A novel approach to Lactiplantibacillus plantarum: From probiotic properties to the omics insights

Lactiplantibacillus plantarum (previously known as Lactobacillus plantarum) strains are one of the lactic acid bacteria (LAB) commonly used in fermentation and their probiotic and functional properties along with their health-promoting roles come to the fore. Food-derived L. plantarum strains have shown good resistance and adhesion in the gastrointestinal tract (GI) and excellent antioxidant and antimicrobial properties. Furthermore, many strains of L. plantarum can produce bacteriocins with interesting antimicrobial activity. This probiotic properties of L. plantarum and existing in different niches give a great potential to have beneficial effects on health. It is also has been shown that L. plantarum can regulate the intestinal microbiota composition in a good way. Recently, omics approaches such as metabolomics, secretomics, proteomics, transcriptomics and genomics try to understand the roles and mechanisms of L. plantarum that are related to its functional characteristics. This review provides an overview of the probiotic properties, including the specific interactions between microbiota and host, and omics insights of L. plantarum.

Gut Microbiota Modulation as a Potential Target for the Treatment of Lung Infections

The gastrointestinal and respiratory systems are colonized by a complex ecosystem of microorganisms called the microbiota. These microorganisms co-evolved over millions of years with the host, creating a symbiotic relationship that is fundamental for promoting host homeostasis by producing bioactive metabolites and antimicrobial molecules, and regulating the immune and inflammatory responses. Imbalance in the abundance, diversity, and function of the gut microbiota (known as dysbiosis) have been shown to increase host susceptibility to infections in the lungs, suggesting crosstalk between these organs. This crosstalk is now referred to as the gut-lung axis. Hence, the use of probiotics, prebiotics, and synbiotics for modulation of gut microbiota has been studied based on their effectiveness in reducing the duration and severity of respiratory tract infections, mainly owing to their effects on preventing pathogen colonization and modulating the immune system. This review discusses the role and responses of probiotics, prebiotics, and synbiotics in the gut-lung axis in the face of lung infections.

Interactions between invasive fungi and symbiotic bacteria

Infection rates and mortality associated with the invasive fungi Candida, Aspergillus, and Cryptococcus are increasing rapidly in prevalence. Meanwhile, screening pressure brought about by traditional antifungal drugs has induced an increase in drug resistance of invasive fungi, which creates a great challenge for the preservation of physical health. Development of new drugs and novel strategies are therefore important to meet these growing challenges. Recent studies have confirmed that the dynamic balance of microorganisms in the body is correlated with the occurrence of infectious diseases. This discovery of interactions between bacteria and fungi provides innovative insight for the treatment of invasive fungal infections. However, different invasive fungi and symbiotic bacteria interact with each other through various ways and targets, leading to different effects on their growth, morphology, and virulence. And the mechanism and implication of these interactions remains largely unknown. The present review aims to summarize the research progress into the interaction between invasive fungi and symbiotic bacteria with a focus on the anti-fungal mechanisms of symbiotic bacteria, providing a new strategy against drug-resistant fungal infections.

Silva L, Gonçales RA, Neves BJ, Soares CM, Pereira M. Setting New Routes for Antifungal Drug Discovery Against Pathogenic Fungi

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Fungal diseases are life-threatening to human health and responsible for millions of deaths around the world. Fungal pathogens lead to a high number of morbidity and mortality. Current antifungal treatment comprises drugs, such as azoles, echinocandins, and polyenes and the cure is not guaranteed. In addition, such drugs are related to severe side effects and the treatment lasts for an extended period. Thus, setting new routes for the discovery of effective and safe antifungal drugs should be a priority within the health care system. The discovery of alternative and efficient antifungal drugs showing fewer side effects is time-consuming and remains a challenge. Natural products can be a source of antifungals and used in combinatorial therapy. The most important natural products are antifungal peptides, antifungal lectins, antifungal plants, and fungi secondary metabolites. Several proteins, enzymes, and metabolic pathways could be targets for the discovery of efficient inhibitor compounds and recently, heat shock proteins, calcineurin, salinomycin, the trehalose biosynthetic pathway, and the glyoxylate cycle have been investigated in several fungal species. HSP protein inhibitors and echinocandins have been shown to have a fungicidal effect against azole-resistant fungi strains. Transcriptomic and proteomic approaches have advanced antifungal drug discovery and pointed to new important specific-pathogen targets. Certain enzymes, such as those from the glyoxylate cycle, have been a target of antifungal compounds in several fungi species. Natural and synthetic compounds inhibited the activity of such enzymes and reduced the ability of fungal cells to transit from mycelium to yeast, proving to be promisor antifungal agents. Finally, computational biology has developed effective approaches, setting new routes for early antifungal drug discovery since normal approaches take several years from discovery to clinical use. Thus, the development of new antifungal strategies might reduce the therapeutic time and increase the quality of life of patients.

Probiotics as antifungal agents: Experimental confirmation and future prospects

Fungal burden throughout the world is very high and it keeps escalating due to increasing numbers of immunocompromised individuals. In contrast, the drugs used in management of fungal infections are so few some with high toxicity. Furthermore, highly resistant fungal pathogens are emerging for example Candida auris, Candida glabrata, Candida gullemondii and Aspergillus species among others. Thus now, more than ever, there is a need for combined efforts and an all round search for possible solutions to curb these problems. Therefore, the role of probiotics in management of fungal infections is indispensable. In fact, the antimicrobial activity of probiotics has been screened with promising results against microbial pathogens. Although, recent reports indicated that probiotics may also contribute to protect against fungal infections, the research done in checking antifungal activity of probiotics has used varied technology. This calls for harmonization of the methods used to screen and confirm the antimicrobial activity of probiotics and other candidate microorganisms. We therefore sought to address issues of disparity in probiotic research and their outcomes. Thus this paper is in order as it comprehensively reviews' publications, provides a summary of the methods and future prospects of probiotics as antifungal agents.

Control of Aspergillus carbonarius in grape berries by Lactobacillus plantarum: A phenotypic and gene transcription study

The in vitro and in situ antifungal activity of Lactobacillus plantarum against the ochratoxigenic fungus Aspergillus carbonarius was investigated in this study. Four different fungal isolates from grape berries were co-cultured with four different strains of L. plantarum on Malt Extract Agar (MEA) plates at 30 °C. Bacterial strains inhibited fungal growth up to 88% and significantly reduced toxin production up to 100%. In addition, L. plantarum was evaluated as biocontrol agent against A. carbonarius growth and OTA production on table grapes. Temporal studies of bacterial antagonism were performed with two different grape cultivars. Artificially wounded and unwounded berries were pre-treated with 10⁸ CFU/mL bacteria and inoculated with 10⁶ spores/mL of A. carbonarius ochratoxigenic isolates. Biocontrol agents displayed high rate of colonization on grapes during 5 days of incubation at 30 °C. Scanning electron microscopy (SEM) also determined the presence of microorganisms on grape surface. Bacterial strains were effective in controlling fungal infection reaching up to 71% inhibition rates. However the presence of wounds on grape skin facilitated infection of berries by A. carbonarius, since unwounded berries showed lower levels of infection. Results also revealed significant reduction in mycotoxin production ranging between 32% and 92%. Transcriptome analysis following exposure to co-cultivation, exhibited differential expression for each gene studied of AcOTAnrps (Aspergillus carbonarius OTA nonribosomal), AcOTApks (Aspergillus carbonarius OTA polyketide synthase) and laeA, emphasizing the significance of strain variability. The genes AcOTAnrps and laeA were most influenced by the presence of L. plantarum. This work is a contribution for the potential biocontrol of toxigenic fungi in table grapes by lactic acid bacteria (LAB). The above findings underline the significance of bacterial strain variability on the effectiveness of biopreservative features of L. plantarum strains.

Antifungal Microbial Agents for Food Biopreservation-A Review

Food spoilage is a major issue for the food industry, leading to food waste, substantial economic losses for manufacturers and consumers, and a negative impact on brand names. Among causes, fungal contamination can be encountered at various stages of the food chain (e.g., post-harvest, during processing or storage). Fungal development leads to food sensory defects varying from visual deterioration to noticeable odor, flavor, or texture changes but can also have negative health impacts via mycotoxin production by some molds. In order to avoid microbial spoilage and thus extend product shelf life, different treatments—including fungicides and chemical preservatives—are used. In parallel, public authorities encourage the food industry to limit the use of these chemical compounds and develop natural methods for food preservation. This is accompanied by a strong societal demand for ‘clean label’ food products, as consumers are looking for more natural, less severely processed and safer products. In this context, microbial agents corresponding to bioprotective cultures, fermentates, culture-free supernatant or purified molecules, exhibiting antifungal activities represent a growing interest as an alternative to chemical preservation. This review presents the main fungal spoilers encountered in food products, the antifungal microorganisms tested for food bioprotection, and their mechanisms of action. A focus is made in particular on the recent in situ studies and the constraints associated with the use of antifungal microbial agents for food biopreservation.

Identification of a putative FR901469 biosynthesis gene cluster in fungal sp. No. 11243 and enhancement of the productivity by overexpressing the transcription factor gene frbF

FR901469 is an antifungal antibiotic produced by fungal sp. No. 11243. Here, we searched for FR901469 biosynthesis genes in the genome of No. 11243. Based on the molecular structure of FR901469 and endogenous functional motifs predicted in each genomic NRPS gene, a putative FR901469 biosynthesis gene cluster harboring the most plausible NRPS gene was identified. A transcription factor gene, designated frbF, was found in the cluster. To improve FR901469 productivity, we constructed a strain in which frbF was overexpressed and named it TFH2-2. FR901469 productivity of TFH2-2 was 3.4 times higher than that of the wild-type strain. Transcriptome analysis revealed that most of the genes in the putative FR901469 biosynthesis gene cluster were upregulated in TFH2-2. It also showed that the expression of genes related to ergosterol biosynthesis, β-1,3-glucan catabolism, and chitin synthesis was inclined to exhibit significant differences in TFH2-2.

Probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 exhibit strong antifungal effects against vulvovaginal candidiasis-causing Candida glabrata isolates

Aims

This study investigates the antagonistic effects of the probiotic strains Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 against vulvovaginal candidiasis (VVC)-causing Candida glabrata.

Methods and Results

Growth inhibitory activities of Lact. rhamnosus GR-1 and Lact. reuteri RC-14 strains against C. glabrata were demonstrated using a spot overlay assay and a plate-based microtitre assay. In addition, these probiotic lactobacilli strains also exhibited potent candidacidal activity against C. glabrata, as demonstrated by a LIVE/DEAD yeast viability assay performed using confocal laser scanning microscopy. The metabolic activities of all C. glabrata strains were completely shut down in response to the challenges by the probiotic lactobacilli strains. In addition, both probiotic lactobacilli strains exhibited strong autoaggregation and coaggregation phenotypes in the presence of C. glabrata, which indicate that these lactobacilli strains may exert their probiotic effects through the formation of aggregates and, thus the consequent prevention of colonization by C. glabrata.

Conclusions

Probiotic Lact. rhamnosus GR-1 and Lact. reuteri RC-14 strains exhibited potent antagonistic activities against all of the tested C. glabrata strains. These lactobacilli exhibited antifungal effects, including those attributed to their aggregation abilities, and their presence caused the cessation of growth and eventual cell death of C. glabrata.

Significance and Impact of the Study

This is the first study to report on the antagonistic effects of these probiotic lactobacilli strains against the non-Candida albicans Candida (NCAC) species C. glabrata.