肿瘤治疗中Clostridium novyi-NT的研究

联合细菌的溶瘤治疗(combined bacteriolytic therapy,COBALT)策略在实体瘤治疗中方兴未艾。此策略是将专性厌氧菌Clostridium novyi-NT联合传统放化疗药物治疗实体瘤,现处于临床Ⅰ期试验阶段。本文分别从有效性及安全性等方面总结了抗肿瘤细菌应具有的标准,并简述了C.novyi-NT的溶瘤机制。

Effects of dietary Clostridium butyricum and rumen protected fat on meat quality,oxidative stability,and chemical composition of finishing goats

Background Clostridium butyricum(CB)is a probiotic that can regulate intestinal microbial composition and improve meat quality.Rumen protected fat(RPF)has been shown to increase the dietary energy density and provide essential fatty acids.However,it is still unknown whether dietary supplementation with CB and RPF exerts beneficial effects on growth performance and nutritional value of goat meat.This study aimed to investigate the effects of dietary CB and RPF supplementation on growth performance,meat quality,oxidative stability,and meat nutritional value of finishing goats.Thirty-two goats(initial body weight,20.5±0.82 kg)were used in a completely randomized block design with a 2 RPF supplementation(0 vs.30 g/d)×2 CB supplementation(0 vs.1.0 g/d)factorial treatment arrangement.The experiment included a 14-d adaptation and 70-d data and sample collection period.The goats were fed a diet consisted of 400 g/kg peanut seedling and 600 g/kg corn-based concentrate(dry matter basis).Result Interaction between CB and RPF was rarely observed on the variables measured,except that shear force was reduced(P<0.05)by adding CB or RPF alone or their combination;the increased intramuscular fat(IMF)content with adding RPF was more pronounced(P<0.05)with CB than without CB addition.The pH24h(P=0.009),a*values(P=0.007),total antioxidant capacity(P=0.050),glutathione peroxidase activities(P=0.006),concentrations of 18:3(P<0.001),20:5(P=0.003)and total polyunsaturated fatty acids(P=0.048)were increased,whereas the L*values(P<0.001),shear force(P=0.050)and malondialdehyde content(P=0.044)were decreased by adding CB.Furthermore,CB supplementation increased essential amino acid(P=0.027),flavor amino acid(P=0.010)and total amino acid contents(P=0.024)as well as upregulated the expression of lipoprotein lipase(P=0.034)and peroxisome proliferator-activated receptorγ(PPARγ)(P=0.012),and downregulated the expression of stearoyl-CoA desaturase(SCD)(P=0.034).The RPF supplementation increased dry matter intake(P=0.005),averaged daily gain(trend,P=0.058),hot carcass weight(P=0.046),backfat thickness(P=0.006),concentrations of 16:0(P<0.001)and c9-18:1(P=0.002),and decreased the shear force(P<0.001),isoleucine(P=0.049)and lysine content(P=0.003)of meat.In addition,the expressions of acetyl-CoA carboxylase(P=0.003),fatty acid synthase(P=0.038),SCD(P<0.001)and PPARγ(P=0.022)were upregulated due to RPF supplementation,resulting in higher(P<0.001)content of IMF.Conclusions CB and RPF could be fed to goats for improving the growth performance,carcass traits and meat quality,and promote fat deposition by upregulating the expression of lipogenic genes of Longissimus thoracis muscle.

Clostridium novyi-NT in cancer therapy

The attenuated anaerobic bacterium Clostridium novyi-NT(C.novyi-NT)is known for its ability to precisely germinate in and eradicate treatment-resistant hypoxic tumors in various experimental animal models and spontaneously occurring canine sarcomas.In this article,we review the therapeutic and toxicologic aspects of C.novyi-NT therapy,key challenges and limitations,and promising strategies to optimize its performance via recombinant DNA technology and immunotherapeutic approaches,to establish C.novyi-NT as an essential tool in cancer therapy.

Detection, Biochemical and Molecular Characterization of Clostridium sporogens in Nono: A Nigerian Traditionally Fermented Yoghurt Drink

Nono is a traditionally fermented milk drink commonly consumed in the Northern parts of Nigeria. It is produced through the spontaneous fermentation of raw cow milk by Lactic Acid Bacteria (LAB), a process that could result to the contamination of the product with such pathogenic organisms as Clostridia spp. The aim of this research was therefore to determine the incidence of Clostridia species in thirty-two (32) ready-to-drink nono samples collected directly from a number of Fulani vendors in randomly selected locations within the Federal Capital Territory (FCT), Abuja, Nigeria. Isolated organisms were further subjected to some morphological and biochemical characterizations using standard microbiological procedures. The results obtained indicate that fourteen (14) isolates were putatively identified to be Clostridium sp., out of which five (5) isolates were confirmed to be Clostridium sporogens by a BLAST analysis of their respective 16SrRNA nucleotide sequence. It was concluded that, the detection of these pathogenic strains in frequently consumed product like nono could pose a public health risk and proactive measures to prevent an outbreak of food borne illness from nono consumption, were recommended.

Efficient reduction ofβ-lactoglobulin allergenicity in milk using Clostridium tyrobutyricum Z816

Milk allergy is one of the most common food allergies,affecting 6%of young children,andβ-lactoglobulin(β-LG)is the main milk allergen.Clostridium tyrobutyricum Z816 was selected for the degradation ofβ-LG,which was successfully reduced by about 90%using permeabilized bacteria under the optimized conditions.The hydrolyzed peptides were identified by liquid chromatography-tandem mass spectrometry(LC-MS/MS)and analyzed by molecular modeling,which indicated that C.tyrobutyricum Z816 could effectively degrade the antigenic epitopes ofβ-LG.Finally,the concentration and digestibility ofβ-LG in actual samples was quantified using enzyme-linked immunosorbent assay(ELISA)and gastrointestinal digestion simulation experiments.The results showed more than 92%ofβ-LG in actual samples was hydrolyzed,and the gastric and total digestibility of whey protein isolate(WPI)was improved by 85.96%and 64.51%,respectively.Therefore,C.tyrobutyricum Z816 offers an effective method to degradeβ-LG and reduce the occurrence of milk allergies,which has great significance for the development of hypoallergenic dairy products.

Clostridium perfringens gas gangrene caused by closed abdominal injury: A case report and review of the literature

BACKGROUND Abdominal Clostridium perfringens(C. perfringens) gas gangrene is a rare infection that has been described in the literature as most frequently occurring in postoperative patients with open trauma. Intra-abdominal gas gangrene caused by C.perfringens infection after closed abdominal injury is extremely rare, difficult to diagnose, and progresses rapidly with high mortality risk. Here, we report a case of C. perfringens infection caused by closed abdominal injury.CASE SUMMARY A 54-year-old male suffered multiple intestinal tears and necrosis after sustaining an injury caused by falling from a high height. These injuries and the subsequent necrosis resulted in intra-abdominal C. perfringens infection. In the first operation,we removed the necrotic intestinal segment, kept the abdomen open and covered the intestine with a Bogota bag. A vacuum sealing drainage system was used to cover the outer layer of the Bogota bag, and the drainage was flushed under negative pressure. The patient was transferred to the intensive care unit for supportive care and empirical antibiotic treatment. The antibiotics were not changed until the results of bacterial culture and drug susceptibility testing were obtained.Two consecutive operations were then performed due to secondary intestinal necrosis. After three definitive operations, the patient successfully survived the perioperative period. Unfortunately, he died of complications related to GuillainBarre syndrome 75 d after the first surgery. This paper presents this case of intraabdominal gas gangrene infection and analyzes the diagnosis and treatment based on a review of current literature.CONCLUSION When the intestines rupture leading to contamination of the abdominal cavity by intestinal contents, C. perfringens bacteria normally present in the intestinal tract may proliferate in large numbers and lead to intra-abdominal infection. Prompt surgical intervention, adequate drainage,appropriate antibiotic therapy, and intensive supportive care comprise the most effective treatment strategy. If the abdominal cavity is heavily contaminated, an open abdominal approach may be a beneficial treatment.

Supplemental Clostridium butyricum modulates lipid metabolism by reshaping the gut microbiota composition and bile acid profile in IUGR suckling piglets

Background Intrauterine growth restriction(IUGR)can cause lipid disorders in infants and have long-term adverse effects on their growth and development.Clostridium butyricum(C.butyricum),a kind of emerging probiotics,has been reported to effectively attenuate lipid metabolism dysfunctions.Therefore,the objective of this study was to investigate the effects of C.butyricum supplementation on hepatic lipid disorders in IUGR suckling piglets.Methods Sixteen IUGR and eight normal birth weight(NBW)neonatal male piglets were used in this study.From d 3to d 24,in addition to drinking milk,the eight NBW piglets(NBW-CON group,n=8)and eight IUGR piglets(IUGR-CON group,n=8)were given 10 mL sterile saline once a day,while the remaining IUGR piglets(IUGR-CB group,n=8)were orally administered C.butyricum at a dose of 2×108colony-forming units(CFU)/kg body weight(suspended in 10 mL sterile saline)at the same frequency.Results The IUGR-CON piglets exhibited restricted growth,impaired hepatic morphology,disordered lipid metabolism,increased abundance of opportunistic pathogens and altered ileum and liver bile acid(BA)profiles.However,C.butyricum supplementation reshaped the gut microbiota of the IUGR-CB piglets,characterized by a decreased abundance of opportunistic pathogens in the ileum,including Streptococcus and Enterococcus.The decrease in these bile salt hydrolase(BSH)-producing microbes increased the content of conjugated BAs,which could be transported to the liver and function as signaling molecules to activate liver X receptorα(LXRα)and farnesoid X receptor(FXR).This activation effectively accelerated the synthesis and oxidation of fatty acids and down-regulated the total cholesterol level by decreasing the synthesis and promoting the efflux of cholesterol.As a result,the growth performance and morphological structure of the liver improved in the IUGR piglets.Conclusion These results indicate that C.butyricum supplementation in IUGR suckling piglets could decrease the abundance of BSH-producing microbes(Streptococcus and Enterococcus).This decrease altered the ileum and liver BA profiles and consequently activated the expression of hepatic LXRαand FXR.The activation of these two signaling molecules could effectively normalize the lipid metabolism and improve the growth performance of IUGR suckling piglets.

丁酸梭菌对花鲈幼鱼生长性能、免疫消化及肠道菌群的影响

【目的】探究丁酸梭菌(Clostridium butyricum)对花鲈(Lateolabrax maculatus)幼鱼生长性能,消化、免疫和抗氧化能力及肠道菌群的影响,为丁酸梭菌在花鲈鱼养殖中的应用提供理论依据。【方法】以花鲈幼鱼为试验材料设饲料中丁酸梭菌添加量为0(D0,对照)、0.25%(D1)、0.50%(D2)、1.00%(D3)、2.00%(D4)和4.00%(D5)6组,投喂花鲈幼鱼56 d,测定其生长性能、肠道消化酶活性、血清生化和免疫指标及肠道形态指标,分析肠道菌群组成。【结果】丁酸梭菌可显著降低饲料系数(P<0.05,下同),显著提高花鲈幼鱼的终末平均体质量,D3、D4和D5组的增重率及特定生长率均显著高于D0组。与D0组相比,D4组肠道糜蛋白酶和脂肪酶活性均显著提高,血清总胆固醇、甘油三酯含量和谷草转氨酶、谷丙转氨酶活性均显著降低。D4组溶菌酶、碱性磷酸酶和总一氧化氮合酶活性均显著高于D0组,D3组酚氧化酶活性显著高于D0组;与D0组相比,D3和D5组过氧化氢酶活性及总抗氧化能力均显著提高,D4组超氧化物歧化酶活性显著提高,丙二醛含量显著降低。D2、D3和D5组花鲈幼鱼肠道肌层厚及绒毛高度均显著高于D0组。D3组花鲈幼鱼肠道菌群OTU数量和Chao1指数均显著高于D0组,各试验组花鲈幼鱼肠道菌群Simpson指数和Shannon指数均显著高于D0组;在门分类水平上,丁酸梭菌降低了变形菌门和厚壁菌门相对丰度,提高了放线菌门、浮霉菌门、酸杆菌门、绿弯菌门、拟杆菌门和芽单胞菌门相对丰度;在属分类水平上,丁酸梭菌降低了劳尔氏菌属、肠弧菌属和弧菌属有害菌相对丰度,提高了节杆菌属和KD4-96_unclassified有益菌相对丰度。【结论】饲料中添加丁酸梭菌能显著提高花鲈幼鱼生长性能,提高消化、免疫和抗氧化能力,调节肠道菌群结构组成及其相对丰度,提高肠道菌群多样性,以2.00%添加量效果最好。

气肿疽梭菌C54-1株的制备与检定

为研究气肿疽梭菌C54-1株(CVCC60001)的菌种特性,制备了1批气肿疽梭菌C54-1株,并对菌种的形态及生化特性、培养特性、血清学特性、真空度、纯粹、剩余水分、毒力及免疫原性、16S rDNA等进行检定,以及对于该菌的适宜培养基促生长能力等方面进行了比较。实验结果表明,该冻干菌种的形态及生化特性、培养特性、血清学特性、真空度、纯粹、剩余水分、毒力及免疫原性均符合《中华人民共和国兽用生物制品规程》二〇〇〇版质量标准的规定。16S rDNA鉴定为气肿疽梭菌,相似度为99.93%。在免疫原性检定中,使用致死剂量攻毒时,免疫组能够4/4被保护,证明该菌明矾苗免疫效果良好。使用商品化梭菌培养基对于该菌培养进行了比对,证实商品化培养基替代厌气肉肝汤的可能性。本研究为气肿疽梭菌的制备和检定提供参考依据,并使用不同培养基进行比对研究,为该菌的稳定培养和疫苗工艺改进提供了研究基础。

新型生物活性玻璃对乳牙根尖周炎常见细菌抗菌效果评价

目的:研究不同浓度新型生物活性玻璃(bioactive glass,BG)对乳牙根尖周炎常见细菌的抗菌效果。方法 :采用纸片扩散法检测并观察新型BG处理粪肠球菌、牙龈卟啉单胞菌和具核梭杆菌后形成的抑菌环直径(mm),同时测定粪肠球菌、牙龈卟啉单胞菌和具核梭杆菌的最小抑菌浓度(minimal inhibitory concentration,MIC)、最小杀菌浓度(minimal bactericidal concentration,MBC)和最小菌斑清除浓度(minimal biofilm eradication concentration,MBEC),20、40、60、80 mg/mL新型BG处理3种菌的混合菌斑24 h,于激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)下摄片观察新型BG对混合菌斑的抑菌效果。采用GraphPad Prism 10.0软件对数据进行统计学分析。结果:新型BG对乳牙根尖周炎常见细菌显示出很强的抗菌潜力;新型BG对菌斑的MBEC显著大于对粪肠球菌、牙龈卟啉单胞菌和具核梭杆菌的MIC和MBC。随着新型BG浓度加大,混合菌斑死菌数量显著增加,与空白对照组有显著差异(P<0.05)。结论:新型BG对乳牙根尖周炎常见细菌粪肠球菌、牙龈卟啉单胞菌和具核梭杆菌具有显著抗菌功效。

饲粮复合添加丁酸梭菌和葡萄糖氧化酶对生长肉兔生长性能、屠宰性能、免疫和抗氧化功能以及盲肠微生物区系的影响

本试验旨在研究饲粮复合添加丁酸梭菌和葡萄糖氧化酶对生长肉兔生长性能、屠宰性能、免疫和抗氧化功能以及盲肠微生物区系的影响。选取250只体重相近的35日龄断奶伊拉商品肉兔,随机分为5组,每组50个重复,每个重复1只兔。对照组饲喂基础饲粮,抗生素组饲喂在基础饲粮中添加有效含量为75 mg/kg金霉素和20 mg/kg恩拉霉素的饲粮,试验组分别饲喂在基础饲粮中添加300 g/t丁酸梭菌(试验1组)、200 g/t丁酸梭菌+200 g/t葡萄糖氧化酶(试验2组)和300 g/t丁酸梭菌+200 g/t葡萄糖氧化酶(试验3组)的饲粮。预试期7 d,正试期35 d。结果表明:1)与对照组相比,试验2组和试验3组肉兔平均日增重(ADG)显著提高(P<0.05),料重比(F/G)显著降低(P<0.05),且这2个组与抗生素组相比均无显著差异(P>0.05);试验2组死亡率显著低于对照组(P<0.05),且腹泻频率和死亡率与抗生素组无显著差异(P>0.05)。由此可见,试验2组替抗效果最好。2)各组肉兔屠宰性能和免疫器官指数均无显著差异(P>0.05)。3)与对照组相比,试验2组肉兔血清促炎细胞因子白细胞介素-1β(IL-1β)含量有降低趋势(P=0.085),血清白细胞介素-6(IL-6)含量显著降低(P<0.05)。4)与对照组相比,试验2组肉兔肝脏谷胱甘肽过氧化物酶(GSH-Px)活性显著提高(P<0.05)。5)与对照组相比,试验2组肉兔盲肠微生物群落丰富度和进化多样性有提高的趋势(0.05<P<0.10)。6)与对照组相比,试验2组肉兔盲肠微生物特有扩增子序列变异(ASV)数提高了42.79%,2组间显著差异的标志物种可能是ASV_19729(P<0.05),属于厚壁菌门的梭菌属。综上所述,肉兔饲粮中复合添加200 g/t丁酸梭菌和200 g/t葡萄糖氧化酶能够提高其生长性能和成活率,降低机体炎症反应,增强肝脏抗氧化能力,改善盲肠微生物群落结构,替代抗生素效果较好。

一例赤大袋鼠梭菌性肠炎的诊断和病原分离鉴定

通过临床症状、尸体剖检、组织病理学、毒素实验和细菌分离鉴定的方法确诊了1例由A型产气荚膜梭菌(Clostridium perfringens)引起的赤大袋鼠(Macropus rufus)梭菌性肠炎的自然病例。动物园1只成年赤大袋鼠突然精神沉郁、厌食,于20 h后死亡,尸体角弓反张,腹围膨大。尸体剖检和组织学检查表明:胃肠道、肝脏和肾脏出现具有梭菌性肠炎证病意义的病变。小白鼠毒素实验结果显示,血样肠内容物内有急性致死性毒素。从出血的肠黏膜面分离到单一、有芽孢、粗大的革兰阳性杆菌,经产气荚膜梭菌毒素基因型多重PCR鉴定为A型产气荚膜梭菌。研究结果可为赤大袋鼠梭菌性肠炎的诊断和防控提供依据。

3种不同添加物对凡纳滨对虾生长、非特异免疫和抗病力的影响

为评估3种不同添加物对凡纳滨对虾(Litopenaeus vannamei)生长性能、非特异免疫反应及抗病力的影响,在基础饲料中分别添加了丁酸梭菌CBG01(Clostridium butyricum CBG01)活菌(CB组)、3%聚β-羟基丁酸酯(PHB组)和1%丁酸钠(BS组)来投喂对虾,对照组投喂基础饲料,养殖6周后测量对虾生长情况、检测血清非特异免疫指标和肝胰腺免疫相关基因表达水平,进行副溶血弧菌(Vibrio parahaemolyticus)攻毒实验。研究表明,CB组和PHB组对虾末体质量和特定生长率显著高于对照组(P<0.05),CB组最高,BS组与对照组差异不显著(P>0.05)。3个处理组对虾成活率和饲料效率均显著高于对照组(P<0.05)。3个处理组对虾血清中溶菌酶、过氧化物酶、超氧化物歧化酶活性以及总抗氧化能力显著高于对照组(P<0.05),CB组对虾血清中碱性磷酸酶、酸性磷酸酶、酚氧化酶活性显著高于对照组(P<0.05),PHB组对虾血清中碱性磷酸酶、酸性磷酸酶、总一氧化氮合酶活性显著高于对照组(P<0.05),BS组对虾血清中酸性磷酸酶活性显著高于对照组(P<0.05)。与对照组相比,CB组对虾肝胰腺中所有免疫相关基因(SOD、LZM、proPO、LGBP、HSP70、Imd、Toll、Relish、TOR、4E-BP、eIF4E1α、eIF4E2)相对表达量均显著上调(P<0.05),而PHB组的Toll基因以及BS组的Imd、Toll、Relish、eIF4E2基因相对表达量与对照组无显著差异(P>0.05)。副溶血弧菌攻毒实验表明,3个处理组对虾的累积死亡率均显著低于对照组(P<0.05)。研究结果表明,饲料中添加丁酸梭菌、PHB和丁酸钠均可不同程度地提高凡纳滨对虾的生长性能和非特异免疫能力,能够显著提高对虾对副溶血弧菌感染的抵抗力。总体比较,添加丁酸梭菌和PHB的作用效果基本相当,在一定程度上要优于添加丁酸钠。在饲料生产加工过程中,在难以添加丁酸梭菌活菌的情况下,建议适当添加聚β-羟基丁酸酯来替代丁酸梭菌。

鸡源产气荚膜梭菌的分离鉴定及耐药性研究

目的:对鸡源产气荚膜梭菌进行分离、鉴定和耐药性研究,以深入了解其生物学特性和潜在威胁。方法:利用TSC琼脂、血琼脂、硫酸亚铁牛乳培养基等进行分离培养,通过形态观察、生化特性鉴定,以及PCR鉴定和耐药性试验等多种方法,系统性地分析产气荚膜梭菌的性状和特性。结果:分离得到的3株产气荚膜梭菌经PCR鉴定均确认为A型。生化鉴定结果显示了其在碳源代谢上的多样性。毒素分型和16S rRNA基因分析验证了其种属身份,同时揭示了它们在分子水平上的相似性。耐药性试验结果表明,这些分离株对庆大霉素、卡那霉素、新霉素、多黏霉素B和复方新诺明表现出耐药性,对头孢唑啉、头孢曲松、头孢呋辛、氨苄青霉素和哌拉西林等抗生素则表现出高度敏感性。结论:本研究全面研究了鸡源产气荚膜梭菌的分子生物学特性,强调了其在碳源代谢和抗药性方面的多样性,为防控鸡源产气荚膜梭菌感染提供了重要的基础数据,同时为未来深入探究其致病机制和合理使用抗生素提供了科学依据。

响应面法优化Clostridium beijerinckii木糖发酵产丁醇培养基的研究

采用响应面法对Clostridium beijerinckii利用木糖发酵生产丁醇的培养基进行了优化,建立了回归方程,得到了Cl·beijerinckii木糖发酵的优化培养基组成为:木糖26·6g/L,酵母浸粉1·38g/L,维生素液5·55mL/L,微量元素液9·67mL/L。在此优化条件下发酵,丁醇产量提高了18·4%,达到6·69g/L。

Clostridium saccharobutylicum利用玉米秸秆水解液发酵生产燃料丁醇

以Clostridium saccharobutylicum DSM 13864为丁醇生产菌株,采用正交优化法确定了以玉米秸秆水解液为底物的最优培养基配方:CaCO32.0 g/L,(NH4)2SO41.0 g/L,K2HPO40.5 g/L,玉米浆干粉15 g/L,MnSO4.H2O 0.01 g/L。采用该最优培养基配方,在3 L发酵罐中发酵培养40 h后,总溶剂为16.1 g/L,其中丁醇10.59 g/L,发酵强度为0.40 g/(L·h),生产率为0.33 g/g。通过对发酵过程进行变温调控证实低温有利于溶剂积累,总溶剂由17.01 g/L提高至19.98 g/L。在稀释率为0.1 h-1的变温连续发酵过程中,从80 h开始进入稳定产溶剂状态并持续至269 h,该阶段平均总溶剂为12.28 g/L(其中丁醇8.50 g/L),发酵强度为1.23 g/(L·h),是变温分批发酵(D方式)的4.92倍。

基于比较基因组学的Clostridium kluyveri己酸代谢途径关键酶生物信息学分析

对3株白酒来源重要的己酸生产菌株Clostridium kluyveri(NBRC 12016、JZZ和DSM 555)全基因组信息进行比较基因组学分析,聚焦于己酸代谢途径核心催化酶,发现NBRC 12016的己酸代谢途径未得到有效注释,JZZ的己酸代谢途径核心催化酶酰基辅酶A脱氢酶存在注释错误。进一步对C. kluyveri模式菌株DSM 555己酸代谢途径的关键酶硫解酶ThlA进行生物信息学分析,发现DSM 555携带3拷贝的ThlA,且具有序列多态性,可能与催化脂肪酸代谢链延长的底物特异性相关。结构分析和分子对接表明,硫解酶Thl A1的底物催化属于氧化还原开关调控机制,并预测了酶的关键催化位点和具体的催化过程。上述分析结果有助于为后续进一步改进菌株的己酸生产性能和更好地应用于白酒酿造提供依据。

产氢菌Clostridium butyricum P22的分离鉴定及其产氢特性研究

从连续生物制氢反应器中分离得到高效产氢细菌P22,利用微生物自动鉴定仪并结合菌株16S rDNA序列分析,将其鉴定为Clostridium butyricum P22。同时还进一步研究了碳源、氮源、初始pH值和培养温度对菌株P22产氢活性的影响。结果表明:该菌株能利用多种碳源氮源产氢,当以葡萄糖作为产氢底物时,其最大产氢量和产氢速率分别为为301.7 mL/g-glucose(2.42 mol/mol-glucose)、31.1 mL(/g-glucose.h)。发酵液的初始pH和培养温度严重影响产氢菌活性,初始pH6.47、35℃培养为该菌种较为适宜的产氢条件。利用Arrehnius方程以葡萄糖为底物拟合得到该菌株产氢反应的活化能为70.7 kcal/mol。经能量分析,Clostridium butyricum P22产氢过程中葡萄糖能量回收率为20.6%。该菌株在生物制氢中具有很好的应用发展前景。

Clostridium autoethanogenum的生长培养基优化

Clostridium autoethanogenum是一种能将H2,CO以及CO2转变成乙醇和乙酸的特殊菌株。文章采用数值方法对C.autoethanogenum的生长培养基进行了优化。首先,用Plackett-Burman设计筛选出酵母膏是唯一影响C.autoethanogenum的显著因素,并得到11种组分的相对较优浓度。然后,用梯度试验进一步确定酵母膏的最佳浓度为1.5 g/L,从而最终确立改良的培养基配方。在试验条件下,优化的培养基能得到399.46 mg/L C.au-toethanogenum。此优化培养基能应用于两步CSTRs发酵合成气制乙醇。

甘草查尔酮A与三种抗生素联用对产气荚膜梭菌感染小鼠的治疗作用

本研究旨在研究中药单体与抗生素联用对产气荚膜梭菌(Clostridium perfringens,CP)感染小鼠的影响。本试验以甘草查尔酮A(licorice chalcone A,LCA)为代表药物,探究LCA与抗生素联用的体外和体内治疗效果,通过联合药敏试验确定与中药单体LCA有协同作用的抗生素,测定了产气荚膜梭菌在不同浓度药物作用下的杀菌曲线、溶血试验、滑动试验以及对小鼠的气性坏疽治疗效果,比较不同种抗生素在不同浓度下与LCA联用的治疗作用。结果表明,克林霉素(clindamycin,CLDM)、四环素(tetracycline,TCN)、替米考星(tilmicosin,TMS)三种抗生素与LCA有协同作用。根据杀菌曲线结果显示,8μg·mL^(-1)LCA和16μg·mL^(-1)TMS几乎可以完全杀灭产气荚膜梭菌;2μg·mL^(-1)LCA与2μg·mL^(-1)TMS联合使用可显著降低细菌的溶血性,溶血几乎完全被抑制(溶血定量为9.08%)。值得注意的是,LCA对细菌的迁移力有一定的促进作用,能够提高菌毛介导的运动性,与TMS联用后其促进作用显著提升。动物体内试验结果表明,CLDM单独使用时对产气荚膜梭菌具有较好的抑制作用,治疗效果显著;TCN和TMS分别与LCA联合使用时表现出协同作用(FIC指数为0.375),同时治疗时也表现出较好的增效效果。因此,在治疗产气荚膜梭菌感染时,TMS与LCA联合作用,可以降低药物使用量并提高治疗效果。