Effect of inulin on growth and bacteriocin production byLactobacillus plantarumin stationary and shaken cultures

Antimicrobial potential of biopolymers against foodborne pathogens: An updated review

Biopolymers are natural polymers produced by the cells of living organisms such as plants, animals, microbes, etc. As these natural molecules possess antimicrobial activities against pathogens, they can be a suitable candidate for antimicrobials combating drug-resistant microorganisms including food-borne pathogens. Plant-derived biopolymers such as cellulose, starch, pullulans; microbes-derived chitosan, poly-L-lysine; animal-derived collagen, gelatin, spongin, etc. are proven to possess antimicrobial properties. They exert their antimicrobial activity against food-borne pathogens namely Salmonella typhi, Vibrio cholerae, Bacillus cereus, Clostridium perfringens, E. coli, Campylobacter jejuni, Staphylococcus aureus, etc. As antimicrobial resistance becomes a global phenomenon and threatens the effective prevention and treatment of infections caused by pathogens, biopolymers could be a promising candidate/substitute for conventional antimicrobials available in markets. Biopolymers can have detrimental effects on microbial cells such as disruption of the cell walls and cell membranes; damage to the DNA caused by strand breakage, unwinding, or cross-linking resulting in impeded DNA transcription and replication; lowering the amount of energy required for metabolic processes by compromising the proton motive force. Biopolymers also interfere with the quorum sensing mechanism and biofilm formation of microbes and modulate the host immune system by downregulating mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways resulting in the decreased production of pro-inflammatory cytokines. Furthermore, conjugating these biopolymers with other antimicrobial agents could be a promising approach to control multidrug-resistant foodborne pathogens. This review provides an overview of the various sources of biopolymers with special reference to their antimicrobial applications, especially against foodborne pathogens, and highlights their antimicrobial mechanisms.

In Vitro Utilization of Prebiotics by Listeria monocytogenes

Listeria monocytognes is an emerging pathogen responsible for the serious foodborne disease, listeriosis. The commensal gut microbiota is the first line of defense against pathogen internalization. The gut microbiome can be modified by prebiotic substrates, which are frequently added to food products and dietary supplements. Prebiotics should selectively support the growth of beneficial microbes and thus improve host health. Nevertheless, little is known about their effect on the growth of L. monocytogenes. The aim of this study was to evaluate the growth ability of four L. monocytogenes strains, representing the most common serotypes, on prebiotic oligosaccharides (beta-(1,3)-D-glucan, inulin, fructooligosaccharides, galactooligosaccharides, lactulose, raffinose, stachyose and 2'-fucosyllactose and a mixture of human milk oligosaccharides) as a sole carbon source. The results showed that only beta-(1,3)-D-glucan was metabolized by L. monocytogenes. These cell culture data suggest that beta-(1,3)-D-glucan may not be selectively utilized by healthy commensal bacteria, and its role in intestinal pathogen growth warrants further exploration in vivo.

The impact of incorporating Lactobacillus acidophilus bacteriocin with inulin and FOS on yogurt quality

The current study aimed to figure out the effect of using a combination of 2% inulin, and 2% Fructo-oligosaccharides (FOS) with Lactobacillus acidophilus and their bacteriocin on some yogurt properties such as coagulation time, extending the shelf life of set yogurt and its microbiological quality, also the acceptance by consumers. The results indicated that coagulation time increased by 22.75% in yogurts prepared with Lactobacillus acidophilus and their bacteriocins compared to the control, and titratable acidity increased gradually in all treatments during storage. Hence control acidity (%) increased from 0.84 ± 0.02^A at zero time to 1.23 ± 0.03^A after 14 days of cold storage, while treatment (T4) was 0.72 ± 0.01^C at zero time and reached 1.20 ± 0.5^A after 39 days at the same conditions. The sensory properties showed the superiority of inulin, FOS, and Lactobacillus acidophilus bacteriocin groups. Lactobacillus bulgaricus, Streptococcus thermophiles, and Lactobacillus acidophilus count increased in the treatments compared to the control group, with an extended shelf life to 39 days of storage in the medicines containing lactobacillus acidophilus bacteriocin. Coliforms, Moulds, and yeasts did not detect in the treatments comprising 2% inulin, 2% FOS, and lactobacillus acidophilus bacteriocin for 39 days of refrigerated storage. This study proved that 2% inulin, 2% FOS, and Lactobacillus acidophilus bacteriocin fortification extended the shelf life by more than 5 weeks.

Viability, Storage Stabilityand In Vitro Gastrointestinal Tolerance of Lactiplantibacillus plantarum Grown in Model Sugar Systems with Inulin and Fructooligosaccharide Supplementation

This study aims to investigate the effects of inulin and fructooligosaccharides (FOS) supplementation on the viability, storage stability, and in vitro gastrointestinal tolerance of Lactiplantibacillus plantarum in different sugar systems using 24 h growth and 10 days survival studies at 37 °C, inulin, and FOS (0%, 0.5%, 1%, 2%, 3% and 4%) supplementation in 2%, 3%, and 4% glucose, fructose, lactose, and sucrose systems. Based on the highest percentage increase in growth index, sucrose and lactose were more suitable sugar substrates for inulin and FOS supplementation. In survival studies, based on cell viability, inulin supplementation showed a better protective effect than FOS in 3% and 4% sucrose and lactose systems. Four selected sucrose and lactose systems supplemented with inulin and FOS were used in a 12-week storage stability study at 4 °C. Inulin (3%, 4%) and FOS (2%, 4%) supplementation in sucrose and lactose systems greatly enhanced the refrigerated storage stability of L. plantarum. In the gastrointestinal tolerance study, an increase in the bacterial survival rate (%) showed that the supplementation of FOS in lactose and sucrose systems improved the storage viability of L. plantarum. Both inulin and FOS supplementation in sucrose and lactose systems improved the hydrophobicity, auto-aggregation, co-aggregation ability of L. plantarum with Escherichia coli and Enterococcus faecalis.

An Updated Overview on Nanonutraceuticals: Focus on Nanoprebiotics and Nanoprobiotics

Over the last few years, the application of nanotechnology to nutraceuticals has been rapidly growing due to its ability to enhance the bioavailability of the loaded active ingredients, resulting in improved therapeutic/nutraceutical outcomes. The focus of this work is nanoprebiotics and nanoprobiotics, terms which stand for the loading of a set of compounds (e.g., prebiotics, probiotics, and synbiotics) in nanoparticles that work as absorption enhancers in the gastrointestinal tract. In this manuscript, the main features of prebiotics and probiotics are highlighted, together with the discussion of emerging applications of nanotechnologies in their formulation. Current research strategies are also discussed, in particular the promising use of nanofibers for the delivery of probiotics. Synbiotic-based nanoparticles represent an innovative trend within this area of interest. As only few experimental studies on nanoprebiotics and nanoprobiotics are available in the scientific literature, research on this prominent field is needed, covering effectiveness, bioavailability, and safety aspects.

Effects of pH and sugar supplements on bacteriocin-like inhibitory substance production by Pediococcus pentosaceus

To improve bacteriocin-like inhibitory substance (BLIS) production by Pediococcus pentosaceus ATCC 43200, the influence of pH as well as the addition of sugars-either prebiotic (inulin) or not (sucrose)-on its metabolism were investigated. This strain was grown at pH 5.0 or 6.0 either in glucose-based MRS medium (control) or after addition of 0.5, 1.0 or 1.5% (w/w) sucrose and inulin (GSI-MRS) in the same percentages. In the control medium at pH 5.0, cell mass concentration after 48 h of fermentation (X_max = 2.26 g/L), maximum specific growth rate (µ_max = 0.180 h^-1) and generation time (T_g = 3.84 h) were statistically coincident with those obtained in supplemented media. At pH 6.0 some variations occurred in these parameters between the control medium (X_max = 2.68 g/L; µ_max = 0.32 h^-1; T_g = 2.17 h) and the above supplemented media (X_max = 1.90, 2.52 and 1.86 g/L; µ_max = 0.26, 0.33 and 0.32 h^-1; T_g = 2.62, 2.06 and 2.11 h, respectively). Lactate production was remarkable at both pH values (13 and 16 g/L) and improved in all supplemented media, being 34 and 54% higher than in their respective control media, regardless of the concentration of these ingredients. Cell-free supernatant of the fermented control medium at pH 5.0 displayed an antimicrobial activity against Enterococcus 101 5.3% higher than that at pH 6.0 and even 20% higher than those of all supplemented media, regardless of the concentration of supplements. BLIS production was favored either at pH 5.0 or in the absence of any additional supplements, which were able, instead, to stimulate growth and lactate production by P. pentosaceus.

Evaluation of Factors Affecting Antimicrobial Activity of Bacteriocin from Lactobacillus plantarum Microencapsulated in Alginate-Gelatin Capsules and Its Application on Pork Meat as a Bio-Preservative

Antimicrobial compounds from traditional fermented foods have shown activity against a wide range of pathogen and spoilage microorganisms for several years. In this study, a Lactic acid bacteria (LAB), isolated from Vietnamese traditional fermented yogurt (Lactobacillus plantarum SC01), was encapsulated in alginate-gelatin (ALG-GEL) and the effect of incubation temperature, medium pH and surfactants were assessed. The aims of this research were to evaluate antimicrobial activity of bacteriocin produced by L. plantarum SC01. Another aim the research was to study the quality of pork meat treated with its Bacteriocin in 2 h as a bio-preservative at different storage times (0 h, 12 h, 24 h and 48 h) in room temperature, compared to control (treated with salt 40.0%). The antimicrobial activity of L. plantarum SC01 was identified through the inhibition rate of five indicator organisms, including Escherichia coli, Salmonella sp., Staphylococcus aureus, Listeria monocytogenes, and Bacillus subtilis by co-culture method. The results showed that L. plantarum SC01 microencapsulated in ALG-GEL (2.5% alginate and 6.0% gelatin, w/v) and 3.0% bacteria supplied into modified MRS medium (MRSOPTSC01) produced highly active compound inhibited the growth of indicator organisms at a density of 10⁴⁻10⁸ CFU/mL. Antibacterial compounds were highly active in a treatment at 80 °C; not to be affected by pH; affected by surfactant as Ethylenediaminetetraacetic acid (EDTA), Sodium dodecyl sulfate (SDS), and Tween. Moreover, LAB obtained from this study show the potent Bacteriocin in its usage as a preservative in food.

In vitro antifungal, probiotic, and antioxidant functional properties of a novel Lactobacillus paraplantarum isolated from fermented dates in Saudi Arabia

BACKGROUND

Fermented foods produced using dates are used in Gulf countries as beneficial and healthful foods. The beneficial microbial flora in fermented dates contributes to maintaining the nutritional properties of dates by preventing the growth of spoilage fungi. Here, we examined the antifungal, probiotic, and antioxidant properties of the novel Lactobacillus strain D-3 isolated from fermented dates.

RESULTS

Analyzing the morphological, physiological, and biochemical characteristics of this strain demonstrated that it was similar to Lactobacillus species, and molecular-level amplification of the 16S rRNA gene showed that it belonged to Lactobacillus paraplantarum. Under shake flask cultivation using date juice, the strain produced significant amounts of ethanol and lactic, succinic, and acetic acids. Purification of benzoic acid extracted from the extracellular fermentation medium was confirmed by nuclear magnetic resonance, and infrared and mass spectral data revealed minimum inhibitory concentration values of 10, 20, 10, 5, and 10 mg mL^-1 for Aspergillus fumigates, Curvularia lunata, Fusarium oxysporum, Gibberella moniliformis, and Penicillium chrysogenum, respectively. The strain showed several advantages, including the ability to survive under conditions similar to the gastrointestinal tract (low pH, bile salts, and antimicrobial susceptibility) and high levels of extracellular enzyme activities. The strain's growth patterns under various concentrations of H₂ O₂ and its scavenging properties towards hydroxyl radical (64.85%) and DPPH (84.97%) were also interesting properties.

CONCLUSION

The antifungal, probiotic, and antioxidant properties of L. paraplantarum D3 may provide health benefits to consumers. © 2017 Society of Chemical Industry.