasis in CRC.

Alopecia, while not life-threatening, significantly impacts mental health, identity, and self-esteem of those afflicted. Current pharmacological and surgical treatments often have side effects and are limited in their ability to regenerate hair follicles (HF). Therefore, effective solutions for alopecia remain elusive. We developed an innovative hair tonic capable of stimulating HF regeneration by harnessing abandoned electric energy generated during human activities, such as the frictional electric field from walking and the electric fields from electronic devices. We devised a convenient, non-volatile, and conductive hair tonic to capture these naturally occurring electric fields. We identified 6-pentyl-α-pyrone (6PP) from Trichoderma gamsii as an antifungal agent effective against the dandruff-associated fungus Malassezia that can influence alopecia and adopted it into our conductive bio-harvesting tonic (CBT). Testing on hair follicle dermal papilla cells (HFDPC) and SKH1 mice showed that CBT significantly enhanced HF proliferation and increased growth factors in vitro and in vivo. In SKH1 mice, application of CBT under electric stimulation visibly increased hair shaft length and follicle counts. Additionally, tests on actual human hair follicles demonstrated delayed hair follicle regression when electric stimulation and 6PP were applied. In conclusion, our innovative CBT offers a promising and convenient approach for improving hair growth and combating alopecia.

Recent research has focused on discovering peptides that effectively target multidrug-resistant bacteria while leaving healthy cells unharmed. In this work, we describe the antimicrobial properties of RK8, a peptide composed of eight amino acid residues. Its activity was tested against multidrug-resistant Gram-negative and Gram-positive bacteria. RK8's efficacy in eradicating mature biofilm and increasing membrane permeability was assessed using Sytox Green. Cytotoxicity assays were conducted both in vitro and in vivo models. Circular dichroism analysis revealed that RK8 adopted an extended structure in water and sodium dodecyl sulfate (SDS). RK8 exhibited MICs of 8-64 μM and MBCs of 4-64 μM against various bacteria, with higher effectiveness observed in Methicillin-resistant Staphylococcus aureus (MRSA) and E. coli KPC+ strains than others. Ciprofloxacin and Vancomycin showed varying MIC and MBC values lower than RK8 for Gram-positive bacteria, but competitive for Gram-negative bacteria. The combination of RK8 and ciprofloxacin showed a synergistic effect. The RK8 peptides could reduce 38% of the mature Acinetobacter baumannii biofilm. Sytox Green reagent achieved 100% membrane permeation of Gram-positive and Gram-negative bacteria. The RK8 peptide did not show cytotoxic effects against murine macrophages (64 μM), erythrocytes (100 μM) or Galleria mellanella larvae (960 μM). In the stability test against peptidases, the RK8 peptide was stable, maintaining around 60% of the molecule intact after 120 min of incubation. These results highlight the potential of RK8 to be a promising strategy for developing a new antimicrobial and antibiofilm agent, inspiring and motivating further research in antimicrobial peptides.

Xiaoqu, a pivotal starter in baijiu fermentation, provides the most microflora and enzymes to initiate and maintain baijiu brewing. This study aims to explore the differences in microbiota and enzyme activities among Xiaoqu samples from seven provinces in southern China using high-throughput sequencing, plate isolation, and activity detection. The analyses revealed significant differences in bacterial and fungal communities across the samples. A total of 22 bacterial species and 17 target fungal species were isolated and identified. Predominant bacteria included Bacillus (Bacillus subtilis) and lactic acid bacteria (LABs), while the fungal communities were primarily composed of yeasts (Saccharomyces cerevisiae) and various molds. The activities of α-amylase and glucoamylase varied significantly among the samples, and samples from HN1 and GZ2 exhibited the highest activities. Correlation analyses highlighted the pivotal role of LABs in maintaining acidity and the importance of molds and yeasts in the saccharification and fermentation processes. These findings shed light on the microbial composition and diversity of Xiaoqu and the critical role of microbes in baijiu production. Moreover, they suggested potential microbial resources for developing artificial Xiaoqu via synthetic microbial community in the future, enhancing baijiu fermentation efficiency and overall product quality.

This study investigated the efficacy of a phlorotannin supplement (PS) in ameliorating scopolamine (SCO)-induced memory deficits in mice, focusing on synaptic function and the underlying molecular mechanisms. Male C57BL/6N mice were divided into six groups and treated with vehicle, donepezil (5 mg/kg body weight, (BW)), or PS (100, 250, or 500 mg/kg BW) for 6 weeks. Behavioral tests were conducted, followed by Golgi staining, immunofluorescence, and immunoblotting to assess synaptic protein expression and signaling pathways. Behavioral tests showed that PS administration significantly improved SCO-induced memory impairment and restored synaptic protein expression (synaptophysin, synapsin1, and postsynaptic density protein 95) in the hippocampus. Additionally, PS enhanced brain-derived neurotrophic factor (BDNF) signaling and activated the extracellular signal-regulated kinase/CAMP response element binding protein (ERK-CREB) pathway, essential for synaptic plasticity. Our findings demonstrate that PS mitigates SCO-induced memory dysfunction by protecting synaptic integrity and activating the BDNF-ERK-CREB signaling pathway, indicating the potential of PS as a natural intervention for treating memory deficits.