Hg2+ removal characteristics of a strain of mercury-tolerant bacteria screened from heavy metal-contaminated soil in a molybdenum-lead mining area.

In this study, the mercury-tolerant strain LTC105 was isolated from a contaminated soil sample collected from a molybdenum-lead mine in Luanchuan County, Henan Province, China. The strain was shown to be highly resistant to mercury, with a minimum inhibitory concentration (MIC) of 32 mg·L-1. After a 24-h incubation in LB medium with 10 mg·L-1 Hg2+, the removal, adsorption, and volatilization rates of Hg2+ were 97.37%, 7.3%, and 90.07%, respectively, indicating that the strain had significant influence on mercury removal. Based on the results of Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), the investigation revealed that the primary function of LTC105 was to encourage the volatilization of mercury. The LTC105 strain also showed strong tolerance to heavy metals such as Mn2+, Zn2+, and Pb2+. According to the results of the soil incubation test, the total mercury removal rate of the LTC105 inoculation increased by 16.34% when the initial mercury concentration of the soil was 100 mg·L-1 and by 62.28% when the initial mercury concentration of the soil was 50 mg·kg-1. These findings indicate that LTC105 has certain bioremediation ability for Hg-contaminated soil and is a suitable candidate strain for microbial remediation of heavy metal-contaminated soil in mining areas.

Bacterial metabolic engineering for the production of second-generation (2 G) bioethanol and biobutanol; a review.

The second generation (2 G) biofuels were introduced to solve the issues associated with first-generation biofuel (dependency on food materials) and fossil fuels, such as reservoirs diminution, high demand, price fluctuation, and lethal greenhouse gases emission. Butanol and ethanol are the main 2 G biofuels. They are used as a disinfectant, antiseptic, and chemical solvent in the pharmaceutical, plastic, textiles, cosmetics, and fuel industries. Currently, their bacterial biological production from lignocellulosic material at the industrial level with primitive microorganisms is under development and not economical and qualitative compatible as compared to that of fossil origin, due to the slow growth rate, low titer, recalcitrant nature of lignocellulose, strain intolerance to a higher amount of butanol and ethanol, and strain inability to tolerate inhibitors accumulated during pretreatment of lignocellulosic materials. Therefore, metabolic engineering strategies such as redirection of carbon flux, knocking out competing pathways, enhancing strain robustness and wide range of substrate utilization ability, and overexpression of enzymes involved in their biological synthesis have been applied to bacteria for enhancing their ability for 2 G ethanol and butanol production in a highly cost-effective amount from lignocellulosic materials. Herein, we summarized and reviewed the progress in metabolic engineering of bacterial species such as Clostridium spp,Escherichia coli, and Zymomonas mobilis for the synthesis of 2 G butanol and ethanol, especially from lignocellulosic materials.

Inhibitory activity of aromatic plant extracts against dairy-related Clostridium species and their use to prevent the late blowing defect of cheese.

The aim of the present work was the selection of aromatic plant essential oils (EOs) and/or ethanolic extracts (EEs) to prevent the late blowing defect (LBD) of cheese caused by Clostridium spp. EEs resulted more effective than EOs to inhibit dairy-borne Clostridium spp. in vitro. Savory, hyssop, lavender and tarragon EEs, which showed the lowest minimal inhibitory concentration against Clostridium tyrobutyricum, were selected to study the prevention of LBD caused by this bacterium in cheese. Addition of savory and lavender EEs to cheese milk delayed LBD by 2 weeks, but at the end of ripening these cheeses showed similar clostridial vegetative cells counts, spoilage symptoms and propionic, and butyric acids levels than blown control cheese. Tarragon EE, with the highest content in caffeic acid, also delayed LBD by 2 weeks, but it was more effective to inhibit Clostridium, since cheese with tarragon EE showed minor LBD symptoms, lower vegetative cells count and lower concentrations of propionic and butyric acids than the rest of cheeses made with EEs. This fact could be also attributable to the greater number of antimicrobial terpenes (1,8-cineole, 4-terpineol, α-terpineol, isoelemicin, methyl eugenol, and methyl trans-isoeugenol) detected in this cheese. This is the first report on the application of EEs to control C. tyrobutyricum in cheese.

Clostridium species diversity in gut microbiota of patients with renal failure.

The Pathology of digestive tract has long been known to be correlated with chronic kidney disease (CKD). The member of the major Firmicutes phylum especially Clostridium subcluster XIVa altered quantitatively and qualitatively in the gut microbiota of patients with End Stage Renal Disease (ESRD) and CKD. Therefore, in this study, the abundance of the species of Clostridium genus of Firmicutes phylum compared between intestine microbiota of patients with kidney failure and healthy individual. Fresh fecal specimens of 20 patients at different stages of CKD and 20 healthy individuals were collected. Bacterial DNA of samples were extracted to use for 16S ribosomal DNA sequencing targeting the V3-V4 region. Next generation sequencing (NGS) method at MiSeq system was used to find the diversity of gut microbiota composition. Totally, 11 (1.68%) of 651 bacterial strains which were isolated from forty fecal samples of both healthy volunteers and CKD/ESRD patients, were identified as Clostridium species. Eight genera of 11 Clostridium genera were related to Clostridium sensu stricto, and 3 other genera were as follows Vallitalea, Acidaminobacter and Caloramator. Among both group, the highest abundance was dedicated to Clostridium celatum genera. Sarcina maxima were not identified. The composition of Clostridium spp. showed the same frequency among CKD/ESRD and healthy groups (p < 0.05). The abundance of Clostridium spp. is virtually the same and not differs among healthy individuals and CKD/ESRD patients. Results of the present indicate despite of critical role of gut microbiota, some pathogens and their metabolites have no role on hemostasis and pathogenesis of kidney disorders.

Culture and genome-based analysis of four soil Clostridium isolates reveal their potential for antimicrobial production.

BACKGROUND: Soil bacteria are a major source of specialized metabolites including antimicrobial compounds. Yet, one of the most diverse genera of bacteria ubiquitously present in soil, Clostridium, has been largely overlooked in bioactive compound discovery. As Clostridium spp. thrive in extreme environments with their metabolic mechanisms adapted to the harsh conditions, they are likely to synthesize molecules with unknown structures, properties, and functions. Therefore, their potential to synthesize small molecules with biological activities should be of great interest in the search for novel antimicrobial compounds. The current study focused on investigating the antimicrobial potential of four soil Clostridium isolates, FS01, FS2.2 FS03, and FS04, using a genome-led approach, validated by culture-based methods. RESULTS: Conditioned/spent media from all four Clostridium isolates showed varying levels of antimicrobial activity against indicator microorganism; all four isolates significantly inhibited the growth of Pseudomonas aeruginosa. FS01, FS2.2, and FS04 were active against Bacillus mycoides and FS03 reduced the growth of Bacillus cereus. Phylogenetic analysis together with DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), and functional genome distribution (FGD) analyses confirmed that FS01, FS2.2, and FS04 belong to the species Paraclostridium bifermentans, Clostridium cadaveris, and Clostridium senegalense respectively, while FS03 may represent a novel species of the genus Clostridium. Bioinformatics analysis using antiSMASH 5.0 predicted the presence of eight biosynthetic gene clusters (BGCs) encoding for the synthesis of ribosomally synthesized post-translationally modified peptides (RiPPs) and non-ribosomal peptides (NRPs) in four genomes. All predicted BGCs showed no similarity with any known BGCs suggesting novelty of the molecules from those predicted gene clusters. In addition, the analysis of genomes for putative virulence factors revealed the presence of four putative Clostridium toxin related genes in FS01 and FS2.2 genomes. No genes associated with the main Clostridium toxins were identified in the FS03 and FS04 genomes. CONCLUSIONS: The presence of BGCs encoding for uncharacterized RiPPs and NRPSs in the genomes of antagonistic Clostridium spp. isolated from farm soil indicated their potential to produce novel secondary metabolites. This study serves as a basis for the identification and characterization of potent antimicrobials from these soil Clostridium spp. and expands the current knowledge base, encouraging future research into bioactive compound production in members of the genus Clostridium.

Spontaneous emphysematous splenitis: Radiographic and ultrasonographic findings in three Golden Retriever dogs.

Spontaneous emphysematous splenitis is a life-threatening condition reported rarely in humans; however, published reports in dogs are currently lacking. The aim of this multicentric, retrospective, case series design study was to describe radiographic and ultrasonographic imaging findings in Golden Retriever dogs diagnosed with spontaneous emphysematous splenitis. A total of three dogs were sampled. All dogs had a history of lethargy, diarrhea, and weight loss. Radiographic findings in all dogs included a mass effect with focal or multifocal coalescing "vesicular-like" gas pattern in the splenic region and focal loss of serosal detail. Ultrasonographic findings in all dogs included focal or multifocal irregularly shaped, hypoechoic areas containing a mixture of hyperechoic fluid and gas within the splenic parenchyma, hyperechoic abdominal free fluid, and generalized hyperechoic mesenteric fat without evidence of splenic torsion. Pneumoperitoneum was detected ultrasonographically and radiographically in two dogs. All three dogs underwent splenectomy and splenic torsion was definitively ruled out at surgery. One dog died three days after surgery, whereas the other two dogs recovered uneventfully. Culture of the splenic tissue and free abdominal fluid was positive for Clostridium spp. in all three cases. Findings supported inclusion of spontaneous emphysematous splenitis and septic peritonitis as differential diagnoses for dogs with this combination of clinical and imaging characteristics.

Gut microbial-derived butyrate is inversely associated with IgE responses to allergens in childhood asthma.

BACKGROUND: A comprehensive metabolomics-based approach to address the impact of specific gut microbiota on allergen sensitization for childhood rhinitis and asthma is still lacking. METHODS: Eighty-five children with rhinitis (n = 27) and with asthma (n = 34) and healthy controls (n = 24) were enrolled. Fecal metabolomic analysis with 1 H-nuclear magnetic resonance (NMR) spectroscopy and microbiome composition analysis by bacterial 16S rRNA sequencing were performed. An integrative analysis of their associations with allergen-specific IgE levels for allergic rhinitis and asthma was also assessed. RESULTS: Amino acid, ß-alanine, and butanoate were the predominant metabolic pathways in the gut. Among them, amino acid metabolism was negatively correlated with the phylum Firmicutes, which was significantly reduced in children with rhinitis and asthma. Levels of histidine and butyrate metabolites were significantly reduced in children with rhinitis (P = 0.029) and asthma (P = 0.009), respectively. In children with asthma, a reduction in butyrate-producing bacteria, including Faecalibacterium and Roseburia spp., and an increase in Clostridium spp. were negatively correlated with fecal amino acids and butyrate, respectively (P < 0.01). Increased Escherichia spp. accompanied by increased ß-alanine and 4-hydroxybutyrate appeared to reduce butyrate production. Low fecal butyrate was significantly associated with increased total serum and mite allergen-specific IgE levels in children with asthma (P < 0.05). CONCLUSION: A reduced fecal butyrate is associated with increased mite-specific IgE levels and the risk of asthma in early childhood. Fecal ß-alanine could be a specific biomarker connecting the metabolic dysbiosis of gut microbiota, Clostridium and Escherichia spp., in childhood asthma.

Dairy farm management practices and the risk of contamination of tank milk from Clostridium spp. and Paenibacillus spp. spores in silage, total mixed ration, dairy cow feces, and raw milk.

The occurrence of Paenibacillus and Clostridium spores in silage is of great concern for dairy producers because their spores can contaminate milk and damage processed milk and semi-hard cheeses. Spoiled silage is considered to be the main contamination source of the total mixed ration (TMR), feces of dairy cows, and consequently bulk tank milk via the contamination of cow teats by dirt during milking. The presence of an anaerobic and facultative anaerobic sporeformer population in different matrices (soil, corn silage, other feeds, TMR, feces, and milk) and its transmission pathway has been studied on 49 dairy farms by coupling plate count data with 16S-DNA identification. The different matrices have shown a high variability in the anaerobic and facultative anaerobic spore count, with the highest values being found in the aerobically deteriorated areas of corn silages. Clostridium tyrobutyricum, Paenibacillus macerans, and Paenibacillus thermophilus were detected in all the matrices. The TMR spore count was influenced by the amount of spoiled corn silage in the TMR and by the care taken when cleaning the spoiled silage before feed-out. Most of the farms that prevent the presence of visible moldy silage in the silo and carefully clean to remove molded spots were able to maintain their TMR spore counts below 4.0 log spores/g. When a level of 4.5 log spores/g of TMR was exceeded, the feces presented a greater contamination than 3.0 log spores/g. Moreover, the higher the number of spores in the feces was, the higher the number of spores in the milk. Most of the farms that presented a feces contamination greater than 5.0 log spores/g had a higher milk spore contamination than 1,000 spores/L. Careful animal cleaning and good milking practices have been found to be essential to maintain low levels of contamination in bulk tank milk, but it has emerged that only by coupling these practices with a correct silage management and cleaning during TMR preparation can the contamination of milk by spores be kept at a low level. It has been found that aerobically deteriorated silage has a great capacity to contaminate TMR and consequently to increase the risk of milk spore contamination, even when routine milking practices are adopted correctly.

Enrichment of antibiotic resistance genes in soil receiving composts derived from swine manure, yard wastes, or food wastes, and evidence for multiyear persistence of swine Clostridium spp.

The impact of amendment with swine manure compost (SMC), yard waste compost (YWC), or food waste compost (FWC) on the abundance of antibiotic resistance genes in soil was evaluated. Following a commercial-scale application of the composts in a field experiment, soils were sampled periodically for a decade, and archived air-dried. Soil DNA was extracted and gene targets quantified by qPCR. Compared with untreated control soil, all 3 amendment types increased the abundance of gene targets for up to 4 years postapplication. The abundance of several gene targets was much higher in soil amended with SMC than in soil receiving either YWC or FWC. The gene target ermB remained higher in the SMC treatment for a decade postapplication. Clostridia were significantly more abundant in the SMC-amended soil throughout the decade following application. Eight percent of Clostridium spp. isolates from the SMC treatment carried ermB. Overall, addition of organic amendments to soils has the potential to increase the abundance of antibiotic resistance genes. Amendments of fecal origin, such as SMC, will in addition entrain bacteria carrying antibiotic resistance genes. Environmentally recalcitrant clostridia, and the antibiotic resistance genes that they carry, will persist for many years under field conditions following the application of SMC.

Comparative pathogenesis of enteric clostridial infections in humans and animals.

Several enteric clostridial diseases can affect humans and animals. Of these, the enteric infections caused by Clostridium perfringens and Clostridium difficile are amongst the most prevalent and they are reviewed here. C. perfringens type A strains encoding alpha toxin (CPA) are frequently associated with enteric disease of many animal mammalian species, but their role in these diseased mammals remains to be clarified. C. perfringens type B encoding CPA, beta (CPB) and epsilon (ETX) toxins causes necro-hemorrhagic enteritis, mostly in sheep, and these strains have been recently suggested to be involved in multiple sclerosis in humans, although evidence of this involvement is lacking. C. perfringens type C strains encode CPA and CPB and cause necrotizing enteritis in humans and animals, while CPA and ETX producing type D strains of C. perfringens produce enterotoxemia in sheep, goats and cattle, but are not known to cause spontaneous disease in humans. The role of C. perfringens type E in animal or human disease remains poorly defined. The newly revised toxinotype F encodes CPA and enterotoxin (CPE), the latter being responsible for food poisoning in humans, and the less prevalent antibiotic associated and sporadic diarrhea. The role of these strains in animal disease has not been fully described and remains controversial. Another newly created toxinotype, G, encodes CPA and necrotic enteritis toxin B-like (NetB), and is responsible for avian necrotic enteritis, but has not been associated with human disease. C. difficile produces colitis and/or enterocolitis in humans and multiple animal species. The main virulence factors of this microorganism are toxins A, B and an ADP-ribosyltransferase (CDT). Other clostridia causing enteric diseases in humans and/or animals are Clostridium spiroforme, Clostridium piliforme, Clostridium colinum, Clostridium sordellii, Clostridium chauvoei, Clostridium septicum, Clostridium botulinum, Clostridium butyricum and Clostridium neonatale. The zoonotic transmission of some, but not all these clostridsial species, has been demonstrated.

Identification of Clostridium spp. derived from a sheep and cattle slaughterhouse by matrix-assisted laser desorption and ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rDNA sequencing.

Clostridia are widespread and some of them are serious human pathogens. Identification of Clostridium spp. is important for managing microbiological risks in the food industry. Samples derived from sheep and cattle carcasses from a slaughterhouse in Iran were analyzed by MALDI-TOF MS using direct transfer and extended direct transfer sample preparation methods and 16S rDNA sequencing. MALDI-TOF MS could identify ten species in 224 out of 240 Clostridium isolates. In comparison to the 16S rDNA sequencing, correct identification rate of the Clostridium spp. at the species level by MALDI-TOF MS technique was 93.3%. 16 isolates were not identified by MALDI-TOF MS but 16s rDNA sequencing identified them as C. estertheticum, C. frigidicarnis, and C. gasigenes species. The most frequently identified Clostridium species were: C. sporogenes (13%), C. cadaveris (12.5%), C. cochlearium (12%) and C. perfringens (10%). Extended direct transfer method [2.26 ± 0.18 log (score)] in comparison to direct transfer method [2.15 ± 0.23 log (score)] improved Clostridium spp. IDENTIFICATION: Using a cut-off score of 1.7 was sufficient for accurate identification of Clostridium species. MALDI-TOF MS identification scores for Clostridium spp. decreased with longer incubation time. Clostridium species predominantly were isolated from carcasses after skinning and evisceration steps in the slaughterhouse. MALDI-TOF MS could be an accurate way to identify Clostridium species. Moreover, continuous improvement of the database and MALDI-TOF MS instrument enhance its performance in food control laboratories.

The remarkable Dr Robertson.

Muriel Robertson (1883-1973) was a pioneering protozoologist who made a staggering number of important contributions to the fields of parasitology, bacteriology and immunology during her career, which spanned nearly 60 years. These contributions were all the more remarkable given the scientific and social times in which she worked. While Muriel is perhaps best known for her work on the life cycle and transmission of the African trypanosome, Trypanosoma brucei, which she carried out in Uganda at the height of a major Sleeping Sickness epidemic, her work on the Clostridia during the First and Second World Wars made significant contributions to the understanding of anaerobes and to the development of anti-toxoid vaccines, and her work on the immunology of Trichomonas foetus infections in cattle, carried out in collaboration with the veterinarian W. R. Kerr, resulted in changes in farming practices that very quickly eradicated trichomoniasis from cattle herds in Northern Ireland. The significance of her work was recognized with the award of Fellow of the Royal Society in 1947 and an Honorary Doctorate of Law from the University of Glasgow, where she had earlier studied, in 1948.

The microbiology of beef carcasses and primals during chilling and commercial storage.

The primary objective of this study was to characterise (microbiology and physical parameters) beef carcasses and primals during chilled storage. A minor aim was to compare observed growth of key spoilage bacteria on carcasses with that predicted by ComBase and the Food Safety Spoilage Predictor (FSSP). Total viable count (TVC), total Enterobacteriacae count (TEC), Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and Clostridium spp. were monitored on beef carcasses (n = 30) and primals (n = 105) during chilled storage using EC Decision 2001/471/EC and ISO sampling/laboratory procedures. The surface and/or core temperature, pH and water activity (aw) were also recorded. Clostridium (1.89 log10 cfu/cm2) and Pseudomonas spp. (2.12 log10 cfu/cm2) were initially the most prevalent bacteria on carcasses and primals, respectively. The shortest mean generation time (G) was observed on carcasses with Br. thermosphacta (20.3 h) and on primals with LAB (G = 68.8 h) and Clostridium spp. (G = 67 h). Over the course of the experiment the surface temperature decreased from 37 °C to 0 °C, pH from 7.07 to 5.65 and aw from 0.97 to 0.93 The observed Pseudomonas spp. and Br. thermosphacta growth was more or less within the range of predictions of Combase. In contrast, the FSSP completely overestimated the growth of LAB. This study contributes to the very limited microbiological data on beef carcasses and primals during chilling.

Productive performance of weanling piglets was improved by administration of a mixture of bacteriophages, targeted to control Coliforms and Clostridium spp. shedding in a challenging environment.

This study was conducted to investigate the effects of bacteriophages in different environments on growth performance, digestibility, ileal and caecal microbiota, gut morphology and immunity of weanling pigs. Two hundred piglets were randomly assigned to four treatment groups with five replicate pens with 10 pigs per pen. A 2 × 2 factorial arrangement of treatments was used to investigate the response of weanling pigs to supplemental bacteriophages (0 and 1.0 g/kg of diet) in contaminated or hygienic environments. Bacteriophages supplementation did not affect average daily gain (ADG), average daily feed intake (ADFI) and gain:feed in phases I and III; however, there was a significant improvement in ADG and gain:feed in phase II. The supplementation of bacteriophages increased the overall gain:feed of pigs. The overall result showed a greater ADG and ADFI in hygienic room. There were reductions in population of both ileal (p < 0.05) and caecal (p < 0.01) Clostridium spp. and ileal coliforms (p < 0.01) with the inclusion of bacteriophages in the diet. Bacteriophages increased ileal Lactobacillus and caecal Bifidobacterium and tended to increase ileal Bifidobacterium (p = 0.08). Contaminated environment decreased ileal Lactobacillus and caecal Bifidobacterium and tended to increase ileal Clostridium (p = 0.08) and coliforms (p = 0.08). Total anaerobic bacteria was tended to decrease (p = 0.06) in contaminated environment. Jejunal villus height increased in pigs received bacteriophages, but they did not affect other morphological items. The interaction between bacteriophages and environment tended to be significant (p = 0.06) for ileal villus height and ileal villus height to crypt depth ratio. The overall faecal score was significantly greater in hygienic environment and bacteriophages groups. The present findings indicate that there is an interactive effect on feed efficiency between bacteriophages and contaminated environment. In addition, bacteriophages improve jejunum morphology, and intestinal microbiota of pigs.

Positive effect of phasin in biohydrogen production of non polyhydroxybutyrate-producing Clostridium acetobutylicum ATCC 824.

In this study, the goal was to enhance the tolerance of Clostridium acetobutylicum ATCC 824 to biomass-based inhibitory compounds for biohydrogen production and evaluate various known genes that enhance the production of biochemicals in various hosts. The introduction of phaP, the major polyhydroxyalkanoate granule-associated protein that has been reported as a chaperone-like protein resulted in increased tolerance to inhibitors and leads to higher levels of hydrogen production, cell growth, and glucose consumption in the presence of these inhibitors. It was observed that the introduction of phaP led to an increase in the transcription of the hydrogenase gene, whereas transcription of the chaperone functional genes decreased compared to the wild type. Finally, the introduction of phaP could significantly enhance biohydrogen production by 2.6-fold from lignocellulosic hydrolysates compared to that of wild type. These findings suggested that the introduction of phaP could enhance growth and biohydrogen production, even in non-polyhydroxyalkanoate-producing strains.

Multiplex-PCR Detection of Clostridium tyrobutyricum, Clostridium butyricum, and Clostridium sporogenes in Raw Milk for Cheesemaking.

Late blowing defects in semi-hard and hard cheeses caused by spore-forming clostridia (e.g., Clostridium tyrobutyricum, Clostridium butyricum, Clostridium sporogenes) pose a major issue for the dairy industry. With this study, we applied a multiplex PCR for the rapid and simultaneous detection of clostridia in raw milk for cheese production. Spore detection in milk usually relies on culture-dependent methods, among which the most probable number (MPN) technique is sensitive but time-consuming and nonspecific. We tested two PCR-based protocols: the one entailed direct milk analysis with results obtained within 24 h; the other included an enrichment step and gave results within 72 h. The second protocol was found to be more sensitive; it detected concentrations as low as 100 cells/L for C. sporogenes and C. butyricum and 800 cells/L for C. tyrobutyricum. Both protocols were applied to field samples (211 samples underwent protocol no. 1; 117 samples underwent protocol no. 2) collected from four dairy processing plants in Piedmont. The prevalence of C. butyricum (protocol no. 1: 9.5%; protocol no. 2: 23%) was higher than either C. sporogenes (0%; 9.4%) or C. tyrobutyricum (0%; 6.8%). Protocol no. 2 detected multiple targets in eight samples, indicating that more than one microorganism was present. Our findings underscore the importance of implementing preventive measures and early detection strategies to mitigate the risk of cheese spoilage due to clostridial contamination.

Health Hazard Associated with the Presence of Clostridium Bacteria in Food Products.

Clostridium bacteria were already known to Hippocrates many years before Christ. The name of the Clostridium species is owed to the Polish microbiologist, Adam Prazmowski. It is now known that these Clostridium bacteria are widespread in the natural environment, and their presence in food products is a threat to human health and life. According to European Food Safety Authority (EFSA) reports, every year, there are poisonings or deaths due to ingestion of bacterial toxins, including those of the Clostridium spp. The strengthening of consumer health awareness has increased interest in consuming products with minimal processing in recent years, which has led to a need to develop new techniques to ensure the safety of microbiological food, including elimination of bacteria from the Clostridium genera. On the other hand, the high biochemical activity of Clostridium bacteria allows them to be used in the chemical, pharmaceutical, and medical industries. Awareness of microbiological food safety is very important for our health. Unfortunately, in 2022, an increase in infections with Clostridium bacteria found in food was recorded. Knowledge about food contamination should thus be widely disseminated.

Clean labelling sodium nitrite at pilot scale: In-situ reduction of nitrate from plant sources and its effects on the overall quality and safety of restructured cooked ham.

Growing health and environmental concerns have increased demand for all-natural products, with a focus on clean labelling. Sodium nitrite is the most widely used additive in the meat industry because it imparts the typical cured flavour and colour to meat products and, most importantly, their microbiological safety. However, due to health concerns, the European Commission is proposing revised regulations to reduce nitrate and nitrite levels in meat products. As a result, the meat industry is actively seeking alternatives. This study explored the production of four cooked hams utilising nitrate-rich vegetable sources combined with two different nitrate-reducing commercial food cultures, alongside a control ham prepared with sodium nitrite (150 ppm). Microbiological, physico-chemical (pH, water activity, nitrate and nitrite concentration, lipid profile, lipid oxidation) and sensory (texture and colour profile) characterisation of the products was carried out. Challenge tests for Listeria monocytogenes, Clostridium sporogenes and Clostridium perfringens have been performed to assess the growth of pathogens, if present in the products. Results revealed comparable microbiological and physico-chemical profiles across ham formulations, with minor differences observed in colour parameters for sample C. The sensory analysis showed that for the pilot ham formulations A and D, there were no significant differences in consumer perception compared to the control ham. In the challenge tests, L. monocytogenes levels were similar in both control and tested hams. There were no significant differences in C. sporogenes and C. perfringens counts at any temperature or between test and control samples. These results indicate that this technology has a potential future in the cured meat sector, as regulators mandate the reduction of added synthetic chemicals and consumers seek healthier and more natural ingredients in their daily diets.

Postpartum clostridial gangrenous metritis in 12 dairy goats in France.

Clostridial infections in goats have been associated frequently with enteric diseases or gas gangrene but very rarely with the reproductive system. We describe here 12 cases of fatal postpartum gangrenous metritis in does associated with infection by several clostridial species. Clinically, these cases were characterized by rapid onset of hyperthermia followed by death after kidding. On postmortem examination, the uteri appeared to be necrotic and were hemorrhagic and edematous. Microscopically, the uteri had diffuse coagulative necrosis, edema, hemorrhage, and fibrinous thrombi with intralesional gram-positive rods. Clostridium perfringens was isolated from 7 of 9 uterine samples cultured, and C. perfringens, C. septicum, C. novyi, or C. chauvoei were demonstrated by immunohistochemistry (IHC) in the 5 cases examined. IHC for Paeniclostridium sordellii was negative in all 5 cases. PCR performed on 3 of the C. perfringens isolates was positive for alpha toxin and perfringolysin, identifying these isolates as type A. Clostridial infection should be considered in cases of postpartum gangrenous metritis of does.

Boosting ethanol production rates from carbon dioxide in MES cells under optimal solventogenic conditions.

Microbial Electrosynthesis (MES) has been widely applied for acetic acid (HA) production from CO2 and electricity. Ethanol (EtOH) has a higher market value than HA, and wide application in industry and as a biofuel. However, it has only been obtained sporadically and at low concentrations, probably due to sub-optimal operating conditions. This study aimed at enhancing EtOH productivity in MES cells by jointly optimising key operation parameters, including pH, H2 and CO2 partial pressure (pH2 and pCO2), and HA concentration, to promote solventogenesis. Two H-type cells were operated in fed-batch mode at -0.8 V vs. SHE with CO2 as the sole carbon source. A mixed culture, enriched with Clostridium ljungdahlii was used as the biocatalyst. The combination of low pH (<4.5) and pCO2 (<0.3 atm), along with high HA concentration (about 6 g L-1) and pH2 (>3 atm), were mandatory conditions for maintaining an efficient solventogenic culture, dominated by Clostridium sp., capable of high-rate EtOH production. The maximum EtOH production rate was 10.95 g m-2 d-1, and a concentration of 5.28 g L-1 was achieved. Up to 30 % of the electrons and 15.2 % of the carbon provided were directed towards EtOH production, and 28.1 kWh were required for the synthesis of 1 kg of EtOH from CO2. These results highlight that strict conditions are required for a continuous, reliable, EtOH production in MES cells. Future investigation should focus on improving cell configuration to achieve EtOH production at higher current densities while minimizing the electric energy input.