Quantification of Factors Which Influence Nisin's Inhibition of CIostridium botulinum 56A in a Model Food System

We modeled nisin's anticlostridial activity and assessed the antagonistic or potentiating influences of food ingredients. The model systems contained yeast extract, proteose peptone, and glucose; were supplemented with protein (0.075, 0.75, 7.5% w/v), phospholipid (0.075, 0.75, 7.5% w/v), or soluble starch (5, 17.5, 30% w/v); and were adjusted to pH 5.5, 6.0, or 6.5. Samples inoculated with 10⁴/mL spores were incubated at 15, 25, or 35°C. Statistical analysis developed an equation (r²= 0.76) that modeled the response and identified temperature as the most significant (α 0.001) variable. Nisin lost effectiveness with increasing temperature. Nisin concentration had significant positive and phospholipid negative, linear effects. Many interactive effects were significant (α 0.20). Nisin inhibited C. botulinum until its residual level dropped below a threshold, which decreased from 154 IU/mL at 35°C to 12 IU/mL at 15°C.     

Improved cellulase production by stable Clostridium cellulolyticum mutants

Methods for the production of mutants of the cellulase producer Clostridium cellulolyticum ATCC 35319 were examined using an agar plate screening technique. Spontaneous and UV light-induced mutants were isolated, some of which exhibited a high level of both endoglucanase and exoglucanase activities as assayed using CMC (carboxymethyl cellulose) and PNPCb (paranitrophenyi-β-cellobioside) respectively. The volumetric enzyme activities were up to 2.5 times those of the wild strain.     

The Multifunctional Sactipeptide Ruminococcin C1 Displays Potent Antibacterial Activity In Vivo as Well as Other Beneficial Properties for Human Health

The world is on the verge of a major antibiotic crisis as the emergence of resistant bacteria is increasing, and very few novel molecules have been discovered since the 1960s. In this context, scientists have been exploring alternatives to conventional antibiotics, such as ribosomally synthesized and post-translationally modified peptides (RiPPs). Interestingly, the highly potent in vitro antibacterial activity and safety of ruminococcin C1, a recently discovered RiPP belonging to the sactipeptide subclass, has been demonstrated. The present results show that ruminococcin C1 is efficient at curing infection and at protecting challenged mice from Clostridium perfringens with a lower dose than the conventional antibiotic vancomycin. Moreover, antimicrobial peptide (AMP) is also effective against this pathogen in the complex microbial community of the gut environment, with a selective impact on a few bacterial genera, while maintaining a global homeostasis of the microbiome. In addition, ruminococcin C1 exhibits other biological activities that could be beneficial for human health, as well as other fields of applications. Overall, this study, by using an in vivo infection approach, confirms the antimicrobial clinical potential and highlights the multiple functional properties of ruminococcin C1, thus extending its therapeutic interest.     

Ozone in the Laundry Industry—Practical Experiences in the United Kingdom

Since the early 1990s, the use of ozone in many commercial and industrial laundering applications has been evolving rapidly. Ozone allows washing to be conducted using cold water, thereby saving considerable heat energy and water consumption. Additionally, ozone enhances the wash process, resulting in a significant reduction in detergent dosage and number of rinses, thus saving water. Ozone/cold water cycles are gentler to fabrics, thus extending linen life. Finally, ozone/cold water laundering is beneficial for effluents, resulting in reductions in COD (chemical oxygen demand). Microorganisms are destroyed effectively in ozone-wash waters, and washing and drying cycles are shorter, thus saving labor. In this paper, the authors describe some specific case studies at commercial laundering installations in the UK, whereby the users of ozone have reaped major benefits, including enhanced microorganism kills/inactivation and significant cost savings.     

Clostridiumnovyi’s Alpha-Toxin Changes Proteome and Phosphoproteome of HEp-2 Cells

C. novyi type A produces the alpha-toxin (TcnA) that belongs to the large clostridial glucosylating toxins (LCGTs) and is able to modify small GTPases by N-acetylglucosamination on conserved threonine residues. In contrast, other LCGTs including Clostridioides difficile toxin A and toxin B (TcdA; TcdB) modify small GTPases by mono-o-glucosylation. Both modifications inactivate the GTPases and cause strong effects on GTPase-dependent signal transduction pathways and the consequent reorganization of the actin cytoskeleton leading to cell rounding and finally cell death. However, the effect of TcnA on target cells is largely unexplored. Therefore, we performed a comprehensive screening approach of TcnA treated HEp-2 cells and analyzed their proteome and their phosphoproteome using LC-MS-based methods. With this data-dependent acquisition (DDA) approach, 5086 proteins and 9427 phosphosites could be identified and quantified. Of these, 35 proteins were found to be significantly altered after toxin treatment, and 1832 phosphosites were responsive to TcnA treatment. By analyzing the TcnA-induced proteomic effects of HEp-2 cells, 23 common signaling pathways were identified to be altered, including Actin Cytoskeleton Signaling, Epithelial Adherens Junction Signaling, and Signaling by Rho Family GTPases. All these pathways are also regulated after application of TcdA or TcdB of C. difficile. After TcnA treatment the regulation on phosphorylation level was much stronger compared to the proteome level, in terms of both strength of regulation and the number of regulated phosphosites. Interestingly, various signaling pathways such as Signaling by Rho Family GTPases or Integrin Signaling were activated on proteome level while being inhibited on phosphorylation level or vice versa as observed for the Role of BRCA1 in DNA Damage Response. ZIP kinase, as well as Calmodulin-dependent protein kinases IV & II, were observed as activated while Aurora-A kinase and CDK kinases tended to be inhibited in cells treated with TcnA based on their substrate regulation pattern.     

几种香辛料精油对产气荚膜梭菌的体外抑菌效果

研究白芷精油、黑胡椒精油、茴香精油、肉桂精油、姜精油和艾草精油对产气荚膜梭菌（Clostridium perfringens,C.perfringens）的抑制作用,筛选出对产气荚膜梭菌有抑菌效果的香辛料精油。采用牛津杯法和两倍稀释法分别判定不同香辛料精油对C.perfringens（ATCC13124、CICC22949、C₁和C₂）的抑菌圈大小和最小抑菌浓度（Minimum inhibitory concentration,MIC）。结果显示:肉桂精油对C.perfringens的抑菌圈直径最大,且对产气荚膜梭菌ATCC13124、CICC22949、C₁和C₂的MIC分别为2.75、2.75、5.5、2.75 mg/m L;艾草精油对C.perfringens的MIC分别为11、2.75、11、2.75 mg/m L;黑胡椒精油对C.perfringens的MIC分别为22、11、11、5.5 mg/m L;茴香精油对C.perfringens的MIC分别为11、5.5、11、2.75 mg/m L;姜精油对C.perfringens的MIC分别为88、22、22、22 mg/m L。结论:除白芷精油以外,其他5种香辛料精油对C.perfringens均有不同程度的抑菌作用,其中肉桂精油对C.perfringens的抑菌效果最佳。      

Involvement of Clostridium gasigenes and C. algidicarnis in 'blown pack' spoilage of Brazilian vacuum-packed beef

The objectives of this study were to isolate psychrotrophic clostridia from Brazilian vacuum-packed beef cuts (spoiled or not) and to identify the isolates by using 16S rRNA gene sequencing. Anaerobic psychrotrophic microorganisms were also enumerated and samples were collected to verify the incidence of psychrotrophic clostridia in the abattoir environment. Vacuum-packed beef cuts (n = 8 grossly distended and n = 5 non-spoiled) and environmental samples were obtained from a beef packing plant located in the state of São Paulo, Brazil. Each sample was divided in three subsamples (exudate, beef surface and beef core) that were analyzed for vegetative forms, total spore-forming, and sulfide reducing spore-forming, both activated by alcohol and heat. Biochemical profiles of the isolates were obtained using API20A, with further identification using 16S rRNA gene sequencing. The growth temperature and the pH range were also assessed. Populations of psychrotrophic anaerobic vegetative microorganisms of up to 10¹⁰ CFU/(g, mL or 100 cm²) were found in ‘blown pack’ samples, while in non-spoiled samples populations of 10⁵ CFU/(g, CFU/mL or CFU/100cm²) was found. Overall, a higher population of total spores and sulfide reducing spores activated by heat in spoiled samples was found. Clostridium gasigenes (n = 10) and C. algidicarnis (n = 2) were identified using 16S rRNA gene sequencing. Among the ten C. gasigenes isolates, six were from spoiled samples (C1, C2 and C9), two were isolated from non-spoiled samples (C4 and C5) and two were isolated from the hide and the abattoir corridor/beef cut conveyor belt. C. algidicarnis was recovered from spoiled beef packs (C2). Although some samples (C3, C7, C10 and C14) presented signs of ‘blown pack’ spoilage, Clostridium was not recovered. C. algidicarnis (n = 1) and C. gasigenes (n = 9) isolates have shown a psychrotrophic behavior, grew in the range 6.2-8.2. This is the first report on the isolation of psychrotrophic Clostridium (C. gasigenes and C. algidicarnis) in Brazil. This study shows that psychrotrophic Clostridium may pose a risk for the stability of vacuum-packed beef produced in tropical countries during shelf-life and highlights the need of adopting control measures to reduce their incidence in abattoir and the occurrence of ‘blown pack’ spoilage.     

C.pasteurianum高产1,3-丙二醇菌株的选育及发酵培养基的研究(Ⅰ)

以淡水湖泊泥土中分离出的 13株梭菌 (Clostridium)为出发菌株 ,利用常规筛选方法选出 2株 1,3 丙二醇产生菌 (Clostridiumpasteurianum)。经UV、DES、NTG、EMS、LiCl单独及复合诱变 ,选育出一株 (CpN 38) 1,3 PD高产突变株。该突变株较出发菌株 ( 98- 77,98- 10 8) 1,3 PD产量提高了 7倍 ,产量为 31.0 0g/L。通过单因素实验 ,确定了CpN 38发酵培养基为 :甘油 ,90g/L ;NH4Cl,1.70g/L ;Fe2 +,0 .0 0 5 % ;Co2 +,0 .0 0 4 %。     

我国首例由丁酸梭菌引起婴儿E型肉毒中毒实验室诊断研究

目的对一起疑似婴儿肉毒中毒进行实验室诊断研究。方法对1例疑似婴儿肉毒中毒病例的粪便、食用过的食品和生活环境涂抹共计30份标本/样品进行梭菌分离鉴定及肉毒毒素检测,对分离菌株进行产毒试验。结果将患儿粪便标本培养物上清液腹腔注射小鼠后可致小鼠出现典型肉毒毒素中毒表现(竖毛、呼吸困难并出现典型的蜂腰、四肢麻痹),继而死亡,且培养物上清液经胰酶处理后毒性增强,表现为小鼠出现中毒及死亡时间较未处理组明显缩短。但培养物上清液经100℃加热处理后再次染毒动物,小鼠未出现中毒和死亡。混合型肉毒毒素诊断血清及单价抗E型肉毒毒素诊断血清可对小鼠起到保护作用。从患儿的粪便标本中分离到G~+芽胞杆菌,该菌在哥伦比亚血平板上呈不规则半透明扁平菌落,边缘根状生长,并携带E型肉毒毒素产毒基因,16S rRNA将其鉴定为丁酸梭菌,产毒试验结果显示该菌株可产E型肉毒毒素。结论该起婴儿中毒事件是由感染产E型肉毒毒素的丁酸梭菌引起。