• Bacterial conjugated linoleic acid production and their applications

      Yang, Bo; Gao, He; STANTON, CATHERINE; Ross, R Paul; Zhang, Hao; Chen, Yong Q.; Chen, Haiqin; Chen, Wei; National Natural Science Foundation of China; National Natural Science Foundation of Jiangsu Province; et al. (Elsevier, 2017-09-07)
      Conjugated linoleic acid (CLA) has been shown to exert various potential physiological properties including anti-carcinogenic, anti-obesity, anti-cardiovascular and anti-diabetic activities, and consequently has been considered as a promising food supplement. Bacterial biosynthesis of CLA is an attractive approach for commercial production due to its high isomer-selectivity and convenient purification process. Many bacterial species have been reported to convert free linoleic acid (LA) to CLA, hitherto only the precise CLA-producing mechanisms in Propionibacterium acnes and Lactobacillus plantarum have been illustrated completely, prompting the development of recombinant technology used in CLA production. The purpose of the article is to review the bacterial CLA producers as well as the recent progress on describing the mechanism of microbial CLA-production. Furthermore, the advances and potential in the heterologous expression of CLA genetic determinants will be presented.
    • Bioaccessibility and Cellular Uptake of β-Carotene Encapsulated in Model O/W Emulsions: Influence of Initial Droplet Size and Emulsifiers

      Lu, Wei; Kelly, Alan; Miao, Song; China Scholarship Council; National Natural Science Foundation of China; 201508300001; 31628016 (MDPI AG, 2017-09-20)
      The effects of the initial emulsion structure (droplet size and emulsifier) on the properties of β-carotene-loaded emulsions and the bioavailability of β-carotene after passing through simulated gastrointestinal tract (GIT) digestion were investigated. Exposure to GIT significantly changed the droplet size, surface charge and composition of all emulsions, and these changes were dependent on their initial droplet size and the emulsifiers used. Whey protein isolate (WPI)-stabilized emulsion showed the highest β-carotene bioaccessibility, while sodium caseinate (SCN)-stabilized emulsion showed the highest cellular uptake of β-carotene. The bioavailability of emulsion-encapsulated β-carotene based on the results of bioaccessibility and cellular uptake showed the same order with the results of cellular uptake being SCN > TW80 > WPI. An inconsistency between the results of bioaccessibility and bioavailability was observed, indicating that the cellular uptake assay is necessary for a reliable evaluation of the bioavailability of emulsion-encapsulated compounds. The findings in this study contribute to a better understanding of the correlation between emulsion structure and the digestive fate of emulsion-encapsulated nutrients, which make it possible to achieve controlled or potential targeted delivery of nutrients by designing the structure of emulsion-based carriers.
    • Comparative genomic analyses of Lactobacillus rhamnosus isolated from Chinese subjects

      Huang, Dan; Yang, Bo; Chen, Yang; STANTON, CATHERINE; Ross, R Paul; Zhao, Jianxin; Zhang, Hao; Chen, Wei; National Natural Science Foundation of China; National First-Class Discipline Program of Food Science and Technology; et al. (Elsevier, 2020-08-31)
      Lactobacillus rhamnosus has been found in many niches, including human intestine, vagina, mouth and dairy products. To intensively investigate the genomic diversity of this species, draft genomes of 70 L. rhamnosus strains isolated from different Chinese subjects were sequenced and further investigated. The pan-genome of L. rhamnosus was open. And gene-trait matching (GTM) was done to explore the carbohydrate utilization ability and antibiotic resistance, and to establish a pattern of gene existence/absence and growth/absence. There were no significant correlations between genetic diversity of the strains and the age or region of the donors. The current results extend the understanding of L. rhamnosus, which could be used as a reference for subsequent research as well as mining and application of the species.
    • Comparative Genomics Analysis of Lactobacillus ruminis from Different Niches

      Wang, Shuo; Yang, Bo; Ross, R. Paul; STANTON, CATHERINE; Zhao, Jianxin; Zhang, Hao; Chen, Wei; National Natural Science Foundation of China; Jiangsu Province; 31771953; et al. (MDPI AG, 2020-01-08)
      Lactobacillus ruminis is a commensal motile lactic acid bacterium living in the intestinal tract of humans and animals. Although a few genomes of L. ruminis were published, most of them were animal derived. To explore the genetic diversity and potential niche-specific adaptation changes of L. ruminis, in the current work, draft genomes of 81 L. ruminis strains isolated from human, bovine, piglet, and other animals were sequenced, and comparative genomic analysis was performed. The genome size and GC content of L. ruminis on average were 2.16 Mb and 43.65%, respectively. Both the origin and the sampling distance of these strains had a great influence on the phylogenetic relationship. For carbohydrate utilization, the human-derived L. ruminis strains had a higher consistency in the utilization of carbon source compared to the animal-derived strains. L. ruminis mainly increased the competitiveness of niches by producing class II bacteriocins. The type of clustered regularly interspaced short palindromic repeats /CRISPR-associated (CRISPR/Cas) system presented in L. ruminis was mainly subtype IIA. The diversity of CRISPR/Cas locus depended on the high denaturation of spacer number and sequence, although cas1 protein was relatively conservative. The genetic differences in those newly sequenced L. ruminis strains highlighted the gene gains and losses attributed to niche adaptations.
    • Comparative genomics and gene-trait matching analysis of Bifidobacterium breve from Chinese children

      Liu, Rui; Yang, Bo; STANTON, CATHERINE; Ross, Paul; Zhao, Jianxin; Zhang, Hao; Chen, Wei; National Natural Science Foundation of China; National First-Class Discipline Program of Food Science and Technology; the Fundamental Research Funds for the Central Universities; et al. (Elsevier BV, 2020-08)
      Bifidobacterium breve is one of the dominant Bifidobacterial species in children. In the current work, 46 strains of B. breve isolated from fecal samples of Chinese children were analyzed using whole-genome sequencing and comparative genomics to explore their genetic diversity, as well as genotype and phenotype analysis for carbohydrate utilization and antibiotic tolerance. The phylogenetic tree was independent of region, age and feeding mode, and without any regularity in the clustering of carbohydrates and antibiotics at the genetic level. Based on genotypic-phenotypic correlation analysis, the diversity of glycosyl hydrolases and the ability of strains to metabolize carbohydrates corroborated the predominance of B. breve in the children's intestines. Simultaneously, the sensitivity of strains to antibiotics increased the understanding of its genetic features and provided a potential basis for safety evaluation.
    • Diversity of Gut Microbiota and Bifidobacterial Community of Chinese Subjects of Different Ages and from Different Regions

      Yang, Bo; Yan, Shuang; Chen, Yang; Ross, R. Paul; STANTON, CATHERINE; Zhao, Jianxin; Zhang, Hao; Chen, Wei; National Natural Science Foundation of China; National First-Class Discipline Program of Food Science and Technology; et al. (MDPI AG, 2020-07-24)
      Gut microbiota composition and functionality are closely linked to host health. In this study, the fecal microbiota and bifidobacterial communities of 111 healthy volunteers from four regions of China of varying age profiles (Child, 1–5 years; Young, 18–50 years; Elder, 60–80 years; Longevity, ≥90 years) were investigated via high-throughput sequencing. Canonical analysis revealed that the gut microbiota, as well as bifidobacteria profiles of the subjects, clustered according to their regions and age. Eight genera were shared among all subjects, however, certain genera distributed differently in subjects grouped by region and age. Faecalibacterium was enriched in samples from Zhongxiang, unclassified Ruminococcaceae and Christensenellaceae were enriched in the Longevity group, and Bifidobacterium was enriched in Child. Within Bifidobacterium, B. longum was the most abundant species in almost all samples except for Child, in which B. pseudocatenulatum was the most abundant. Additionally, the abundances of B. adolescentis and B. dentium were lower in Child. In conclusion, our results suggest that geography and age affect the structure of the gut microbiota, as well as Bifidobacterium composition, and this variation may greatly associate with the metabolic and immune changes that occur during the process of aging.
    • Heat-induced Maillard reaction of the tripeptide IPP and ribose: Structural characterization and implication on bioactivity

      Jiang, Zhanmei; Rai, Dilip K.; O'Connor, Paula M.; Brodkorb, Andre; National Natural Science Foundation of China; Innovative Research Team of Higher Education of Heilongjiang Province (Elsevier, 28/09/2012)
      Maillard reaction products (MRPs) were prepared from aqueous model mixtures containing 60 g L− 1 ribose and 30 g L− 1 of the bioactive tripeptide IPP (Ile-Pro-Pro), heated at 98 °C. MRP and associated reactions with changes in IPP were observed within one hour of heat-treatment. The pH of MRPs decreased significantly during the heat treatment of IPP–ribose mixtures from 9.0 to 7.6 after one hour. The amino group content, IPP and ribose concentration decreased significantly during heat treatment. The fluorescence intensity of the IPP–ribose MRPs reached the maximum within 2 h. Modification of the UV/vis spectra for IPP–ribose MRPs was mainly due to a condensation reaction of IPP with ribose. Compounds with molecular weight between 300 and 650 Da were dominant while compounds smaller than 250 Da were also produced during the reactions, as characterized by size exclusion chromatography. Mass spectrometry revealed that IPP was conjugated to ribose at the N-terminal (m/z of 458.3) upon heat-treatment. The presence of ribose also promoted peptide degradation to dehydrated IP (m/z of 211.1). IPP–ribose MRPs lost the known angiotensin-I-converting enzyme (ACE) inhibitory activity of IPP; however, strong antioxidant properties were detected.
    • Improved emulsion stability and modified nutrient release by structuring O/W emulsions using konjac glucomannan

      Lu, Wei; Zheng, Baodong; Miao, Song; National Natural Science Foundation of China; China Scholarship Council; 31628016; 201508300001 (Elsevier, 2018-02-22)
      Functional konjac glucomannan (KGM) was used to structure the water phase of O/W emulsions containing a lipophilic bioactive compound (β-carotene). KGM greatly increased the viscosity of the water phase and thus the viscosity of final emulsions. Results of Fourier-transform infrared spectroscopy (FT-IR) showed that there is no significant non-covalent interaction between KGM and whey proteins in the water phase. KGM significantly improved the creaming and pH stability of whey-protein-stabilized emulsions (p < 0.05), and significantly decreased the oiling-off of emulsions during freeze-thaw test. Emulsions with or without KGM all had good thermal stability at 80 °C. Microscopy observations indicated obvious aggregation of free proteins and oil droplets in gastric phase and an enzymatic-induced break-down of droplets, mainly in the intestinal phase of the simulated gastrointestinal tract (GIT) digestion. Emulsions with KGM-structured water phase showed a lower final release rate of encapsulated β-carotene than emulsion without KGM (p < 0.05), and the release rate decreased with the increasing KGM content. The findings of this study contribute to a better understanding of the influence of the water phase on the release of encapsulated compounds from emulsions, and make it possible to achieve controlled release of encapsulated compounds, and/or to deliver multiple health-beneficial nutrients at once by structuring emulsion-based carriers with functional natural biopolymers.
    • Lactobacillus acidophilus JCM 1132 Strain and Its Mutant with Different Bacteriocin-Producing Behaviour Have Various In Situ Effects on the Gut Microbiota of Healthy Mice

      Wang, Gang; Yu, Yunxia; Garcia-Gutierrez, Enriqueta; Jin, Xing; He, Yufeng; Wang, Linlin; Tian, Peijun; Liu, Zhenmin; Zhao, Jianxin; Zhang, Hao; et al. (MDPI AG, 2019-12-25)
      The production of bacteriocin is considered to be a probiotic trait of lactic acid bacteria (LAB). However, not all strains of LAB harbour bacteriocin genes, even within the same species. Moreover, the effects of bacteriocins on the host gut microbiota and on host physiological indicators are rarely studied. This study evaluated the effects of the bacteriocin-producing Lactobacillus acidophilus strain JCM1132 and its non-producing spontaneous mutant, L. acidophilus CCFM720, on the physiological statuses and gut microbiota of healthy mice. Mice that received the bacteriocin-producing strain JCM1132 exhibited reduced water and food intake. Furthermore, the administration of these strains induced significant changes in the compositional abundance of faecal microbiota at the phylum and genus levels, and some of these changes were more pronounced after one week of withdrawal. The effects of CCFM720 treatment on the gut microbiota seemed to favour the prevention of metabolic diseases to some extent. However, individuals that received JCM1132 treatment exhibited weaker inflammatory responses than those that received CCFM720 treatment. Our results indicate that treatment with bacteriocin-producing or non-producing strains can have different effects on the host. Accordingly, this trait should be considered in the applications of LAB.
    • Preparation and characterization of lotus seed starch-fatty acid complexes formed by microfluidization

      Chen, Bingyan; Guo, Zebin; Miao, Song; Zeng, Shaoxiao; Jia, Xiangze; Zhang, Yi; Zheng, Baodong; National Natural Science Foundation of China; Scientific and Technological Innovation Team Support Plan of Institution of Higher Learning in Fujian Province; Construction Projects of Top University; et al. (Elsevier, 2018-05-22)
      Using dynamic high pressure microfluidization, we prepared starch-lipid complexes from lotus seed starch (LS) and six saturated fatty acids (FAs) of different carbon chain length and analyzed their semi-crystalline structure and digestibility. Iodine blue value analysis showed the highest complex index (86.3%) was observed between LS and octanoic acid (C8). X-ray diffraction analysis showed crystal structure changed from V6II to V6I type with decreasing FA chain length. Small angle x-ray scattering and differential scanning calorimetry analyses confirmed the presence of a strong V6I-type mass fractal structure with a Bragg distance of 12.3 nm in LS-C8, which can be considered to be a type-II complex with high melting temperature (Tp = 123.98 °C). Scanning electron microscopy results showed the complexes had more spherocrystals with decreasing FA chain length. Compared to other FAs, C8 significantly reduced the LS susceptibility to digestive enzymes, increased slowly digestion starch content (26.06%) and decreased digestion rate (3.59 × 10−2).