Antiseptic Efficacy of A Soap Made from Biosurfactants Isolated from Bacillus and Lactobacillus against Pathogenic Bacteria

The aim of our study was to use a biosurfactant produced by Bacillus and Lactobacillus isolates as an antiseptic in the formulation of local soap. A total of 60 isolates were characterized by microbiological techniques (30 Bacillus and 30 Lactobacillus) and the ability to produce biosurfactants was demonstrated by a hydrocarbon emulsification index (E24). The emulsification indexes (E24) varied from 9% to 100% for Bacillus and from 33% to 100% for Lactobacillus as well. The antagonistic assay showed that biosurfactants were able to inhibit the formation of biofilms and growth of pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Salmonella typhirium, Shigella boydii and Proteus mirabilis. The biosurfactant consortium (BioC) from Bacillus consortium and from Lactobacillus was able to inhibit biofilm formation and the pathogens growth. The BioC was stable to alkaline pH and the temperatures stability of Biosurfactant was ranging from 50°C to 90°C. The soap was made by the cold saponification process using one biosurfactant consortium formulated. This soap has a pH of 10 and showed good cleaning power and good foam stability. Similarly, the soap showed good antiseptic power and disinfection power against all pathogens tested. Handwashing is critical to preventing disease transmission. The persistence of pathogens in waste water was evaluated. The BioS produced showed good disinfection power against all pathogens tested. The valor of reduction on the hands and in the waste water was significantly more than compared to the control soaps used. This soap could be used in the prevention, fighting, and treatment of bacterial and viral infections.

Mn^(2+)促进Bacillus altitudinis LZP02生物膜形成

【目的】Bacillus altitudinis LZP02是一株水稻根际促生菌(PGPR),能定殖于水稻根部,形成生物膜,且Mn^(2+)对LZP02菌株生物膜形成具有促进作用,但调控机制尚不明确,旨在探究Mn^(2+)对LZP02菌株生物膜形成的促进机制。【方法】采用结晶紫染色法进行生物膜定量分析、蒽酮-硫酸法测定胞外多糖产量、扫描电镜(SEM)观察LZP02菌株在水稻根际定殖情况、转录组学测序技术分析差异表达基因(DEGs)。【结果】添加4 mmol/L Mn^(2+)和8 mmol/L Mn^(2+)显著提高了LZP02菌株的成膜能力和胞外多糖产量,扫描电镜发现4 mmol/L Mn^(2+)和8 mmol/L Mn^(2+)提高了LZP02菌株在水稻根际的定殖能力,随着Mn^(2+)浓度的增加,DEGs数量显著增多,其主要富集在芽孢形成、毒素代谢途径和双组分系统中。1 mmol/L Mn^(2+)和4 mmol/L Mn^(2+)处理组发现skf操纵子中基因的表达均上调。扫描电镜观察发现在1 mmol/L Mn^(2+)和4 mmol/L Mn^(2+)处理组中LZP02菌体存在损伤。4 mmol/L Mn^(2+)处理组双组分系统中KinE和Spo0A基因均显著上调。【结论】Mn^(2+)通过“嗜食同类”和双组分系统中KinE基因激活Spo0A~P提高了菌株LZP02的成膜能力。

纳豆芽孢杆菌Bacillus natto NK4液态发酵产纳豆激酶的工艺优化

为提高纳豆激酶的产量,采用单因素试验及正交试验对纳豆芽孢杆菌Bacillus natto NK4进行发酵条件优化,获得该菌种液体发酵产酶的最优条件。结果表明,纳豆芽孢杆菌产纳豆激酶最佳的发酵条件为接种量2%,培养基初始pH值6.0,培养温度34℃,发酵时间72 h。此时,纳豆激酶酶活力由848.28 IU/mL提高到1569.31 IU/mL。

生物炭载Bacillus subtilis菌粒对连作芹菜生长的影响

为解决土壤连作障碍对蔬菜生长发育的不利影响,本研究以连作3年的芹菜土壤为研究对象,采用随机区组试验,设置5种处理:单独施加生物炭(BC)、单独施加Bacillus subtilis菌剂(BS)、生物炭与菌剂混合施加(BB)、施加生物炭载B.subtilis菌粒(BP)、不施加生物炭与菌剂(CK),盆栽种植芹菜,测定其生长与品质指标,探究生物炭和B.subtilis对连作芹菜生长的影响。结果表明,BB、BP处理组芹菜的生长和品质指标都高于其他土壤处理组,BP处理组的芹菜鲜质量、可溶性蛋白含量以及纤维素含量均显著高于BB处理组,分别为60.25 g/棵、27.25 mg/g、2.48%,其他指标两处理间无显著差异。不同土壤处理组芹菜的生长和品质指标都高于CK处理,其中BP处理组各指标值最高,尤其是芹菜鲜质量,增幅高达226.56%。因此,施加生物炭载B.subtilis菌粒提高了连作芹菜生长指标与品质,为农业生产上缓解蔬菜连作障碍奠定了理论基础。

Bioleaching of vanadium from stone coal vanadium ore by Bacillus mucilaginosus:Influencing factors and mechanism

Vanadium and its derivatives are used in various industries,including steel,metallurgy,pharmaceuticals,and aerospace engineering.Although China has massive reserves of stone coal resources,these resources have low grades.Therefore,the effective extraction and recovery of metallic vanadium from stone coal is an important way to realize the efficient resource utilization of stone coal vanadium ore.Herein,Bacillus mucilaginosus was selected as the leaching strain.The vanadium leaching rate reached 35.5%after 20 d of bioleaching under optimal operating conditions.The cumulative vanadium leaching rate in the contact group reached 35.5%,which was higher than that in the noncontact group(9.3%).The metabolites of B.mucilaginosus,such as oxalic,tartaric,citric,and malic acids,dominated in bioleaching,accounting for 73.8%of the vanadium leaching rate.Interestingly,during leaching,the presence of stone coal stimulated the expression of carbonic anhydrase in bacterial cells,and enzyme activity increased by 1.335-1.905 U.Enzyme activity positively promoted the production of metabolite organic acids,and total organic acid content increased by 39.31 mg·L^(-1),resulting in a reduction of 2.51 in the pH of the leaching system with stone coal.This effect favored the leaching of vanadium from stone coal.Atomic force microscopy illustrated that bacterial leaching exacerbated corrosion on the surface of stone coal beyond 10 nm.Our study provides a clear and promising strategy for exploring the bioleaching mechanism from the perspective of microbial enzyme activity and metabolites.

Research advance of Bacillus velezensis:bioinformatics,characteristics,and applications

Bacillus velezensis is a Gram-positive and spore-forming bacterium.It has potent antimicrobial properties that can be used to promote plant growth and as a pesticide by inhibiting pathogens.B.velezensis has the capability to generate a diverse range of enzymes that have potential applications in various fields,such as enzyme production,fermented food,degradation of pollutants,and bioenergy.In addition,B.velezensis is a promising probiotic.It possesses high bile-salt tolerance characteristics and has a high success rate of colonization in the intestinal mucosa.Besides,the strain can also regulate gut microbiota constitute by increasing the number of beneficial microorganisms and decreasing the number of pathogens.Furthermore,based on its special properties,including high-yield protease production and high salt-tolerance,B.velezensis shows potential for use in marine protein fermentation,opening up new avenues for the development of novel food products and bioactive peptides.In addition,B.velezensis can shorten the fermentation time as well as improve the nutritional value and flavor of fermented food.The safety of B.velezensis for food production was evaluated.This review provides valuable insights into the potential uses and benefits of B.velezensis,particularly in the context of fermented foods.

Induced CTL-S15 gene expression by Bacillus thuringiensis declines susceptibility in Spodoptera exigua

It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects.However,to date,which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear.In this study,33 CTL genes were identified from S.exigua.Based on the number of carbohydrate-recognition domains(CRDs)and the domain architectures,they were classified into three groups:(1)nineteen CTL-S(single-CRD),(2)eight immulectin(dual-CRD)and(3)six CTL-X(CRD with other domains).RT-qPCR analysis revealed that expression levels of SeCTL-S15,IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab.Tissue and developmental stage expression analysis showed that only SeCTL-S15 was mainly expressed in the midgut and larva,respectively.Knockdown of SeCTL-S15 significantly increased Bt susceptibility,as indicated by reduced survival and larval weight.These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S.exigua.Our results provide new insights into CTL function in insects.

Enhanced extracellular production of alpha-lactalbumin from Bacillus subtilis through signal peptide and promoter screening

Alpha-lactalbumin(α-LA)is a major whey protein found in breast milk and plays a crucial role in the growth and development of infants.In this study,Bacillus subtilis RIK1285 harboring AprE signal peptide(SP)was selected as the original strain for the production ofα-LA.It was found thatα-LA was identified in the pellet after ultrasonic disruption and centrifugation instead of in the fermentation supernatant.The original strain most likely only producedα-LA intracellular,but not extracellular.To improve the expression and secretion ofα-LA in RIK1285,a library of 173 homologous SPs from the B.subtilis 168 genome was fused with target LALBA gene in the pBE-S vector and expressed extracellularly in RIK1285.SP YjcN was determined to be the best signal peptide.Bands in supernatant were observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and purified by nickel column to calculate the highest yield signal peptide.In addition,different promoters(P_(aprE),P_(43),and P_(glv))were compared and applied.The results indicated that the strain RIK1285-pBE-P_(glv)-YjcN-LALBA had the highestα-LA yield,reaching 122.04μg/mL.This study demonstrates successful expression and secretion of humanα-LA in B.subtilis and establishes a foundation for simulating breast milk for infant formulas and developing bioengineered milk.

耐低温降解菌Bacillus mobilis10的生物学特性及其对海参养殖水质的净化作用

以分离自沿海土壤中的1株芽孢杆菌10为试验对象,研究其在低温条件下(15℃)的生物学特性,实现该菌剂的中试工程化生产以及在海参养殖中对水质净化的示范应用。该菌株通过形态观察及16S rRNA基因序列分析被鉴定为Bacillus mobilis。15℃,经透明圈法确定该菌株具有蛋白酶活性、淀粉酶活性和纤维素酶活性;发酵56 h蛋白酶活性达到9.05 U/mL;在8%质量分数NaCl条件下仍可以存活。利用海参饵料培养基检测菌株对溶解物的降解能力,试验结果显示,B.mobilis 10接种8 h后对饵料培养基中蛋白的降解率达(36.72±0.53)%,对化学需氧量的清除率达(22.80±0.81)%。中试规模(50 L)发酵制备微生物制剂并以终密度约1.0×10^(4)cfu/mL的菌液泼洒海参池,对水体中B.mobilis 10的活菌数、pH、蛋白质含量及化学需氧量进行为期8 d的动态监测,结果表明,以B.mobilis 10制备的微生物制剂能够显著降低海参养殖水体中蛋白和化学需氧量,起到净化水质的目的。试验结果可为水产生态养殖及微生物制剂的开发提供理论基础和应用示范实例。

Oral administration of Bacillus coagulans TQ-35 alleviates allergic responses in OVA-sensitive BALB/c mice

Bacillus coagulans has been extensively studied so far,but there has been a lack of research on its usage in allergy.In this study,we designed to assess the effect of different concentrations of B.coagulans on food allergy in a BALB/c mouse model of ovalbumin(OVA)-induced food allergy and its effect on gut microbes.The assessment of symptoms,specific immunoglobulin E(IgE),T-cell differentiation,and related gene expression levels in sensitized mice by assay indicated that high doses of oral B.coagulans could alleviate allergic symptoms.Treatment with B.coagulans,in the high-dose group,significantly reduced IgE and IgG1 levels and modulated the balance of T helper type 1 cell(Th1)and Th2 and the expression of relevant genes in the spleen.16S rRNA analysis showed that probiotics improved the structure of the microbiota,in particular by boosting the percentage of Clostridia,Bacteroides vulgatus and Enterococcus faecium,and by increasing the abundance of microbial species,thereby modulating the immune system.Therefore,this study can provide insights into the practical application of B.coagulans doses to alleviate OVA allergy.

Bacillus tropicus来源β-D-呋喃果糖苷酶基因的克隆与表达及其酶学特性研究

为获得新β-D-呋喃果糖苷酶资源并探究其酶学性质及在转化糖中的应用潜力,挖掘出Bacillus tropicus来源的β-D-呋喃果糖苷酶基因BtFFase8,成功合成后表达在大肠杆菌宿主中。通过数据库筛选β-D-呋喃果糖苷酶的基因序列,将基因克隆至载体pET-28a(+)中。将获得的重组质粒转化至大肠杆菌BL21,构建重组菌株大肠杆菌BL21/pET28a-BtFFase8。采用亲和层析纯化克隆酶,用SDS-PAGE法分析蛋白分子量,通过葡萄糖试剂盒检测酶水解产物的能力得到酶活力,用福林酚试剂法测定蛋白质含量。克隆酶BtFFase8的分子质量为57.0 kDa,对蔗糖底物的比酶活力为13.4 U/mg;BtFFase8的最适pH和最适温度分别为pH 6.5和45℃,且在pH 5.0~8.0和40℃及以下温度保持酶活力稳定,残余酶活力大于80%;BtFFase8能耐受碱性蛋白酶、酸性蛋白酶和胰蛋白酶的水解,残余酶活力大于70%。BtFFase8的发现及克隆酶优良的酶学功能为其未来应用于食品加工,特别是在转化糖的生产中奠定了良好的理论基础。

矿化细菌Bacillus paramycoides对重金属Pb(Ⅱ)和Cd(Ⅱ)的去除及矿化特性

微生物诱导生物矿化可有效固定重金属离子,被认为是一种重要的重金属污染环境修复工艺,对重金属污染生态修复有重要的现实意义。从贵州黔西北某铅锌矿区周边土壤中分离出一株耐Pb(Ⅱ)和Cd(Ⅱ)菌株GS-2,经形态学特征和16S rRNA鉴定为Bacillus paramycoides,菌株GS-2对Pb(Ⅱ)和Cd(Ⅱ)的耐受分别高达1500和50 mg/L,对250 mg/L Pb(Ⅱ)和5 mg/L Cd(Ⅱ)去除率分别为99.54%和69.04%,对重金属Pb(Ⅱ)和Cd(Ⅱ)(均为25 mg/L)混合去除率分别为99.73%和71.46%。SEM-EDS、FTIR和XRD结果显示,菌株通过表面的羟基、羧基、酰胺基和磷酸基团等官能团将Pb(Ⅱ)和Cd(Ⅱ)诱导矿化成Ca_(2.5)Pb_(7.5)(OH)_(2)(PO_(4))_(6)、Ca_(2.1)Pb_(7.9)Cl_(2)(PO_(4))_(6)、Pb_(3)(PO_(4))_(2)、Pb_(5)(PO_(4))_(3)OH、Pb_(9)(PO_(4))_(6)、Pb_(10)(PO_(4))_(6)(OH)_(2)和Ca_(0.67)Cd_(0.33)CO_(3)等晶体矿物。菌株GS-2具有较好的去除和矿化能力,对环境中Pb(Ⅱ)和Cd(Ⅱ)污染的生物修复具有一定应用潜力。

Liver failure after Bacillus cereus food poisoning,an underrecognized entity:A case report

BACKGROUND Bacillus cereus(B.cereus)is known to cause 2 types of foodborne diseases;the diarrheal and emetic syndromes.They are largely underreported due to their usually self-limiting course.Rare and sometimes fatal cases of liver failure,pulmonary hemorrhage and cerebral oedema have been reported mainly in children and young adults.We present here a case of liver failure associated with B.cereus food poisoning in a middle-aged patient.CASE SUMMARY A 48-year-old female patient presented to the emergency department for emesis,diarrhea,chills without fever,asthenia and diffuse abdominal cramps that started less than 30 minutes after eating a rice salad.Her past medical history was relevant for cholecystectomy and a cured Hashimoto’s disease.She did not take any medication,drugs and declared a consumption of one glass of wine per week.In the emergency department,she was treated with acetaminophen,metoclopramide,ondansetron,and an intravenous normal saline infusion.Blood gas analysis revealed a metabolic acidosis with hyperlactatemia,coagulation revealed a low prothrombin activity[32%;normal values(N):70-140]and a low Factor V activity(15%;N:>70).Transaminases were elevated with hyperbilirubinemia,elevated lipase and rhabdomyolysis.N-acetylcysteine treatment was introduced.Abdominal echography revealed no signs of chronic hepatopathy or hepatomegaly.Day after the admission,psychomotor activity improved,transaminases and lipase started decreasing.Rhabdomyolysis gradually worsened to peak on day 3.Screening tests for liver disease were negative for viral and autoimmune cause of liver failure.Stools cultures were positive for colonies of the B.cereus group which were also identified in the rice salad samples processed whereas blood cultures were negative.The patient’s condition improved gradually including her liver function parameters and psychomotor activity which allowed her discharged home on day 9.CONCLUSION We describe a rare case of hepatocellular dysfunction due to a foodborne B.cereus intoxication in an adult patient.Even if it is uncommon,the severity of liver dysfunction reported and mechanism of the cereulide toxin toxicity on liver suggest that acetaminophen should be avoided in case of a foodborne intoxication and n-acetylcysteine could be a potential therapy helping to prevent hepatocytes necrosis due to the oxidative stress induced by mitochondrial dysfunction.

Animal Safety Test of Bacillus thuringiensis BT Protein

[Objectives]To determine the biological safety of BT protein from Bacillus thuringiensis(Bt)fermentation broth to mammals at high doses.[Methods]Healthy mice were randomly divided into 4 groups with 10 mice in each group.The experimental groups were fed with Bt fermentation supernatant at 0.2,0.6 and 1.0 mL/kg,respectively,once a day for 7 consecutive days.The blank control group was fed normally without intragastric administration.[Results]There was no significant difference in blood routine and blood biochemical analysis between the experimental group and the control group.After intragastric administration,the mice were dissected,and no obvious pathological changes were found;the heart,liver,spleen,lung and kidney were taken to make tissue sections,and no pathological changes were found by microscopic observation.[Conclusions]Mice can tolerate high doses of BT protein from B.thuringiensis fermentation broth.

Comparison of Antibacterial Activities of Six Bacillus amyloliquefaciens Strains

In this study, six bacterial strains were isolated from the sediment, probiotic fermentation products, and lake sediments, they were identified as Bacillus amyloliquefaciens using genetic evolution analysis, which were named B3, B4, B5, XD3, YF6, and YF8. The comparison of the antibacterial activity, hemolytic activity, and antibiotic sensitivity of six Bacillus amyloliquefaciens strains laid a foundation for the development and application of antimicrobial peptide products. A surface activity assay was used to determine the production of biosurfactants in six Bacillus amyloliquefaciens strains. With Staphylococcus aureus and Escherichia coli as indicator bacteria, their antibacterial activity was determined using the agar diffusion method;the same diffusion method was used to determine the antibiotic susceptibility of Bacillus amyloliquefaciens. The results showed that the six Bacillus amyloliquefaciens strains had obvious biosurface activity, and the bacteria inhibited Staphylococcus aureus and Escherichia coli, from strong to weak: YF8, XD3, B3, B4, YF6, and B5. Strain YF8 had the best broad-spectrum bacteriostatic effect, followed by strain XD3. All Bacillus amyloliquefaciens strains were susceptible to 16 common drugs, except for Bacillus amyloliquefaciens strain YF8, which was intermediate to neomycin. The study shows that Bacillus amyloliquefaciens and secondary metabolites have the ability to produce a variety of active peptides, exert a certain inhibitory effect on common pathogens, and have the potential to develop as animal probiotics.

Isolation and Experimental Study on Bacteriostasis of Bacillus haynesii

This experiment aims to isolate and inhibit three bacteria strains to provide candidate strains for the development and application of probiotics.Using bacterial morphological identification,16S rDNA sequence alignment,and genetic evolution analysis,three strains were identified as Bacillus haynesii,named HP01,HD02,and HK03.Through biosurfactant activity tests,C-TAB tests,hemolysis tests,and antibacterial activity analyses,the results showed that all three strains of B.haynesii exhibited significant biosurfactant activity.Additionally,the solutions of the three strains demonstrated a pronounced antibacterial effect on Staphylococcus aureus.The resistance and safety of commonly used drugs were evaluated using the tablet diffusion method and a mouse feeding test.The results indicated that the three strains were not resistant to commonly used antibacterial drugs,and the oral bacterial solution was not pathogenic and had high safety in mice.The study concluded that all three B.haynesii strains met the basic conditions for use,with B.haynesii HP01 being the most promising candidate.

Lactobacillus rhamnosus GR-1 attenuates foodborne Bacillus cereus-induced NLRP3 inflammasome activity in bovine mammary epithelial cells by protecting intercellular tight junctions

Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it cannot be inactivated by high-temperature short-time pasteurization.Therefore,B.cereus can enter the market through pasteurized milk and other dairy products,imposing enormous hidden dangers on food safety and human health.Results:In this study,B.cereus 2101(BC)was isolated from milk samples of cows with mastitis.BC grew rapidly with strong hemolysis,making it difficult to prevent mastitis and ensure food security.MAC-T cells were treated with BC and/or Lactobacillus rhamnosus GR-1(LGR-1).Pretreatment with LGR-1 protected the integrity of tight junctions and the expression of zonula occludens-1(ZO-1)and occludin destroyed by BC.Furthermore,LGR-1 pretreatment reduced the expression of NOD-like receptor family member pyrin domain-containing protein 3(NLRP3),caspase recruitment and activation domain(ASC),Caspase-1 p20,gasdermin D(GSDMD)p30,inflammatory factors(interleukin(IL)-1βand IL-18),and cell death induced by BC.Moreover,LGR-1 pretreatment reduced NLRP3 inflammasome activity and increased expressions of ZO-1 and occludin induced by lipopolysaccharides(LPS)+ATP stimulation.MAC-T cells were transfected with NLRP3 si RNA or MCC950 and/or treated with BC and/or LGR-1.NLRP3-si RNA transfection and MCC950 attenuated BC-induced NLRP3 inflammasome activity.Expression of inflammatory cytokines and cell death suggested that the inflammatory pathway might play an important role in the induction of the NLRP3 inflammasome by BC and the protection of LGR-1.Conclusions:These results suggest that LGR-1 might be a probiotic alternative to antibiotics and could be administered to prevent mastitis in dairy cows,thus ensuring food security.

Bacillus sp.B110胞内麦芽糖淀粉酶基因克隆与酶学特性

目的:对菌株Bacillus sp.B110的胞内麦芽糖淀粉酶BMAL进行基因克隆、异源表达、纯化及酶学性质研究,为后期开发新的淀粉加工用酶打下基础。方法:使用PCR技术对Bacillus sp.B110的胞内麦芽糖淀粉酶bmal基因序列进行全长克隆,异源表达,使用Ni2+-NTA进行纯化,再对其酶学特性进行测定,使用序列分析工具BioEdit、MEGA等对其氨基酸序列进行分析,使用AlphaFold2对其三级结构进行预测分析。结果:BMAL基因全长1770 bp,编码一个589氨基酸残基的蛋白。重组酶rBMAL经Ni2+-NTA亲和层析纯化后,SDS-PAGE电泳结果显示其分子量大小为63 kDa。氨基酸序列分析和三维建模表明BMAL与来源于B.subtilis 168和B.subtilis SUH4-2的麦芽糖淀粉酶有较高的一致性,且BMAL具有一个麦芽糖淀粉酶所独有的N端结构域以及由Asp328-Glu357-Asp424三个氨基酸残基所构成的催化中心。重组酶rBMAL最适反应温度为45℃,最适反应pH为6.0。重组酶rBMAL在30℃条件下保藏7 h残留酶活为60%,但在60℃条件下保藏2 h残留酶活力下降98%,说明BMAL对热敏感。重组酶rBMAL在4℃,pH7.0~9.5保藏12 h活性稳定。当存在1 mmol/L的金属离子Mg2+时,重组酶rBMAL活力提高36%,而Ni2+、Fe3+、Co2+、Cu2+、Zn2+、Al3+、Ca2+对重组酶rBMAL有抑制作用,酶活力减少85%~48%。有机溶剂和化学试剂甲醇、乙醇、丙酮、异腈、EDTA和SDS对重组酶rBMAL有较强的抑制作用,酶活力减少至32.3%~64.8%。底物特异性实验结果证实BMAL最适底物为环精糊。结论:Bacillus sp.B110的胞内麦芽糖淀粉酶BMAL具有良好的催化特性和pH稳定性,在面包烘焙工业上具有潜在的应用价值。

U(Ⅵ)在芽孢杆菌Bacillus sp.dwc-2上的矿化动力学研究

微生物诱导的U(Ⅵ)生物矿化会影响铀在环境中的化学形态和迁移行为,但目前对于生长和繁殖阶段的微生物诱导U(Ⅵ)矿化的动力学行为研究不多,相关的机制也不明确。本文从某拟用作极低放射性废物处置场场所的土壤中分离出1株芽孢杆菌Bacillus sp.dwc-2,考察了pH值、甘油磷酸钠(SGP)、U(Ⅵ)初始浓度等因素对Bacillus sp.dwc-2在生长繁殖过程中诱导U(Ⅵ)矿化动力学行为的影响,并对其矿化机制进行了探讨。结果表明,Bacillus sp.dwc-2可诱导U(Ⅵ)形成钠铀云母(NaUO_(2)PO_(4)·3H_(2)O)的晶体矿物,该过程作为一种酶促反应,受pH值、SGP浓度、U(Ⅵ)初始浓度等因素的显著影响;当U(Ⅵ)初始浓度从50 mg/L增加至150 mg/L时,刺激了处于生长迟滞期至对数期(培养0~12 h)菌体磷酸酶活性的表达和磷酸盐的代谢,使其诱导U(Ⅵ)的矿化行为发生在生长对数期(培养12 h);SGP浓度的增加促进了磷酸酶的催化反应速率,进而促进了U(Ⅵ)的矿化,当SGP的浓度从25 mmol/L增加到125 mmol/L时,Bacillus sp.dwc-2诱导U(Ⅵ)的矿化时间从其生长稳定期(培养24 h)提前至生长对数期(培养12 h);中性和碱性条件下,磷酸酶活性在生长迟滞期至对数期(培养0~12 h)快速增加,从而促进了磷酸盐的消耗和U(Ⅵ)的矿化,特别是在碱性条件下,沉积物在生长对数期(培养8 h)时即转化为明显的晶体矿物。

The synbiotic mixture of lactulose and Bacillus coagulans protects intestinal barrier dysfunction and apoptosis in weaned piglets challenged with lipopolysaccharide

Background Lactulose as an effective prebiotic protects intestinal mucosal injury.Bacillus coagulans is widely used in feed additives because of its ability to promote intestinal health.Our previous study suggests that the combination of lactulose and Bacillus coagulans may be a good candidate as alternative for antibiotic growth promoters.However,the in vivo effects of lactulose and Bacillus coagulans on growth and intestinal health under immune challenge in piglets remains unclear.The objective of this study is to explore the protective effects of synbiotic containing lactu-lose and Bacillus coagulans on the intestinal mucosal injury and barrier dysfunction under immune challenge in weaned piglets.Methods Twenty four weaned piglets were assigned to 4 groups.Piglets in the CON-_(saline)and LPS-_(LPS)group were fed the basal diet,while others were fed either with chlortetracycline(CTC)or synbiotic mixture of lactulose and Bacillus coagulans for 32 d before injection of saline or lipopolysaccharide(LPS).Piglets were sacrificed 4 h after LPS injection to collect samples to determine intestinal morphology,integrity and barrier functions as well as relative genes and proteins.Results Our data showed that no differences were observed in the growth performance of the four test groups.LPS injection induced higher serum diamine oxidase activities,D-lactic acid levels,and endotoxin status,lower villus height and ratio of villus height to crypt depth,greater mRNA and lower protein expression related tight junction in both jejunum and ileum.In addition,a higher apoptosis index,and protein expression of Bax and caspase-3 were also observed in the LPS challenge group.Interestingly,dietary synbiotic mixture with lactulose and Bacillus coagulans protected against LPS-induced intestinal damage,barrier dysfunction and higher apoptosis as well as CTC.Conclusions Our data suggest that dietary supplementation of synbiotic mixture with lactulose and Bacillus coagu-lans showed resilience to LPS-induced intestinal morphological damage,barrier dysfunction and aggressive apoptosis in piglets as well as the protective effects of CTC.These results indicate that synbiotic mixture of lactulose and Bacillus coagulans showed beneficial effects on performance and resilience to acute immune stress in weaned piglets.