In this study,a total of 1125 actinobacteria were isolated from the selected mangrove species:Avicennia marina,Rhizopora mucronata and Ceriops tagal from three study stations viz.,Minnie Bay,Carbyn’s Cove and Burmanallah.Among these three stations,the highest number of actinobacteria was recorded in Carbyn’s Cove(64.97%),followed by(25.51%)at Burmanallah and the minimum of(9.51%)was recorded in Minnie Bay.Maximum number of actinobacteria was recorded from Ceriops tagal(40.44%)than the other selected mangrove species Avicennia marina(34.13%)and Rhizopora mucronata(25.42%).Among the 1,125 mangrove-associated actinobacteria,103 morphologically different isolates from the Minnie Bay station was selected for the further characterization studies.In antibacterial assay,30.11%of the isolates revealed inhibitory activ-ity against all tested clinical pathogens and 65%isolates displayed inhibitory activity against minimum of 04 tested clinical pathogens.Growth survival studies of the actinobacterial isolates also accomplished to withstand in varied NaCl and pH levels.Of 103 isolates,all were found to synthesize gelatinase enzyme,73 isolates demonstrated amylolytic activity,38 isolates exhibited proteolytic and 63 isolates displayed urease activity.Interestingly,56 isolates exhibited excellent DNase activity and 71 isolates revealed positive for l-asparaginase production.To our recognition,11 isolates exhibited constructive results in the production of 06 extracellular enzymes of industrial importance.Of 103 isolates,48 isolates were confirmed by molecular level identification.Based on the phylogenetic analysis,the isolates were categorized under the genera:Strep-tomyces,Nocardiopsis,Salinispora and Actinomadura.
To explore pharmaceutical actinobacteria from salty environments in Siberia,8 soil samples were collected from different depths of Gudzhirganskoe saline lake,the Republic of Buryatia,Russia.Totally,635 actinobacterial strains affiliated with 21 genera in 12 families of 7 orders were obtained by culture-dependent approaches.The predominant genus was Streptomyces(74.5%),followed by Microbacterium(4.9%),Agromyces(3.5%),Nocardiopsis(3.0%),and Kitasatospora(2.5%).Seven strains showed relatively low 16 S rRNA similarities(<98.65%)with validly described species.Seventy-seven strains were selected as representatives to evaluate their antimicrobial activities and underlying mechanisms by paper-disk diffusion method and a double fluorescent protein reporter system(pDualrep 2),respectively.Streptomyces sp.S 6 b 3-1 was highlighted due to its strong inhibitory activities against Gram-positive bacteria and underlying antibacterial mechanism by inducing the SOS response in the reporter system.LG-1,(R)-6-[1-(benzoyloxy)ethyl]-phenazine-1-carboxylic acid,an analogue of saphenamycin was finally isolated from the culture broth of Streptomyces strain.This study preliminarily explored the actinobacterial diversity of soil samples collected in the highly alkaline and saline lake Gudzhirganskoe by culture-dependent approach and their capacity to produce antibiotics for the first time,which revealed that it deserves to make more efforts to discover new actinobacterial species and potential new antibiotics from the saline lake in Eastern Siberia.
【背景】放线菌是一类极其重要的微生物,代谢产物丰富,在医药、生物技术、农业和酶工业等领域均有广泛应用。【目的】客观分析放线菌代谢产物的研究进展,为该领域相关工作人员提供有效情报,推动该领域高质量发展。【方法】对Web of Science(WOS)和中国知网(China National Knowledge Infrastructure,CNKI)数据库中放线菌代谢产物的发文数量、发文国家、发文机构、发文期刊、发文出版社、发文作者、被引文章和研究方向进行统计分析,利用H指数对相关影响力进行综合评价,其研究热点、发展趋势通过CiteSpace和VOSviewer软件进行可视化分析。【结果】WOS结果显示,放线菌代谢产物研究领域全球影响力最大的国家是美国,影响力最大的机构是美国加利福利亚大学,影响力最大的期刊是美国Applied and Environmental Microbiology,影响力最大的出版社是Elsevier,影响力最大的作者是来自英国约翰英纳斯研究中心微生物学部的Mervyn J Bibb教授。全球放线菌代谢产物领域的主要研究方向是微生物学,研究热点是生物合成。研究趋势由2000年前对基因和抗生素相关的研究,转变为2000年后对肠道微生物群和天然产物发现相关的研究。CNKI结果显示,放线菌代谢产物研究领域中国影响力最大的机构是西北农林科技大学,影响力最大的期刊是微生物学通报,影响力最大的作者是云南大学徐丽华教授。放线菌代谢产物领域的主要研究方向是生物学,研究热点是放线菌。研究趋势由2000年前对抗生素和生物合成相关的研究,转变为2000年后对多样性和鉴定相关的研究。【结论】目前全球放线菌代谢产物研究在快速发展,美国在该领域处于全球领先地位,其发文数量、H指数均排名世界首位,发文机构、发文期刊、发文出版社在世界范围内具有较大影响力。中国发文数量全球排名第二,H指数全球排名第五,相
A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz.,point of the eruption(M),middle of the volcano(MD),and the dried part of the mud volcano(E).Based on the biochemical and molecular characterization,the isolates were categorized under the phyla Proteobacteria,Firmicutes and Proteobacteria included representatives of Classes Alphaproteobacteria,Gammaproteobacteria and Deltaproteobacteria of 29 genera with 38 distinct ribotypes.Thirty-eight bacterial strains from four different regions of mud volcano revealed excellent activity for indole-3-acetic acid(IAA)production.Excellent antagonistic property,plant growth promoting properties such as IAA production,phosphate,potassium and zinc solubilization were identified in Bacillus megaterium NIOT_MV 31 strain of 38 studied isolates.In this study,we investigated the optimization of IAA production by B.megaterium NIOT_MV 31 and its formulation as a plant growth promoter to improve economic and agricultural development.Maximum IAA yield was achieved using optimal conditions(42.63 mg/mL)in the presence of optimized tryptophan after 4 days of incubation.Twofold increase in the plant growth parameters were observed to that of control plants.Optimization of culture conditions resulted in a fourfold increase in IAA production by B.megaterium NIOT_MV 31 cells.The results clearly demonstrated that,B.megaterium NIOT_MV 31 holds great potential as a source for IAA production and may be useful for commercial applications.
Synthetic genomics,as one of the important parts of synthetic biology,has become a hotspot in recent years,and several bacterial genomes and yeast chromosomes have been designed and synthesized from de novo.However,during genome synthesis,one technical challenge is the efficient cloning and editing of large genome fragments.At the same time,with the advent of the genomics era,actinobacteria(e.g.Streptomyces)is again regarded as a rich source for novel natural products.However,most of Streptomyces and nearly half the actinomycetes are high GC content.
Agricultural areas of land are deteriorating every day owing to population increase, rapid urbanization, and industrialization. To feed today’s huge populations, increased crop production is required from smaller areas, which warrants the continuous application of high doses of inorganic fertilizers to agricultural land. These cause damage to soil health and, therefore, nutrient imbalance conditions in arable soils. Under these conditions, the benefits of microbial inoculants (such as Actinobacteria) as replacements for harmful chemicals and promoting ecofriendly sustainable farming practices have been made clear through recent technological advances. There are multifunctional traits involved in the production of different types of bioactive compounds responsible for plant growth promotion, and the biocontrol of phytopathogens has reduced the use of chemical fertilizers and pesticides. There are some well-known groups of nitrogen-fixing Actinobacteria, such as Frankia, which undergo mutualism with plants and offer enhanced symbiotic trade-offs.In addition to nitrogen fixation, increasing availability of major plant nutrients in soil due to the solubilization of immobilized forms of phosphorus and potassium compounds, production of phytohormones, such as indole-3-acetic acid, indole-3-pyruvic acid, gibberellins, and cytokinins, improving organic matter decomposition by releasing cellulases, xylanase, glucanases, lipases, and proteases, and suppression of soil-borne pathogens by the production of siderophores, ammonia, hydrogen cyanide, and chitinase are important features of Actinobacteria useful for combating biotic and abiotic stresses in plants.The positive influence of Actinobacteria on soil fertility and plant health has motivated us to compile this review of important findings associated with sustaining plant productivity in the long run.
