Acetolactate Decarboxylase as an Important Regulator of Intracellular Acidification, Morphological Features, and Antagonism Properties in the Probiotic Lactobacillus reuteri.

SCORE: This study identifies the coding gene (aldB) of acetolactate decarboxylase (ALDC) as an important regulatory gene of the intracellular pH in Lactobacillus reuteri (L. reuteri), uncovering the important role of ALDC in regulating intracellular pH, morphological features, and antagonism properties in the probiotic organism L. reuteri. METHODS AND RESULTS: The aldB mutant (ΔaldB) of L. reuteri is established using the homologous recombination method. Compare to the wild-type (WT) strain, the ΔaldB strain shows a smaller body size, grows more slowly, and contains more acid in the cell cytoplasm. The survival rate of the ΔaldB strain is much lower in low pH and simulated gastric fluid (SGF) than that of the WT strain, but higher in simulated intestinal fluid (SIF). The antagonism test demonstrates the ΔaldB strain can inhibit Listeria monocytogenes (L. monocytogenes) and Salmonella more effectively than the WT strain. Additionally, there is a dramatic decrease in the adhesion rate of Salmonella to Caco-2 and HT-29 cells in the presence of the ΔaldB strain compared to the WT strain. Simultaneously analyze, the auto-aggregation, co-aggregation, cell surface hydrophobicity (CSH), hemolytic, temperature, NaCl, oxidative stress, and antibiotic susceptibility of the ΔaldB strain are consistent with the features of probiotics. CONCLUSION: This study highlights that the aldB gene plays a significant role in the growth and antibacterial properties of L. reuteri.

A 0D-2D Heterojunction Bismuth Molybdate-Anchored Multifunctional Hydrogel for Highly Efficient Eradication of Drug-Resistant Bacteria.

Due to the increasing antibiotic resistance and the lack of broad-spectrum antibiotics, there is an urgent requirement to develop fresh strategies to combat multidrug-resistant pathogens. Herein, defect-rich bismuth molybdate heterojunctions [zero-dimensional (0D) Bi4MoO9/two-dimensional (2D) Bi2MoO6, MBO] were designed for rapid capture of bacteria and synergistic photocatalytic sterilization. The as-prepared MBO was experimentally and theoretically demonstrated to possess defects, heterojunctions, and irradiation triple-enhanced photocatalytic activity for efficient generation of reactive oxygen species (ROS) due to the exposure of more active sites and separation of effective electron-hole pairs. Meanwhile, dopamine-modified MBO (pMBO) achieved a positively charged and rough surface, which conferred strong bacterial adhesion and physical penetration to the nanosheets, effectively trapping bacteria within the damage range and enhancing ROS damage. Based on this potent antibacterial ability of pMBO, a multifunctional hydrogel consisting of poly(vinyl alcohol) cross-linked tannic acid-coated cellulose nanocrystals (CPTB) and pMBO, namely CPTB@pMBO, is developed and convincingly effective against methicillin-resistant Staphylococcus aureus in a mouse skin infection model. In addition, the strategy of combining a failed beta-lactam antibiotic with CPTB@pMBO to photoinactivation with no resistance observed was developed, which presented an idea to address the issue of antibiotic resistance in bacteria and to explore facile anti-infection methods. In addition, CPTB@pMBO can reduce excessive proteolysis of tissue and inflammatory response by regulating the expression of genes and pro-inflammatory factors in vivo, holding great potential for the effective treatment of wound infections caused by drug-resistant bacteria.

ROS-responsive hyaluronic acid hydrogel for targeted delivery of probiotics to relieve colitis.

Probiotics are generally used as therapeutic intervention in inflammatory bowel disease. However, the low survival rate in harsh gastrointestinal environment and limited retention in intestine greatly restrict their health benefits. To address this problem, a ROS-responsive hydrogel based on hyaluronic acid (HA) was developed for encapsulation and targeted delivery of probiotics. The hydrogel was prepared facilely by physiological crosslink with methacrylated HA and thiolated thioketal. As a model probiotic, Lactobacillu reuteri showed a significantly increased survival rate in simulated digestive conditions after encapsulated in hydrogel. The negative properties conferred the hydrogel preferential adhesions to inflammation sites. Meanwhile, the excess reactive oxygen species (ROS) produced by inflamed colon tissues selectively cleaved thioketal linkages resulted in hydrogel degradation and local probiotics release. Furthermore, the hydrogel exerted an appropriate ROS-scavenge capacity and protected HT-29 cells from oxidative damage. Animal experiments indicated that hydrogel-encapsulated L. reuteri could remarkably alleviate the symptoms and improve the survival rate of mice with dextran sulfate sodium (DSS)-induced colitis. These results suggested that the biocompatible hydrogel may be a delivery platform to target inflamed intestines and expand the application of probiotics as pharmaceuticals.

Carboxymethyl chitosan-based multifunctional hydrogels incorporated with photothermal therapy against drug-resistant bacterial wound infection.

Wound infection especially that induced by drug resistant bacteria has been considered an increasing medical crisis. Herein a biocompatible wound dressing is conveniently constructed by incorporating (Sr0.6Bi0.305)2Bi2O7 (denoted as SBO) with excellent photothermal performance into a facile antibacterial hydrogel (gel) obtained from multiple physical crosslinks among Ag+, carboxymethyl chitosan and polyacrylic acid. The prepared SBO gel features excellent bactericidal activities, hemostasis, adequate mechanical properties, adhesiveness and adsorption capacities to bacterial cells and toxin. The gel can disperse SBO homogeneously in the network and SBO effectively convert visible light energy into localized heat for synergistic sterilization. In vitro assays confirm the potent broad-spectrum bactericidal activities of SBO gel to some common pathogens and drug resistant strains such as MRSA and CAPA. Mice model of MRSA-induced wound infections verified the practical efficacy of SBO gel in combating bacterial infections and accelerating wound healing. Moreover, this is the first report of SBO as a photothermal agent applied in anti-infection treatment. All of these results highlight the potential application of SBO gel in drug-resistant bacteria associated wound management.

Comparative transcriptional survey between self-incompatibility and self-compatibility in Citrus reticulata Blanco.

Seedlessness is an excellent economical trait, and self-incompatibility (SI) is one of important factors resulting in seedless fruit in Citrus. However, SI molecular mechanism in Citrus is still unclear. In this study, RNA-Seq technology was used to identify differentially expressed genes related to SI reaction of 'Wuzishatangju' (Citrus reticulata Blanco). A total of 35.67GB raw RNA-Seq data was generated and was de novo assembled into 50,364 unigenes with an average length of 897bp and N50 value of 1549. Twenty-three candidate unigenes related to SI were analyzed using qPCR at different tissues and stages after self- and cross-pollination. Seven pollen S genes (Unigene0050323, Unigene0001060, Unigene0004230, Unigene0004222, Unigene0012037, Unigene0048889 and Unigene0004272), three pistil S genes (Unigene0019191, Unigene0040115, Unigene0036542) and three genes (Unigene0038751, Unigene0031435 and Unigene0029897) associated with the pathway of ubiquitin-mediated proteolysis were identified. Unigene0031435, Unigene0038751 and Unigene0029897 are probably involved in SI reaction of 'Wuzishatangju' based on expression analyses. The present study provides a new insight into the molecular mechanism of SI in Citrus at the transcriptional level.