An Acid Up-Regulated Surface Protein of Lactobacillus paracasei Strain GCRL 46 is Phylogenetically Related to the Secreted Glucan- (GpbB) and Immunoglobulin-Binding (SibA) Protein of Pathogenic Streptococci

Study protocol: The role of milk matrix lipids in programming the immunoreactivity of proteins derived from lactic acid bacteria

Food allergy is widely recognized as a significant health issue, having escalated into a global epidemic, subsequently giving rise to the development of numerous additional complications. Currently, the sole efficient method to curb the progression of allergy is through the implementation of an elimination diet. The increasing number of newly identified allergens makes it harder to completely remove or avoid them effectively. The immunoreactivity of proteins of bacterial origin remains an unexplored topic. Despite the substantial consumption of microbial proteins in our diets, the immunologic mechanisms they might induce require thorough validation. This stands as the primary objective of this study. The primary objective of this study was to evaluate the effects of bacterial proteins on the intestinal barrier and immune system parameters during hypersensitivity induction in both developing and mature organisms. The secondary objective was to evaluate the role of lipids in the immunoreactivity programming of these bacterial proteins. Notably, in this complex, comprehensively designed in vitro, in vivo, and ex vivo trial, the immunoreactivity of various bacterial proteins will be examined. In summary, the proposed study intends to address the knowledge gaps regarding the effects of Lactobacillus microbial proteins on inflammation, apoptosis, autophagy, and intestinal barrier integrity in a single study.

The Manifold Bioactivity and Immunoreactivity of Microbial Proteins of Cow and Human Mature Milk in Late Lactation

Simple Summary

The debate over the validity and benefits of breastfeeding children after the age of 1 and the superiority of human over cow’s milk is still ongoing. The recommendation of exclusive breastfeeding for about 6 months, followed by continued breastfeeding as a complementary food source for 1 year or longer, seems justified under many circumstances. The microbiological parameters of the milk play a vital role in this respect. So far, the focus has been on the qualitative profile of the microbiota, bacterial interactions with milk compounds, and the metabolites produced by bacteria. However, the role of bacterial proteins in milk, according to the authors’ knowledge, has been analyzed. It is reported that due to the disruption of the regulatory axis of the immune system in the course of hypersensitivity, organisms may give rise to decreased IgA-mediated (physiological) and increased IgE-mediated (hypersensitive) responses even to host gut microbiota proteins. In this publication, the aim was to compare whether the bacterial proteins in the mature human milk of late lactation and cow’s milk of different breeds can determine the different immunoreactive and bioactive properties of milk.

Abstract

(1) Human milk (HM) is a source of many microorganisms, whose structure contains microbial protein (MP). In addition to the known health-promoting properties of HM, many activities, including immunoreactivity, may result from the presence of MP. Cow’s milk (CM)-derived MP may be 10 times more abundant than MP derived from HM. (2) Raw cow’s milk samples of Holstein and Jersey breeds, commercially available pasteurized milk, and milk from three human donors in the late lactation phase were subjected to chemical and microbiological analyzes. Microorganisms from the milk material were recovered, cultured, and their activities were tested. MPs were extracted and their immunoreactivity was tested with human high IgE pooled sera. The milk types were subjected to simulated digestion. Milk and microbial proteins were identified with LCMS and subjected to an in silico analysis of their activities. Their antioxidant potential was analysed with the DPPH method. (3) The MP of HM shows a stronger IgE and IgG immunoreactivity in the tests with human sera compared to the MP of CM (p = 0.001; p = 0.02, respectively). There were no significant differences between the microbes in the MP of different cattle breeds. The MS-identification and in silico tests of milk and microbial proteins confirmed the presence of MP with immunoreactivity and antioxidant potential. (4) MPs possess a broad bioactive effect, which was determined by an in silico tools. The balance between an MP’s individual properties probably determines the raw material’s safety, which undoubtedly requires further research.

Safety Evaluation of Bifidobacterium lactis BL-99 and Lacticaseibacillus paracasei K56 and ET-22 in vitro and in vivo

Probiotics have been reported to play a major role in maintaining the balance of microbiota in host. Consumption of food with probiotics has increased with consumer concerns regarding healthy diets and wellness. Correspondingly, safety evaluation of probiotics for human consumption has become increasingly important in food industry. Herein, we aimed to test the safety of Bifidobacterium lactis BL-99 and Lacticaseibacillus paracasei K56 and ET-22 strains in vitro and in vivo. In results, these strains were found to be negative for mucin degradation and platelet aggregation test. Additionally, the three strains were susceptible to eight antibiotics. In accordance with bacterial reversion mutation (Ames) assay, the tested strains had no genetic mutagenicity. Finally, it was confirmed that there were no dose-dependent mortality and toxicity throughout multidose oral toxicity tests in rats. Our findings demonstrated that B. lactis BL-99 and L. paracasei K56 and ET-22 can achieve the generally recognized as safe (GRAS) status as probiotics in the future.

Imbalance between peptidoglycan synthases and hydrolases regulated lysis of Lactobacillus bulgaricus in batch culture

Lactobacillus bulgaricus is an important starter culture in the dairy industry, cell lysis is negative to the high density of this strain. This work describes the response of peptidoglycan synthases and hydrolases in Lactobacillus bulgaricus sp1.1 when pH decreasing in batch culture. First, the cell lysis was investigated by measuring the cytosolic lactate dehydrogenase released to the fermentation broth, a continuous increase in extracellular lactate dehydrogenase was observed after the lag phase in batch culture. Then, the peptidoglycan hydrolases profile analyzed using the zymogram method showed that eight proteins have the ability of peptidoglycan hydrolysis, three of the eight proteins were considered to contribute lysis of L. bulgaricus sp1.1 according to the changes and extents of peptidoglycan hydrolysis. In silico analysis showed that three putative peptidoglycan hydrolases, including N-acetylmuramyl-L-Ala amidase (protein ID: ALT46642.1), amidase (protein ID: ALT46641.1), and N-acetylmuramidase (protein ID: WP_013439201.1) were compatible with these proteins. Finally, the transcription of the three putative peptidoglycan hydrolases was upregulated in batch culture, in contrast, the expression of four peptidoglycan synthases was downregulated. These observations suggested the imbalance between peptidoglycan synthases and hydrolases involved in the lysis of Lactobacillus bulgaricus sp1.1.

In vivo murine breast cancer targeting by magnetic iron nanoparticles involving L. GG cytoplasmic fraction

OBJECTIVES

Use of chemical anti-cancer drugs frequently creates serious side effects. However, probiotics are natural and treat different kinds of cancer without undesired effects.

MATERIALS AND METHODS

In this study, a nano delivery system was planned to transport the Lactobacillus rhamnosus GG (L. GG) cytoplasmic fraction (Cf) to cancerous tissue in a mouse model. Magnetic iron nanoparticles (MINPs) were synthesized and loaded with L. GG-Cf(0, 0.312, 0.625, 1.25, and 2.5 mg/ml) and were administrated for three weeks to treat experimentally induced murine breast cancer in a constant magnetic field. At the end of the trial, the treating efficacy of this complex molecule was evaluated via western blotting, immunohistochemistry, and qPCR.

RESULTS

Results showed that MINPS can deliver and accumulate L. GG-Cf in cancer tissue, and reduce the size and volume of the tumors. Additionally, in cancer tissues of treated mice with 2.5 mg/ml of Cf-MINPs, significantly induced apoptosis was seen compared with untreated mice (control), and our data proved that this induction may be due to the caspase-3 pathway.

CONCLUSION

L. GG-Cf could treat murine breast cancer, and MINPs are a suitable candidate for drug delivery because of their safety, uniformity, and magnetic properties.

ODFM, an omics data resource from microorganisms associated with fermented foods

ODFM is a data management system that integrates comprehensive omics information for microorganisms associated with various fermented foods, additive ingredients, and seasonings (e.g. kimchi, Korean fermented vegetables, fermented seafood, solar salt, soybean paste, vinegar, beer, cheese, sake, and yogurt). The ODFM archives genome, metagenome, metataxonome, and (meta)transcriptome sequences of fermented food-associated bacteria, archaea, eukaryotic microorganisms, and viruses; 131 bacterial, 38 archaeal, and 28 eukaryotic genomes are now available to users. The ODFM provides both the Basic Local Alignment Search Tool search-based local alignment function as well as average nucleotide identity-based genetic relatedness measurement, enabling gene diversity and taxonomic analyses of an input query against the database. Genome sequences and annotation results of microorganisms are directly downloadable, and the microbial strains registered in the archive library will be available from our culture collection of fermented food-associated microorganisms. The ODFM is a comprehensive database that covers the genomes of an entire microbiome within a specific food ecosystem, providing basic information to evaluate microbial isolates as candidate fermentation starters for fermented food production.

Prolonged Heat Stress of Lactobacillus paracasei GCRL163 Improves Binding to Human Colorectal Adenocarcinoma HT-29 Cells and Modulates the Relative Abundance of Secreted and Cell Surface-Located Proteins

Lactobacillus casei group bacteria improve cheese ripening and may interact with host intestinal cells as probiotics, where surface proteins play a key role. Three complementary methods [trypsin shaving (TS), LiCl-sucrose (LS) extraction, and extracellular culture fluid precipitation] were used to analyze cell surface proteins of Lactobacillus paracasei GCRL163 by label-free quantitative proteomics after culture to the mid-exponential phase in bioreactors at pH 6.5 and temperatures of 30-45 °C. A total of 416 proteins, including 300 with transmembrane, cell wall anchoring, and secretory motifs and 116 cytoplasmic proteins, were quantified as surface proteins. Although LS caused significantly greater cell lysis as growth temperature increased, higher numbers of extracytoplasmic proteins were exclusively obtained by LS treatment. Together with the increased positive surface charge of cells cultured at supra-optimal temperatures, proteins including cell wall hydrolases Msp1/p75 and Msp2/p40, α-fucosidase AlfB, SecA, and a PspC-domain putative adhesin were upregulated in surface or secreted protein fractions, suggesting that cell adhesion may be altered. Prolonged heat stress (PHS) increased binding of L. paracasei GCRL163 to human colorectal adenocarcinoma HT-29 cells, relative to acid-stressed cells. This study demonstrates that PHS influences cell adhesion and relative abundance of proteins located on the surface, which may impact probiotic functionality, and the detected novel surface proteins likely linked to the cell cycle and envelope stress.