Shiwei Chen

Aims Infantile eczema, usually coupled with a range of hypersensitive phenotypes, has come into notice with its rising prevalence and unclear pathogenesis. Recent studies show close ties between eczema and an infant’s intestinal flora. To gain a further understanding of the interactions between microbiota and eczema, we studied the breast milk flora as a new factor and present the links among breast milk flora, infant intestinal flora and infantile eczema through a cohort study in Northeast China. Methods and Results Fifty‐two families were recruited with either an eczema or healthy infant younger than 6 months. Analysis and predictions using amplicon sequencing of microbiota found that Bifidobacterium and Bacteroidetes were enriched in healthy‐ and eczema‐infant stools, respectively, consistent with previous reports. For breast milk flora, more ‘positive’ bacteria such as Akkermansia were enriched in breast milk from healthy infants’ mothers. Further, higher bacterial delivery efficiencies were found in pairs of breast milk flora and infants’ stool flora of families with eczema‐infants compared with families with healthy infants. Bacteroidetes, a widely known indicator of eczema, was found delivered more in eczema pairs. Further metagenomic predictions revealed that the breast milk microbiota participated significantly less in metabolism and immune system pathways, particularly in antigen processing and presentation and in Th17 cell‐related pathways. Conclusions In conclusion, as with other components of breast milk, the breast milk microbiota closely associates with infants’ health via mother‐infant bacterial delivery and metabolic functions. Significance and Impact of Study Our research aimed to fill the gap between the eczema and breast milk flora and describe the connections among breast milk and intestinal flora and eczema.

Lactic acid has been proved to inhibit the proliferation of lactic acid bacteria in the fermentation process. To shed light on the cell cycle alterations in acidic conditions, the cell division of Lactobacillus bulgaricus sp1.1 in batch culture was analyzed directly by implementing of the intracellular fluorescent tracking assay in different pH adjusted by lactic acid. Cell proliferation and cell division were investigated to be negatively controlled by the decrease of pH, and pH 4.1 was the critical condition of downregulating cell division but retains cell culturability. The cell area and cell length in pH 4.1 were examined by using fluorescent labeling, and they reduced to about 29.18–34.89% and 32.67–40% of cells cultured in the unacidified medium, respectively. The DNA replication initiation was undergoing prompted by the low extent of DNA condensation and higher expression of the dnaA gene in this critical pH. The results indicated that the cell cycle progressions of Lactobacillus bulgaricus sp1.1 in acidic conditions were arrested at intracellular biomass accumulation and cell division stage. These findings provide fundamental insight into cell cycle control of the acidic environment in Lactobacillus bulgaricus sp1.1.

Aims The purpose of this study was to investigate the characteristics of gut microbiota of children with obesity in Harbin, China and to screen anti‐obesity strains in vitro and in vivo. Methods and Results The gut microbiota of children with obesity and normal‐weight children were investigated by high‐throughput sequencing, and based on the different composition in gut microbiota, the strains with potential anti‐obesity properties were screened in vitro and in vivo. Compared with normal‐weight children, the Firmicutes to Bacteroidetes ratio in children with obesity decreased. Moreover, the relative abundances of Lactobacillus and Bifidobacterium in children with obesity were decreased, while the relative abundance of Akkermansia increased. After a series of screening in vitro and in vivo, nine strains were found inhibiting the body weight gain of HFD‐fed mice, of which two strains showed significant effects (P<0.05). Conclusions There were significant changes in gut microbiota of children with obesity from Harbin, China. The obtained strains showed obvious anti‐obesity effects, and the screening methods used in this study were effective. Significance and Impact of Study This study enriched the research results on the characteristics of gut microbiota of children with obesity in different regions of the world. Moreover, we established a new and effective method for screening anti‐obesity strains, and obtained effective strains.

The effects of fructose on plantaricin Q7 biosynthesis in Lactobacillus plantarum (L. plantarum) Q7 were investigated. Fructose induced and accelerated plantaricin Q7 production in the early stages of biosynthesis. Two-dimensional electrophoresis and quantitative real-time reverse transcriptase PCR (qRT-PCR) revealed that shock-related proteins were overexpressed in L. plantarum grown in MRS-fructose compared with cultures grown in MRS broth. A preheat-shock (PHS) treatment was used to overexpress shock-related proteins to enhance plantaricin Q7 production. The final plantaricin Q7 level reached 2873.08 IU/mL following PHS treatment, which was 23.36% higher than that obtained using a control strategy without PHS treatment. qRT-PCR analyses indicated that only groL was induced (by 10-fold) following PHS treatment. Evidently, groL plays a critical role in plantaricin Q7 biosynthesis. These results demonstrate that PHS treatment is an efficient approach to improving plantaricin Q7 production. The information obtained in this study may increase the amount of efficient antimicrobial peptide production using L. plantarum.

Kieselguhr, bentonite, and montmorillonite were investigated as potential carriers of plantaricin Q7. Highest level of adsorption of plantaricin Q7 was obtained with montmorillonite. Meanwhile, visible inhibition zones were observed against Listeria monocytogenes for montmorillonite adsorbed with plantaricin Q7. Adsorption kinetics showed that the adsorption behaviour followed the pseudo‐first‐order and Weber's intra‐particle diffusion models, suggesting two steps had taken place during the adsorption process. X‐ray diffraction assays revealed that plantaricin Q7 was intercalated into the interlayer space of montmorillonites. Electrostatic, hydrogen bonding and hydrophobic interactions proved to play important roles in the mechanisms of interaction between montmorillonite and plantaricin Q7, as shown by infrared spectroscopy analysis. In addition, plantaricin Q7 production was inhibited by feedback regulation with its high concentrations. In order to remove product feedback inhibition in plantaricin Q7 production, a strategy was implemented for its adsorption onto montmorillonite during fermentation. The final plantaricin Q7 output reached 3713.40 IU/mL during fermentation using montmorillonite to adsorb plantaricin Q7, 41.61% higher than that of non‐ montmorillonite. These results indicate that montmorillonites are suitable carriers for plantaricin Q7 adsorption, and the adsorption of plantaricin Q7 onto montmorillonite during fermentation could be a good method to increase final plantaricin Q7 production.

In this study, a novel sampling method was established to study changes in the activity of lactic acid bacteria during spray drying. Before spray drying, a sampling device with a refrigerant and a magnet was pre-cooled and positioned in a spray-drying tower. Carbonyl iron powder (CIP) was added to the drying media to increase the sampling mass by the magnetic effect. During drying, a temperature sensor measured the particle contact temperature. After drying, the sample in the sampling device was taken out to analyze the characteristics, including the mass, water content, and bacteria livability in the sample. The sampling device and method were optimized with a sampling cup with a depth of 3.5 cm (for contact temperatures below 79.1°C) or 5 cm (for contact temperatures below 89.1°C). The ratio of CIP to reconstituted skim milk (RSM) was 1:10, and RSM concentration was not lower than 20% (w/w). This method was then applied to spray drying of Lactobacillus bulgaricus sp1.1. Furthermore, it was demonstrated that 2 mL of sterile water placed in the sampling cup prior to drying resulted in a more accurate measurement of cell viability. This sampling method can be used in practical spray drying applications for biological materials without using a special instrument or drying tower.

The individual and interactive effects of skimmed milk powder, lactose, and sodium ascorbate on the number of viable cells and freeze-drying survival for vacuum freeze-dried powder formulation of Lactobacillus bulgaricus were studied by response surface methodology, and the optimal compound lyoprotectant formulations were gained. It is shown that skim milk powder, lactose, and sodium ascorbate had a significant impact on variables and survival of cultures after freeze-drying. Also, their protective abilities could be enhanced significantly when using them as a mixture of 28% w/v skim milk, 24% w/v lactose, and 4.8% w/v sodium ascorbate. The optimal freeze-drying survival rate and the number of viable cells of Lactobacillus bulgaricus were observed to be (64.41 ± 0.02)% and (3.22 ± 0.02) × 10¹¹ colony-forming units (CFU)/g using the optimal compound protectants, which were very close to the expected values 64.47% and 3.28 × 10¹¹ CFU/g.