Aims: In this study, lactic acid bacteria (LAB) were isolated from 42 healthy infants and determined for probiotic properties. Twelve LAB isolates with potential probiotic properties were selected and screened for their feasibility of heterologous protein expression by selection of erythromycin sensitive isolates. Methodology and results: One of eleven erythromycin-sensitive LAB isolates identified and designated as Lactobacillus fermentum 47-7 was able to acquire and stable maintain the Escherichia coli-Lactobacillus shuttle vector, pRCEID-LC13.9. Further electrotransformation of L. fermentum 47-7 with the recombinant pLC13.9:LDH-PRO1:GFPuv containing green fluorescent protein (GFP) gene found that recombinant L. fermentum can express GFP. Conclusion, significance and impact of study: The probiotic L. fermentum isolate can be used as host for expression of heterologous proteins and could possibly be further developed as the alternate oral delivery system for various biomolecules for biotechnological application.
Probiotic ; Lactobacillus fermentum

4,6-α-glucosyltransferases (4,6-α-GTs), which converts amylose into α(1-6) bonds-containing α-glucan, possesses great application potential in enzymatic synthesis of dietary fiber. Primers were designed according to the conserved motifs existing in the amino acid sequence of 4,6-α-GTs, and used to amplify a putative GTFB-Like 4,6-α-GTs gene (named as gtf16) from the genomic DNA of Lactobacillus. The gtf16 gene was cloned into the plasmid pET15b, expressed in Escherichia coli BL21(DE3), followed by purification and characterization. The optimum pH and the optimum temperature of the purified enzyme were 5.0 and 40 °C, respectively. The biotransformation product of this enzyme was systematically characterized by thin-layer chromatography, NMR spectroscopy, and hydrolysis reaction. The Gtf16-catalyzed product shows a similar structure to that of the isomalto/malto-polysaccharide (IMMP), which is the amylose-derived product catalyzed by GtfB from Lactobacillus reuteri 121. Moreover, The Gtf16-catalyzed product contains up to 75% of α(1-6) bonds and has an average molecular weight of 23 793 Da. Furthermore, the content of the anti-digestive components was 88.22% upon hydrolysis with digestive enzymes.
Bacterial Proteins/genetics* ; Glucans ; Glucosyltransferases/genetics* ; Lactobacillus fermentum/enzymology*

Biogenic amines (BAs) are low molecular weight organic compounds that present in fermented foods. Large amount of ingested biogenic amines can cause allergy or significant symptoms. Reduction of BAs by enzymatic reaction in fermented foods is one of the most efficient methods for removal of biohazard compounds and assurance food safety. In this study, the multicopper oxidase (MCO) gene in the genome of Lactobacillus fermentum was successfully cloned in Escherichia coli BL21 and expressed at 484 U/L. The recombinant MCO was purified by the immobilized metal affinity chromatography method. The optimal reaction temperature and pH for this enzyme was detected to be 50 °C and 3.5. The Km and Vmax values of the recombinant MCO was determined to be 1.30 mmol/L and 7.67×10⁻² mmol/(L·min). Moreover, this MCO dramatically degrades histamine and tyramine by 51.6% and 40.9%, and can degrade other BAs including tryptamine, phenylethylamine, putrescine, cadaverine and spermidine, and was found to be tolerant to 18% (W/V) NaCl. The recombinant MCO is also capable of degrading BAs in soy sauce. The degradation rate of total BAs in soy sauce reaches 10.6% though a relatively low level of enzyme (500 U/L) is used. Multicopper oxidase has the potential to degrade biogenic amines in fermented foods, which lays a foundation for the further application of this kind of food enzymes.
Biogenic Amines ; Cadaverine ; Escherichia coli ; Lactobacillus fermentum ; Oxidoreductases

Animals ; Body Weight ; Feeding Behavior ; Female ; Lactobacillus fermentum ; Male ; Probiotics ; toxicity ; Rats ; Rats, Sprague-Dawley ; Toxicity Tests, Subchronic

Propionibacterium acnes is the most common causative agent of acne. Staphylococcus epidermidis is another major bacterial strain to be found in acne lesions. Two strains of lactic acid bacteria (LAB) were isolated from normal inhabitants of humans, which inhibited the proliferation of P. acnes and S. epidermidis. The growth of P. acnes and S. epidermidis was decreased by 4-log scales after incubation for 24 h with LAB isolates, whereas the growth rate of selected LAB isolates were not affected by these pathogenic bacteria. This antibacterial activity of LAB isolates was related to lactic acids, hydrogen peroxide and bacteriocin-like compound production. Two LAB isolates efficiently adhered to human keratinocytes HaCaT and were identified by API 50 CHL medium kit and 16S rDNA partial sequencing analysis. The similarity of 16S rDNA sequences between one isolate and Lactobacillus salivarius subsp. salicinius was 100%, which suggests that they were L. salivarius subsp. salicinius. On the other hand, 16S rDNA sequence similarity between the other isolate and Lactobacillus fermentum was 99.04%, which indicates that it was L. fermentum. In conclusion, these results demonstrate that the two LAB strains isolated from human body were identified as L. salivarius subsp. salicinius and L. fermentum, which inhibit the proliferation of P. acnes and S. epidermidis.
Acne Vulgaris ; Bacteria ; DNA, Ribosomal ; Hand ; Human Body ; Humans ; Hydrogen Peroxide ; Keratinocytes ; Lactic Acid ; Lactobacillus ; Lactobacillus fermentum ; Propionibacterium ; Propionibacterium acnes ; Pyridines ; Sprains and Strains ; Staphylococcus ; Staphylococcus epidermidis ; Thiazoles ; Weights and Measures