Screening and Identification of Cotton Verticillium Wilt Antagonistic Bacteria Strain 7-30

[Objective]The aim of this study was to screen the antagonistic spore-forming bacteria of Verticillium dahliae and identify its physiological and biochemical characteristics.[Method]Taking the cotton verticillium wilt pathogen Verticillium dahliae V-190 as the test microorganism,the antagonistic spore-forming bacteria were screened.Through the preliminary screening and secondary screening,an antagonistic bacteria strain 7-30 with stronger antibacterial activity was obtained,and its morphological characteristics,physiological and biochemical characteristics were also identified.[Result]84 antagonistic bacteria strains were isolated from soil in various places by the preliminary screening.Especially,18 strains with better antagonistic ability were screened again,so an antagonistic bacteria strain 7-30 with the diameter of inhibition zone 18.9 mm and stronger antibacterial activity was obtained.According to its morphological characteristics,physiological and biochemical characteristics,the antagonistic bacteria strain 7-30 was identified as Bacillus subtilis primarily.[Conclusion]The strain 7-30 was obtained as the antagonistic spore-forming bacteria of Verticillium dahliae.

Studies on the Isolation of Endophytic Bacteria from Tomato Plants and Their Growth-promoting Activities

[Objective] The study aimed to investigate the growth-promoting activities of endophytic bacteria from tomato plants.[Method]The endophytic bacteria isolated from different tissues of tomato plants were analyzed for the effects of their growth-promoting activities on the germination and growth of tomato plants.The bacteria with growth-promoting activity were preliminarily identified.[Result]Totally 59 endophytic bacterial strains were isolated from roots and stems of tomatoes,of which 4 showed significantly growth-promoting activity to germination and growth of tomato.The results suggest that these strains are endowed with the potential capability of growth-promoting.[Conclusion]The endophytic bacteria with growth-promoting activity were found among the isolates from tomato plants.This provided a good foundation for utilization of these bacteria with growth-promoting activity.

Screening and Identification of Antagonistic Bacteria against Soil-borne Diseases of Tomato

[Objective] This study was conducted to screen resources for biological control of soil-borne diseases of tomato. [Method] Antagonistic bacteria against Ral- stonia solanacearum and Fusarium oxysporum were isolated and purified from soil samples by dilution plating and confronting incubation on PDA plates, then the antibacterial spectrum and metabolic secretions of the bacterial isolates were measured, and their species were identified by establishing phylogenetic trees with Neighbor-Joining method. [Result] From the 60 soil samples, 10 of 59 antagonistic bacteria isolates against R. solanacearum showed inhibition zone diameter 〉 25 mm, and 4 of 30 strains against F. oxysporum exhibited inhibition rate 〉 30%. The bacteriostatic substances and antibacterial spectrum analysis on above 14 isolates revealed that four strains N23-2, N58-2, NF59-3 and NF61-1 had good antago- nism against pathogenic bacteria and fungi; 12 strains produced cellulose, 11 strains produced proteases, and 6 strains produced siderophores. The molecular identification experiments indicated that four strains were members of Paenibacillus, three strains of Streptomyces, three strains of Pseudomonas strains, and four strains of Bacillus strains.

Determination of Growth-promoting and Antagonistic Action of Endophytic Bacteria Strains Itb57 and Itb295 of Tobacco

[ Objective ] The paper was to study the growth-promoting and antagonistic action of endophytic bacteria strains Itb57 and Itb295 of tobacco to explore their functions in biological control. [ Method] The growth-promoting effects of bacterial suspension ~ff endophytic bacteria Itb57 and Itb295 on tobacco seedling un- der different treatment modes were studied using potting method in greenhouse. The antagonistic action of bacterial suspension of endophytic bacteria Itb57 and Itb295 on Phytophthora nicotianae, Alternaria alternata and Botrytis cinerea were measured by duel culture method. [ Result] Bacterial suspensions of enduphytic bacteria Itb57 and Itb295 had certain growth-promoting effects on tobacco seedling, which could significantly increase the fresh weight and dry weight in aerial part; the growth-promoting effect of soaking ＋ spraying and irrigating treatment was the best. Itb57 strain had good antagonistic action against P. nicotianae. A. alterna- ta and B. cinerea, while Itb295 strain only had good antifungal effect against P. nicotianae. [ Conclusion] The results provided basis for the study and application of tobacco endophytic bacteria strains Itb57 and Itb295 in biocontrol of tobacco diseases.

Identification of Growth-promoting Bacteria from Rhizosphere of Pastures and Their Effects on Growth of Lotus corniculatus L.

[Objectives] This study was conducted to explore the interaction between nitrogen-fixing and phosphate-solubilizing strains and the optimal combination of different functional strains,in order to provide a theoretical basis for the development of PGPR compound fertilizers suitable for local environment.[Methods] In this study,16S rDNA gene sequence analysis was used to identify fast-growing and competitive strains from pasture nodules and rhizosphere soils in Guizhou Province,and three representative Rhizobia and phosphorus-solubilizing bacteria were chosen for the test of bacterial combination when reducing 50% of nitrogen and 30% of phosphorus.The effects of different strain combinations on the plant height,root length,aboveground and underground biomass of Lotus corniculatus L.were investigated,and the total nitrogen and total phosphorus contents of the plants were determined.[Results] The mixed bacterial agents could promote the increase of root biomass,and the effects of A1,A3,B3 and C3 were the most obvious.The fresh weight and dry weight of the roots of L.corniculatus increased by 30.35%-168.45% and 26.43%-180.00%,respectively,and A3,B3,B2 and C3 had the best effects.The total phosphorus content of the plants increased by 12.79%-55.25% compared with the CK2;and most of the bacterial agents with significant growth-promoting effects showed decreased total nitrogen contents,while those with non-significant growth-promoting effects showed significantly-increased total nitrogen contents,which were not as much as the CK1.Comprehensively,the most productive combination was C3,namely R27-2 Rhinohizobium fredii and P33-3 Stenotrophomonas rhizophila.[Conclusions] This study can provide a theoretical basis for the production and promotion of bacterial fertilizers.

Plant growth-promoting properties and anti-fungal activity of endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta in arid lands

Endophytes,as crucial components of plant microbial communities,significantly contribute to enhancing the absorption of nutrients such as nitrogen and phosphorus by their hosts,promote plant growth,and degrade pathogenic fungal mycelia.In this study,an experiment was conducted in August 2022 to explore the growth-promoting potential of endophytic bacterial strains isolated from two medical plant species,Thymus altaicus and Salvia deserta,using a series of screening media.Plant samples of Thymus altaicus and Salvia deserta were collected from Zhaosu County and Habahe County in Xinjiang Uygur Autonomous Region,China,in July 2021.Additionally,the inhibitory effects of endophytic bacterial strains on the four pathogenic fungi(Fusarium oxysporum,Fulvia fulva,Alternaria solani,and Valsa mali)were determined through the plate confrontation method.A total of 80 endophytic bacterial strains were isolated from Thymus altaicus,while a total of 60 endophytic bacterial strains were isolated from Salvia deserta.The endophytic bacterial strains from both Thymus altaicus and Salvia deserta exhibited plant growth-promoting properties.Specifically,the strains of Bacillus sp.TR002,Bacillus sp.TR005,Microbacterium sp.TSB5,and Rhodococcus sp.TR013 demonstrated strong cellulase-producing activity,siderophore-producing activity,phosphate solubilization activity,and nitrogen-fixing activity,respectively.Out of 140 endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta,104 strains displayed anti-fungal activity against Fulvia fulva,Alternaria solani,Fusarium oxysporum,and Valsa mali.Furthermore,the strains of Bacillus sp.TR005,Bacillus sp.TS003,and Bacillus sp.TSB7 exhibited robust inhibition rates against all the four pathogenic fungi.In conclusion,the endophytic bacterial strains from Thymus altaicus and Salvia deserta possess both plant growth-promoting and anti-fungal properties,making them promising candidates for future development as growth-promoting agents and biocontrol tools for plant diseases.

Isolation and Screening of Cd-tolerant Bacterial Strains from Paddy Soils around Lead-zinc Tailings

Microorganisms being used in Cd-contaminated soil remediation have broad prospects in application.In order to obtain more Cd-tolerant microbial resources,paddy soils around lead-zinc tailings were collected to extract Cdtolerant bacterial strains by using the methods of enrichment culture,purification and gradient screening.The strains were identified by morphological and biochemical characteristics and 16S rDNA sequence analysis.The Cd-tolerance and Cdadsorption abilities were then analyzed.The results showed that 6 Cd-tolerant bacterial strains were isolated,3 strains could grow in solid medium which had a cadmium concentration of 700 mg/L.These three strains(i.e.KGJ,KDT,and TU)were members of the Pseudomonas genus(Pseudomonas sp.)identified by morphological and biochemical characteristics and 16S rDNA sequence analysis.The growth curve indicated that the growth rates of the strains were obviously inhibited under 250 mg/L cadmium treatment.The three strains were tolerant of cadmium concentrations over 250 mg/L for long periods of time up to the stationary phase,and TU had the strongest Cd-tolerance.The order of metal tolerance of TU to different heavy metals was Cd^2+ >Zn^2+ >Pb^2+respectively.Chemical analysis showed that the adsorption quantity of the 3 bacterial strains of KGJ,KDT,and TU were 7.596 mg/g,12.237 mg/g and 36.926 mg/g respectively by dry-weight,when the concentration of cadmium was 150 mg/L.All 3 strains had good tolerance and ability to adsorb cadmium,and therefore are considered important potential microbial resources for the remediation of Cd pollution in soil.

Application Progress of Plant Growth-promoting Bacteria in Crops

Plant growth-promoting bacteria(PGPBs)can promote plant growth and improve crop yield.They can induce plant systemic resistance to resist biotic and abiotic stresses.In recent years,with the development of green ecological agriculture,new biological fertilizers such as microbial inocula and microbial fertilizers based on PGPBs have been gradually applied in crop planting.Based on plant growth promotion and disease control,the application progress of PGPBs in crops from the aspects of growth promotion mechanism,growth promotion effect,resistance to biological and abiotic stresses were discussed,aiming to provide reference for the relevant research and application of PGPBs in crops.

Isolation and Screening of Rhizobacteria from Scirpus Grossus Plant after Lead （Pb） Exposure

Phytoremediation is one of method which can be applied to remediate the contaminated environment. In most cases, microorganisms bacteria and fungi, living in the rhizosphere closely associated with plants, may contribute to mobilize metal ions by increasing the bioavailable fraction. Some studies have evidenced that heavy metal-resistant bacteria can enhance metal uptake by hyperaccumulator plants. Lead-resistant bacteria which could help to increase the lead uptake by Scirpus grossus was isolated and screened. The samples were taken from plant roots after being exposed in a range finding test by spiking analytical grade of Pb（NO3）2 solution in variation of Pb concentrations. The results of rhizobacteria isolation showed that there were several colonies having resistance to grow and survive in contaminated environment even the host plant had withered. Only a few of rhizobacteria colonies were affected by high concentrations of lead exposure during screening test. The screening test was conducted by growing the isolated colonies on plates containing tryptic soy agar （TSA） medium containing of 200, 400 and 600 mg/L Pb solution including the plate with only TSA media without any lead exposure acting as a control medium, and incubating them at 30℃ for 72 hours. Isolation of bacteria from rhizosphere had found 47 colonies including several colonies from the withered plants. These all 47 colonies then become 28 after characterization by using color and colony morphology, followed by Gram stain, catalase, oxidase and motility test. The screening test of lead resistant bacteria colonies resulted 3 groups which is scored high, medium and low. The screened colonies will then be used for further study.

Screening and molecular classification of low-temperature protease from Antarctic microorganism and its characterization

107 strains producing protease were screened from 260 strains of Antarctic psychrophilic bacteria, among which proteolytic activity of five strains was more than 45 U ml^-1. The 16S rRNA gcne sequences homology and phylogcnetic analysis of five Antarctic psychrophillc bacteria showed that NJ276, NJS-9, NJ16-70,NJ345 belonged tO the described genus Pseudoalteromonas and NJ341 belonged to the genus Colwellia. The growth and the protease characteristic of four Antarctic psychrophilic bacteria had been studied, and the result showed that the 6ptimal temperature for growth and protease-produeing of four strains was about 10℃. Their growth and protease-produeing were still high during incubatlng 2-5 days. The maximum proteolytic activity occurred at pH 9 for four Antarctic psychrophilic bacteria. The optimal temperature of protease action of both strains NJ276 and NJ5-9 was about 50℃, however, the optimal temperature of protease aetlon of both strains NJ341 and NJ345 was about 40 ℃, and their proteolytic activity under 0℃ exhibited nearly 30% of the maximum activity, but their thermal stabilities were weaker. These results indicated that proteases from NJ341 and NJ345 were low-temperature proteases.

内蒙古地区自然发酵乳中乳酸菌的分离鉴定及优良菌株筛选

鲜乳及其发酵乳是牧民日常饮食中主要的营养物来源之一,其中含有丰富的乳酸菌资源。为了从纯培养角度了解不同乳源中乳酸菌的菌群结构并获取其中宝贵的乳酸菌菌种,该研究采用纯培养技术从内蒙古牧区21份样品中分离得到411株乳酸菌,包括10个属,21个种。其中乳酸乳球菌(Lactococcus lactis)分离株的数量最多,其次为瑞士乳杆菌(Lactobacillus helveticus)和马乳酒样乳杆菌(Lactobacillus kefiranofaciens)。优势菌群分析发现不同乳源的菌群结构差异较大,酸马乳的菌群多样性最丰富,马乳酒样乳杆菌是其优势菌种之一。根据酸马乳低pH值、低酒精含量的特点,从93株马乳酒样乳杆菌中筛选出4株在低pH值(pH 3.0)和6%(体积分数)乙醇环境下耐受性较好的菌株,然后进一步研究其人工胃肠液耐受性、乙醇耐受性和对3种食品中常见致病菌的抑菌能力。最终筛选出2株马乳酒样乳杆菌分别为:IMAU12331与IMAU12208,具有较好的耐受性和抑菌特性,可作为潜在益生菌开发利用,具有较高的潜在应用价值。

伊犁地区奶疙瘩中乳酸菌的筛选及其特性研究

为筛选出传统发酵食品中具有优良功能特性的乳酸菌,对伊犁地区奶疙瘩中的乳酸菌进行分离鉴定,并对其益生特性和功能特性进行研究。从奶疙瘩中分离出乳酸菌菌株并进行分子生物学鉴定,通过耐酸、耐胆盐、自聚集、疏水性和模拟胃肠液耐受性等益生特性指标对菌株筛选,并测定菌株的自由基清除能力和α-葡萄糖苷酶抑制率等功能特性。结果表明:从奶疙瘩样品中分离出的8株乳酸菌均表现出耐酸和耐胆盐能力,其中乳酸片球菌KT-7疏水率最高(77.2%),KT-7在胃液存活率最高(109.7%),副干酪乳杆菌KT-2在肠液存活率最高(103.4%);发酵上清液抗氧化实验中,KT-2的DPPH自由基清除率最高(79.8%),戊糖片球菌KT-8对羟基自由基清除率最高(96.8%),抑制α-葡萄糖苷酶活性实验中,菌株KT-2、KT-7、KT-8对α-葡萄糖苷酶的抑制率在20.0%以上,其中KT-8抑制率最高(34.9%)。因此,从伊犁地区奶疙瘩中筛选出的3株乳酸菌副干酪乳杆菌KT-2、乳酸片球菌KT-7、戊糖片球菌KT-8具有良好的益生特性与功能特性,可作为功能发酵食品的潜在菌株。

不同食物诱导东亚飞蝗肠道高产纤维素酶菌株筛选

通过利用皇竹草、玉米秸秆、麦麸饲养东亚飞蝗,诱导建立肠道菌群,测定纤维素、半纤维素的消化率,利用羧甲基纤维素钠培养基和刚果红透明圈染色法,分离筛选肠道高产纤维素酶菌株并测定纤维素酶活力。结果表明:从3种纤维素源诱导东亚飞蝗肠道菌群中,筛选出9株高产纤维素分解菌,其中M-3、H-1菌株的酶活力比其他7株的活力高;M-3最高,达127.98 U/mL;H-1次之,为94.24U/mL;3种饲料中麦麸饲养的东亚飞蝗肠道内分离得到M-3菌株酶活力最大。

产酸乳酸菌筛选、鉴定及其后生元抗氧化活性比较

从60株菌中筛选具有高产酸能力的乳酸菌,通过菌落形态、革兰氏染色和16S rDNA技术对其进行鉴定,并对筛选菌株的代谢产物进行非靶代谢组学分析,对活菌体及后生元进行抗氧化评价。结果表明,筛选出4株具有高产酸能力的乳酸菌,分别命名为植物乳植杆菌JLSC2-6、植物乳植杆菌CXG-9、植物乳植杆菌SXSCCH-1和植物乳植杆菌HNLJJ-2,均具有良好的耐酸、耐胆盐能力及亚硝酸盐降解能力。代谢组学分析发现,植物乳植杆菌SXSCCH-1的代谢产物与其它菌株具有差异性,这些差异化合物主要是羧酸及其衍生物、脂肪酰基类化合物和甘油磷脂类化合物。抗氧化结果表明,不同菌株及同一菌株各部分的抗氧化能力差异较大,菌株JLSC2-6无论是活菌体还是后生元均具有较好的铁离子还原能力和DPPH自由基清除能力,菌株SXSCCH-1死菌片段具有较强的ABTS^(+)自由基清除能力和抑制亚油酸过氧化能力,菌株HNLJJ-2的活菌体具有较好的ABTS^(+)自由基清除能力。

Antagonistic Effects of Sphingomonas and Pseudomonas aeruginosa on 4 Kinds of Pathogenic Bacteria of Ginseng

[Objectives]To explore effective biocontrol methods for diseases in the process of ginseng cultivation,and develop an efficient and environmentally friendly biocontrol agent.[Methods]In this study,2 strains were isolated from biogas slurry,and Cylindrocarpon destructans(XF),Fusarium solani(GF),Botrytis cinerea Pers(HM)and Alternaria panax Whetz(HB)were used as test materials.The strains were isolated and identified by dilution plate method,16S rDNA sequence identification method,confrontation culture method,filter paper method and ultraviolet spectrophotometer method,and the bacteriostatic activity and bacteriostatic rate were tested.[Results]Strain 15(Sphingomonas)and strain 19(Pseudomonas aeruginosa)were screened out through identification and analysis,and they grew stably within 8-10 d.The bacteriostatic rates of strain 15 against A.panax and B.cinerea were 47.37%and 43.40%,respectively,and the bacteriostatic rates of strain 19 against A.panax and B.cinerea were 62.30%and 63.27%,respectively.The bacteriostatic activity of the extract of strain 19 increased with the increase of OD_(600) value,and the bacteriostatic effect was optimal when the OD_(600) value was in the range of 0.8-1.0,up to 70%,so it had a strong biocontrol potential.[Conclusions]This experiment provides convenience for more effective inoculation,establishes a fast,simple and accurate method for the determination of the best bacteriostatic rate of P.aeruginosa culture solution to HM,and lays a foundation for large-scale culture of P.aeruginosa culture solution.Besides,it is expected to provide a theoretical basis for the efficient control of ginseng B.cinerea in field production,use it for the prevention and control of ginseng shoot diseases,and provide a reference for the efficient and diverse development of biocontrol agents for ginseng shoot diseases.

Isolation and Identification of Cellulose- decomposing Bacteria from Deep-litter Systems

In this study, 43 cellulose-decomposing strains were isolated from deep-litter systems. After preliminary screening with Congo red identification medium and filter paper strip medium, five strains with large transparent circles that disintegrated filter paper strips were obtained. After further liquid fermentation, CMC activity, FPA activity and natural eellulase activity of these five strains were determined, and two cellulose-decomposing strains with higher enzyme activity were screened, which were named F7 and F21. Based on molecular biological identification and phylogenetic analysis of 16S rRNA gene sequences, these two cellulose- decomposing strains were identified as Bacillus subtilis and Streptomyces sp. , respectively.

Rhizobacteria facilitate physiological and biochemical drought tolerance of Halimodendron halodendron (Pall.) Voss

Growth-promoting bacteria(GPB)have shown promising effects on serving plants against environmental constraints such as drought.Nevertheless,simultaneous effects of different GPB have less been considered for arid land plants and under field conditions.We investigated the effects of single and combined application of GPB,including free-living nitrogen-fixing bacteria(NFB),phosphate solubilizing bacteria(PSB),potassium solubilizing bacteria(KSB),a combination of NFB,PSB,and KSB(NPK),and control,at three drought stress treatments.In order to better understand the interactions between drought and GPB,we measured the morphological,biochemical,and physiological plant traits.The target plant was salt tree(Halimodendron Halodendron(Pall.)Voss),a legume shrub native to arid lands of Central and West Asia.All biofertilizer treatments enhanced the growth,physiology,and biochemistry of salt tree seedlings,and there were significant differences among the treatments.KSB and PSB treatments increased photosynthetic pigments,but KSB treatment was more efficient in transpiration rate and stomatal regulation and increased the soluble carbohydrates.PSB treatment had the highest effect on root traits,such as taproot length,root volume,cumulative root length,and the ratio of root to shoot.NFB treatment enhanced root diameter and induced biomass translocation between root systems.However,only the application of mixed biofertilizer(i.e.,NPK treatment)was the most significant treatment to improve all plant morphological and physiological characteristics of salt tree under drought stress.Therefore,our results provided improvement of some specific plant traits simultaneous with application of three biofertilizers to increase growth and establishment of salt tree seedlings in the degraded arid lands.

Phytochemical Determination and Antibacterial Activity of Punica granatum Peel Extracts against Plant Pathogenic Bacteria

Plant pathogenic bacteria are recognized to be harmful microbes able to decrease the quantity and quality of crop production in the world. Punica granatum peel was screened for its potential use as biological control agent for plant pathogenic bacteria. P. granatum peel was successfully extract using n-hexane, methanol and ethyl acetate by maceration. The highest yield obtained by ethyl acetate showed that ethyl acetate extracted more compounds that readily soluble to methanol and n-hexane. For in-vitro antibacterial activity, three different species of plant pathogenic bacteria were used namely Erwinia carotovorum subsp. Carotovorum, Ralstonia solanacearum, and Xanthomonas gardneri. For all crude extracts, four different concentrations 25, 50, 100 and 200 mg/ml were used in cup-plate agar diffusion method. Streptomycin sulfate at concentration 30 μg/ml was used as positive control while each respective solvent used for peel extraction was used as negative control. The results obtained from in vitro studies showed only ethyl acetate extract possessed antibacterial activity tested on the plant pathogenic bacteria. Methanol and n-hexane did not show any antibacterial activity against plant pathogenic bacteria selected where no inhibition zones were recorded. R. solanacearum recorded the highest diameter of inhibition zones for all range of concentrations introduced followed by E. carotovorum subsp. Carotovorum and X. gardneri. For the minimum inhbitory concentration (MIC) and minimum bactericidal concentration (MBC), only the ethyl acetate extract was subjected to the assay as only ethyl acetate extract exhibited antibacterial activity. The minimum concentration of ethyl acetate extract that was able to inhibit plant pathogenic bacteria was recorded at a concentration of 3.12 mg/ml which inhibited R. solancearum and E. carotovorum subsp. Carotovorum, followed by X. gardneri at concentration 6.25 mg/ml. For the minimum bactericidal concentration (MBC), the results showed that at the concentration of 12.5 mg/ml, the extract was still capable of killing the pathogenic bacteria, R. solanacearum, and P. caratovora sub.sp. caratovora while for the bacteria X. gardneri, the concentration that was able to kill the bacteria was 25 mg/ml. The qualitative estimation of phytochemical constituents within P. granatum L. ethyl acetate peel extracts had revealed the presence of tannins, flavonoids, phenols alkaloid, Saponins, and terpenoids. This study has demonstrated that Ethyl Acetate peel extracts of P. granatum has significant antibacterial activity against pathogenic plant bacterial, and it could be of high agricultural value.

Fingerprinting of the Acacia nilotica （L.） Bark Extract Having Antibacterial Property

Acacia nilotica （L.） Delile, commonly known as ＂Babul＂, is reported for its medicinal property since ages. Plant is recognized for its medicinal use in traditional practices. For the study, phytochemicals were extracted as well as identified from four different solvents and their antibacterial property was determined. The fingerprinting was accomplished using HPTLC and the MIC （Minimum Inhibitory Concentration） was elucidated using standard protocols. Two Gram positive （Staphylococcus aureus and Bacillus subtilis） and two Gram negative （Escherichia coli and Pseudomonas aeruginosa） bacteria were selected for the antibacterial screening. The major phytochemicals identified in the extract of the bark of A. nilotica were catechin/epicatechin, ellagic acid and m-digallic acid. Excellent antimicrobial activity was found in chloroform （40 ~tg/mL） and methanol （60 ~g/mL） extracts against Pseudomonas aeruginosa. The chloroform extracts consist of higher number of phytochemicals/bands as compared with other extracts and demonstrated significant antibacterial activity against all the test bacterial species.

益生菌基因组学在乳酸菌筛选和功能评价中的应用

乳杆菌和双歧杆菌是益生菌筛选的主要微生物类群,在促进人类、动物甚至植物健康方面都有重要的应用价值,被广泛应用于多种功能性食品、动物饲料和微生物菌肥。然而,这些细菌对宿主健康产生积极影响的分子机制还远未完全了解。另外,传统的益生菌筛选技术主要依靠表型和生理生化特性的测定以及随机对照试验,这些方法不仅耗时、费力,而且数据难以重复。不同研究小组之间数据难以共享,不能实现菌株有益特性的均一性和标准化验证,严重制约了益生菌科学研究的发展和菌株的产业化开发利用。基于新的测序技术和强大的计算机分析方法,被称为益生菌基因组学新学科的出现,允许研究者在短时间内通过筛选大量的生物学和基因组数据,显著提高益生菌筛选的效率和准确性。本文综述了通过基因组数据的分析,帮助人们高效、快速地确定益生菌,开辟益生菌新功能的评价途径。总结益生菌基因组学在阐明益生特性功效评价的分子基础等方面的最新研究成果,以期为扩展研究人员对这些有益微生物生物学的认知,揭示益生菌促进健康特性的分子机制提供新视角。