AIMS Microbiology最新文献

Microplastics (MPs), synthetic polymer particles less than 5 mm in size, are an emerging contaminant with implications for both human and ecosystem health. Being widespread in food and water sources, MPs can disrupt gastrointestinal integrity, alter the microbiota composition, and provoke oxidative and inflammatory responses. Probiotics, live microorganisms known for their gut health benefits, are now being explored for their ability to mitigate these effects. This review synthesizes evidence from in vitro and in vivo studies on how MPs impact probiotic viability, adhesion, and biofilm formation, and how certain strains may counter MP-induced toxicity by modulating oxidative stress, immune function, and the epithelial barrier integrity. Additionally, this manuscript discusses emerging applications in environmental microbiology, such as the potential use of native and engineered probiotics for microplastic bioremediation. Although the current data highlight promising avenues, key gaps remain in our understanding of strain-specific mechanisms, long-term efficacy, and real-world applicability. Addressing these will be essential to advance probiotic-based strategies in both human and environmental contexts.

Chronic inflammation is identified to be an underlying pathophysiology in different conditions including inflammatory bowel disease (IBD). Since the aberrant interaction of the mucosal immune system with the dysbiotic flora has been reported to contribute to IBD development, probiotics have been studied for potential prophylaxis and treatment. In this regard, fermented dairy foods are a rich source of probiotics and bioactive compounds. However, limited studies have determined the impact of fermented dairy products in the context of chronic inflammation. In particular, a potential role for dairy starter cultures is not well studied. Hence, in this study we evaluated the anti-inflammatory effect of two cheese starter cultures (Lactococcus lactis subsp. lactis M58 and Streptococcus thermophilus TA 61) in comparison with commercial probiotic strains (Bifidobacterium animalis subsp. lactis BB-12, Lactobacillus acidophilus LA-5) using the Cmax-induced Caco-2 inflammation model. Specifically, we characterized their ability to attenuate inflammatory response via modulation of IL-8 secretion, NF-κB activation, barrier integrity (TEER), and tight junction gene expression. Overall, pre-exposure to the starter cultures before Cmax treatment significantly reduced the activation and nuclear translocation of NF-κB, compared to cytokine control (P < 0.05). Further, the reduction in pNF-κB was found to be associated with a significant reduction in IL 8 secretion (P < 0.05). Moreover, the cultures protected the Caco-2 monolayer from inflammation-induced increase in permeability by upregulating the genes associated with ZO-1 and occludin production. Furthermore, the protective effect of the starter cultures was comparable to that of the commercial probiotics with known anti-inflammatory properties. Therefore, cheese starter cultures could be a potential strategy against chronic gut inflammation.

Paenibacillus polymyxa is a multifaceted bacterium with widespread applications in agriculture, environmental management, medicine, and industry. In agricultural settings, it plays a crucial role in soil enhancement, plant growth promotion, and natural pathogen control, reducing the need for chemical interventions. Additionally, P. polymyxa exhibits promising potential in medical applications by aiding in infection prevention and supporting gastrointestinal health. In the realm of environmental management, this bacterium contributes to pollution remediation through biodegradation processes. Industrially, P. polymyxa is involved in producing enzymes, biofertilizers, bioplastics, and platform chemicals, offering sustainable alternatives that underscore its importance in driving sustainability initiatives. Despite these valuable attributes, widespread utilization of bioresources derived from naturally occurring P. polymyxa has been hampered by limited genetic manipulation capabilities and tools. In this comprehensive analysis, we aimed to provide a thorough understanding of P. polymyxa's characteristics, genetic resources, and metabolic capabilities, while highlighting its potential as a versatile platform for protein expression, metabolic engineering, and synthetic biology. We delved into the diverse sustainable applications of P. polymyxa in these domains, emphasizing its benefits, challenges, and future outlook in advancing sustainable practices. Furthermore, we underscore the critical need for continued research and development of advanced engineering techniques and genetic editing technologies tailored specifically for this bacterium.

Chickpea (Cicer arietinum L.) is considered a cheap source of plant protein. In Mediterranean regions, and particularly in Tunisia, fungal attacks are likely to further aggravate drought stress and increase the economic vulnerability of chickpea production. Plant growth-promoting rhizobacteria (PGPR) and rhizobia have the potential to enhance plant growth and mitigate the adverse effects of biotic and abiotic stresses. The objective of this study was to isolate non-rhizobial rhizosphere bacteria from the soil and evaluate their ability to enhance plants' growth and symbiotic performance and to control chickpea wilt caused by F. redolens. A total of 26 bacterial isolates from rhizosphere soil samples were subsequently evaluated for their antagonistic properties against five phytopathogenic fungi (Fusarium oxysporum solani, Fusarium oxysporum matthioli, Fusarium oxysporum MN-2, Fusarium oxysporum 184, and Fusarium rdolens). Seven bacterial isolates demonstrated in vitro plant-beneficial characteristics and/or antagonistic activity against 5 Fusarium strains. Two bacterial strains including Streptomyces diastaticus subsp. diastaticus and Bacillus subtilis were chosen for additional investigation because they showed the greatest number of plant growth-promoting (PGP) traits and exhibited an antagonistic effect on pathogens. Assays conducted in pots showed that PGPRs co-inoculated with Mesorhizobium sp. Bj1 protected chickpea plants from F. redolens infection and enhanced plant growth and nutrient uptake. Pot experiments carried out in a greenhouse further demonstrated that the co-inoculation of chickpea plants with the bacterial strains and a Mesorhizobium strain lessened the severity of the F. redolens infection. These results suggest that co-inoculation with S. diastaticus subsp. diastaticus and Mesorhizobium sp. Bj1 may act as a helpful bioformulation to boost chickpea plants' growth and protect them from wilting. Other PGPR candidates included Mesorhizobium spp. and B. subtilis strains. Both Mesorhizobium sp. Bj1 and the uninoculated plants were used as controls. The association of PGPR with other inoculants potentially could substitute for chemical fertilizers, and testing of PGPR under field conditions will further elucidate their effectiveness on grain yields of chickpea.

The human oral microbiome can affect brain functions directly through the trigeminal nerve and olfactory system and indirectly via the oral-gut-brain axis. However, the potential link between the oral microbiome and mental health remains an area that requires further investigation. Taking into consideration that gut microbiota dysbiosis plays a role in the onset and progression of several mental disorders, as well as the potential influence of the oral microbiome on mental health via direct pathways, the present narrative review explores the role of the human oral microbiome in health and disease, along with the factors that affect its composition, with a particular focus on its potential impact on mental health, including its involvement in a range of mental disorders and brain-related conditions, such as Alzheimer's disease, Parkinson's disease, autism spectrum disorder, anxiety, depression, stress, bipolar disorder, Down's syndrome, cerebral palsy, epilepsy, and schizophrenia. Chronic oral diseases can impair the oral mucosal barrier, allowing microorganisms and endotoxins to enter the bloodstream, triggering systemic inflammation, and affecting the blood-brain barrier. This pathway can lead to neuroinflammation and cognitive dysfunction and contribute to adverse mental health effects. Additionally, translocation of oral bacteria to the gut can drive persistent inflammation and thereby affect brain health. Multiple studies suggest a potential relationship between the oral microbiome and several mental disorders, but further research is needed to strengthen the evidence surrounding these associations and to fully clarify the underlying mechanisms linking the oral microbiome to these conditions. Given the promising implications, future research should focus on elucidating the biological mechanisms through which alterations in the oral microbiome influence the development and progression of determinate neurodegenerative and neuropsychiatric disorders. Additionally, identifying reliable biomarkers linked to the oral microbiome could enhance early detection, diagnosis, and monitoring of these conditions.

Food safety is a major public health concern. The zoonotic pathogen non-typhoidal Salmonella, responsible for salmonellosis, is a leading cause of bacterial food poisoning globally, making its detection and control essential. Understanding the infectious dose of Salmonella is crucial for identifying appropriate risk management strategies; however, significant uncertainties remain, warranting a systematic review. Following PRISMA guidelines, we conducted a comprehensive search across multiple databases (Web of Science, PubMed, and CAB Abstracts) to identify relevant studies examining the relationship between Salmonella dose and foodborne illness in humans. Four main types of studies were identified: experimental trials, case reports, case series, and mathematical modelling. An analysis of these studies revealed their respective strengths and limitations. The data showed considerable variability, with the dose required to cause illness depending on factors such as Salmonella serovar, food type, and the health status of the exposed population. A key challenge identified was the lack of sufficient data on collective food poisoning incidents, which complicates the development of more reliable dose-response models. Despite these limitations, this review underscores the importance of targeted food safety interventions and risk assessments tailored to specific food products and population groups. The findings provide a foundation for enhanced food safety measures and support ongoing efforts to protect public health from foodborne illnesses.

Candida haemulonii is an emerging, opportunistic, and multidrug-resistant fungal pathogen. Recently, our group reported the ability of C. haemulonii to form biofilm and secrete aspartic-type peptidases (Saps). Herein, we investigated the correlation between Saps production and biofilm formation along C. haemulonii growth in yeast carbon base medium supplemented with albumin (a Sap-inducing condition) and in the presence of the classical Sap inhibitor pepstatin A. Under these conditions, the biofilm biomass increased on a polystyrene surface, reaching its maximum at 96 h, while maximum biofilm viability was detected at 48 h. The release of Saps during biofilm formation showed an inverse trend, with the highest enzymatic activity measured after 24 h. In the presence of pepstatin A, a significant reduction in biofilm parameters (biomass and viability), as well as in albumin consumption by biofilm-forming cells was detected. These findings underscore the importance of Saps during the biofilm development in C. haemulonii.

This study compared the potential of three white-rot fungi (Pleurotus spp.) to enhance the nutritional value of corn stover as a feed resource for ruminants. A mixture of shredded corn stover and wheat bran (ratio 9:1) was moisturized (65%), loaded into polypropylene bags, and sterilized at 121 °C for 1 h. Four replicate bags were each inoculated with P. ostreatus (isolates P1 and P3) and P. pulmonarius (isolate P2) and incubated at 25 °C for 0, 2, 4, 6, and 8 weeks. After inoculation and incubation of the corn stover, the resultant substrates and rumen fluid obtained from three ruminally cannulated beef cows were investigated using an in vitro batch culture study, designed as a 3 × 5 factorial with six replicates. Results revealed a significant (p < 0.001) effect on dry matter digestibility (DMD), with the highest DMD observed at 8 weeks for all Pleurotus isolates tested. The best (p < 0.001) performance was seen in corn stover treated with P2 at weeks 6 and 8. Additionally, P1 at 0 and 6 weeks had the lowest ash and highest (p < 0.001) organic matter (OM) concentrations, respectively, compared to P2 at 8 weeks, which had the highest ash and the lowest OM concentrations. The highest (p = 0.011) crude protein (CP) content was recorded in P1 at week 8, while P1 at week 0 had the lowest CP content. Compared to untreated corn stover, higher (p < 0.001) acid detergent fiber digestibility was recorded in corn stover treated with P2 at 8 weeks, while higher (p < 0.001) neutral detergent fiber digestibility was observed in P3 at 2 weeks. Pleurotus strains and incubation periods affected microbial mass production (p < 0.001), with minimal effects on total and individual volatile fatty acids. However, P3 at 2 weeks increased (p = 0.035) acetate and decreased (p = 0.001) propionate proportions. The results indicate that different isolates affected corn stover differently, but in general, all isolates improved the nutritional value of corn stover. P. pulmonarius had the highest DMD and lowest fiber content among the isolates tested and improved energy and nutrient utilization.

Marine sponges are well-known for their production of bioactive compounds, many of which are synthesized by their associated symbiotic microorganisms. Among these, Actinomycetes are of particular interest due to their ability to produce secondary metabolites with antimicrobial and antitumor activities. We aimed to investigate the bacterial microbiome of tropical marine sponges, with an emphasis on the diversity and distribution of Actinomycetes, employing both culture-dependent and culture-independent approaches. Five sponge samples (PF01-PF05) were collected from Sichang Island, Chonburi Province, Thailand. The bacterial communities were analyzed using 16S rRNA gene sequencing and bioinformatics tools, revealing a significant microbial diversity dominated by Cyanobacteria, Actinomycetota, and Chloroflexi. Notably, PF01 (Penares nux) exhibited the highest microbial diversity, while PF05 (Cacospongia sp.) had the lowest. Actinomycetes, particularly the genus Micromonospora, were successfully isolated from all samples, with PF03 (Ircinia mutans) yielding the highest number of strains. Culture-independent analysis identified a greater proportion of unculturable Actinomycetes compared to those isolated through traditional methods, underscoring the limitations of culture-dependent techniques. This study enhances our understanding of sponge-associated microbial diversity and highlights the potential for isolating Actinomycetes from these sponges for novel drug discovery and other bioprospective applications.

Neonatal enterovirus infections have the potential to cause devastating illness and death in this vulnerable age group. Existing evidence suggests that the incidence of enteroviral infections in the post-natal period may be higher than previously thought. Because neonates infected with enterovirus are at risk of severe sequelae, and healthcare-associated outbreaks in neonatal settings can occur, enteroviral infection in hospitalized neonates is a serious concern. Thus, it is essential to conduct surveillance for these infections and to deploy robust infection control measures once the virus has been detected in a neonatal care setting. Here, we report an outbreak of enterovirus in a neonatal intensive care unit (NICU) that was rapidly identified and contained, resulting in relatively few cases but requiring temporary closure of the unit. Additionally, we present our review of the literature describing the characteristics of enteroviral outbreaks in NICU and nursery settings to compare published outcomes of outbreaks to those of our outcome.