Probiotics are live bacteria, generally administered in food, conferring beneficial effects to the host because they help to prevent or treat diseases, the majority of which are gastrointestinal. Numerous investigations have verified the beneficial effect of probiotic strains in biofilm form, including increased resistance to temperature, gastric pH and mechanical forces to that of their planktonic counterparts. In addition, the development of new encapsulation technologies, which have exploited the properties of biofilms in the creation of double coated capsules, has given origin to fourth generation probiotics. Up to now, reviews have focused on the detrimental effects of biofilms associated with pathogenic bacteria. Therefore, this work aims to amalgamate information describing the biofilms of Lactobacillus strains which are used as probiotics, particularly L. rhamnosus, L. plantarum, L. reuteri, and L. fermentum. Additionally, we have reviewed the development of probiotics using technology inspired by biofilms.

Cancer is defined as an uncontrolled proliferation of malignant cells in a host and it is one of the main causes of death worldwide. Genetic and environmental factors play an important role in its development, and the involvement of microbial communities has also recently been recognized. The close relationship that characterizes the colonization by human commensal communities involves health risks, particularly when the homeostasis is disturbed. It has been hypothesized that this process may lead to cancer by modulating the inflammatory response of the host, by the production of carcinogenic metabolic products or by the production of toxins, which disrupt the cell cycle. The metabolic effects of the intestinal microbiota have been studied in greater detail in the gastrointestinal tract, and it has been recognized that microbial communities of other body surfaces can cause effects either locally or at a distance. In vitro and in vivo studies have allowed the characterization of the microbiota and the establishment of a cause and effect relationship with some types of cancer. Nevertheless, despite the results, representative studies are necessary to validate the findings and definitively establish the role of microbiota in cancer development in order to open the possibility of promising therapeutic and diagnostic applications. Thus, the aims of this review are to briefly examine the available evidence, and to analyse the mechanisms described for pancreatic, lung, colorectal cancer , oral squamous cell carcinoma and hepatocellular carcinoma and the impact of the current knowledge about the effects of the microbiota on carcinogenesis.

Lactobacillus fermentum UCO-979C, a strain isolated from a human stomach, was previously characterized by its potential probiotic properties. The UCO-979C strain displayed the ability to beneficially regulate the innate immune response triggered by Helicobacter pylori infection in human gastric epithelial cells. In this work, we conducted further in vitro studies in intestinal epithelial cells (IECs) and in vivo experiments in mice in order to characterize the potential immunomodulatory effects of L. fermentum UCO-979C on the intestinal mucosa. Results demonstrated that the UCO-979C strain is capable to differentially modulate the immune response of IECs triggered by Toll-like receptor 4 (TLR4) activation through the modulation of TLR negative regulators' expression. In addition, we demonstrated for the first time that L. fermentum UCO-979C is able to exert its immunomodulatory effect in the intestinal mucosa in vivo. The feeding of mice with L. fermentum UCO-979C significantly increased the production of intestinal IFN-γ, stimulated intestinal and peritoneal macrophages and increased the number of Peyer's patches CD4⁺ T cells. In addition, L. fermentum UCO-979C augmented intestinal IL-6, reduced the number of immature B220⁺CD24^high B cells from Peyer's patches, enhanced the number of mature B B220⁺CD24^low cells, and significantly increased intestinal IgA content. The results of this work revealed that L. fermentum UCO-979C has several characteristics making it an excellent candidate for the development of immunobiotic functional foods aimed to differentially regulate immune responses against gastric and intestinal pathogens.

Helicobacter pylori (H. pylori) is a Gram negative pathogen that selectively colonizes the human gastric epithelium. Over 50% of the world population is infected with H. pylori reaching up to 90% of infected individuals in developing countries. Nonetheless the increased impact upon public health care, its reservoir and the transmission pathway of the species has not been clearly established yet. Molecular studies allowed the detection of H. pylori in various aquatic environments, even forming biofilm in tap water distribution systems in several countries, suggesting a role of water as a possible reservoir of the pathogen. The persistence of human infection with H. pylori and the resistance of clinical isolates to commonly used antibiotics in eradication therapy have been related to the genetic variability of the species and its ability to develop biofilm, demonstrated both in vivo and in vitro experiments. Thus, during the last years, experimental work with this pathogen has been focused in the search for biofilm inhibitors and biofilm destabilizing agents. However, only two anti- H. pylori biofilm disrupting agents have been successfully used: Curcumin - a natural dye - and N-acetyl cysteine - a mucolytic agent used in respiratory diseases. The main goal of this review was to discuss the evidences available in the literature supporting the ability of H. pylori to form biofilm upon various surfaces in aquatic environments, both in vivo and in vitro. The results published and our own observations suggest that the ability of H. pylori to form biofilm may be important for surviving under stress conditions or in the spread of the infection among humans, mainly through natural water sources and water distribution systems.

The ability of the human isolate Lactobacillus fermentum UCO-979C to form biofilm and synthesize exopolysaccharide on abiotic and biotic models is described. These properties were compared with the well-known Lactobacillus casei Shirota to better understand their anti-Helicobacter pylori probiotic activities. The two strains of lactobacilli synthesized exopolysaccharide as detected by the Dubois method and formed biofilm on abiotic and biotic surfaces visualized by crystal violet staining and scanning electron microscopy. Concomitantly, these strains inhibited H. pylori urease activity by up to 80.4% (strain UCO-979C) and 66.8% (strain Shirota) in gastric adenocarcinoma (AGS) cells, but the two species showed equal levels of inhibition (~84%) in colorectal adenocarcinoma (Caco-2) cells. The results suggest that L. fermentum UCO-979C has probiotic potential against H. pylori infections. However, further analyses are needed to explain the increased activity observed against the pathogen in AGS cells as compared to L. casei Shirota.