Isolation and identification of new lactobacilli from goatling stomach and investigation of reuterin production in Lactobacillus reuteri strains

Impact of culture medium on the interpretation of qRT-PCR data in HepG2 incubated with lactobacilli

Recently, an increasing number of studies have investigated the mechanism of action of lactobacilli in the treatment of non-alcoholic fatty liver disease. Using four computational tools (NormFinder, geNorm, Delta Ct, and BestKeeper), six potential reference genes (RGs) were analyzed in the human liver cell line HepG2 cultivated 24 h in the presence of two strains of heat-killed lactobacilli, Limosilactobacillus reuteri E and Lactiplantibacillus plantarum KG4, respectively, in different cultivation media [Dulbecco´s Modified Eagle´s Medium (DMEM) high glucose or Roswell Park Memorial Institute (RPMI)]. The analysis revealed that the suitability of RG was similar between the two lactobacilli but quite different between the two media. The commonly used RGs, 18S rRNA and glyceraldehyde-3-phosphate dehydrogenase were the most unstable in DMEM high glucose. Normalization of the mRNA expression of the target gene encoding sterol regulatory element-binding protein 1c (SREBP-1c) to different RGs resulted in different expression profiles. This demonstrates that validation of candidate RGs under specific experimental conditions is crucial for the correct interpretation of quantitative polymerase chain reaction data. In addition, the choice of media has a profound impact on the effect of lactobacilli on lipogenesis at the gene expression level, as shown by the transcription factor SREBP-1c.

Fusarium biocontrol: antagonism and mycotoxin elimination by lactic acid bacteria

Mycotoxins produced by Fusarium species are secondary metabolites with low molecular weight formed by filamentous fungi generally resistant to different environmental factors and, therefore, undergo slow degradation. Contamination by Fusarium mycotoxins in cereals and millets is the foremost quality challenge the food and feed industry faces across the globe. Several types of chemical preservatives are employed in the mitigation process of these mycotoxins, and they help in long-term storage; however, chemical preservatives can be used only to some extent, so the complete elimination of toxins from foods is still a herculean task. The growing demand for green-labeled food drives to evade the use of chemicals in the production processes is getting much demand. Thus, the biocontrol of food toxins is important in the developing food sector. Fusarium mycotoxins are world-spread contaminants naturally occurring in commodities, food, and feed. The major mycotoxins Fusarium species produce are deoxynivalenol, fumonisins, zearalenone, and T2/HT2 toxins. Lactic acid bacteria (LAB), generally regarded as safe (GRAS), is a well-explored bacterial community in food preparations and preservation for ages. Recent research suggests that LAB are the best choice for extenuating Fusarium mycotoxins. Apart from Fusarium mycotoxins, this review focuses on the latest studies on the mechanisms of how LAB effectively detoxify and remove these mycotoxins through their various bioactive molecules and background information of these molecules.

In Vitro Study of Immune Properties of New Lactobacilli Isolates from Pheasant Gut

The goal of this paper was to study the effect of Lactobacillus reuteri B1/1, B2/1 and B6/1 on the relative expression of selected interleukins (IL-1β, IL-15), macrophage inflammatory protein (MIP-1β), and the relative percentage of T lymphocyte subpopulations in peripheral mononuclear blood cells (PMBCs). The mRNA expression levels of interleukins and MIP-1β of PMBCs were evaluated at 24 h and 48 h post inoculation using the quantitative real-time polymerase chain reaction (qRT-PCR). The percentage of T lymphocyte subpopulations in PMBCs was determined by flow cytometry. The group that was administered L. reuteri B1/1 had the most significant stimulation of the expression of pro-inflammatory interleukins and MIP-1β, in particular after 24 h. Similarly, we observed a rise in the relative percentage of T cells including CD3+, CD4+ and CD8+ lymphocytes in the groups with L. reuteri B1/1 and L. reuteri B2/1. Overall, L. reuteri B1/1 and L. reuteri B2/1 showed a promising stimulatory effect on the relative expression of pro-inflammatory interleukins, MIP-1β and percentage of T cell subpopulations in vitro. On the flip side, L. reuteri B6/1 did not induce the expression of the IL-1β gene.

Human phagocytic cell response to histamine derived from potential probiotic strains of Lactobacillus reuteri

Histamine derived from lactobacilli isolates is considered to be a potential immunomodulator able to interact with the host immune system. We tested the effect of pure histamine (0.413 mM) together with the effect of cell-culture supernatants (CCS) containing different concentration of histamine produced by two of Lactobacillus reuteri isolates on the activities of antioxidant enzyme, as well as on the phagocytic activity of human leucocytes (HL). Phagocytic activity represents the non-specific immune response of HL homogenate, in vitro. Analysed histamine-producers were represented by a goatling isolate named L. reuteri KO5 and a lamb isolate named L. reuteri E and histamine production was determined using HPLC method connected with UV detection. Concretely, the samples contained the mixture of isolated HL and the addition of lactobacilli CCS at three different final concentrations of histamine ∼ 0.1, 1.8 and 5.4 mM. It was found that pure histamine (0.413 mM) did not significantly influence the oxidant-antioxidant balance in HL demonstrated by unchanged degree of HL lipid peroxidation. However, at the same time, the final activity of catalase and superoxide dismutase were significantly changed (p ≤ 0.001). Moreover, the phagocytic index (p ≤ 0.01), lysozyme (p ≤ 0.05) and peroxidase activity (p ≤ 0.001), and production of IL-1β significantly decreased. CCS containing different concentration of produced histamine were also able to modulate the host non-specific immune response together with the enzymatic activity of SOD and catalase too. However, our findings indicated that the impact of lactobacilli histamine is strictly strain-dependent and concentration dependent. Moreover, it seems that histamine is not the only one lactobacilli metabolite, which may play an important role in overall immunomodulatory and antioxidant potential of tested lactobacilli.

Analysis of antimicrobial and immunomodulatory substances produced by heterofermentative Lactobacillus reuteri

Antimicrobial and immunomodulatory potential of various Lactobacillus reuteri strains is closely connected to their metabolite production profile under given cultivation conditions. We determined the in vitro production of antimicrobial substances such as organic acids, ethanol, and reuterin by four strains of L. reuteri (L. reuteri E, L. reuteri KO5, L. reuteri CCM 3625, and L. reuteri ATCC 55730). All studied L. reuteri strains showed the ability to produce lactic acid, acetic acid, and ethanol with concominant consumption of glucose and together with phenyllactic acid-a potent antifungal compound-with concominant consumption of phenylalanine. The reuterin production from glycerol was confirmed for all analyzed lactobacilli strains except L. reuteri CCM 3625. Production of organic acids, ethanol, and reuterin is significantly involved in antimicrobial activity of lactobacilli which was determined using the dual-culture overlay diffusion method against six indicator bacteria and five indicator moulds. In comparison to the referential L. reuteri ATCC 55730, the highest inhibition potential was observed against Escherichia coli CCM 3988 and Pseudomonas aeruginosa CCM 3955. Among analyzed indicators of moulds, the growth of Alternaria alternata CCM F-128 was the most inhibited by all four analyzed L. reuteri strains. Finally, the immunomodulatory potential of analyzed lactobacilli were proven by the determination of the in vitro production of biogenic amines histamine and tyramine. L. reuteri CCM 3625 was able to produce tyramine, and L. reuteri E and L. reuteri KO5 were able to produce histamine under given cultivation conditions.

Loss of GD1-positive Lactobacillus correlates with inflammation in human lungs with COPD

OBJECTIVES

The present study assesses the relationship between contents of GD1 (glycerol dehydratase)-positive Lactobacillus, presence of Lactobacillus and the inflammatory response measured in host lung tissue in mild to moderate chronic obstructive pulmonary disease (COPD). We hypothesise that there will be a loss of GD1 producing Lactobacillus with increasing severity of COPD and that GD1 has anti-inflammatory properties.

SETTING

Secondary care, 1 participating centre in Vancouver, British Columbia, Canada.

PARTICIPANTS

74 individuals who donated non-cancerous portions of their lungs or lobes removed as treatment for lung cancer (normal lung function controls (n=28), persons with mild (GOLD 1) (n=21) and moderate (GOLD 2) COPD (n=25)).

OUTCOME MEASURES

Primary outcome measure was GD1 positivity within each group and whether or not this impacted quantitative histological measures of lung inflammation. Secondary outcome measures included Lactobacillus presence and quantification, and quantitative histological measurements of inflammation and remodelling in early COPD.

RESULTS

Total bacterial count (p>0.05) and prevalence of Lactobacillus (p>0.05) did not differ between groups. However, the GD1 gene was detected more frequently in the controls (14%) than in either mild (5%) or moderate (0%) COPD (p<0.05) samples. Macrophage and neutrophil volume fractions (0.012±0.005 (mean±SD) vs 0.026±0.017 and 0.005±0.002 vs 0.015±0.014, respectively) in peripheral lung tissue were reduced in samples positive for the GD1 gene (p<0.0035).

CONCLUSIONS

A reduction in GD1 positivity is associated with an increased tissue immune inflammatory response in early stage COPD. There is potential for Lactobacillus to be used as a possible therapeutic, however, validation of these results need to be completed before an anti-inflammatory role of Lactobacillus in COPD can be confirmed.