两种天然植物提取物的抑菌效果的快速评价与比较

本文研究了绿茶和桑叶提取物在不同浓度时对细菌的抑制作用,采用D值计算法快速评价了它们的抑菌效果。结果表明,绿茶提取物对金黄色葡萄球菌和大肠杆菌的最低抑制浓度分别为0.034%,0.42%;而桑叶提取物分别为0.86%,1.54%。绿茶的抑菌效果更好。     

桑叶提取物抑菌作用的研究

研究了桑叶水煎剂对常见微生物的抑菌作用,以及在不同pH值条件下的抑菌效果.结果表明:提取液对霉菌的生长没有明显的抑制作用;对供试细菌有效,其中对微球菌的抑制最强,其次为沙门氏菌和大肠杆菌,对枯草芽孢杆菌的作用较弱.抑菌效果随着桑叶水煎剂浓度的增加而加强.在酸性条件下,桑叶水煎剂的抑菌作用都有不同程度的增加,但效果均不如0.05%苯甲酸钠.     

桑叶水提浸膏的抑菌作用研究

研究桑叶水提浸膏对五种食品常见污染菌的抑菌作用。通过滤纸片扩散法测定其相对抑菌活性。结果表明,桑叶水提浸膏对金黄色葡萄球菌有较强的抑制作用,对大肠杆菌作用次之,对枯草芽孢杆菌、荧光假单孢杆菌、巨大芽孢杆菌抑菌效果较差。桑叶水提浸膏对金黄色葡萄球菌的最小抑菌浓度是5%,抑菌作用受pH和温度的影响较大,在酸性条件下抑菌效果较好,低于60℃处理样品对抑菌效果影响不大,但高于80℃处理,样品抑菌活性明显降低。     

新型乳杆菌素产生菌的筛选及菌株特性的研究

从酸菜汁中分离出 2 4株乳酸杆菌 ,采用牛津杯定量扩散法筛选出 1株抑菌活性较高的乳酸杆菌 ,经鉴定为戊糖乳杆菌。排除乳酸对指示菌作用的干扰 ,该菌株的离心发酵液不仅对革兰氏阳性细菌有抑制作用 ,而且对大肠杆菌 (E .coli.) ,沙门氏菌 (Salmonellatyphi)等革兰氏阴性细菌也有一定的抑制作用     

大蒜汁对枯草芽孢杆菌抑制作用的研究

通过测定菌体浓度、抑菌圈直径和2,6-吡啶二羧酸(DPA)含量,研究大蒜汁对枯草芽孢杆菌(BS)的营养体及芽孢生长、发芽的影响,并采用响应面分析法优化确定大蒜汁抑菌适宜处理条件.结果表明:(1)大蒜汁对BS的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)分别为0.4%和1%;(2)大蒜汁抑制作用主要是延长了BS的生长延缓期,0.3%的大蒜汁可使BS延缓期增加12 h;(3)大蒜汁对BS的芽孢和DPA形成有明显的抑制作用,但对芽孢的发芽无抑制作用;(4)加热温度超过35℃、时间大于5 h时处理的大蒜汁,对BS的抑制作用明显降低.在pH 3～8范围的大蒜汁都有很好的抑菌活性,但pH＞8.5时抑菌活性急剧下降;(5)响应面试验分析法优化确立了大蒜汁对BS抑制的二次回归方程和适宜处理条件,即在pH 4.5、温度45℃加热处理5 h的大蒜汁抑菌效果最好.     

枯草芽胞杆菌FB123细菌素的理化性质及抑菌谱的研究

研究了细菌素产生菌枯草芽胞杆菌(Bacillus subtilis)FB123 所产细菌素的理化性质及其抑菌谱.枯草芽胞杆菌FB123经过 28 ℃、32 h的发酵得到发酵上清液,用饱和度为50%的硫酸铵溶液沉淀发酵上清液中的细菌素.以革兰阴性菌大肠杆菌和革兰阳性菌金黄色葡萄球菌为指示菌,采用牛津杯法检测细菌素抑菌活性,对细菌素粗品进行理化性质的研究.结果表明该细菌素最适作用pH为 6.0,最适作用温度 40 ℃,具有较宽的pH作用范围和较好的热稳定性.各种蛋白酶、金属离子对其活性有不同程度的影响.抑菌谱试验结果表明,该细菌素对多种革兰阳性菌和革兰阴性菌有明显的抑制作用,虽然对部分真菌有抑制作用,但抑制作用较弱.     

糊米汁对烟叶发酵过程中微生物的影响

研究了糊米汁对烟叶发酵过程中微生物种群及种群数量的变化,初步了解了糊米汁对烟叶微生物的影响。通过添加糊米汁的培养基对烟叶微生物进行液态培养和固态培养。结果表明:在糊米汁堆积式发酵与糊米汁培养基中,糊米汁对烟叶的好氧细菌、厌氧细菌都有非常明显的抑制作用,糊米汁用量越多,抑制作用越明显;但是在普通培养基中施加糊米汁,却对霉菌和酵母没有明显的抑制作用。糊米汁只在烟叶堆积式固态发酵过程中表现出抑制霉菌和酵母的作用,说明糊米汁抑制微生物生长的机制主要是它具有黏性,施加到烟叶中会使烟叶相互粘结,阻碍了O2的传递进而抑制了霉菌和酵母的生长。     

桑叶凝集素分离纯化及抑菌活性研究

采用磷酸缓冲液提取桑叶凝集素,经硫酸铵分级沉淀法初步纯化、Cellulose DE-52阴离子柱层析、CMSepharose Fast Flow阳离子柱层析、Sephadex G-75分子筛柱层析对其进行逐级纯化,采用牛津杯法进行抑菌活性测试。结果表明桑叶凝集素经聚丙烯酰胺凝胶电泳检测显示为单一条带,SDS聚丙烯酰胺凝胶电泳检测其亚基分子量为35.95、30.35 KD;该凝集素对供试菌具有较好的抑制作用,对绿色木霉、苹果落叶病菌、西瓜枯萎病菌及烟草黑胫病菌抑菌直径分别为20、30、15、18 mm。桑叶凝集素具有较好的抑菌活性,可为新农药创制领域提供有用的天然产物先导化合物。     

2种蓼科植物体外抑菌试验研究

为研究蓼科植物水蓼、火炭母体外抑菌效果,制备水煎煮液,测定其对枯草芽胞杆菌、大肠埃希菌、金黄色葡萄球菌、黑曲霉、青霉、酿酒酵母的抑菌圈直径、最小抑菌浓度及灭菌前后水煎煮液抑菌效果的变化。结果表明：当水蓼液浓度大于0.6 g/mL,火炭母液浓度大于0.2 g/mL时,2者对细菌的抑菌效果均依次为：金黄色葡萄球菌〉大肠埃希菌〉枯草芽胞杆菌。2种水煎煮液对3种真菌无抑制作用。火炭母液对3种细菌的最小抑菌浓度分别为1/8、1/16和1/64 g/mL,都比水蓼液的结果1/4、1/8和1/16 g/mL低。药液经121℃高压蒸汽灭菌处理后,水蓼液对3种细菌的抑制作用有所增强,火炭母液则对金黄色葡萄球菌的抑制作用有所增强。2种水煎煮液对3种细菌均有不同程度的抑制作用,可考虑以其为原料进行植物源抗菌剂的开发,拓宽其应用领域。     

多棘海盘车皂甙抗菌活性研究

采用有机溶剂法从多棘海盘车中提取皂甙化合物,通过中性氧化铝柱的色素吸附以及AmberLite XAD-2树脂柱的富集,得到海星皂甙。采用“管碟法”分别研究了海星皂甙对4种细菌和4种真菌的体外抑菌作用。对细菌的抗菌效果表明：海星皂甙对金黄色葡萄球菌、腊样芽孢杆菌的生长有较好的抑制作用,最低抑菌浓度分别是10、12．5mg／mL,而对大肠杆菌则无抑菌作用;对真菌的抗菌效果表明：海星皂甙对黑曲霉的生长有显著的抑制作用,而对啤酒酵母、青霉、根霉则无抑菌作用。从而说明海星皂甙对细菌和真菌的抑制作用均有一定的选择性。     

Simple and rapid determination of 1-deoxynojirimycin in mulberry leaves

A simple and rapid method for determining 1-deoxynojirimycin (DNJ), a potent glucosidase inhibitor present in mulberry leaves (Morus alba and Morus bombysis), by high performance liquid chromatography coupled to an evaporative light scattering detector (ELSD) has been developed. DNJ was separated from extract of mulberry leaves on TSK gel Amide-80 column, which is a representative column for hydrophilic interaction chromatography. During post column detection, DNJ was detected by ELSD and concurrently identified by mass spectrometry. The detection limit was 100 ng. This method is sufficiently sensitive for determining DNJ in mulberry leaves and other related products.     

Protective effects of Morus alba leaves extract on ocular functions of pups from diabetic and hypercholesterolemic mother rats

Phytotherapy is frequently considered to be less toxic and free from side effects than synthetic drugs. Hence, the present study was designed to investigate the protective use of crude water extract of Morus alba leaves on ocular functions including cataractogenesis, biochemical diabetic and hypercholesterolemic markers, retinal neurotransmitters and retinopathy of rat pups maternally subjected to either diabetes and/or hypercholesterolemia. Application of crude water extract of Morus alba resulted in amelioration of the alterations of maternal serum glucose, LDL, HDL, total cholesterol and creatine phosphokinase activity as well as retinal neurotransmitters including acetylcholine (ACE), adrenaline (AD), nor-adrenaline (NAD), serotonin (5-HT), histamine (HS), dopamine (DA) and gamma amino butyric acid (GABA). The retina of pups of either diabetic and/or hypercholesterolemia mothers exhibited massive alterations of retinal neurotransmitters. The alterations of retinal neurotransmitters were correlated with the observed pathological alterations of retinal pigmented epithelium, photoreceptor inner segment and ganglion cells and increased incidence of DNA fragmentation and apoptosis cell death. However, protection with Morus alba extract led to amelioration of the pathological alterations of retinal neurons and estimated neurotransmitters. Furthermore, a striking incidence of cataract was detected in pups of either diabetic and/or hypercholesterolemic mothers. Highest cataractogenesis was observed in pups of combined -treated groups. Our data indicate that experimental maternal diabetes alone or in combination with hypercholesterolemia led to alteration in the ocular structures of their pups, with an increasing incidence of cataract and retinopathy, and the effects of the extract might be attributed to the hypoglycaemic, antihypercholesterolemic and anti-oxidative potential of flavonoids, the major components of the plant extract.     

Genome sequence of the Enterobacter mori type strain, LMG 25706, a pathogenic bacterium of Morus alba L

Enterobacter mori is a plant-pathogenic enterobacterium responsible for the bacterial wilt of Morus alba L. Here we present the draft genome sequence of the type strain, LMG 25706. To the best of our knowledge, this is the first genome sequence of a plant-pathogenic bacterium in the genus Enterobacter.     

Enhancement of the Tyrosinase Inhibitory Activity of Mori Cortex Radicis Extract by Biotransformation Using Leuconostoc paramesenteroides PR

Mori Cortex Radicis (MCR), the root bark of Morus alba L., consists of various phytochemicals and exhibits a strong inhibitory effect on tyrosinase. To enhance the tyrosinase inhibitory activity of MCR extract without further purification of bioactive compounds, whole MCR extract was biotransformed with crude enzyme extract from a selected lactic acid bacterium, Leuconostoc paramesenteroides PR (LP). Mulberroside A (MA), a major stilbene glucoside of MCR, contains two β-glucosyl residues at the C3 and C4' positions of oxyresveratrol (OXY). The crude enzyme of LP hydrolyzed the two glycosidic bonds of MA effectively, and 97.1% of MA was biotransformed into OXY within 2 h. Commercial almond β-glucosidase hydrolyzed only one site of the two glycosidic bonds of MA, and 68.7% of MA was biotransformed to OXY-glucoside. The tyrosinase inhibitory activity of the crude extract of MCR was increased approximately 6.5-fold by biotransformation using LP, and the IC(50) value of the transformed MCR was 3.7 μg/mL.     

Apical dominance in mulberry (Morus alba): Effects of position of lateral and accessory buds and leaves

Suzuki, T. 1990. Apical dominance in mulberry ( Morus alba ): Effects of position of lateral and accessory buds and leaves. – Physiol. Plant. 78: 468-474.
Removing apical portions of current growth coppice shoots from field-grown, low-pruned stumps of mulberry ( Morus alba L. cv. Shin-ichinose) caused sprouting of one or more upper main buds, almost concurrently with that of accessory buds. However, removal of the new sprouts, including those from accessory buds, slightly enhanced the sprouting of buds immediately below them, and did not affect buds lower down. In contrast, mature leaves inhibited the buds in their axils. Budless, leafy nodes on the upper part of pruned shoots tended to swell after treatment, perhaps due to the accumulation of substances translocated from the roots and possibly from the remaining leaves. Lateral buds at different positions along the shoot differed in their sprouting ability with buds lower on the shoot being more inhibited. This inhibition gradient dissappeared when all coppice shoots on one stump were pruned to the same bud position, suggesting inhibition from neighboring, actively growing shoots. These results demonstrate that acropetal influences are important in bud dominance relationships.     

辽西北风沙地区不同无性系桑树抗旱性

为选育适合辽西北风沙地区生长的优良桑树品种,以沈阳农业大学选育的"沈桑1号"(SS)、辽宁省阜新市彰武县优株(ZW)、吉林省通化市集安县桑树优株(JS)3种优质桑树无性系以及东北主栽品种"龙桑1号"(LS)为试验材料,通过测定不同无性系桑树在干旱胁迫下的叶片光合色素含量、光响应曲线、不同光强对气体交换参数的影响以及光系...     

次黄筒天牛的生物学特性及其防治

人黄筒天牛Ｏｂｅｒｅａ ｉｎｆｒａｔｅｓｔｏｃｅａＰｉｃ的形态学和生物学特性的研究,表明该虫在江苏太仓地区１年发生１代,以幼虫越冬。幼虫蛀食桑树枝条,成虫取食嫩叶和叶脉,寄主除桑树外,作者发现还有构树。本文还提出了次黄筒天牛的防治方法。     

Purification and identification of flavonoids from the yellow green cocoon shell (Sasamayu) of the silkworm,Bombyx mori

Three quercetin glycosides, quercetin 5-O-beta-D-glucoside, quercetin 7-O-beta-D-glucoside, and quercetin 4'-O-beta-D-glucoside, and two kaempferol glycosides, kaempferol 5-O-beta-D-glucoside and kaempferol 7-O-beta-D-glucoside, along with their aglycones, quercetin and kaempferol, were isolated from an ethanolic extract of Sasamayu cocoon shells. The chemical structures were characterized by chemical and spectroscopic methods including UV spectrometry and HPLC-ESI-MS. The five flavonol glycosides of the shell are different structurally from those of the leaves of mulberry (Morus alba). It was suggested that potent antioxidative activity in the cocoon is mainly due to flavonoid compounds since free radical scavenging activity was found in the cocoon flavonoids identified here.     

Antiviral flavonoids from the root bark of Morus alba L

A prenylated flavonoid, moralbanone, along with seven known compounds kuwanon S, mulberroside C, cyclomorusin, eudraflavone B hydroperoxide, oxydihydromorusin, leachianone G and alpha-acetyl-amyrin were isolated from the root bark of Morus alba L. Leachianone G showed potent antiviral activity (IC(50) = 1.6 microg/ml), whereas mulberroside C showed weak activity (IC(50) = 75.4 microg/ml) against herpes simplex type 1 virus (HSV-1). Their structures were elucidated by spectroscopic methods.