Search Results (203)

Edible insects are gaining traction worldwide; however, the existing data regarding their microbiological quality remain inadequate. This study investigated the bacterial communities and microbiological quality of five types of frozen edible insects commercially available in Thailand. Amplicon sequencing revealed Firmicutes (Bacillota) and Proteobacteria (Pseudomonadota) as the main phyla across all samples; Bacteroidota was predominant in house crickets, Actinobacteriota in silkworms, and Desulfobacterota was exclusively found in house and mole crickets. Culture-based assays showed total viable counts, lactic acid bacteria, yeasts–molds, and spore-formers ranging from 3.41–6.58, 2.52–7.41, 1.83–5.62, to 2.00–4.70 log CFU·g⁻¹, respectively. In some samples, Enterobacteriaceae and Escherichia coli, key hygiene indicators, reached 5.05 and 2.70 log CFU·g⁻¹, respectively. Among foodborne pathogens, presumptive Bacillus cereus was found to vary from <1.70 to 3.93 log CFU·g⁻¹, while Clostridium perfringens and Staphylococcus aureus were under the quantitation limit, and Salmonella was absent. Overall, the results indicate significant variation in microbial diversity and quality among different insect types. The high levels of microbial hygiene indicators and foodborne pathogens in some samples raised food safety concerns and point to the need to develop or implement production guidelines and microbiological criteria for frozen edible insects to ensure food safety. Full article

Spore-forming Bacilli have been explored due to their potential biotechnological features and applications in human health and functional food research. This study focuses on the genetic and phenotypical characterization of the functional probiotic properties of Bacillus velezensis P45, a strain isolated from fish intestines. B. velezensis P45 exhibited antimicrobial activity against Gram-positive and Gram-negative pathogens and demonstrated strong autoaggregation and biofilm formation properties in vitro. The strain also showed tolerance to gastrointestinal conditions and ability to metabolize and adhere to mucin. In silico analysis confirmed the absence of virulence factors and antibiotic resistance genes, reinforcing its safety as a probiotic candidate. Genome mining revealed the presence of genes related to adhesion, such as fibronectin-binding protein and enolases, and for the synthesis of secondary metabolites, including the antimicrobial lipopeptides fengycin, surfactin, and bacillibactin. In addition, phylogenetic comparison using the yloA (rqcH) gene associated with gut adhesion clustered strain P45 with other probiotic Bacillus and B. velezensis strains, while separating it from pathogenic bacteria. Thus, the strain B. velezensis P45 could be a valuable candidate as a probiotic due to its functional properties and safety. Full article

In the African Sahel, fonio (Digitaria sp.) is a cereal crop that alleviates mid-season hunger before other main crops are harvested. As fonio is valued for its ability to grow under low nutrient and drought conditions, it was hypothesized that it may contain endophytic bacteria that can tolerate such extreme stress. White fonio seeds were obtained from a dry environment (Mali) and a moderate rainfall environment (Guinea). Plants were grown indoors on field soil mixed with sand to mimic Sahelian soils, grown at 30 °C, and exposed to drought, optimal water, and low nitrogen stress conditions. In total, 73 cultured bacteria were classified using full-length 16S rRNA sequencing followed by searching three 16S reference databases. Selected strains were tested in vitro for tolerance to relevant abiotic stresses. Including nine isolates from seeds, the candidate root/shoot endophytes spanned 27 genera and 18–39 top-match species. Several well-known nitrogen-fixing bacteria were cultured, including Ensifer. Leaves were dominated by Bacilli (spore-formers known to withstand dry conditions). There were five root isolates of Variovorax. Leifsonia was isolated from the leaves and showed 100% sequence identity with seed isolates, suggestive of transmission from seed to shoot. In vitro experiments showed that seed isolates, including Leifsonia, survived diverse abiotic stresses relevant to the Sahel. Combined, these results suggest that white fonio hosts stress-tolerant microbiota, and points to Leifsonia as a candidate seed-to-plant transmitted endophyte, pending confirmation by future whole genome sequencing. This microbial collection serves as a starting point for long-term experiments to understand stress tolerance in this under-studied crop. Full article

This study evaluates various strains of soil bacterial for use in the development of new biopreparations. Mesophilic spore-forming bacteria were isolated from cultivated soil and analysed for their enzymatic activity, ability to decompose crop residues, and antagonistic properties towards selected phytopathogens. Notably, this is the first cytotoxicity assessment of soil bacterial metabolites on Spodoptera frugiperda Sf-9 (fall armyworm). Bacillus subtilis, Bacillus licheniformis, Bacillus velezensis, Paenibacillus amylolyticus, and Prestia megaterium demonstrated the highest hydrolytic potential for the degradation of post-harvest residues from maize, winter barley, and triticale. They exhibited antimicrobial activity against at least three of the tested phytopathogens and demonstrated the ability to solubilize phosphorus. Metabolites of B. licheniformis (IC50 = 8.3 mg/mL) and B. subtilis (IC50 = 144.9 mg/mL) were the most cytotoxic against Sf-9. We recommend the use of the tested strains in industrial practice as biocontrol agents, plant growth biostimulants, crop residue decomposition stimulants, and bioinsecticides. Future studies should focus on assessing the efficacy of using these strains under conditions simulating the target use, such as plant microcosms and greenhouses and the impact of these strains on the abundance and biodiversity of native soil microbiota. This research can serve as a model procedure for screening other strains of bacteria for agricultural purposes. Full article

Untreated olive oil mill wastewater (OOMW) from conventionally farmed olives was used in bread production to create a new functional product. Two types of bread were developed with 50% OOMW (EXP-1) and 100% OOMW (EXP-2) replacing water. Two leavening processes were tested: sourdough inoculum (S) vs. biga-like inoculum (B), with controls (CTR) without OOMW addition. The doughs were monitored throughout the acidification process by measuring pH, total titratable acidity, and the development of key fermentative microorganisms. To assess the hygienic quality during fermentation, plate count techniques were employed. After baking, the breads were evaluated for various quality parameters, including weight loss, specific volume, crumb and crust colors, image analysis, and the presence of spore-forming bacteria. Volatile compounds released from the breads were identified using solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC/MS). Polyphenolic compounds were analyzed via liquid chromatography–mass spectrometry (LC-MS). To assess the functional properties of the final products, the breads were homogenized with synthetic human saliva and subjected to in vitro digestion. OOMW did not significantly affect the growth of yeasts and lactic acid bacteria (LAB) or the acidification process. However, in terms of the specific volume and alveolation, breads from the S process and OOMW had poor quality, while those from the B process had better quality. Experimental breads (EXP_B-1 and EXP_B-2) contained higher levels of alcohols (especially ethanol and isobutyl alcohol), carbonyl compounds (like benzaldehyde), esters (such as ethyl caproate and ethyl caprylate), and terpenes. OOMW introduced phenolic compounds like hydroxytyrosol, coumaric acid, caffeic acid, and trans-hydroxycinnamic acid, which were absent in CTR_B breads. Functionalization of EXP_B-1 and EXP_B-2 breads was demonstrated by a 2.4- and 3.9-fold increase in Trolox equivalents, respectively. However, OOMW did not reduce post-prandial hyper-glycemia, as starch digestibility was similar between CTR_B and EXP_B breads. The sensory analysis, which focused solely on the visual, structural, and olfactory characteristics of the breads, excluding taste testing to prevent potential health risks from residual pesticides, showed a high appreciation for EXP_B-1 and EXP_B-2 breads, scoring higher than CTR_B in the overall assessment. Full article

Recent advances in the production of meat and dairy analogues and plant-based products have introduced new food safety challenges, as these foods are susceptible to contamination by both pathogens and spoilage microorganisms originating from raw materials and processing environments. In addition, plant-based analogues often exhibit physicochemical properties such as high water activity, near-neutral pH, and elevated protein and moisture content that favour the survival and growth of microorganisms, as evidenced by the detection of Salmonella sp., Listeria monocytogenes, and Enterobacteriaceae in commercial products. While extrusion and thermal processing effectively reduce microbial loads, these treatments may not inactivate all spores, including spore-forming bacteria like Bacillus cereus and Clostridium spp. Critical findings seem to highlight that some protein isolates are particularly prone to higher microbial contamination, and that outbreaks linked to pathogens such as Salmonella, L. monocytogenes, and E. coli have already occurred in plant-based analogues in Europe and North America. Here we discuss the microbiology and sources of microbial contamination of these products. In addition, we further discuss the integration of non-thermal technologies and biocontrol methods, such as protective cultures, bacteriocins, and bacteriophages, as promising approaches to enhance food safety while addressing clean-label demands. Full article

Kytococcus belongs to the family Kytococcaceae, in the order Micrococcales, in the class Actinomycetes, and the phylum Actinomycetota. Kytococcus are aerobic, Gram-positive, non-spore forming bacteria that form coccoid, non-motile, non-encapsulated cells, and their colonies on agar have a yellow color. Infections by these species are increasingly identified nowadays. This narrative review aimed to present all available cases of Kytococcus spp. infections in humans, emphasizing data on the epidemiology, antimicrobial resistance, antimicrobial treatment, and mortality. A narrative review based on a literature search of the PubMed/MedLine and Scopus databases was performed. Results: In total, 26 articles providing data on 30 patients with Kytococcus spp. infections were included in this analysis. The median age was 59.5 years, while 56.7% were male. The presence of a prosthetic cardiac valve was the main predisposing factor in 36.7% of patients (100% among those with infective endocarditis), while immunosuppression due to underlying hematological malignancy under chemotherapy was the second most common. Bacteremia was the most common type of infection, with infective endocarditis being the most common subtype in this infection type, while respiratory tract infections and osteoarticular infections were also relatively common. K. schroeteri was the most commonly identified species. Microbial identification required the use of advanced molecular techniques such as 16s rRNA sequencing in most cases. Kytotoccus spp. was resistant to all beta-lactams with the exception of carbapenems and macrolides. The most commonly used antimicrobials were vancomycin and rifampicin. Mortality was significant (30%). Due to the potential of Kytotoccus spp. to cause infective endocarditis in patients with prosthetic cardiac valves and respiratory tract infections with concomitant bacteremia in patients with hematological malignancy under chemotherapy along with the difficulties in pathogen identification, clinicians and laboratory personnel should consider this pathogen in the differential diagnosis in patients with typical predisposing factors and clinical presentation, especially when traditional microbiological techniques are used for pathogen identification. Full article

Clostridioides difficile (CD) is a Gram-positive, spore-forming anaerobic bacterium, usually transmitted through the fecal–oral route, that can result from direct person-to-person contact, exposure to contaminated environmental surfaces, or contact with the hands of colonized healthcare personnel. An increased number of infections, especially healthcare-associated, with this etiology has been observed in most countries. As a spore-forming organism, CD is resistant to alcohol formulations and is a challenge for chemical disinfection. The solution could be the supplementation of traditional disinfection with non-touch techniques, such as UV-C radiation. The adoption of UV-C as a supplementary disinfection method in hospitals has significantly increased since the COVID-19 pandemic. However, there are no current guidelines concerning the use of UV-C disinfection in hospitals. The aim of this study was to evaluate the effectiveness of UV-C irradiation in inactivating Clostridioides difficile from different types of surfaces in hospital settings. The study was based on laboratory tests evaluating the efficacy in eliminating three different C. difficile strains on carriers made of plastic, metal and glass after 10 min exposure to UV-C (wavelength, 253.7 nm). We observed a wide range of reductions in the C. difficile suspensions depending on the density of the carrier contamination, type of carrier, strains and the location of the carrier. The percentage reductions ranged from 0 to 100%, but the best results were observed for glass, with lower initial suspension density and carrier placement on a door frame. Statistically significant differences were only seen in different suspension densities. Our experiment was a continuation of the tests done for non-sporing bacteria and C. auris, and there were some interesting differences in C. difficile reflecting its biology, especially its sensitivity to an aerobic atmosphere during the sample drying. Although the elimination of C. difficile by UV-C radiation was confirmed in our experiment, it was lower than in the case of non-spore-forming bacteria. Thus, this method may be used in healthcare settings (hospitals) for improving environmental safety and preventing C. difficile spreading. Full article

The live microbiota of tea has not been extensively investigated. This study aimed to identify the live, culturable microbiota from four types of tea with varying oxidation levels, before and after brewing. Tea leaves and brews from oolong and fermented teas were analyzed for total viable counts of aerobic bacteria, lactobacilli, fungi, and Enterobacteriaceae. Cultivation was performed and isolates were identified by Sanger sequencing. Heat resistance was assessed at 70 °C and 90 °C. Random Amplified Polymorphic DNA (RAPD) was used to determine strain-level diversity. Fully oxidized, post-fermented Pu-erh tea had the highest viable bacterial count. Most isolates belonged to Bacillaceae, Staphylococcaceae, and Paenibacillaceae, families associated with soil or human skin. Only two potentially pathogenic species were identified: Staphylococcus epidermidis and Bacillus cereus. In Pu-erh, live bacteria were detected after brewing at 90 °C, including Heyndrickxia coagulans, a spore forming probiotic species. H. coagulans strains remained in vegetative state after hot water exposure and survived at 70 °C, indicating thermotolerance. RAPD-analysis revealed nine distinct H. coagulans strains across six Pu-erh teas. Conclusion: This study provides new insight into the viable microbiota of different teas and their survival during brewing, highlighting safety concerns and probiotic species like H. coagulans. Full article

Allicin is a chemically complex bioactive compound synthesized in many varieties of garlic. The wide range of biological properties of allicin provides the basis for its potential use as an alternative to antibiotic growth promoters that are currently prohibited in farm animal breeding. Among the many benefits resulting from the use of allicin in animal breeding, especially poultry, its modulating effect on intestinal microbiota, which includes the anaerobic spore-forming bacteria of the genus Clostridium spp., seems to be important. The material for this study consists of intestinal content collected from the caecums of Japanese quails (Coturnix japonica). Culture methods were used to isolate the strains, and the obtained isolates were identified based on their phenotypic characteristics. In addition, PCR methods were used for the detection of the ntnh gene-encoding non-haemagglutinin component of botulinum neurotoxins (BoNTs), the detection of individual genes responsible for the production of major toxins by Clostridium perfringens, and the amplification of conservative 16S rDNA genes. The 16S rDNA amplicons were subsequently submitted to Sanger sequencing. The obtained sequences were analyzed using the Basic Local Alignment Search Tool (BLAST). The ntnh gene was not found in the genetic material of the isolated strains. Among the isolates suspected of belonging to the Clostridium perfringens species, the plc gene determining the production of the alpha toxin was detected, which justifies the classification of the strains into toxotype A. The Sanger sequencing results confirm the presence of mainly saprophytic species in the studied material. The statistical analysis indicated a statistically significant reduction in the level of Clostridium spp., obtained by the use of an appropriate dose of allicin. The presented research results indicate the significant impact of an appropriate dose of allicin on reducing the occurrence of anaerobic intestinal microbiota, while providing important information on the potential application of this compound in animal production in the future. Full article

Clinics and hospitals inherently increase the risk of adverse events, including hospital-acquired infections (HAIs) transmitted between healthcare personnel and patients. This study aimed to identify bacterial strains present on frequently touched surfaces in outpatient clinics used by patients as well as medical and non-medical personnel. This study was conducted in four outpatient care centers located in two major cities in Poland. A total of 85 samples were collected from frequently touched surfaces, including 53 samples from areas accessed by patients and 32 samples from surfaces used by medical staff. A statistically significant increase in moderate-to-heavy growth was observed in samples containing microbiota compared to those containing other microorganisms (p = 0.003). Similarly, a higher prevalence of spore-forming bacteria was noted compared to non-spore-forming bacteria (p = 0.001). A significant difference was also observed between samples with no or scant growth versus those with moderate-to-heavy growth in both the microbiota and other microorganism groups (p = 0.003), as well as between the spore-forming and non-spore-forming groups (p = 0.001). The findings of this study prompted revisions in cleaning procedures. The frequency of training for medical staff was increased, and systematic quality control of the cleaning company’s performance was implemented. Full article

Fungal chlamydospores are asexual spores formed by fungi under adverse conditions and could be used in biological pretreatment for biogas projects fed by lignocellulosic substrates. In this study, Trichoderma viride (Tv) chlamydospores were used as the pretreatment agent to enhance the methane yield of spent mushroom substrates (SMSs). Lignocellulosic composition, methanogenesis performance, and anaerobic microbial communities were investigated for different Tv pretreatment durations (0 h, 12 h, 24 h, 48 h, 96 h, and 192 h). The results showed that the optimal Tv pretreatment duration was 24 h, and the cumulative methane yield reached 173.4 mL/gVS, which was 16.8% higher than that of the control. A pretreatment duration longer than 48 h was not conducive to methanogenesis. Sequencing analysis of anaerobic microbial communities showed that the pretreatment duration was directly proportional to the relative abundance of Tv at the beginning of digestion. When the initial Tv abundance was higher than 50%, Trichoderma became the absolute dominant fungus with an abundance higher than 97% in fungal communities in the later stage of digestion. The correlation network among fungi, bacteria, and archaea showed that Tv was directly related to 11 genera, and through these taxa, Tv affected 58% of the taxa in the whole microbial network. Cost accounting showed that Tv pretreatment has a net income of 45.5 CNY/1000 kg SMS, and is a promising technology. This study provides important guidance for the use of fungal chlamydospores in pretreatment and also promotes the understanding of fungi in anaerobic digestion. Full article

Despite ongoing advancements, cancer remains a significant global health concern, with a persistent challenge in identifying a definitive cure. While various cancer therapies have been developed and approved, offering treatments for smaller neoplasms, their efficacy diminishes in solid tumors and hypoxic environments, particularly for chemotherapy and radiation therapy. A novel approach, Clostridium-based therapy, has emerged as a promising candidate for current solid tumor treatments due to its unique affinity for the hypoxic tumor microenvironment. This review examines the potential of Clostridium in cancer treatment, encompassing direct tumor lysis, immune modulation, and synergistic effects with existing cancer therapies. Advancements in synthetic biology have further enhanced its potential through genetic modifications, such as the removal of alpha toxin gene from Clostridium novyi-NT, the implementation of targeted approaches, and reduction in systemic toxicity. Although preclinical and clinical studies have demonstrated that Clostridium-based treatments combined with other therapies hold promise for complete cancer eradication, challenges persist. Through this review, we also propose that the integration of various methods and technologies together with Clostridium-based therapy may lead to the complete eradication of cancer in the future. Full article

Weizmannia coagulans BC99, a Gram-positive, spore-forming, lactic acid-producing bacterium is renowned for its resilience and health-promoting properties, W. coagulans BC99 survives harsh environments, including high temperatures and gastric acidity, enabling effective delivery to the intestines. The consequences of chronic sleep deprivation (SD) include memory deficits and gastrointestinal dysfunction. In this study, a chronic sleep deprivation cognitive impairment model was established by using a sleep deprivation instrument and W. coagulans BC99 was given by gavage for 4 weeks to explore the mechanism by which BC99 improves cognitive impairment in sleep-deprived mice. BC99 improved cognitive abnormalities in novel object recognition tests induced by chronic sleep deprivation and showed behavior related to spatial memory in the Morris water maze test. W. coagulans BC99 reduced the heart mass index of sleep-deprived mice, increased the sleep-related neurotransmitters 5-HT and DA, decreased corticosterone and norepinephrine, and increased alpha diversity and community similarity. It reduced the abundance of harmful bacteria such as Olsenella, increased the abundance of beneficial bacteria such as Lactobacillus and Bifidobacterium, and promoted the production of short-chain fatty acids (SCFAs). W. coagulans BC99 also inhibits LPS translocation and the elevation of peripheral inflammatory factors by maintaining the integrity of the intestinal barrier and inhibiting the expression of the NLRP3 signaling pathway in the jejunum, thereby inhibiting the NLRP3 inflammasome in the brain of mice and reducing inflammatory factors in the brain, providing a favorable environment for the recovery of cognitive function. The present study confirmed that W. coagulans BC99 ameliorated cognitive impairment in chronic sleep-deprived mice by improving gut microbiota, especially by promoting SCFAs production and inhibiting the NLRP3 signaling pathway in the jejunum and brain. These findings may help guide the treatment of insomnia or other sleep disorders through dietary strategies. Full article

Honey, a super-saturated solution produced by Apis mellifera, is well-known for its historical medicinal uses, as well as culinary applications. Comprising sugars, phenols, enzymes, and more, its complex composition contributes to its medicinal properties. The microbiome, dominated by spore-forming bacteria and yeasts, is also a crucial factor in the health benefit properties of honey. The identification of the microbiome of honeys contributes to a better understanding of their microbial landscape and health-benefit properties and is also relevant to the environmental aspect. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is emerging as a key tool for microbial identification, but challenges remain in ensuring accuracy under different conditions. This study focuses on developing optimal conditions for microbial isolation and culture, aiming to balance diversity and avoid negative effects on identification. It further has the objective of evaluating the influence of geographic and botanical factors on the composition and diversity of the honey microbiome. Full article