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Ingested dietary fibres are hydrolysed by colon microbiota to produce energy-providing short-chain fatty acids (SCFA) that stimulate anti-inflammatory effects. SCFA-producing bacteria were screened from bacteria isolated from human faeces using bromothymol blue as an acid indicator and gas chromatography for SCFA profiling. The beneficial functions (antagonistic activity, haemolytic activities, antibiotic susceptibility, mucus adherent percentage and toxin gene detection) were evaluated for the top five SCFA-producing bacteria isolated from three healthy volunteers that identified as Escherichia coli strains. They produced acetic, propionic, isobutyric, butyric, isovaleric, valeric and caproic acids at average concentrations of 15.9, 1.8, 1.1, 1.9, 1.8, 2.7 and 3.4 mM, respectively. The SCFA production by  E. coli  strains was rapidly increased during the first 8 h of incubation and gradually decreased after 16 h of incubation. All E. coli strains showed acid and bile tolerance, resulting in a survival rate greater than 70% with no haemolytic activity, mucus adherence greater than 40% and susceptibility to conventional antibiotics. Hence, the selected E. coli strains exhibited promising probiotic properties with neither enterotoxin nor LPS producibility was detected. The present results confirm the existence of friendly and harmless  E. coli  strains in human microbiota as potential probiotics., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest in the publication., (© King Abdulaziz City for Science and Technology 2020.)

Probiotic is an alternative method to treat intestinal infection disease caused by antibiotic-resistant bacteria. In this study, Lactococcus lactis KA-FF 1-4 demonstrated to have the potential to inhibit the growth of Vancomycin-resistant enterococci (VRE) by producing anti-microbial substance. In co-culture, L. lactis KA-FF 1-4 (10 8  CFU/mL) inhibited the growth of VRE from 10 3 -10 4  CFU/mL to zero after 6 h of exposure. However, in a gut model contained human gut microbiota, this anti-VRE activity of L. lactis KA-FF 1-4 was reduced to only 3.59-6.12%. The unexpected difference in efficacy between the experimental models could be explained by the fact that the growth of L. lactis KA-FF 1-4 was stable in the gut model. Leaving aside these limitations, we observed that adding L. lactis KA-FF 1-4 into the human gut model containing VRE was able to enhance microbial richness and diversity. Specifically, a higher abundance of beneficial microbes from the group of Bifidobacterium spp. and Bacteroides fragilis . L. lactis KA-FF 1-4 also enhanced the abundance of Parabacteroides , Lactococcus , and Fusobacterium and promoted the production of lactic acid in the gut model. However, these effects were not observed in the gut model without L. lactis KA-FF 1-4. Even though this study could not demonstrate a significant anti-VRE effect of the L. lactis KA-FF 1-4 in a gut model, our results still offer evidence that L. lactis KA-FF 1-4 could positively modulate the gut microbiota by promoting the growth of beneficial microbes and their metabolite. L. lactis KA-FF 1-4 has probiotic properties to fight against VRE infection, therefore further investigation in animal model is needed., Competing Interests: Conflict of interestOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© King Abdulaziz City for Science and Technology 2020.)

The gut microbial diversity of Thai people was investigated between two large cohorts, adult and elderly subjects, from the middle region of Thailand; the cohorts were divided into different age groups of healthy adult ( 73 ) and elderly subjects ( 47 ) . The diversities of the groups were characterized using a pyrosequencing technique with primers targeting the V6-V8 region of the 16S rRNA gene, and a significant decrease in the Firmicutes and Bacteroidetes ratio from 7.3 to 4.5 was observed with increased age . The microbiota of the adult and elderly groups had a significantly higher abundance of the phylum Actinobacteria , including the three species Bifidobacterium adolescentis , Bifidobacterium longum and Bifidobacterium pseudocatenulatum , and the phylum Bacteroidetes containing the four species Bacteroides uniformis , Bacteroides ovatus , Bacteroides caccae and Bacteroides thetaiotaomicron . Firmicutes showed no significant differences between the two groups. Eleven species belonging to Firmicutes , Bacteroidetes and Proteobacteria were shared by at least 90% of all subjects and defined as core gut microbiota of healthy Thai, among which a high abundance of Escherichia coli was particularly characterized in Thai elderly individuals. Multiple linear regression analysis of age, gender, BMI and diet consumption frequency showed the correlation of age with Bacteroides and Bifidobacterium . Rice consumption frequency showed a significant positive correlation with Bacteroides , while no correlation was found for other factors. Taken together, in the gut of Thai adults, Bifidobacterium decreased and Bacteroides increased with age, while rice consumption increased the abundance of Bacteroides . These link of age and food, especially rice carbohydrate, to gut microbiota and health could be ultimately proposed as the Thai feature., Competing Interests: Conflict of interestThe authors declare that have no conflict of interest in the publication., (© King Abdulaziz City for Science and Technology 2020.)

Hydrolysis products of defatted copra meal (DCM) hydrolysis were investigated with either recombinant β-mannanases from Klebsiella oxytoca KUB-CW2-3 (KMAN-3) or Bacillus circulans NT 6.7 (MAN 6.7). Morphological changes and functional groups of solid residues were also determined by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Results revealed that the Michaelis-Menten constant ( K m ) and maximum velocity ( V max ) values of KMAN-3 on DCM were 2.4 mg/ml and 5.4 U/mg, respectively, while MAN 6.7 recorded K m and V max at 2.0 mg/ml and 4.3 U/mg, respectively. Both enzymes efficiently randomly hydrolysed DCM and produced a range of different manno-oligosaccharides (MOS). The profile of hydrolysis products was different for each enzyme used. Main products from hydrolysis of DCM by KMAN-3 and MAN 6.7 were various MOS including mannobiose (M2), mannotriose (M3), mannotetraose (M4), and mannose, whereas mannopentaose (M5) was only found from KMAN-3. Amount of M3 produced by KMAN-3 was about three times higher than from MAN 6.7. Total MOS yield for KMAN-3 was 1.5-folds higher than for MAN 6.7. SEM analysis showed that enzymatic hydrolysis with KMAN-3 and MAN 6.7 resulted in deconstruction of the DCM structure which generated a variety of MOS products. FTIR spectra revealed that the properties of both hydrolysed solids were not significantly different compared to the original DCM. Results suggested that KMAN-3 was a promising candidate for production of high MOS content from copra meal., Competing Interests: Conflict of interestThe authors declare no conflict of interest., (© King Abdulaziz City for Science and Technology 2020.)

Several studies have reported a complex microbial community in human breast milk. This community impacts the shape of the infant gut microbiota and consequently impacts host health. Lactobacillus is an important probiotic and has many applications in the functional food industry. This study isolated and evaluated the potential probiotic bacteria from human milk. Two Lactobacillus species, L . plantarum and L . pentosus , were isolated from the breast milk of Thai women. L . pentosus HM04-22, L . pentosus HM04-3, L . plantarum HM04-80, L . plantarum HM04-88 and L . plantarum HM01-1 showed good adhesion activity (> 55%) and resistance in gastric (pH 2) and bile (pH 8) conditions. Characterization of the probiotic properties indicated that all selected Lactobacillus isolates had anti-adhesion properties against Escherichia coli and Salmonella Typhimurium. Lactobacillus isolates protected Caco-2 cells from pathogen adhesion at 25-40%. In addition, the five selected strains presented anti-inflammatory properties by reducing interleukin (IL)-8 expression at 0.14 ± 0.16 to 0.52 ± 0.117-fold. However, the strains had no effect on the expression of tight junction genes, including zona occludens (ZO)-1, occludin and claudin-1. In conclusion, five selected Lactobacillus isolates from human milk were candidates for use as probiotics to promote health. However, more tests in animal models and clinical trials need to be performed., Competing Interests: Conflict of interestOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© King Abdulaziz City for Science and Technology 2019.)

Copra meal hydrolysate (CMH) is obtained by hydrolyzing defatted copra meal with β-mannanase from Bacillus circulans NT 6.7. In this study, we investigated the resistance of CMH to upper gastrointestinal tract digestion and the fecal fermentation profiles of CMH. Fecal slurries from four healthy human donors were used as inocula, and fructooligosaccharides (FOS) were used as a positive prebiotic control. Fecal batch cultures were performed at 37 °C under anaerobic conditions. Samples were collected at 0, 10, 24 and 34 h for bacterial enumeration via fluorescent in situ hybridization and organic acid (OA) analysis. In vitro gastric stomach and human pancreatic α-amylase simulations demonstrated that CMH was highly resistant to hydrolysis. Acetate was the main fermentation product of all the substrates. The proportions of acetate production of the total OAs from FOS, CMH and yeast mannooligosaccharides (MOS) after 34 h of fermentation did not significantly differ (69.76, 65.24 and 53.93%, respectively). At 24 h of fermentation, CMH promoted the growth of Lactobacillus and Bifidobacterium groups ( P  < 0.01) and did not significantly differ from the results obtained using FOS. The results of in vitro fecal fermentation of CMH indicate that CMH can promote the growth of beneficial bacteria., Competing Interests: Compliance with ethical standardsThe authors declare that there are no conflicts of interest.

Enzymatic hydrolysis of palm kernel cake to improve the quality of substrates with multi-response criteria based on the Taguchi orthogonal array. Nine experimental runs were performed based on an L9 orthogonal array. Percent substrate, incubation time, and enzyme units were optimized considering multiple performance characteristics. Analysis of variance was also applied to identify the most significant factors. Results determined percent substrate as the most important factor for enzymatic hydrolysis followed by incubation time and enzyme units. Enzymatic hydrolysis conditions were optimized as percent substrate, incubation time and enzyme units at 14%, 6 h and 750 units, respectively. Tests were conducted to compare experimental and model results. The experimental result (protein release) at optimal condition were three times higher than the predicted mode., Competing Interests: Compliance with ethical standardsThe authors declare that they have no conflict of interest in the publication.

The aim of this study was to carry out preliminary investigations on the in vitro fermentation selectivity of copra meal hydrolysate (CMH) by chicken gut microbiota. The ileum and cecum contents from three 35-day-old birds were used as inocula. Yeast mannooligosaccharide (yeast-MOS) or α-mannan was selected as a positive control. Batch culture fermentation with fecal bacteria was performed at 42 °C for 24 h in an anaerobic chamber. Samples were collected at 0, 6, 12, 18 and 24 h of fermentation and evaluated using real-time PCR and short-chain fatty acid (SCFA) analysis. Results showed that the medium containing ileum and both CMH and yeast-MOS substrates led to an increase in the growth of the dominant groups as Lactobacillus , Enterobacteriaceae and Enterococcus spp. compared with 0-h fermentation. Campylobacter spp. and Bifidobacterium spp. were not detected in any samples. A significant decrease in Acinetobacter was observed in all substrates tested after 6 h of fermentation ( P  < 0.05). Only the sample from CMH fermentation showed a significantly greater reduction in the population of Pseudomonas after 18-h fermentation with ileum content ( P  < 0.05). Propionate was the main fermentation product found in both ileum and cecum fermentation followed by lactate and acetate. CMH can be utilized by ileum and cecum microbial of chickens, and CMH has a generally desirable effect on the microbiota. CMH has the potential for use as a supplementary diet with similar or improved benefits and lower costs compared to commercial prebiotics. Further experiments in animal trials would seem to be justified., Competing Interests: Compliance with ethical standardsThe authors declare that there is no conflict of interest regarding publication of this paper.

Three bacteriocins from Lactobacillus plantarum KL-1 were successfully purified using ammonium sulfate precipitation, cation-exchange chromatography and reverse-phase HPLC. The bacteriocin peptides KL-1X, -1Y and -1Z had molecular masses of 3053.82, 3498.16 and 3533.16 Da, respectively. All three peptides were stable at pH 2-12 and 25 °C and at high temperatures of 80 and 100 °C for 30 min and 121 °C for 15 min. However, they differed in their susceptibility to proteolytic enzymes and their inhibition spectra. KL-1Y showed broad inhibitory activities against Gram-positive and Gram-negative bacteria, including Salmonella enterica serovar Enteritidis DMST 17368, Pseudomonas aeruginosa ATCC 15442, P. aeruginosa ATCC 9027, Escherichia coli O157:H7 and E. coli ATCC 8739. KL-1X and -1Z inhibited only Gram-positive bacteria. KL-1X, KL-1Y and KL-1Z exhibited synergistic activity. The successful amino acid sequencing of KL-1Y had a hydrophobicity of approximately 30 % and no cysteine residues suggested its novelty, and it was designated "plantaricin KL-1Y". Plantaricin KL-1Y exhibited bactericidal activity against Bacillus cereus JCM 2152(T). Compared to nisin, KL-1Y displayed broad inhibitory activities of 200, 800, 1600, 800, 400 and 400 AU/mL against the growth of Bacillus coagulans JCM 2257(T), B. cereus JCM 2152(T), Listeria innocua ATCC 33090(T), Staphylococcus aureus TISTR 118, E. coli O157:H7 and E. coli ATCC 8739, respectively, whereas nisin had similar activities against only B. coagulans JCM 2257(T) and B. cereus JCM 2152(T). Therefore, the novel plantaricin KL-1Y is a promising antimicrobial substance for food safety uses in the future.