EPS-producing LAB are widely used in the dairy industry since these polymers improve the viscosity and texture of the products. Besides, EPS might be responsible for several health benefits ...attributed to probiotic strains. However, growth conditions (culture media, temperature, pH) could modify EPS production affecting both technological and probiotic properties. In this work, the influence of growth temperature on EPS production was evaluated, as well as the consequences of these changes in the probiotic properties of the strains. All Lactobacillus paracasei strains used in the study showed changes in EPS production caused by growth temperature, evidenced by the appearance of a high molecular weight fraction and an increment in the total amount of produced EPS at lower temperature. Nevertheless, these changes do not affect the probiotic properties of the strains; L. paracasei strains grown at 20 °C, 30 °C and 37 °C were able to survive in simulated gastrointestinal conditions, to adhere to Caco-2 cells after that treatment and to modulate the epithelial innate immune response. The results suggest that selected L. paracasei strains are new probiotic candidates that can be used in a wide range of functional foods in which temperature could be used as a tool to improve the technological properties of the product.
•Growth temperature affects EPS production by L. paracasei strains.•A higher amount of EPS containing a HMW fraction was obtained at low temperature.•Surface EPS has a protective role against adverse gastrointestinal conditions.•The three strains adhere to Caco-2 cells after acid and bile stress.•The probiotic properties of the strains are not affected by growth temperature.
•Highest yield of yoghurt peptides was obtained in ultrasound-treated fermentation.•An empirical model was established for predicting the yield of yoghurt peptides.•Ultrasound-immediately-activated ...extracellular enzymes resulted in peptide increase.•Ultrasound-activated enzyme activity disappeared after ultrasound was removed.
Herein the effect of low intensity ultrasound on the fermentation of skim milk medium by Lactobacillus paracasei were investigated to obtain optimum ultrasonic conditions for the highest yield of yoghurt peptides. The results showed that the fermented skim milk medium treated with ultrasound with its seed culture without ultrasonic treatment was an optimum scheme. In this scheme with the ultrasonic conditions of 28 kHz, ultrasonic pulsed model of on-time 100 s and off-time 10 s, 100 W/L for the treatment time of 30 min after the fermentation time of 9 h, the peptide content in the fermented skim milk media increased by 49.5% and the viable cells in the same media increased by 43.5% compared with those in the untreated samples. By response surface methodology (RSM) analysis and its verification experiments, a reasonably accurate empirical model was established for investigating and predicting the relationship between skim milk concentration, ultrasonic treatment time, power and the yield of yoghurt peptides. The former two parameters 12.6% w/v and 35 min were taken in the verification experiments in which the peptide content of the fermented media reached 5.9 mg/mL with an increase by 64.23% and the peptide yield was 14.2%, similar to its theoretical value of 14.6% according to the empirical model. The comparison of extracellular enzyme activities in the fermented skim milk media between with and without ultrasonic treatment under the conditions in the optimum scheme indicated that the mechanism of the ultrasound-activated peptide content increment might be the extracellular enzyme activities immediately activated by the ultrasound, effect of which would disappear in the progress of fermentation after the ultrasound was removed.
•An osmotic-tolerant mutant was obtained by high-throughput screening technology.•Fatty acid composition and intermediates contributed to improve osmotic tolerance.•248 g/L glucose was totally ...consumed by neutralizing agent combination strategy.•223.7 g/L lactic acid was produced with an overall productivity of 5.53 g/L/h.•Open fermentation was carried out for highly efficient lactic acid production.
High titer, productivity and yield are the main pre-requisites of an efficient lactic acid production process. However, the hyperosmotic stress inhibits cell metabolism in the later phase of fermentation. In this study, an osmotic-tolerant mutant named Lactobacillus paracasei NCBIO01-M2 was obtained through a high-throughput screening technology, which exhibited a higher tolerance to osmotic stress due to its more flexible regulation of the unsaturated fatty acid proportion along with the intracellular compatible solute pools. The mutant successfully consumed all 248 g/L initial glucose and produced 223.7 g/L lactic acid with a productivity of 5.53 g/L/h in a single batch fermentation by the neutralizing agent strategy. Moreover, similar fermentation performances were also achieved in the open fermentation mode without sterilization by the mutant, which suggested that the mutant would be a potential for cost-effective commercial lactic acid production.
Lactobacillus paracasei SD1 is a potential probiotic strain due to its ability to survive several conditions in human dental cavities. To ascertain its safety for human use, we therefore performed a ...comprehensive bioinformatics analysis and characterization of the bacterial protein toxins produced by this strain. We report the complete genome of Lactobacillus paracasei SD1 and its comparison to other Lactobacillus genomes. Additionally, we identify and analyze its protein toxins and antimicrobial proteins using reliable online database resources and establish its phylogenetic relationship with other bacterial genomes. Our investigation suggests that this strain is safe for human use and contains several bacteriocins that confer health benefits to the host. An in silico analysis of protein-protein interactions between the target bacteriocins and the microbial proteins gtfB and luxS of Streptococcus mutans was performed and is discussed here.
Lactobacillus paracasei SMN-LBK (serial number: CCTCC M 2017429) is an ethanol-resistant lactic acid bacteria (LAB) in kumiss. However, the anti-ethanol stress mechanism of L. paracasei SMN-LBK ...remains unclear. Hence, we performed a transcriptome analysis between L. paracasei SX10 (L. paracasei SMN-LBK under 10% ethanol stress strain, abbreviated as SX10) and L. paracasei SMN-LBK (abbreviated as S10) by RNA sequencing. We performed real-time quantitative PCR (RT-qPCR) to verify the accuracy of the transcription data. The transcriptome data revealed that 315 genes exhibited upregulated expression, and 332 genes were downregulated in the SX10 compared with the S10 group. The PFK, LDH, GPDH, and GK genes were upregulated, with a log2-fold change of 1.10, 0.30, 0.56, and 1.512, respectively. A gene ontology enrichment analysis revealed significant enrichment of ribosomes, ribonucleoprotein complex, non-membrane-bounded organelles, and intracellular non-membrane-bound organelles. Analysis using the Kyoto Encyclopedia of Genes and Genomes database revealed differential genes associated with ribosome function, pyruvate metabolism, biosynthesis of amino acids, fatty acid biosynthesis, fatty acid metabolism, ATP-binding cassette (ABC) transporter, glycolysis, and glycerophospholipid metabolism. The RT-qPCR results were consistent with the transcriptome results. Lactococcus lactis NZ9000 is a typical host bacterium. We performed PFK and GK overexpression to verify the function of the L. paracaseiSX10 resistance gene in Lactococcus lactis NZ9000. Using sodium dodecyl sulfate (SDS)-PAGE electrophoresis, these resistance genes were successfully expressed in Lactococcus lactis NZ9000. The survival rate and key enzyme activity of the recombinant strains were determined under ethanol stress. The survival rate of Lactococcus lactis NZ9000-pNZ8148-PFK and Lactococcus lactis NZ9000-pNZ8148-GK under 10% ethanol stress were 3.43- and 3.80-fold higher compared with the Lactococcus lactis NZ9000-pNZ8148 control, respectively. These results indicate that PFK and GK are important for the ethanol tolerance of LAB and can increase the ethanol tolerance of Lactococcus lactis NZ9000. Hence, PFK and GK were identified as key genes of L. paracasei SX10 with a high ethanol tolerance. Our results provide novel insight for further studies to perform a systematic analysis of the differentially expressed genes and to determine their potential functions in the ethanol tolerance mechanism of LAB.
The whole genome sequence of
Lactobacillus paracasei
DTA72, isolated from healthy infant feces, is reported, along with the Carbohydrates-Active enZymes (CAZymes) analysis and an in silico safety ...assessment. Strain DTA72 had previously demonstrated some interesting potential probiotic features, such as a good resistance to gastrointestinal conditions and an anti-
Listeria
activity. The 3.1 Mb sequenced genome consists of 3116 protein-coding sequences distributed on 340 SEED subsystems. In the present study, we analyzed the fermentation capability of strain DTA72 on six different carbohydrate sources, namely, glucose, fructose, lactose, galactose, xylose, and inulin by using phenotypical and genomic approaches. Interestingly,
L
.
paracasei
DTA72 evidenced the best growth performances on inulin with a much shorter lag phase and higher number of cells at the stationary phase in comparison with all the sugars tested. The CAZyme analysis using the predicted amino acid sequences detected 80 enzymes, distributed into the five CAZymes classes. Moreover, the in silico analysis revealed the absence of blood hemolytic genes, transmissible antibiotic resistances, and plasmids in DTA72. The results described in this study, together with those previously reported and particularly the strong capability to utilize inulin as energy source, make DTA72 a very interesting potential probiotic strain to be considered for the production of synbiotic foods. The complete genome data have been deposited in GenBank under the accession number WUJH00000000.
Amidst the rising popularity of craft beers, it would be opportune to develop a novel, unfiltered and unpasteurized sour beer with high probiotic live counts. However, as beer typically contains hop ...iso-α-acids that prevent the growth and survival of probiotic lactic acid bacteria, the use of suitable fermentation strategies is crucial. The growth, and survival of the probiotic bacterium, Lactobacillus paracasei L26, were assessed during a 10-day co-fermentation period with a brewer's yeast, Saccharomyces cerevisiae S-04, in unhopped wort. Isomerized hop extract was added prior to storage of the beers at 25 °C and 5 °C. During co-fermentation in unhopped wort, L. paracasei L26 maintained high viable cell counts above 8 Log CFU/mL, indicating species compatibility with the yeast. The majority of fermentable sugars were attenuated by S. cerevisiae S-04, with a concomitant production of alcohols and esters. Significant amounts of lactic acid were produced by L. paracasei L26 (P < 0.05). During storage with added isomerized hop extract, maximal probiotic viability enhancing effects were observed in the presence of live S. cerevisiae S-04, in combination with refrigeration. The results suggest that beers could be a vehicle for probiotic delivery under appropriate conditions. This was the first study demonstrating the feasibility of utilizing probiotic lactobacilli as starter cultures in beer brewing.
•Probiotic lactobacilli are unable to grow and survive in hopped wort.•In unhopped wort, Lactobacillus paracasei could grow when co-fermented with yeast.•Refrigeration and live yeast enhanced probiotic viability during storage with added iso-α-acids.•A novel unfiltered and unpasteurized beer with viable probiotics was developed.
Aims
The population of the Himalayan region is known to consume a variety of fermented and nonfermented foods and as a result they have been benefited in terms of overall health, because of the ...associated beneficial microbes. Therefore, the focus of the present study was to identify new strains of lactic acid bacteria (LAB) from dairy products such as milk (cow, goat, buffalo) and fermented products (curd and buttermilk) with properties suitable for use as probiotic cultures.
Methods and Results
A total of 75 isolates tentatively identified as LAB from 100 samples were initially screened for production of β‐haemolysin as indicators of virulence which resulted in 38 isolates with no haemolytic activity. Further subtractive screening based on resistance to gastrointestinal tract barriers (acid and bile salts) resulted in the selection of the eight most promising strains. All these eight strains were resistant to pH 2·0, 1% bile concentration and pancreatin (1 mg l−1). Among the eight isolates, three isolates were identified as Brevibacillus thermoruber and the others as Brevibacillus aydinogluensis, Lactobacillus gastricus, L. paracasei, Enterococcus sp. Weisella confusa based on 16S rDNA region. Among these isolates, L. paracasei CD4 and L. gastricus BTM7 indicated maximum tolerance to simulated gastric environment. Both the isolates possessed highest score for cell surface hydrophobicity, cell autoaggregation, adherence to Caco‐2 cell lines and antimicrobial activity against clinical isolates of Escherichia coli and Shigella sp. comparable to standard strain of Lactobacillus rhamnosus GG. Further principal component analysis and clustering analysis based on Euclidean Similarity index of probiotic characters revealed that L. paracasei strain CD4 and L. gastricus strain BTM7 were placed closest to reference strain L. rhamnosus GG and were therefore identified as most promising probiotic candidate cultures.
Conclusions
These characteristics suggest that these strains could be excellent candidates for probiotics.
Significance and Impact of the Study
Milk‐based products serve as reservoir for bacterial species with probiotic attributes.
We recently demonstrated that cow's milk fermented with the probiotic
CBA L74 (FM-CBAL74) reduces the incidence of respiratory and gastrointestinal tract infections in young children attending ...school. This effect apparently derives from a complex regulation of non-immune and immune protective mechanisms. We investigated whether FM-CBAL74 could regulate gut microbiota composition and butyrate production. We randomly selected 20 healthy children (12 to 48 months) from the previous randomized controlled trial, before (t0) and after 3 months (t3) of dietary treatment with FM-CBAL74 (FM) or placebo (PL). Fecal microbiota was profiled using 16S rRNA gene amplicon sequencing, and the fecal butyrate concentration was also measured. Microbial alpha and beta diversities were not significantly different between groups prior to treatment. FM-CBAL74 but not PL treatment increased the relative abundance of
Individual
,
, and
oligotypes were associated with FM-CBAL74 treatment and demonstrated correlative associations with immune biomarkers. Accordingly, PICRUSt analysis predicted an increase in the proportion of genes involved in butyrate production pathways, consistent with an increase in fecal butyrate observed only in the FM group. Dietary supplementation with FM-CBAL74 induces specific signatures in gut microbiota composition and stimulates butyrate production. These effects are associated with changes in innate and acquired immunity.
The use of a fermented milk product containing the heat-killed probiotic strain
CBAL74 induces changes in the gut microbiota, promoting the development of butyrate producers. These changes in the gut microbiota composition correlate with increased levels of innate and acquired immunity biomarkers.
Various
Lactobacillus paracasei
strains are found in diverse environments, including dairy and plant materials and the intestinal tract of humans and animals, and are also used in the food industry ...or as probiotics. In this study, we have isolated a new strain
L. paracasei
subsp.
paracasei
IBB3423 from samples of raw cow milk collected in a citizen science project. IBB3423 showed some desired probiotic features such as high adhesion capacity and ability to metabolize inulin. Its complete genome sequence comprising the chromosome of 3,183,386 bp and two plasmids of 5986 bp and 51,211 bp was determined. In silico analysis revealed numerous genes encoding proteins involved in carbohydrate metabolism and of extracellular localization likely supporting interaction with host tissues. In vitro tests confirmed the high adhesion capacity of IBB3423 and showed that it even exceeds that of the highly adhesive
L. rhamnosus
GG. Curing of the larger plasmid indicated that the adhesive properties depend on the plasmid and thus could be determined by its pilus-encoding
spaCBA
genes.
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