Actinomycete Strain Research Articles

Biocontrol of Soil-Borne Pathogens of Solanum lycopersicum L. and Daucuscarota L. by Plant Growth-Promoting Actinomycetes: In Vitro and In Planta Antagonistic Activity.

Biotic stress caused by pathogenic microorganisms leads to damage in crops. Tomato and carrot are among the most important vegetables cultivated worldwide. These plants are attacked by several pathogens, affecting their growth and productivity. Fourteen plant growth-promoting actinomycetes (PGPA) were screened for their in vitro biocontrol activity against Solanum lycopersicum and Daucus carota microbial phytopathogens. Their antifungal activity was evaluated against Fusarium oxysporum f. sp. radicis-lycopersici (FORL) and Rhizoctonia solani (RHS). Antibacterial activity was evaluated against Pseudomonas syringae, Pseudomonas corrugata, Pseudomonas syringae pv. actinidiae, and Pectobacterium carotovorum subsp. carotovorum. Strains that showed good in vitro results were further investigated in vitro (cell-free supernatants activity, scanning electron microscope observations of fungal inhibition). The consortium of the most active PGPA was then utilized as biocontrol agents in planta experiments on S. lycopersicum and D. carota. The Streptomyces albidoflavus H12 and Nocardiopsis aegyptica H14 strains showed the best in vitro biocontrol activities. The diffusible and volatile compounds and cell-free supernatants of these strains showed both antifungal (in vitro inhibition up to 85%, hyphal desegregation and fungicidal properties) and antibacterial activity (in vitro inhibition >25 mm and bactericidal properties). Their consortium was also able to counteract the infection symptoms of microbial phytopathogens during in planta experiments, improving plant status. The results obtained highlight the efficacy of the selected actinomycetes strains as biocontrol agents of S. lycopersicum and D. carota.

ISOLATION AND IDENTIFICATION OF CHOLESTEROL OXIDASE PRODUCING ACTINOMYCETES FROM EGYPTIAN SOIL FOR A LARGE SCALE FERMENTATION IN SUBMERGED CULTURES

Isolation and identification of new microbial isolates capable of producing cholesterol oxidase enzyme (CHO) is of great potential in the field of biotechnology of industrial enzymes. Four producing strains of actinomycetes were isolated from Egyptian soils demonstrated high activity in cholesterol degradation compared to the other isolates. Based on different standard morphological, biochemical as well as molecular techniques using 16S rRNA sequencing, these actinomycetes were identified as Streptomyces sp. strain NHIA_CH3 MK680299, Streptomyces sp. strain NHIA_CH5 MK680300 , Streptomyces griseus strain NHIA_CH6 MK680301 and Streptomyces drozdowiczii strain NHIA_CH10 MK680302. In order to optimize the CHO enzyme activity, different fermentation media were tested in submerged cultures at shake flask level. Maximum activity (23.7 U/mL) was observed in culture of Streptomyces sp. strain NHIA_CH5 which was scaled up to the 5L volume of the stirred tank bioreactor. Results of the batch fermentation showed an earlier production of CHO enzyme with 4% increase in activity compared to that obtained from shake flask cultures indicated that Streptomyces sp. strain NHIA_CH5 could be a potential source of CHO enzyme for commercial purpose.

Pseudonocardia abyssalis sp. nov. and Pseudonocardia oceani sp. nov., two novel actinomycetes isolated from the deep Southern Ocean.

The actinomycetes strains KRD168T and KRD185T were isolated from sediments collected from the deep Southern Ocean and, in this work, they are described as representing two novel species of the genus Pseudonocardia through a polyphasic approach. Despite sharing >99 % 16S rRNA gene sequence similarity with other members of the genus, comparative genomic analysis allowed species delimitation based on average nucleotide identity and digital DNA–DNA hybridization. The KRD168T genome is characterized by a size of 6.31 Mbp and a G+C content of 73.44 mol%, while the KRD185T genome has a size of 6.82 Mbp and a G+C content of 73.98 mol%. Both strains contain meso-diaminopimelic acid as the diagnostic diamino acid, glucose as the major whole-cell sugar, MK-8(H4) as a major menaquinone and iso-branched hexadecanoic acid as a major fatty acid. Biochemical and fatty acid analyses also revealed differences between these strains and their phylogenetic neighbours, supporting their status as distinct species. The names Pseudonocardia abyssalis sp. nov. (type strain KRD168T=DSM 111918T=NCIMB 15270T) and Pseudonocardia oceani (type strain KRD185T=DSM 111919T=NCIMB 15269T) are proposed.

Nocardioides baculatus sp. nov., a novel actinomycete isolated from the rhizosphere of Tagetes patula.

An aerobic, Gram-stain-positive, non-motile, dull-yellow, short rod-shaped actinomycete strain, designated G10T, was isolated from Tagetes patula (marigold) roots collected from Goyang in the Republic of Korea. The isolate showed best growth on Reasoner's 2A agar at 25 °C, pH 6.5.0 and with 0% NaCl (w/v). The strain was negative for oxidase activity and positive for catalase activity. On the basis of 16S RNA gene sequence similarity, strain G10T was affiliated to the genus Nocardioides and the closest species were Nocardioides glacieisoli HLT3-15T (98.8 %), Nocardioides zhouii HLT2-9T (98.8 %), Nocardioides ganghwensis JC2055T (98.7 %), Nocardioides cavernae YIM A1136T (98.6 %), Nocardioides flavus Y4T (98.5 %), Nocardioides oleivorans DSM 16090T (98.3 %), Nocardioides alpinus Cr7-14T (98.2 %), Nocardioides exalbidus DSM 22017T (98.1 %) and Nocardioides hwasunensis KCTC 19197T (98.1 %). Strain G10T formed a monophyletic cluster with N. glacieisoli HLT3-15T, N. zhouii HLT2-9T and N. hwasunensis KCTC 19197T in all phylogenetic trees. The cell-wall peptidoglycan of strain G10T contained ll-diaminopimelic acid as the diagnostic amino acid. The predominant fatty acids were iso-C16 : 0 and C17 : 1 ω8c. MK-8(H4) was the major isoprenoid quinone. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. Average nucleotide identity and digital DNA-DNA hybridization values were 78.6-88.7 % and 21.5-36.2 %, respectively, with the type strains of related species of the genus Nocardioides, suggesting that strain G10T represents a novel species. The genome of strain G10T is 4 231 000 bp long with a DNA G+C content of 71.5 mol% and encodes 4071 predicted proteins, six rRNAs and 46 tRNAs. The genome of strain G10T comprises the biosynthetic gene cluster for T3PKS, terpene, NRPS-like fragment and RRE-containing element as secondary metabolites. The results of taxonomic, phylogenetic, biochemical, chemotaxonomic and genomic analysis clearly supported that strain G10T represent a novel species within the genus Nocardioides, for which the name Nocardioides baculatus sp. nov is proposed and the type strain is G10T (=KCTC 49626T=NBRC 114801T).

Comparative Metabolomics Reveals Fungal Conversion of Co-Existing Bacterial Metabolites within a Synthetic Aspergillus-Streptomyces Community.

In nature, secondary metabolites have been proven to be the essential communication media between co-occurring microorganisms and to influence their relationship with each other. In this study, we conducted a metabolomics survey of the secondary metabolites of an artificial co-culture related to a hydrothermal vent fungal–bacterial community comprising Aspergillus sclerotiorum and Streptomyces and their reciprocal relationship. The fungal strain was found to increase the secretion of notoamides and the compound cyclo(Pro-Trp) produced by the actinomycetes strain was discovered to be the responsible molecule. This led to the hypothesis that the fungi transformed cyclo(Pro-Trp) synthesized by the actinomycetes as the biosynthetic precursors of notoamides in the chemical communication. Further analysis showed Streptomyces sp. WU20 was efficient in transforming amino acids into cyclo(Pro-Trp) and adding tryptophan as well as proline into the chemical communication enhanced the induction of the notoamide accumulation. Thus, we propose that the microbial transformation during the synthetic metabolically-mediated chemical communication might be a promising means of speeding up the discovery of novel bioactive molecules. The objective of this research was to clarify the mechanism of microbial transformation for the chemical communication. Besides, this research also highlights the utility of mass spectrometry-based metabolomics as an effective tool in the direct biochemical analysis of community metabolites.

Multiple strain analysis of Streptomyces species\xa0from Philippine marine sediments reveals intraspecies heterogeneity in antibiotic activities

The marine ecosystem has become the hotspot for finding antibiotic-producing actinomycetes across the globe. Although marine-derived actinomycetes display strain-level genomic and chemodiversity, it is unclear whether functional traits, i.e., antibiotic activity, vary in near-identical Streptomyces species. Here, we report culture-dependent isolation, antibiotic activity, phylogeny, biodiversity, abundance, and distribution of Streptomyces isolated from marine sediments across the west-central Philippines. Out of 2212 marine sediment-derived actinomycete strains isolated from 11 geographical sites, 92 strains exhibited antibacterial activities against multidrug-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The 16S rRNA and rpoB gene sequence analyses confirmed that antibiotic-producing strains belong to the genus Streptomyces, highlighting Streptomyces parvulus as the most dominant species and three possible new species. Antibiotic-producing Streptomyces strains were highly diverse in Southern Antique, and species diversity increase with marine sediment depth. Multiple strains with near-identical 16S rRNA and rpoB gene sequences displayed varying strength of antibiotic activities. The genotyping of PKS and NRPS genes revealed that closely related antibiotic-producing strains have similar BGC domains supported by their close phylogenetic proximity. These findings collectively suggest Streptomyces' intraspecies adaptive characteristics in distinct ecological niches that resulted in outcompeting other bacteria through differential antibiotic production.

CHARACTERIZATION, IDENTIFICATION AND OPTIMIZATION OF CHITINOLYTIC RARE ACTINOMYCETES ISOLATED FROM SINAI SOIL, EGYPT

Actinomycetes are highly economic and biotechnologically useful prokaryotes able to produce wide range of bioactive secondary metabolites such as antibiotics and enzymes. The present study, aimed to isolate and screen actinomycetes from various soil samples collected from different regions of Saini, Egypt for chitinase production. In instantaneous isolation and screening of actinomycetes from Sixty-one soil samples, only eight isolates were found to have the capability to produce chitinase on colloidal media. Actinomycete strain A13 exhibit highest chitinase production while other strain shown poor production as compared to an index of relative enzyme activity. The most potent chitinolytic actinomycete isolate No. A13 was selected for further studies concerning their identification. Morphological, physiological, and phylogenetic analysis (16S rRNA). In addition to biochemical studies and culture characteristics as well as the chemical analysis of the cell wall, were carried out for the isolate under study. Based on the phenotypic and genotypic accumulated characteristics of the most potent chitinolytic actinomycetes isolate and consulting the recommended International Key’s of Bergey’s Manual for identification of actinomycetes, it was found that this isolate matched with Amycolatopsis orientalis by 97% with some differences and was given the name Amycolatopsis orientalis A13 sp. nova. The results revealed that the chitinase produced by Amycolatopsis orientalis A13 sp. nova can be optimized to produce the highest yield of chitinase and used as biocontrol agent.

Two new α-Methoxy-γ-Pyrones From the Mangrove Sediment-Derived Streptomyces psammoticus SCSIO NS126

Two new α-methoxy- γ-pyrone analogs, 2-methoxy-3-methyl-5,6-diethyl- γ-pyrone (2) and 2-methoxy-3,5-dimethyl-6-propyl- γ-pyrone (3), together with 2-methoxy-3,5-dimethyl-6-ethyl- γ-pyrone (1), firstly isolated from natural sources, were obtained from the EtOAc-solube extract of the mangrove sediment-derived actinomycete strain Streptomyces psammoticus SCSIO NS126, under the optimized fermentation conditions. Their structures were elucidated by detailed spectroscopic analysis and by comparison of their spectroscopic data with those reported in the literature. Those α-methoxy-γ-pyrones were evaluated for their acetylcholinesterase inhibitory activity; however, none of them exhibited obvious activity. Moreover, their biosynthetic relationship with piericidins was also discussed.

Exploration of Culturable Marine Streptomyces from Southern Coastal Region of India with Antibacterial Properties

The Southern coastal region is a geographically positioned area with rich source of microbial diversity, of which producing broad spectrum of bioactive compounds. The marine sediments are collected from the various sites of south east coastal region of Tamil nadu and are processed. Out of 78 isolates, the 4 strains of actinomycetes are showing broad spectrum activity against Klebsiella pneumoniae (MTCC 1687), Proteus vulgaris (MTCC 3160), Salmonella typhi (MTCC 3231), Shigella dysenteriae (MTCC 3642) and Vibrio cholerae (MTCC 3906). The bioactive isolates are proceeded for further morphological features like growth pattern and mycelial coloration, biochemical and polyphasic taxonomical characterisation were documented. Isolates are investigated for abiotic stress condition to study the growth rate of isolates. Finally, the 16S rRNA molecular identification and phylogenetic analysis of the isolates were explored. Further, bioactive isolates may be potential source for discovery of molecules with industrial applications.

Qaidamihabitans albus gen. nov., sp. nov., a new member of the family Pseudonocardiaceae, and transfer of Prauserella shujinwangii to Qaidamihabitans gen. nov. as Qaidamihabitans shujinwangii comb. nov.

A novel mycelium-forming actinomycete strain, designated YIM S01255T were isolated from a salt lake. Optimal growth occurred in the presence of 0-5.0% (w/v) NaCl, at pH 7.0-8.0, and at 37°C. Strain YIM S01255T contained meso-diaminopimelic acid as the diagnostic diamino acid, and glucose, galactose and arabinose as the whole-cell sugars. The major fatty acid (> 5.0%) were iso-C16:0, iso-C16:1H and iso-C15:0. The major menaquinone were MK-9(H4) and MK-8(H4). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylinositolmannoside and phosphatidylinositol. The DNA G + C content was 70.7mol%. The 16S rRNA gene sequence of the strain showed high similarity to members of genera in the family Pseudonocardiaceae with values less than 95.8%, and most closely related to the genus Amycolatopsis. Both of phylogenetic analysis based on 16S rRNA gene sequences and the up-to-date bacterial genome sequences analysis revealed that strains YIM S01255T and Prauserella shujinwangii XJ46T formed a distinct monophyletic clade and was separated from the other members within the family Pseudonocardiaceae. The average nucleotide identity (ANI) values and digital DNA-DNA hybridization (dDDH) between the two strains were 81.0% and 40.6%, respectively. The distinctive polyphasic evidences differentiated YIM S01255T from members of the family Pseudonocardiaceae, so strain YIM S01255T is considered to represent a novel species of a novel genus of the family Pseudonocardiaceae, for which the name Qaidamihabitans albus gen. nov., sp. nov. is proposed. The type strain of genus Qaidamihabitans is YIM S01255T (= KCTC 49476T = CGMCC 4.7684T). Moreover, Prauserella shujinwangii is also proposed to being transferred into the genus Qaidamihabitans as Qaidamihabitans shujinwangii comb. nov. (type strain XJ46T = CGMCC 4.7125T = JCM 19736T).

Antimicrobial Activity and Identification of the Biosynthetic Gene Cluster of X-14952B From Streptomyces sp. 135.

The bacterial genus Streptomyces is an important source of antibiotics, and genome mining is a valuable tool to explore the potential of microbial biosynthesis in members of this genus. This study reports an actinomycete strain 135, which was isolated from Qinghai-Tibet Plateau in China and displayed broad antimicrobial activity. The fermentation broth of strain 135 displayed strong antifungal activity (>70%) against Sclerotinia sclerotiorum, Botrytis cinerea, Valsa mali, Phytophthora capsici, Glomerella cingulata, Magnaporthe grisea, Bipolaris maydis, Exserohilum turcicum in vitro, meanwhile possessed significant preventive and curative efficacy against S. sclerotiorum, Gaeumannomyces graminis, and P. capsici on rape leaves (54.04 and 74.18%), wheat (90.66 and 67.99%), and pepper plants (79.33 and 66.67%). X-14952B showed the greatest antifungal activity against S. sclerotiorum and Fusarium graminearum which the 50% inhibition concentration (EC50) were up to 0.049 and 0.04 μg/mL, respectively. Characterization of strain 135 using a polyphasic approach revealed that the strain displayed typical features of the genus Streptomyces. 16S rRNA gene sequencing and phylogenetic analysis demonstrated that the isolate was most closely related to and formed a clade with Streptomyces huasconensis HST28T (98.96% 16S rRNA gene sequence similarity). Average nucleotide identity (ANI) and DNA-DNA hybridization (DDH) values in strain 135 and related type strains were both below the threshold of species determination (91.39 and 56.5%, respectively). OrthoANI values between strain 135 and related type strains are under the cutoff of determining species (<95%). The biosynthetic gene cluster (BGC) designated to X-14952B biosynthesis was identified through genome mining and the possible biosynthesis process was deduced.

Process parameter studies by central composite design of response surface methodology for lipase activity of newly obtained Actinomycete

Actinomycete strains from cottonseed soap-stock (a dark gelatinous waste from oil refinery) were obtained. Cultures were analyzed for the enzyme lipase, protease and cellulase production using plate assay(s). Best lipolytic isolates were further quantitatively analyzed for lipase production, using substrate p-nitrophenyl palmitate (p-NPP). Cultures were characterized by morphological and molecular studies. The potent lipase producing strain of actinomycete was optimized for pH, temperature, inoculum size, carbon and nitrogen sources. Further, the lipolytic strain of actinomycete was grown on synthetic media and growth factors were optimized by RSM (Response Surface Methodology) for maximum production of lipase. Total 49 cultures were obtained from enriched soap-stock samples; among them 7 isolates were strains of actinomycete. Potent actinomycete strains were identified as Nocardiopsis alba , Streptomyces leeuwenhoekii , Streptomyces caelestis , Streptomyces werraensis and Streptomyces sclerotialus . Based on quantitative lipase production study, Nocardiopsis alba was selected as the best lipase producer. Optimized results of process parameter studies for lipase production by Nocardiopsis alba were: 5mL inoculum size, temperature 40 ∘ C, shaking at 130 rpm, pH 8.0 and cottonseed oil as the best carbon source. Cottonseed oil, K 2 HPO 4 and cellulose were noted as main factors as optimized by Central Composite Design (CCD), where the culture showed highest (65.78 U/mL/min) lipase production. Findings of the research would offer potential environmental benefits along with socio-economic benefits if implemented suitably. • Response surface methodology has been reported to study Lipase production by Actinomycete • Analysis of variance (ANOVA) has been used in this study. • Highest extracellular lipase production was observed at 40°C at pH 8 of the growth medium. • Nocardiopsis alba can be used on higher scale under optimized process parameters.

PRODUCTION, PURIFICATION AND CHARACTERIZATION OF AN ANTIBACTERIAL COMPOUND FROM STREPTOMYCES GRISEUS TBG19NRA1 ISOLATED FROM THE FOREST SOILS OF THE WESTERN GHATS OF KERALA, INDIA

A new actinomycete strain designated TBG19NRA1, exhibiting antimicrobial activities against Gram-positive and Gram-negative bacteria, was isolated from forest soil of Neyyar Wild Life Sanctuary, Thiruvananthapuram, Kerala. Cultural characteristics strongly suggested that this isolate belongs to the genus Streptomyces. Polyphasic taxonomic studies including phylogenetic analysis based on 16S rDNA sequence suggests that the isolate is a strain of S. griseus. Studies on the effect of different nutritional compounds on antibiotic activity revealed that the highest antibacterial activity was obtained when 1% starch (w/v) was used as the sole carbon source along with mineral trace elements. Extraction and purification of TBG19NRA1 culture supernatant led to the isolation of a pure molecule with good antibacterial activity. The compound has been identified as the cyclic polyether lasalocid A on the basis IR, MS and 13C NMR data interpretation and comparison with reference data from literature.

Cytotoxic Minor Piericidin Derivatives from the Actinomycete Strain Streptomycespsammoticus SCSIO NS126.

The mangrove-sediment-derived actinomycete strain Streptomyces psammoticus SCSIO NS126 was found to have productive piericidin metabolites featuring anti-renal cell carcinoma activities. In this study, in order to explore more diverse piericidin derivatives, and therefore to discover superior anti-tumor lead compounds, the NS126 strain was further fermented at a 300-L scale under optimized fermentation conditions. As a result, eight new minor piericidin derivatives (piericidins L-R (1–7) and 11-demethyl-glucopiericidin A (8)) were obtained, along with glucopiericidin B (9). The new structures including absolute configurations were determined by spectroscopic methods coupled with experimental and calculated electronic circular dichroism. We also proposed plausible biosynthetic pathways for these unusual post-modified piericidins. Compounds 1 and 6 showed selective cytotoxic activities against OS-RC-2 cells, and 2–5 exhibited potent cytotoxicity against HL-60 cells, with IC50 values lower than 0.1 μM. The new piericidin glycoside 8 was cytotoxic against ACHN, HL-60 and K562, with IC50 values of 2.3, 1.3 and 5.5 μM, respectively. The ability to arrest the cell cycle and cell apoptosis effects induced by 1 and 6 in OS-RC-2 cells, 2 in HL-60 cells, and 8 in ACHN cells were then further investigated. This study enriched the structural diversity of piericidin derivatives and confirmed that piericidins deserve further investigations as promising anti-tumor agents.

Amycolatopsis dendrobii sp. nov., an endophytic actinomycete isolated from Dendrobium heterocarpum Lindl.

Three novel actinomycete strains, designated as DR6-1T, DR6-2 and DR6-4, isolated from the roots of Dendrobium heterocarpum Lindl in Thailand were studied using a polyphasic taxonomic approach. The strains grew at 20-37 °C, at pH 5-10 and with 5 % (w/v) NaCl. They contained meso-diaminopimelic acid in the cell-wall peptidoglycan and MK-9(H4) was a major menaquinone. Arabinose and galactose were the major sugars in the cell wall. The predominant cellular fatty acids were iso-C16 : 0 and iso-C15 : 0. The detected polar lipids were diphosphatidylglycerol, hydroxyphosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylglycerol. Strains DR6-1T, DR6-2 and DR6-4 shared 99.9-100 % 16S rRNA gene sequence similarity and were closely related to Amycolatopsis echigonensis JCM 21831T (98.7-98.8%). The approximate genome size of strain DR6-1T was 9.6 Mb with a G+C content of 69.6 mol%. The ANIb and dDDH values between genomic sequences of strain DR6-1T and Amycolatopsis echigonensis JCM21831T, Amycolatopsis rubida JCM 10871T and Amycolatopsis nivea KCTC 39515T were 90.55, 92.25, 92.60%, and 47.20, 52.10 and 52.50%, respectively. Based on the phenotypic, chemotaxonomic and genotypic characteristics, it has been concluded that strains DR6-1T, DR6-2 and DR6-4 represent a novel species of the genus Amycolatopsis for which the name Amycolatopsis dendrobii sp. nov. is proposed. The type strain is DR6-1T (=JCM 33742T=KCTC 49546T=TISTR 2840T).

Identification of the cognate response regulator of the orphan histidine kinase OhkA involved in both secondary metabolism and morphological differentiation in Streptomyces coelicolor.

In the model actinomycete strain, Streptomyces coelicolor, an orphan histidine kinase (HK) named OhkA (encoded by SCO1596), which belongs to bacterial two-component regulatory systems (TCSs), has been identified as being involved in the regulation of both antibiotic biosynthesis and morphological development. However, its cognate response regulator (RR) remains unknown due to its isolated genetic location on the genome, which impedes the elucidation of the mechanism underlying OhkA-mediated regulation. Here, we identified the orphan RR OrrA (encoded by SCO3008) as the cognate RR of OhkA according to mutant phenotypic changes, transcriptomics analysis, and bacterial two-hybrid experiment. Considering that the partner RR of the orphan HK is also orphan, a library of mutants with in-frame individual deletion of these functionally unknown orphan RR-encoding genes were generated. Through phenotypic analysis, it was found that the ∆orrA mutant exhibited similar phenotypic changes as that of the ∆ohkA mutant, showing increased production of actinorhodin (ACT) and undecylprodigiosin (RED), and pink colony surface. Further transcriptomics analysis showed these two mutants exhibited highly similar transcriptomics profiles. Finally, the direct interaction between OhkA and OrrA was revealed by bacterial two-hybrid system. The identification of the partner RR of OhkA lays a good foundation for an in-depth elucidation of the molecular mechanism underlying OhkA-mediated regulation of development and antibiotic biosynthesis in Streptomyces. KEY POINTS: • OrrA was identified as the partner RR of the orphan histidine kinase OhkA. • The ∆orrA and ∆ohkA mutants showed similar phenotype and transcriptomic profiling. • Specific interaction of OrrA and OhkA was revealed by bacterial two-hybrid system.

Isolation of Actinomycetes from Different Soil Sample (NCR Region) &amp; Screening their Antibacterial Activity Against E.Coli and Bacillus

In the extant study, the soil samples were gathered up from NCR region. A total 9 Actinomycetes strains were isolated from the NCR. These Actinomycetes had been cloistered with respect to capability against Gram-positive and Gram-negative bacteria. Soil sample was isolated for their antibacterial activity. They were assess for their constraint activities on 2 test organism. The culture characteristics of screened bacteria were also studies in non-identical culture media. The results specify that 9 Actinomycetes isolates were highly active against E. Coli, and Bacillus strains. 9 Actinomycetes isolates were extremely vigorous with an inhibition zone more than 16 mm in diameter. All the antibiotics producing actinomycetes were isolated at 28 °C from soil sample. 9 Actinomycetes isolates showed activity against bacteria in which chiefly from alkaline soil. Where the less intervention by human for agriculture or other purpose. These Micro-organisms may have capability to produce powerful &amp; essential medicines factories. Most of bacteria have elaborated resistance to almost all antibiotics. An infamous instance of multi-resistant bacteria is the ‘hospital superbug’, MRSA. Seeking of new antibiotics has become an aqueduct against time.

Anti-bacterial effect of marine sea grasses mediated endophytic actinomycetes against K. pneumoniae

In this study, the pure, pale white, powdery nature and pigment produced endophytic actinomycetes strains were isolated from marine Sea grasses sample. The isolated strains were endophytes as confirmed by surface sterilization and validation methods. The anti-bacterial efficacy materials of the crude compound were extracted by liquid–liquid extraction using various organic solvents. Anti-bacterial efficacy of the isolated actinomycetes strain RMN 10 was exhibited excellent anti-bacterial activity against K. pneumoniae at increasing concentration. In addition, the minimum inhibition concentration (MIC) of the crude actinomycetes compound has excellent anti-bacterial activity at 250 µg/mL concentration and this concentration was fixed as a MIC. Further, the structural and shape damages of actinomycetes crude compound treated K. pneumoniae cells were clearly identified in SEM images. All the invitro experiments were proved that the actinomycetes compound has excellent anti-bacterial activity against K. pneumoniae.

Gold Nanoparticles: Green Synthesis, Characterization and Biological Activities

This study aims to introduce a green, eco-friendly, fast and cost effective method to synthesis gold nano-sized particles (Au NPs) from actinomycete strain; Streptomyces sp. U30 (KP109810), isolated from metal containing rock. The biosynthesized gold nanoparticles were formed at lower conditions of pH, mass weight and incubation time (7 hours only). The bio-formed Au NPs were fully characterized with different techniques to study their nano-metrological measurements. The X-ray diffraction (XRD) technique and high resolution transmission electron microscopy (HR-TEM) were used to determine the crystal structure, size and shape of Au NPs. Fourier transform infrared spectroscopy (FTIR) studies were done to investigate the distinct functional groups present on the surface. The zetasizer technique was used to define the stability of biosynthesized gold nanoparticles. The antimicrobial activities of biosynthesized gold nanoparticles were studied against gram positive and gram negative bacteria at three different concentrations, 10, 30 and 50 μg/disc, using agar well diffusion method. The obtained results prove that the biosynthesized Au NPs gave different antimicrobial action which was strain dependent. All the tested bacterial strains were inhibited by the examined concentrations with variations in the inhibition zone diameters, except Candida albicans showed resistant to the biosynthesized Au NPs. The bio-formed gold nanoparticles can be used in different applications.

Partially purified actinomycetes compounds enhance the intracellular damages in multi-drug resistant P. aeruginosa and K. pneumoniae.

Based on the excellent nutrient level, the current study was focused on isolation and anti-bacterial activity of the actinomycetes from marine mangrove soil samples. As result, 10 different strains of actinomycetes strains were identified on actinomycetes isolation agar plates. The identified strains were shown with white, clear, uncontaminated well matured spore producing ability. Based on the initial observation, the isolated colonies were actinomycetes. The partially extracted crude compound shown excellent anti-bacterial activity against P. aeruginosa and K. pneumoniae with 15 mm and 13 mm zone of inhibitions were observed at 500 μL concentrations. The minimum inhibition concentration result was also confirmed the 500 μL concentration against both the tested concentration with high inhibition rate. Then, the intracellular damages, decreased cell growth of the crude actinomycetes extract treated bacterial strains were clearly observed by confocal laser scanning electron microscope. The extracellular damages of bacterial cell wall and shape of the both the pathogens were clearly shown by scanning electron microscope. Therefore, all the results were clearly supported to the partially extracted crude compound and it has excellent anti-bacterial activity against tested multi drug resistant bacteria.