Enterococcus mundtii A2 biofilm and its anti-adherence potential against pathogenic microorganisms on stainless steel 316L.

Pathogenic bacterial biofilms present significant challenges, particularly in food safety and material deterioration. Therefore, using Enterococcus mundtii A2, known for its antagonistic activity against pathogen adhesion, could serve as a novel strategy to reduce pathogenic colonization within the food sector. This study aimed to investigate the biofilm-forming ability of E. mundtii A2, isolated from camel milk, on two widely used stainless steels within the agri-food domain and to assess its anti-adhesive properties against various pathogens, especially on stainless steel 316L. Additionally, investigations into auto-aggregation and co-aggregation were also conducted. Plate count methodologies revealed increased biofilm formation by E. mundtii A2 on 316L, followed by 304L. Scanning electron microscopy (SEM) analysis revealed a dense yet thin biofilm layer, playing a critical role in reducing the adhesion of L. monocytogenes CECT 4032 and Staphylococcus aureus CECT 976, with a significant reduction of ≈ 2 Log CFU/cm2. However, Gram-negative strains, P. aeruginosa ATCC 27853 and E. coli ATCC 25922, exhibit modest adhesion reduction (~ 0.7 Log CFU/cm2). The findings demonstrate the potential of applying E. mundtii A2 biofilms as an effective strategy to reduce the adhesion and propagation of potentially pathogenic bacterial species on stainless steel 316L.

Coaggregative interactions between rhizobacteria are promoted by exopolysaccharides from Sinorhizobium meliloti.

Bacterial surface components and extracellular compounds such as exopolysaccharides (EPSs) are crucial for interactions between cells, tolerance to different types of stress, and host colonization. Sinorhizobium meliloti produces two EPSs: Succinoglycan (EPS I), which is involved in the establishment of symbiosis with Medicago sativa, and galactoglucan (EPS II), associated with biofilm formation and the promotion of aggregation. Here, we aimed to assess their role in aggregative interactions between cells of the same strain of a given species (auto-aggregation), and between genetically different strains of the same or different species (intra- or intergeneric coaggregation). To do this, we used S. meliloti mutants which are defective in the production of EPS I, EPS II, or both. Macroscopic and microscopic coaggregation tests were performed with combinations or pairs of different bacterial strains. The EPS II-producing strains were more capable of coaggregation than those that cannot produce EPS II. This was true both for coaggregations between different S. meliloti strains, and between S. meliloti and other common rhizobacteria of agricultural relevance, such as Pseudomonas fluorescens and Azospirillum brasilense. The exogenous addition of EPS II strongly promoted coaggregation, thus confirming the polymer's importance for this phenotype. EPS II may therefore be a key factor in events of physiological significance for environmental survival, such as aggregative interactions and biofilm development. Furthermore, it might be a connecting molecule with relevant properties at an ecological, biotechnological, and agricultural level.

Comparison of probiotic Lactobacillus strains isolated from dairy and Iranian traditional food products with those from human source on intestinal microbiota using BALB/C mice model.

This study compares the probiotic Lactobacillus strains isolated from dairy and Iranian traditional food products with those from human sources on intestinal microbiota using BALB/C mice model. First, Lactiplantibacillus plantarum (M11), Limosilactobacillus fermentum (19SH), Lactobacillus acidophilus (AC2), and Lactobacillus gasseri (52b) strains, isolated from either Iranian traditionally fermented products or human (healthy woman vaginal secretions), identified with molecular methods and selected based on the surface hydrophobicity, auto- and co-aggregation, were investigated for their probiotic properties and compared with their standard probiotic strains in vitro. The native strains and their mixtures (MIX) were then orally fed to five groups of female inbred BALB/C mice over the course of 38 days by gavage at 0.5 and 4 McFarland, respectively, equal to 1.5 × 108 and 1 × 109 cfu/ml. Feeding paused for 6 days to test the bacteria's adhesion in vivo. According to the findings, the probiotic Lactobacillus strain isolated from human source (52b) exhibited the best in vitro and in vivo adhesion ability. Probiotic Lactobacillus strains isolated from Iranian traditional food products (19SH and AC2) had the most co-aggregation with Listeria monocytogenes (ATTC 7644), Salmonella enterica subsp. enterica (ATCC 13,076), and Escherichia coli (NCTC 12,900 O157:H7) in vitro. These strains produced the most profound decreasing effect on the mice intestinal microbiota and pathogens in vivo. The difference in the strains and their probiotic potential is related to the sources from which they are isolated as well as their cell walls. The results suggest that (19SH and 52b strains) are the best candidates to investigate the cell wall and its effect on the host immune system.

Multiple surface interaction mechanisms direct the anchoring, co-aggregation and formation of dual-species biofilm between Candida albicans and Helicobacter pylori.

Introduction: Polymicrobial biofilms have a significant impact on pathogenesis of infectious microorganisms. Many human diseases are affected by colonization of multi-species communities affecting negatively the treatments and increase the risks for the health. In particular, in the epithelium of the stomach co-existence between C. albicans and H. pylori has been described, which has been associated to a synergistic effect on ulcer pathogenesis. Objective: The objective of this work was to advance in the understanding of surface interaction between H. pylori and C. albicans for the formation of polymicrobial biofilms. Methods: Studies of microbial surfaces both bacterium, yeast and co-cultures of them were carried out by infrared spectroscopy, deconvolution analysis, transmission and scanning electron microscopies, and optic microscopy. Additional methods were used to contrast the results as dynamic light scattering, contact angle, agarose gel electrophoresis and gene amplification. Results: Several surface interaction mechanisms promote the anchoring of H. pylori on C. albicans, cell co-aggregation, and polymicrobial biofilm formation, main identified interactions were: (i) hydrophobic interactions between non-polar peptide chains and lipid structures, characterized by θw among 84.9 ± 1.6 (γ = 22.78 mJ/m2 with 95.3 of dispersive contribution) and 76.6 ± 3.8 (γ = 17.34 mJ/m2, 40.2 of dispersive contribution) for C. albicans and H. pylori, respectively, (ii) hydrogen bonds between surface components of yeast and bacterium (e.g., -S-H⋅⋅⋅NH2- or -S-H⋅⋅⋅O[bond, double bond]CO-) and (iii) thiol-mediated surface interactions identified by displacements to lower wavenumbers (Δv = 5 cm-1). Evidence of internalization and electrostatic interactions were not evidenced. All observations were congruent with the biofilm formation, including the identification of small-size biostructures (i.e., 122-459 nm) associated with extracellular proteins, extracellular DNA, or outer membrane vesicles were observed characteristic of biofilm formation. Conclusion: It is concluded that biofilm is formed by co-aggregation after anchoring of H. pylori on C. albicans. Several surface interactions were associated with the prevalence of H. pylori, the possibility to find C. albicans in the stomach epithelium infected by H. pylori, but also, strength interactions could be interfering in experimental observations associated with bacterial-DNA detection in culture mixtures.

Structural and foaming properties of whey and soy protein isolates in mixed systems before and after heat treatment.

The partial replacement of proteins from animal sources by plant proteins in formulated food products has been proposed as useful to improve sustainability aspects of the products without dramatically changing their techno-functional properties. Although several research groups have published on the gelling properties of mixed systems containing whey and soy protein isolates (WPI and SPI), their foaming properties are much less described. In this context, the main objective of this paper was to evaluate the structural and foaming properties of samples containing different mass ratios of WPI:SPI (100:0, 75:25, 50:50, 25:75 and 0:100) before and after heat treatment. The samples were evaluated according to their solubility, foaming capacity (FC), foam microstructure and foam stability (FS). Before heat treatment, mixing SPI to WPI did not affect the solubility of whey proteins, but, after heat treatment, insoluble co-aggregates were formed. Similar FC was measured for all samples despite their WPI:SPI ratio and the applied heat treatment. The partial replacement of WPI by SPI changed the microstructure of the foams and had an antagonistic effect on the FS of the samples, due to the negative effect of insoluble soy protein aggregates and/or insoluble co-aggregates on the reinforcement of the air-water interfacial film.

Development of alginate-based aggregate inoculants of Methylobacterium sp. and Azospirillum brasilense tested under in vitro conditions to promote plant growth.

AIM: To develop co-aggregated bacterial inoculant comprising of Methylobacterium oryzae CBMB20/Methylobacterium suomiense CBMB120 strains with Azospirillum brasilense (CW903) strain and testing their efficiency as inoculants for plant growth promotion (PGP). METHODS AND RESULTS: Biofilm formation and co-aggregation efficiency was studied between A. brasilense CW903 and methylobacterial strains M. oryzae CBMB20 and M. suomiense CBMB120. Survival and release of these co-aggregated bacterial strains entrapped in alginate beads were assessed. PGP attributes of the co-aggregated bacterial inoculant were tested in tomato plants under water-stressed conditions. Results suggest that the biofilm formation efficiency of the CBMB20 and CBMB120 strains increased by 15 and 34%, respectively, when co-cultivated with CW903. Co-aggregation with CW903 enhanced the survivability of CBMB20 strain in alginate beads. Water stress index score showed least stress index in plants inoculated with CW903 and CBMB20 strains maintained as a co-aggregated inoculant. CONCLUSIONS: This study reports the development of co-aggregated cell inoculants containing M. oryzae CBMB20 and A. brasilense CW903 strains conferred better shelf life and stress abatement in inoculated tomato plants. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings could be extended to other PGP bacterial species to develop multigeneric bioinoculants with multiple benefits for various crops.

Influência da co-agregação entre candida. albicans e lactobacillus acidophilus na capacidade de adesão destes microrganismos às células epiteliais vaginais humanas (CEVH) / Influence of the co-aggregation between candida. albicans e lactobacillus acidophilus on the adhesion capacity these microorganisms in the human ephitelial vaginal cells (HEVC)

Este trabalho teve por objetivo avaliar a influência da co-agregação in vitro entre Candida albicans e Lactobacillus acidophilus na capacidade de adesão destes microrganismos às células epiteliais vaginais humanas (CEVH). Foram utilizados um isolado vaginal de C. albicans e uma cepa ATCC de L. acidophilus. Uma suspensão de cada microrganismo isoladamente e do coagregado foram incubados com as CEVH obtidas de uma doadora saudável. Foram feitos esfregaços por cristal violeta e Papanicolaou, e o número de leveduras, lactobacilos ou coagregados aderidos às células foi contado (em 300 células superficiais-CS e 300 intermediárias- CI). A Microscopia eletrônica de varredura (MEV) foi realizada em todas as situações dos ensaios. Leveduras e lactobacilos aderiram fortemente as CEVH, tanto em CS quanto em CI. A coagregação levou a um aumento na capacidade de adesão das leveduras (p < 0,001) e diminuiu a dos lactobacilos (p < 0,001). A adesão dos microrganismos isolados ou co-agregados não apresentou diferença entre CS e CI (p > 0,05). Havendo correlação com o que acontece in vivo, probióticos à base de L. acidophillus e mesmo uma flora lactobacilar vaginal não surtiriam efeito protetor contra a adesão de C. albicans as CEVH e do possível desenvolvimento de candidíase vulvovaginal.

This work has aimed to evaluate the influence of the L. acidophilus and Candida albicans co-aggregation on the adhesion capacity this microorganisms in the human ephitelial vaginal cells (HEVC). One vaginal isolated of C. albicans and one ATCC strain of L. acidophilus was used. A suspension of the isolated and co-aggregated microorganisms was incubated with HVEC obtained from a healthy donor. After one hour, smears were made with crystal violet and Papanicolaou, and the number of yeasts adhered to HVEC was evaluated (300 superficial-SC and 300 intermediate cells-IC). Scanning electron microscopy (SEM) was made in all situations of the assays. Yeasts and lactobacilli adhered strongly to the HEVC, both SC and IC. The co-aggregation there was an increase in the adhesion capacity of the yeasts (p < 0.001) and a diminished adhesion of the lactobacilli (p < 0.001) in SC and IC. The adhesion of isolated and co-aggregated microorganisms was not significantly different between SC and IC (p > 0.05). Supposing that of these findings correlated with the conditions in vivo, the use of probiotics based on L. acidophilus or its presence in the vaginal microbiota would not protect against the adhesion of C. albicans to the HVEC and possible consequent vulvovaginal candidiasis.