Metabolomics study on fermentation of Lactiplantibacillus plantarum ST-III with food grade proliferators in milk.

Milk is a naturally complex medium that is suitable for the growth of most lactic acid bacteria. Unfortunately, Lactiplantibacillus plantarum ST-III grow poorly in milk without supplementation. To solve this problem, we use fresh pineapple and mung beans juice to develop an edible proliferator for L. plantarum ST-III. Our comparative analysis of metabolomics changes before and after fermentation reveals that amino acids and dipeptides are the most consumed compounds, with other substances including nucleotides and vitamins, implying the mechanism of proliferation. Combining the KEGG metabolic pathway analysis, substances that may promote the growth of L. plantarum ST-III in milk were screened. To explore which component of the proliferator is required for L. plantarum ST-III cultivate, we supplemented with several combinations of molecules aforementioned in milk. The simulation addition experiment results of L. plantarum ST-III in milk show that if any additions are missing, the concentration of viable bacteria is lower. Only when it contains all additives can the highest concentration of viable bacteria be obtained. Compared with the control, the fold change of the viable bacteria is about 32. Thus, it proves that milk primarily lacked available amino acids, dipeptides, uracil, xanthine, nicotinamide, and manganese for the growth of L. plantarum ST-III.

16S ribosomal RNA-depletion PCR and its application in cause analysis of yogurt package shrinkage.

Fermentative bacteria, the main microbiota in yogurt, interfere with the detection of unintended bacterial contaminants. The removal of fermentative bacteria and enrichment of unintended bacterial contaminants is a challenging task in bacterial detection. The present study developed a new 16S rRNA-depletion PCR for such enrichment and detection. Specifically, a single-guide RNA was designed and synthesized based on the 16S rRNA sequence of Streptococcus thermophilus, with the highest DNA abundance in the yogurt. The CRISPR-Cas9 system was used to specifically cleave and remove the genomic DNA of the fermentative bacteria, followed by PCR amplification. This method improved the detection sensitivity, simplified the operation steps, and reduced the detection cost of PCR analysis. We also used the 16S rRNA-depletion PCR to amplify and detect the unintended bacterial contaminants in yogurts with shrunken packages and analyzed the underlying reasons to prevent this issue of product quality.

Protoplast fusion between Blakeslea trispora 14,271 (+) and 14,272 (-) enhanced the yield of lycopene and ß-carotene.

Blakeslea trispora, a heterothallic Zygomycota with two mating types (termed "plus" and "minus"), is an ideal source of lycopene and ß-carotene. The lycopene and ß-carotene yields when the two type strains are used for fermentation separately are lower than those when they are joint together. To enhance the yield of lycopene and ß-carotene in B. trispora, protoplast fusion technology was carried out between ATCC 14,271 (+) and ATCC 14,272 (-). After protoplast preparation, protoplast fusion, fusion sorting, fusion regeneration, and high-throughput screening, two fusions (Fu-1and Fu-2) with high lycopene and ß-carotene yields were obtained. The lycopene yields of Fu-1 and Fu-2 were increased to 0.60 mg/gDW and 0.90 mg/gDW, which were respectively 3.62- and 5.44-fold those of 14,271 and 1.76- and 2.64-fold those of 14,272. The ß-carotene yields of Fu-1 and Fu-2 were increased to 22.07 mg/gDW and 36.93 mg/gDW, which were respectively 1.72- and 2.89-fold those of 14,271 and 1.23- and 2.06-fold those of 14,272. In this study, the protoplast fusion technique was successfully used in Blakeslea trispora, providing new ideas for improving lycopene and ß-carotene production.

In vitro toxicity and molecular interacting mechanisms of chloroacetic acid to catalase.

Chloroacetic acid (CAA), one of typical disinfection by-products (DBPs), has attracted considerable concerns for its biological safety. Antioxidant enzyme catalase (CAT) plays a crucial part in the regulation of redox state balance. Herein, CAA was used to test its adverse effects on CAT and explore the underlying mechanism. The cell viability of mouse primary hepatocytes decreased under CAA exposure. A bell-shaped response to CAA exposure was observed in intracellular CAT activity, whose change was partly influenced by molecular CAT activity. CAA binds to CAT mainly via van der Waals forces and hydrogen bonds with a stoichiometry of 9.2. The binding caused structural changes in CAT with the unfolding of polypeptide chains and the decrease of α-helical content. CAA interacts with the amino acid residues surrounding the active sites and substrate channel of CAT. These interactions result in the decrease of molecular CAT activity, which could be restored by high ionic strength. This study has provided a combined molecular and cellular tactics for studying the adverse effects of DBPs on biomarkers and the underlying mechanisms.

A simple one-step PCR walking method and its application of bacterial rRNA for sequencing identification.

There are many PCR walking methods applied currently, and they all have examples of successful application in organisms which are more complex than bacteria. However, to a certain extent, it will be more convenient for researchers if the complicated operation and poor specificity for bacteria can be improved. Here, we introduced an improved one-step PCR walking method of bacteria. Using a specific primer of the known sequence together with a universal semirandom primer, the unknown sequence adjacent to a known sequence can be obtained easily by just one ordinary round PCR. The products can be gel purified and directly sequenced. Specific primers were designed according to the gene sequence of bacterial rRNA, and the variable and adjacent gene sequences were obtained by this method. The sequence analysis of the product showed that it can improve the resolution of bacterial identification to the species level.

A simple one-step PCR walking method and its application of bacterial rRNA for sequencing identification.

There are many PCR walking methods applied currently, and they all have examples of successful application in organisms which are more complex than bacteria. However, to a certain extent, it will be more convenient for researchers if the complicated operation and poor specificity for bacteria can be improved. Here, we introduced an improved one-step PCR walking method of bacteria. Using a specific primer of the known sequence together with a universal semi-random primer, the unknown sequence adjacent to a known sequence can be obtained easily by just one ordinary round PCR. The products can be gel-purified and directly sequenced. Specific primers were designed according to the gene sequence of bacterial rRNA, and the variable and adjacent gene sequences were obtained by this method. The sequence analysis of the product showed that it can improve the resolution of bacterial identification to the species level.

Recent Studies and Applications of Hydrogel-Based Biosensors in Food Safety.

Food safety has increasingly become a human health issue that concerns all countries in the world. Some substances in food that can pose a significant threat to human health include, but are not limited to, pesticides, biotoxins, antibiotics, pathogenic bacteria, food quality indicators, heavy metals, and illegal additives. The traditional methods of food contaminant detection have practical limitations or analytical defects, restricting their on-site application. Hydrogels with the merits of a large surface area, highly porous structure, good shape-adaptability, excellent biocompatibility, and mechanical stability have been widely studied in the field of food safety sensing. The classification, response mechanism, and recent application of hydrogel-based biosensors in food safety are reviewed in this paper. Furthermore, the challenges and future trends of hydrogel biosensors are also discussed.

Lactiplantibacillus plantarum ST-III-fermented milk improves autistic-like behaviors in valproic acid-induced autism spectrum disorder mice by altering gut microbiota.

Introduction: Autism spectrum disorder (ASD) is a serious neurodevelopmental disorder with a rising incidence. More and more studies have shown that abnormal microbiota composition may aggravate the behavioral symptoms and biological signs of ASD, and interventions of probiotics and diet have emerged as a potential improvement measure. Methods: Lactiplantibacillus plantarum ST-III-fermented milk was applied as an oral intervention in a valproic acid (VPA)-induced ASD mice model, and the effect of probiotic intake on autistic-related behaviors and gut microbiota composition was evaluated by behavioral tests and 16S rRNA gene sequencing. Results: Gender specificity was shown in VPA-induced behavioral abnormalities in a mouse model, and L. plantarum ST-III-fermented milk was effective in ameliorating the impaired social interaction in male ASD mouse models, but not for the anxiety behavior exhibited by female ASD mouse models. Meanwhile, dietary changes were found to be the main cause of the altered gut microbiota in mice, and additional intake of L. plantarum ST-III-fermented milk seemed to improve autistic-like behaviors in male ASD mouse models by modulating specific gut microbes. Discussion: These findings suggest that L. plantarum ST-III-fermented milk may play a beneficial role in improving the behavioral symptoms of ASD and is expected to be one of the candidate functional foods for ASD.

Lactobacillus plantarum ST-III modulates abnormal behavior and gut microbiota in a mouse model of autism spectrum disorder.

Probiotic treatment might improve autism spectrum disorder (ASD) behavior. In this study, we investigated the improvement effects of Lactobacillus plantarum ST-III on a mouse model of ASD, which was constructed using triclosan. After two weeks of L. plantarum ST-III oral feeding, autism-like social deficits in male mouse models were ameliorated. L. plantarum ST-III also attenuated the self-grooming and freezing times of female mice. High-throughput sequencing revealed changes in the gut microbiota after L. plantarum ST-III intervention. In the female probiotic group, the abundance of beneficial Lachnospiraceae bacteria increased, whereas that of harmful Alistipes bacteria decreased. Correlation analysis showed that amelioration of abnormal behavior in a mouse model of ASD was related to the involvement of certain metabolic pathways. A reduction in the abundance of Alistipes was involved in stereotyped behavioral improvement. Thus, oral supplementation with L. plantarum ST-III can help improve social behavior in a male mouse model of ASD and contribute to more balanced intestinal homeostasis.

Bulk Modification of Thermoplastic Polyurethanes for Self-Sterilization of Trachea Intubation.

Implantable medical devices are widely used, but biomaterial-associated infections (BAIs) impose a huge economic burden and increase the mortality of patients. Therefore, BAIs are a serious concern that must be urgently resolved. Materials with antibacterial properties have become hotspots of current research and development. In the present work, quaternized chitosan (QCS) is used as an antibacterial agent and blended with thermoplastic polyurethane (TPU) to create an antibacterial material for tracheal intubation tubes. The modified TPU material (QCS-TPU) exhibited good mechanical properties and excellent long-term antibacterial performance. Under in vitro hydrodynamic conditions, QCS-TPU retained its strong antibacterial properties. QCS-TPU also possessed a low hemolysis rate and cytotoxicity. The current work is expected to provide a facile and feasible strategy for the preparation of antibacterial catheters and aid in the discovery of promising clinical applications to prevent BAIs.

Exploring the conformational changes in fibrinogen by forming protein corona with CdTe quantum dots and the related cytotoxicity.

This study describes synthesis of N­acetyl­l­cysteine-capped CdTe quantum dots (QDs) and investigates their interaction with plasma protein fibrinogen (FIB) and the structural changes of FIB. It is shown that the interaction of QDs with FIB is a spontaneous process and the major driving forces are van der Waals forces and hydrogen bonds. Multi-spectroscopic measurements show that the intrinsic fluorescence of FIB was quenched and secondary and tertiary structures were altered due to the interaction with QDs. In addition, the aggregation state of FIB was altered in the presence of QDs. Furthermore, the formed complexes of FIB with QDs reduced the cytotoxicity of QDs. The coating of FIB on QDs could lower intracellular QDs uptake and therefore result in less released cadmium ions and ROS productions. This study, therefore, might be helpful to the comprehensive understanding of QDs toxicity and provide evidence for assessing the safe application of nanoparticles.