Paenibacillus spp.BD3526发酵小麦麸皮生产凝乳酶

对Paenibacillus spp.BD3526凝乳酶的发酵条件和凝乳性能进行了研究,探讨了不同培养基、发酵时间、碳源、氮源和装液量对凝乳酶活力和活菌数的影响,并与商业化的小牛皱胃酶、重组凝乳酶、Rhizomucor miehei来源凝乳酶进行凝乳性能比较。实验结果表明:发酵时间、碳源、氮源和装液量对BD3526凝乳酶活力(milkclotting activity,MCA)和蛋白水解活力(proteolytic activity,PA)均有不同程度的影响。选用小麦麸皮培养基进行发酵至24 h时,MCA达到最大至3 279.76±67.11 SU/m L,凝乳性能强,PA值在整个发酵期间变化不大;添加碳源或氮源会不同程度地降低MCA值;装液量为30 m L时,发酵上清液中菌体浓度最高、MCA达到6 000 SU/m L。与商业化的凝乳酶相比,BD3256凝乳酶在凝乳过程中未使凝乳块产生过度水解,也无乳清析出现象,具有应用到干酪生产中的潜力。

海洋生境芽孢杆菌(Bacillus spp.)的培养条件及产生的胞外抗菌蛋白

测试了 4株海洋芽孢杆菌的培养条件对其产生抗菌蛋白的影响 ;提取的粗蛋白的性质以及对 6种病原指示菌的抑菌活性 ,结果表明 ,4株海洋芽孢杆菌在2 2 1 6E ,EMB ,CM培养液 ;1 5～ 35℃ ;NaCl浓度 0 %～ 5 % ;pH3～ 9的条件下均能生长 ,适宜生长温度 2 0～ 2 8℃ ;NaCl浓度 1 %～ 3% ;pH5～ 8.菌株分别培养 84～1 0 8h抑菌活性最强 .(NH4) 2 SO4沉淀抗菌粗蛋白的最适饱和度为 5 0 %～ 70 % .粗蛋白对病原菌尤其对病原真菌具有强烈的抑制作用 .粗蛋白性质稳定 ,对高温和蛋白酶不敏感 .

Paenibacillus spp.BD3526金属蛋白酶对乳蛋白水解位点分析

为了比较具有凝乳功能的Paenibacillus spp.BD3526来源的金属蛋白酶与基因重组凝乳酶对乳蛋白水解位点的差异,采用BD3526金属蛋白酶和凝乳酶对α_(s1)-酪蛋白(casein,CN)、α_(s2)-CN、β-乳球蛋白(lactoglobulin,Lg)和κ-CN进行酶解,分别对不同时间的酶解产物采用高效液相色谱与四极杆飞行时间串联质谱(high performance liquid chromatography of quadrupole time of flight-tandem mass spectrometry,HPLC-Q-TOF-MS/MS)进行分析。结果表明:BD3526金属蛋白酶与凝乳酶在对乳蛋白的水解位点上具有较高的相似性,前者对α_(s1)-CN、α_(s2)-CN、β-Lg和κ-CN水解能力较后者弱,对P1为K(Lys)、R(Arg)且P1'为T(Thr)、F(Phe)和Y(Tyr)间的肽键水解特异性很高,并主要水解K-T(Lys-Thr)、K-F(Lys-Phe)、R-F(Arg-Phe)、R-Y(Arg-Tyr)肽键,水解生成的肽具有血管紧张素转换酶(angiotensin converting enzyme,ACE)抑制、抗菌、免疫调节等功能。

果汁中脂环酸芽孢杆菌(Alicyclobacillus spp.)的危害及其控制

脂环酸芽孢杆菌(Alicyclobacillus spp.)对果汁风味影响较大,成为果汁的主要安全性指标备受国际社会关注。本文系统分析了脂环酸芽孢杆菌的代谢产物及其对果汁的危害、污染果汁的途径及安全性问题,提出:①通过原料选择、清洗、膜过滤和高温灭菌能较有效控制果汁中脂环酸芽孢杆菌;②ClO2、乳酸链球菌素、促肠活动素等被研究证实均对脂环酸芽孢杆菌有很好的杀灭作用,但还未应用于工业化生产;③辐照杀菌、脉冲电场、超声波杀菌等非热杀菌技术亟待研究开发,在果汁中脂环酸芽孢杆菌的控制应用方面前景广阔。

环境因子对乳酸杆菌(Lactobacillus spp)LH生长的影响

在实验室条件下测定pH、温度、盐度和溶解氧对乳酸杆菌LH生长的影响。结果显示,在起始pH3～10的范围内,乳酸杆菌LH都能良好生长,最适pH为6～7;在5～30℃范围内,随着温度的上升,乳杆菌LH的生长加快,在30～40℃,乳酸杆菌LH生长速度基本一致;在盐度0～40范围内,乳杆菌LH能较好地生长,其生长速度随着盐度的上升而下降;在不同氧气条件下,乳杆菌LH都能良好生长。表明乳酸杆菌LH对环境条件能很好地适应。

基于改进YOLOv3-SPP算法的道路车辆检测

针对在城市道路场景下视觉检测车辆时,车辆密集和远处车辆呈现小尺度,导致出现检测精度低或者漏检的问题,提出了一种基于改进的YOLOv3-SPP算法,对激活函数进行优化,以DIOU-NMS Loss作为边界框损失函数,增强网络的表达能力。为提高所提算法对小目标和遮挡目标的特征提取能力,引入空洞卷积模块,增大目标的感受野。实验结果表明,所提算法在检测车辆目标时m AP提高了1.79%,也有效减少了在检测紧密车辆目标时出现的漏检现象。

蚯蚓联合生防细菌Bacillus velezensis改善连作百合土壤细菌群落结构及防治枯萎病的效果

【目的】从土壤理化性状和微生物群落结构及多样性角度,研究蚯蚓联合生防细菌改善百合连作障碍的机理和效果,为湖南百合产业化种植提供技术措施。【方法】采用盆栽试验方法,在湖南长沙连续种植了两季百合(Lilium lancifolium Thunb.)。供试土壤为红壤,生防菌为Bacillales velezensis YFB3-1菌液(菌体浓度为10^(9) CFU/mL),蚯蚓为赤子爱胜蚓(Eisenia fetida)。试验设单施菌液(T1)、只接种蚯蚓(T2)、同时使用菌液和蚯蚓(T3) 3个处理,以不使用菌剂和蚯蚓为对照(CK)。调查了两茬百合产量和枯萎病病情指数,分析了第二茬百合根际土壤理化性质、细菌群落结构和多样性,以及连作百合产量与根际土壤理化性质、细菌群落和枯萎病的相关性。【结果】与第一茬相比,同一处理的第二茬百合产量都显著下降。两年连作百合产量都以同时使用菌液和蚯蚓(T3)处理为最高,分别为16464、15674 kg/hm^(2),都显著高于同年份其他处理。两年连作百合枯萎病发病率和病情指数都以T3为最低,都显著低于同年份其他处理,T3处理百合枯萎病病情指数分别为18.15(2019年)、25.00 (2020年),并且两年的防治效果(T3)都明显优于单施菌液(T1)和接种蚯蚓(T2)。相比于对照(CK),2019、2020年T3处理百合枯萎病防治效果分别为44.55%、37.66%,分别增产15.05%、14.78%。蚯蚓联合生防菌YFB3-1增加了根际土壤Rhizobiales、Flavobacteriales、Pseudomonadales、Bacillales等有益微生物的种群丰度,蚯蚓与生防菌YFB3-1在抑制连作百合枯萎病方面具有显著的互作效应,因而缓解连作百合产量下降的效果最佳。【结论】在施用芽孢杆菌生防菌剂防治连作百合枯萎病的同时,可以增施有机肥(牛粪)来提高土壤中蚯蚓数量,有效预防百合枯萎病发生,减少连作百合产量损失。

Antagonistic Activities of Volatiles from Four Strains of Bacillus spp. and Paenibacillus spp. Against Soil-Borne Plant Pathogens

The four effective antagonistic Bacillus strains, isolated from the rhizosphere soil of cucumber in a greenhouse, produced antifungal volatiles. These volatiles strongly inhibited the growth of the most tested pathogenic fungi with wide host plants, induced the mycelial morphological abnormalities, and decreased the sclerotoid production of Sclerotinia sclerotiorum in sealed plates. Spores of Botrytis cinerea exposed to these volatiles for 24-48 h in cavity slides cracked and the sporaceous inclusion became brown and effused to the suspension. An interesting phenomenon observed was that all the bacterial volatiles exhibited intense inhibitory activities against the pigment formation of tested pathogenic fungi, including Ascochyta citrullina, Alternaria solani, Alternaria brassicae, and so on. Interactions mediated by microbial volatiles could be widespread in soils, and volatiles may play an important role in reducing disease levels. A phylogenetic analysis based on 16S rDNA sequence placed the four bacteria in three species Paenibacillus polymyxa （BMP-11）, Bacillus subtilis （BL02）, and Bacillus pumilus （BSH-4 and ZB 13）. Through headspace sampling and GC-MS analysis, a rich profile was found from B. subtilis and overlapping volatile patterns could be found among the different species. Studies are under the way to find the possible action mechanisms and to seek the effective application of bacterial volatiles in greenhouse.

基于转录组学分析揭示蜡样芽胞杆菌(Bacillus cereus)AR1002阻控黄曲霉生长的生理机制研究

黄曲霉(Aspergillus flavus)极易侵染油料等农产品,其次级代谢产物黄曲霉毒素严重危害人体健康,阻控黄曲霉污染已成为亟待解决的国际难题。为探明蜡样芽胞杆菌(Bacillus cereus)AR1002抑制黄曲霉生长、阻控黄曲霉污染的生理及分子机制。该研究采用AR1002代谢产物对黄曲霉进行处理,并对黄曲霉生长及产孢表型进行鉴定,通过显微结构及转录组学分析,对AR1002的抑菌机制进行了初探。蜡样芽胞杆菌AR1002代谢物可抑制黄曲霉菌丝生长、干物质积累分别达24.73%,65.00%,减少孢子数量达98.80%;AR1002通过抑制glpA和AYR1等关键基因表达调控黄曲霉甘油磷酸代谢,通过抑制SEC61A、RAD23、ATP13A1、UBE2G2等关键基因的表达调控内质网中蛋白质加工;此外,AR1002代谢产物通过下调RAD51和RAD54B等DNA修复机制相关基因,抑制黄曲霉同源重组及非同源性末端连接过程,最终达到抑制黄曲霉生长及产孢的目的。上述结果表明,蜡样芽胞杆菌(Bacillus cereus)AR1002有望应用于实际生产中以应对黄曲霉污染问题。

FOSB、SPP1基因表达对经肝动脉介入化疗栓塞术治疗的中晚期肝癌生存期预测价值

目的探讨骨肉瘤原癌基凶同源物B(FOSB)、分泌性磷蛋白1(SPP 1)基因表达对经肝动脉介入化疗栓塞术治疗的中晚期肝癌患者术后生存期的预测价值。方法回顾性分析2016年1月—2017年10月在西安医学院第一附属医院进行诊治的中晚期肝癌患者115例作为研究对象,根据FOSB、SPP 1基因表达水平分为FOSB高表达组(n=52)、FOSB低表达组(n=63)及SPP 1高表达组(n=89)、SPP 1低表达组(n=26)。同时选取115例健康体检者为健康对照组。分析FOSB、SPP 1表达与中晚期肝癌患者临床病理特征的关系。对纳入研究的患者进行为期60个月的随访,Logistics风险回归模型分析影响患者生存期的危险因素。Kaplan-Meier生存曲线分析FOSB、SPP 1表达水平与患者生存预后的关系。结果肝癌患者外周血单个核细胞中FOSB mRNA表达水平明显低于健康对照组,SPP 1 mRNA表达水平明显高于健康对照组,差异具有统计学意义(P<0.05)。FOSB、SPP 1表达在中晚期肝癌患者肿瘤大小、Child-Pugh分级、淋巴转移、BCLC分期方面比较差异具有统计学意义(P<0.05)。单因素分析结果显示,存活组和死亡组在肿瘤大小、Child-Pugh分级、淋巴转移、BCLC分期、FOSB、SPP 1表达方面比较,差异均具有统计学意义(P<0.05)。肿瘤大小、Child-Pugh分级、淋巴转移、BCLC分期、FOSB低表达、SPP 1高表达均为中晚期肝癌患者生存期的独立危险因素(P<0.05)。随访时间60个月,患者生存率为17.39%(20/115),FOSB高表达组中位生存时间为39.7个月,明显高于FOSB低表达组的19.3个月(P<0.05);SPP 1低表达组中位生存时间为40个月,明显高于SPP 1高表达组的18个月(P<0.05)。结论FOSB在中晚期肝癌患者中表达明显下调,SPP 1表达上调,其对预测中晚期肝癌患者肝动脉介入化疗栓塞术治疗生存期具有一定的价值。FOSB、SPP 1有望成为评估介入术治疗患者预后的潜在指标,可协同肿瘤大小、Child-Pugh分级、淋巴转移、BCLC分期等临床指标预测或评估肝癌患者术后生存情况。

Dietary Bacillus spp.enhanced growth and disease resistance of weaned pigs by modulating intestinal microbiota and systemic immunity

Background:Previous research has shown that dietary supplementation of Bacillus spp.probiotics exerts beneficial effects on animals’growth.However,limited studies have evaluated the efficacy of Bacillus spp.on weaned pigs and their effects on host gut health and microbiome,and systemic immunity using a disease challenge model.The objective of this experiment was to investigate the effects of two Bacillus spp.strains(Bacillus subtilis DSM 32540 and Bacillus pumilus DSM 32539)on growth performance,diarrhea,intestinal health,microbiome,and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli(ETEC).Results:Pigs in PRO1(Bacillus subtilis DSM 32540)had greater(P<0.05)body weight on d 7 and 14 PI,greater(P<0.05)ADG from d 0 to 7 and d 7 to 14 PI,compared with pigs in CON(Control).Pigs in PRO1 had milder(P<0.05)diarrhea on d 2 and 3 PI compared with pigs in CON.However,no differences were observed in growth performance and diarrhea score between PRO2(Bacillus pumilus DSM 32539)and CON groups.Supplementation of PRO1 decreased(P<0.05)lymphocyte counts on d 7 and 14 PI,compared with CON.Supplementation of PRO1 and PRO2 both reduced(P<0.05)total coliforms in mesenteric lymph nodes on d 21 PI.Pigs in PRO2 had greater(P<0.05)goblet cell number and sulfomucin percentage in duodenal villi and greater(P<0.05)sialomucin percentage in jejunal villi than pigs in CON.Supplementation of PRO1 up-regulated(P<0.05)MUC2 gene expression in jejunal mucosa and reduced(P<0.05)PTGS-2 and IL1B gene expression in ileal mucosa on d 21 PI,compared with CON.Pigs in PRO1 had reduced(P<0.05)relative abundance of families Lachnospiraceae,Peptostreptococcaceae and Pasteurellaceae in the ileum.Conclusions:Supplementation of Bacillus subtilis DSM 32540 improved growth performance,alleviated diarrhea severity,enhanced gut health,and reduced systemic inflammation of weaned pigs infected with ETEC F18.Although Bacillus pumilus DSM 32539 was able to alleviate systemic inflammation,it had limited impacts on growth performance and severity of diarrhea of ETEC F18 challenged weaned pigs.

南瓜白粉病拮抗内生细菌Bacillus cereus B4-2的分离鉴定及生防效果

从高抗白粉病的南瓜植株内分离筛选出对南瓜白粉病有较好防治效果的内生拮抗细菌菌株,为南瓜白粉病的生物防治提供新途径。采用孢子萌发抑制法、叶盘漂浮法和温室盆栽试验筛选出有较好防效的内生细菌,用形态观察、生理生化测定和分子生物学方法进行鉴定。结果表明,从高抗白粉病的南瓜自交系22G3植株内分离获得29株内生拮抗细菌菌株,5个菌株对南瓜白粉菌的孢子萌发抑制率在50%以上,其中菌株B4-2对白粉菌的孢子萌发抑制率最高,为88.65%。叶盘和室内盆栽试验结果均表明,菌株B4-2对南瓜白粉病的防治效果最好,防治效果分别达79.58%和83.21%。不同稀释倍数的B4-2发酵液对南瓜白粉病均有一定的防治效果,随着稀释倍数的增大,防治效果降低,其中菌株B4-2发酵液原液对南瓜白粉病的防治效果最好,达82.14%。通过形态特征、生理生化特征及基因序列分析,鉴定菌株B4-2为蜡样芽孢杆菌(Bacillus cereus)。综上所述,蜡样芽孢杆菌B4-2能较好地防治南瓜白粉病,有一定的开发潜力。

芽孢杆菌(Bacillus spp.)防治豇豆根腐病效果

采用生长抑制法,发现芽孢杆菌(Bacillus spp.)对豇豆根腐菌(Fusarium spp.)具有较好的抑制作用,其代谢产物对豇豆根腐菌的抑制中浓度(EC50)为24.4 mg/L。采用拌种法,测定了芽孢杆菌对豇豆根腐病的室内预防效果,其中以药种比100 mL∶1 kg的防效最高,为92.1%,与对照30%噁霉灵水剂防效相当。田间灌根试验结果显示,芽孢杆菌发酵液稀释50倍,对豇豆根腐病的防效达到74.9%,与对照30%噁霉灵水剂防效相当。

莫海威芽孢杆菌(Bacillus mojavensis)ZLX10对发酵雪茄烟叶中性致香成分的影响

为探究烟草源微生物单菌发酵对雪茄烟叶挥发性致香成分的影响,采用GC-MS检测莫海威芽孢杆菌(Bacillus mojavensis)ZLX10发酵雪茄烟叶中性致香成分,筛选差异致香成分,并与感官评价进行相关性分析,结合ROAV值变化,明确ZLX10提升雪茄烟叶感官品质的关键致香成分。结果表明,ZLX10发酵雪茄烟叶后,香气总量和大多数中性致香成分含量均显著提高,共筛选得到15种差异中性致香成分,共有10种致香成分显著上调(P<0.05),其中巨豆三烯酮A、巨豆三烯酮B、6-甲基-5-庚烯-2-酮、2,6,6-三甲基-2-环己烯-1,4-二酮、茄酮和植物醇与烟叶香气呈显著正相关(P<0.05),可认为是增加烟叶干香和花香的关键差异致香成分;共有5种致香成分显著下调(P<0.05),其中苯乙醛和2,4-二叔丁基-6-硝基苯酚与烟叶刺激性呈显著正相关(P<0.05),对烟叶香气有较大的负面影响。由此可知,ZLX10发酵能促进雪茄烟叶香气质和香气量得到提升,这为人工接菌发酵雪茄烟叶提供了基础。

Isolation, screening and identifi cation of Bacillus spp. as direct-fed microbial candidates for aflatoxin B_1 biodegradation

Objective: To evaluate the ability of Bacillus spp. as direct-fed microbials(DFM) to biodegrade al atoxin B1(AFB1) by using an in vitro digestive model simulating in vivo conditions.Methods: Sixty-nine Bacillus isolates were obtained from intestines, and soil samples were screened by using a selective media method against 0.25 and 1.00 μg/m L of AFB1 in modii ed Czapek-Dox medium. Plates were incubated at 37 °C and observed every two days for two weeks. Physiological properties of the three Bacillus spp. candidates were characterized biochemically and by 16 S r RNA sequence analyzes for identii cation. Tolerance to acidic p H, osmotic concentrations of Na Cl, bile salts were tested, and antimicrobial sensitivity proi les were also determined. Bacillus candidates were individually sporulated by using a solid fermentation method and combined. Spores were incorporated into 1 of 3 experimental feed groups: 1) Negative control group, with unmedicated starter broiler feed without AFB1; 2) Positive control group, with negative control feed contaminated with 0.01% AFB1; 3) DFM treated group, with positive control feed supplemented with 109 spores/g. After digestion time(3:15 h), supernatants and digesta were collected for high-performance liquid chromatography l uorescence detection analysis by triplicate.Results: Three out of those sixty-nine DFM candidates showed ability to biodegrade AFB1 in vitro based on growth as well as reduction of l uorescence and area of clearance around each colony in modii ed Czapek-Dox medium which was clearly visible under day light after 48 h of evaluation. Analysis of 16S-DNA identii ed the strains as Bacillus amyloliquefaciens, Bacillus megaterium and Bacillus subtilis. The three Bacillus strains were tolerant to acidic conditions(p H 2.0), tolerant to a high osmotic pressure(Na Cl at 6.5%), and were able to tolerate 0.037% bile salts after 24 h of incubation. No signii cant dif erences(P > 0.05) were observed in the concentrations of AFB1 in neither the supernatants nor digesta samples evaluated by highperformance liquid chromatography with l uorescence detection between positive control or DFM treated groups. Conclusions: In vitro digestion time was not enough to confirm biodegradation of AFB1. Further studies to evaluate the possible biodegradation ef ects of the BacillusDFM when continuously administered in experimentally contaminated feed with AFB1, are in progress.

1株抗真菌贝莱斯芽孢杆菌(Bacillus velezensis)lut-Y1的鉴定及抑菌活性研究

【目的】探究1株来自枸杞果实的贝莱斯芽孢杆菌lut-Y1的生长特性及抑菌活性,为微生态制剂的开发和应用提供参考。【方法】通过形态观察和16S rDNA基因测序分析对该菌株进行鉴定;测定该菌株生长曲线及最适pH、碳源、氮源及盐耐受度;采用平板对峙法观察该菌株对链格孢菌(Alternaria alternate)、小麦根腐离蠕孢(Bipolaris sorokiniana)和小孢壳二孢(Ascochyta leptospora)的颉颃作用,并分析该菌株发酵液对3种病原真菌的抑菌活性。【结果】lut-Y1菌株在LB、NA和PDA培养基上均生长良好。根据形态和16S rDNA基因序列特征将lut-Y1菌株鉴定为贝莱斯芽孢杆菌(Bacillus velezensis)。在LB液体培养基中,lut-Y1菌株在0~3 h为迟滞期,3~18 h为对数期,18~62 h为稳定期,62 h后进入衰亡期;最适pH为7.0,最适碳源和氮源分别为蔗糖和蛋白胨,对NaCl的耐受量不超过2.0 g/L。lut-Y1菌株对链格孢菌有明显的颉颃作用,对小麦根腐离蠕孢和小孢壳二孢的颉颃作用较弱。对峙平板的两菌交界处,链格孢菌基内菌丝细弱、弯曲;小麦根腐离蠕孢基内菌丝细胞壁被破坏,有泡状突起。发酵液添加量为25%时生长圈直径分别缩小72.80%和83.24%。【结论】贝莱斯芽孢杆菌lut-Y1具有较好的抑菌活性,可为开发以芽孢杆菌为主要活性成分的微生态制剂提供材料。

不同有机废弃物载体对Bacillus megaterium有效性的影响

为了给Bacillus megaterium选择理想的吸附载体。测定了草炭、金针菇渣、腐熟鸡粪、牛粪、羊粪的吸菌量及其载体菌剂的有效活菌数、胞外多糖(EPS)含量和发芽指数。草炭的吸菌量最高为1.64 mL/g,但随存放时间延长,草炭载体菌剂的有效活菌数和EPS含量急剧降低,且38 d内的发芽指数均小于80%,表现植物毒性。鸡粪和金针菇渣的吸菌量虽小于草炭,但随存放时间延长,鸡粪载体菌剂的有效活菌数和EPS含量逐渐增大,金针菇渣载体菌剂的EPS含量逐渐增加、有效活菌数降低幅度缓慢,且存放7 d后发芽指数均大于80%,表现植物无毒性。第38天时鸡粪和金针菇渣载体菌剂的有效活菌数分别为1.29×10^(9)CFU/g和6.20×10^(8)CFU/g,EPS含量分别为535.29 mg/kg和559.34 mg/kg,均显著高于其他载体菌剂。鸡粪和金针菇渣是B.megaterium较为理想的吸附载体。

Modified Green Tea Polyphenols, EGCG-S and LTP, Inhibit Endospore in Three <i>Bacillus</i>spp.

Endospores have the ability to withstand extreme temperature, desiccation, ultraviolet radiation and chemicals which make them a threat to the food and healthcare industry. Green tea polyphenols (GTP), contain anti-microbial and anti-spore properties but not stable. In this study, two modified lipophilic green tea polyphenols, epigallocatechin-3-gallate-sterate (EGCG-S) and crude lipophilic green tea polyphenols (LTP), were used to compare their anti-spore effect with EGCG and crude GTP. Purified endospores from Bacillus cereus (B. cereus), B. megaterium and B. subtilis were treated with 1% or 5% of four tea polyphenols. Log reduction showed colony forming units (CFU) reduced significantly in all treated samples, ranging from 1.27 to 4.31 with no survivals (CFU = 0) in four samples (P < 0.05). Average percentage of inhibition for these poly-phenols treatment ranged from 91.68% to 100%. The EGCG-S and LTP have equal or better anti-spore activities compared with EGCG and GTP. EGCG-S and LTP were further used to carry out time course study on B. cereus. The results indicated that 15 min of treatment of 1% and 5% LTP and EGCG-S are able to inhibit 98.7% to 100% of germination. Transmission and scanning electron microscopy studies showed that EGCG-S caused surface disruption and damaged spores structural integrity. EGCG-S and LTP are stable anti-spore agents may aid in preventing food and beverage spoilage caused by spore-forming bacteria as well as preventing contamination in the medical industry.

Biochemical Characterization of Lipase Produced by <i>Bacillus</i>spp. Isolated from Soil and Oil Effluent

The aim of the present work was to isolate Bacillus spp. With high lipase activity;to characterize the isolates using both biochemical and molecular methods;to produce lipase using Bacillus isolates and to study the biochemical and biophysical characteristics of the produced lipase. Sixty five Bacillus isolates were isolated from soil 20 isolates from guar field soil (G), 15 isolates from Abusabein field soil (B), 15 isolates from sun flower field soil (S) and 15 isolates from oil effluent (O). Lipase producing isolates were screened;a Chromogenic plate’s method was used. Enzyme activity was quantitatively assayed. Lipase production under submerged fermentation (SMF) conditions using a production medium that contained metal salts, Tween-20 and olive oil as substrate at different period 24, 48, 72 and 96 h, the optimum pH, temperature for lipase activity was determinated and kinetics as well. The isolates showed the highest lipase activity which was identified as Bacillus sp. The optimum pH, temperature, thermostability and kinetic of the produced enzymes were found in three isolates G14, O1 and B10 with the highest enzyme activity and best stability. The isolates G14, O1 and B10 revealed the highest lipase activity of 63.4, 41.2 and 28.3 U/ml, respectively. The results showed optimum pH of the lipase activity from isolates G14, O1 and B10 8.0, 6.0 and 6.0 and the optimum temperature 40, 60 and 75˚C, respectively. Lipase enzymes from isolates O1 and B10 were found to be more thermostable after incubation time for 120 min at 90˚C. The Vmax and Km values of lipase for isolates G14, OI and B10 were 17.6, 135 and 24.4 μmole∙min−1 and 1.3, 1.6 and 0.681 mM, respectively. According to these results Bacillus spp. with high lipase activity and thermostability can be used to promote food, pharmaceuticals, paper, detergents agrochemicals industries and pollution control in Sudan.

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。