Researcher/Lecturer I, University of Lagos, Nigeria
Broad-spectrum activities of Streptomyces coelicolor strain isolated from a tropical estuary.
My research focus is centered on antimicrobial drug resistance and understanding of the various heritable sources of bacterial resistance called resistance genes that usually provide the bacteria special resistant abilities such as antibiotic hydrolyzing enzymes, mobile genetic elements etc. which often leads to antibiotic resistant abilities of bacteria to several classes of available antibiotics for the human therapeutic purpose. It has been established within the frame of my investigation that bacteria of my country origin harbor multiple mechanisms of transmissible antibiotic resistance which is similar to what has been reported in other developed countries. This knowledge borne the idea of bioprospecting for novel drugs that are efficient in terms of efficacy and affordability as a means of solving a global menace of antimicrobial resistant bacteria. My chosen environment for the search of natural raw material is the marine habitat which has been recently discovered is abundance of rich biodiversity of microorganisms capable of producing natural compounds which can serve as a lead agent for novel drug production. Hence my research involves investigating the potential abilities of certain marine organisms that can produce unique substances with the ability to kill other bacteria or provide other health benefits. In this quest, the West African marine environment has been totally understudied in the bioprospecting for novel drugs from marine microorganism. Despite its rich biodiversity, there is definitively a paucity of studies on marine isolates from West Africa and in particular from Nigeria. This form the basis of my area of research and choice of environment. Recently, it has been confirmed within the frame of our investigation along with my team comprising of undergraduates and postgraduate as well as postdoc students , that Lagos lagoon, located in Southwest Nigeria, is in abundance of rich novel marine bacteria species which demonstrated potent antimicrobial activities towards a broad range of disease causing microorganisms such as Staphylococcus aureus, Escherichia coli and Salmonella typhi. My study highlights the need for the continuous search for bioactive products of microbial origin and also affirm that West African marine is a potential source of beneficial living organisms which can help in solving the global health challenge of antibiotic resistance.
Abstract: In the present study, fifteen endophytic actinobacterial isolates recovered from Solanum lycopersicum were studied for their antagonistic potential and plant-growth-promoting (PGP) traits. Among them, eight isolates showed significant antagonistic and PGP traits, identified by amplification of the 16S rRNA gene. Isolate number DBT204, identified as Streptomyces sp., showed multiple PGP traits tested in planta and improved a range of growth parameters in seedlings of chili (Capsicum annuum L.) and tomato (Solanum lycopersicum L.). Further, genes of indole acetic acid (iaaM) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase (acdS) were successively amplified from five strains. Six antibiotics (trimethoprim, fluconazole, chloramphenicol, nalidixic acid, rifampicin and streptomycin) and two phytohormones [indole acetic acid (IAA) and kinetin (KI)] were detected and quantified in Streptomyces sp. strain DBT204 using UPLC-ESI-MS/MS. The study indicates the potential of these PGP strains for production of phytohormones and shows the presence of biosynthetic genes responsible for production of secondary metabolites. It is the first report showing production of phytohormones (IAA and KI) by endophytic actinobacteria having PGP and biosynthetic potential. We propose Streptomyces sp. strain DBT204 for inoculums production and development of biofertilizers for enhancing growth of chili and tomato seedlings.
Pub.: 12 Jul '16, Pinned: 26 Aug '17
Abstract: Actinomycetes mediated biogenic synthesis of metal nanoparticles and their antimicrobial activities are well documented. Actinomycetes facilitate both intracellular and extracellular metal nanoparticles synthesis and are efficient candidates for the production of polydispersed, stable and ultra-small size metal nanoparticles. Secondary metabolites and new chemical entities derived from actinomycetes have not been extensively studied for the synthesis of metal/ metal oxide nanoparticles. The present review focuses on biogenic synthesis of metal nanoparticles from actinomycetes and the scope for exploring actinomycetes derived compounds (enzymes, organics acids and bioactive compounds) as metal and metal oxide reducing agents for the synthesis of desired nanoparticles. This review also focuses on challenges faced in the applications nanoparticles and the methods to synthesise biogenic metal nanoparticles with desired physiochemical properties such as ultra-small size, large surface to mass ratio, high reactivity etc. Methods to evade their toxicity and unique interactions with biological systems to improve their chance as an alternative therapeutic agent in medical and pharmaceutical industry are also discussed. This article is protected by copyright. All rights reserved.
Pub.: 08 Mar '17, Pinned: 26 Aug '17
Abstract: The aim of the present study was to evaluate the ability of D-Ala(2)GIP, a gastric inhibitory polypeptide (GIP) receptor agonist, to attenuate the behavioral phenotype of Parkinson's disease caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in mice. In the behavioral studies, MPTP administration led to spontaneous locomotor activity deficits, impaired rotarod performance, akinesia, muscular rigidity and increased tremor amplitude, which was attenuated by pretreatment with D-Ala(2)GIP (50-100 nmol/kg, i.p.). This acute neuroprotective response by D-Ala(2)GIP was found to be blocked by a selective GIP receptor antagonist, (Pro(3))GIP (50 nmol/kg, i.p.), indicating that the observed effects are mediated through GIP receptor mediated signaling pathway. Biochemical studies revealed that D-Ala(2)GIP reduced the brain malondialdehyde levels and enhanced the brain glutathione levels, thereby mitigating the MPTP-induced oxidative stress. MPTP administration resulted in reduction of the striatal concentration of dopamine and its metabolites, homovanillic acid (HVA) and 3, 4-Dihydroxyphenylacetic acid (DOPAC). Pretreatment with D-Ala(2)GIP attenuated the loss of striatal dopamine levels without affecting the normal dopamine catabolism. Thus, the observed effects in the MPTP-induced Parkinsonism model could be in part attributable to the antioxidant properties of D-Ala(2)GIP and enhanced turnover of dopamine in the nigrostriatal pathways in mouse brain. These findings together suggest that GIP receptor could be a therapeutic target in the management of symptoms of Parkinson's disease.
Pub.: 04 Apr '17, Pinned: 26 Aug '17
Abstract: The aim of the present study was to isolate antibacterial compound from Streptomyces sp. VITMK1 isolated from mangrove soil of Pichavaram, Tamil Nadu, India. A total of 31 actinomycetes isolates were isolated from soil samples collected at the mangrove region. Actinomycetes isolates were screened for antibacterial activity by well diffusion method. The potential isolate was identified and characterized using morphological, biochemical and molecular taxonomic methods. The partial 16S r-RNA gene sequence of the potential isolate was submitted to GenBank under the accession number KF493733. The isolate was mass cultured on Tryptone Yeast Extract (ISP 1) medium followed by solvent extraction using ethyl acetate (EA). The EA extract showed antibacterial activity with a maximum zone of inhibition against Proteusvulgaris (23 mm), Salmonellaparatyphi (21 mm), Staphylococcusaureus (20 mm) and Bacilluscereus (20 mm). The EA extract was purified using silica gel column chromatography using chloroform and EA (9:1 v/v) as solvent system and the active fraction was subjected to compound identification using spectral techniques such as fourier transform infrared spectroscopy, gas chromatography–mass spectrometry and hydrogen and carbon nuclear magnetic resonance spectroscopy. The compound was identified as Pyrrolo [1, 2-A] pyrazine-1, 4-dione, hexahydro-3-(2-methylpropyl) with a molecular weight of 210 kDa. The extracted compound showed high antibacterial activity.
Pub.: 02 Aug '15, Pinned: 26 Aug '17
Abstract: Abstract We present the microbial green synthesis of silver nanoparticles (NPs) by Streptomyces ghanaensis VITHM1 strain (MTCC No. 12465). The secondary metabolites in the cell free supernatant of this bacterium when incubated with 1 mmol/L AgNO3, mediated the biological synthesis of AgNPs. The synthesized AgNPs were characterized by UV-visible spectrum, X-ray diffraction (XRD), atomic force microscope, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, FT-IR spectroscopy, dynamic light scattering and zeta potential. They were highly stable and, spherical in shape with the average size of 30‒50 nm. The secondary metabolites involved in the formation of AgNPs were identified gas chromatographymass spectrography. The 3D structure of the unit cell of the synthesized AgNPs was determined using XRD data base. The synthesized AgNPs exhibited significant antibacterial activity against tested bacterial pathogens, and did not show haemolysis on human red blood cells. This green synthesis could provide a new platform to explore and use AgNPs as antibacterial therapeutic agents. AbstractWe present the microbial green synthesis of silver nanoparticles (NPs) by Streptomyces ghanaensis VITHM1 strain (MTCC No. 12465). The secondary metabolites in the cell free supernatant of this bacterium when incubated with 1 mmol/L AgNO3, mediated the biological synthesis of AgNPs. The synthesized AgNPs were characterized by UV-visible spectrum, X-ray diffraction (XRD), atomic force microscope, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, FT-IR spectroscopy, dynamic light scattering and zeta potential. They were highly stable and, spherical in shape with the average size of 30‒50 nm. The secondary metabolites involved in the formation of AgNPs were identified gas chromatographymass spectrography. The 3D structure of the unit cell of the synthesized AgNPs was determined using XRD data base. The synthesized AgNPs exhibited significant antibacterial activity against tested bacterial pathogens, and did not show haemolysis on human red blood cells. This green synthesis could provide a new platform to explore and use AgNPs as antibacterial therapeutic agents. Streptomyces ghanaensis3
Pub.: 01 Dec '16, Pinned: 26 Aug '17
Abstract: New broad spectrum antimicrobial agents are urgently needed to combat frequently emerging multi drug resistant pathogens. Actinomycetes, the most talented group of microorganisms isolated from unexplored regions of the world may be the ultimate solution to this problem. Thus the aim of this study was to isolate several bioactive actinomycetes strains capable of producing antimicrobial secondary metabolite from Sundarbans, the only mangrove tiger land of the world.Fifty four actinomycetes were isolated and analyzed for antimicrobial activity against fifteen test organisms including three phytopathogens. Nine morphologically distinct and biologically active isolates were subjected to polyphasic identification study.16 s rDNA sequencing indicated eight isolates to reveal maximum similarity to the genus streptomyces, whereas one isolate presented only 93.57% similarity with Streptomyces albogriseolus NRRL B-1305(T). Seventy-one carbon sources and twenty-three chemical sources utilization assay revealed their metabolic relatedness. Among these nine isolates three specific strains were found to have notably higher degree of antimicrobial potential effective in a broader range including phyto-pathogenic fungus. Finally the strain SMS_SU21, which showed antimicrobial activity with MIC value of 0.05 mg ml(-1) and antioxidant activity with IC50 value of 0.242 ± 0.33 mg ml(-1) was detected to be the most potential one. True prospective of this strain was evaluated utilizing GC-MS and the bioactive compound responsible for antimicrobial activity was purified.Rare bioactive actinomycetes were isolated from unexplored heritage site. Antimicrobial compound has also been identified and purified which is active against a broad range of pathogens.
Pub.: 22 Aug '15, Pinned: 26 Aug '17
Abstract: Marine actinobacteriology is one of the major emerging areas of research in tropics. Marine actinobacteria are the most economically as well as biotechnologically valuable prokaryotes. Many representatives of the order Actinomycetales are prolific producers of thousands of biologically active secondary metabolites. Among the actinobacteria, streptomycetes group are considered economically important because out of the approximately more than 10,000 known antibiotics, 50-55% are produced by this genus. The ecological role of actinobacteria in the marine ecosystem is largely neglected and various assumptions meant there was little incentive to isolate marine strains for search and discovery of new drugs. The search for and discovery of novel actinobacteria are of significant interest to drug discovery due to a growing need for the development of new and potent therapeutic agents. In this review an evaluation is made on the present state of research on marine actinobacterial metabolites and its perspectives. The highlights include the production and biotechnological applications of metabolites such as antibiotics, anticancer compounds, melanins, enzymes and enzyme inhibitors, single cell protein and as probiotics in aquaculture. With increasing advancement in science and technology, there would be greater demands in future for new bioactive compounds synthesized by actinobacteria from various marine sources.
Pub.: 14 Mar '13, Pinned: 26 Aug '17
Abstract: Marine actinobacteria are one of the most efficient groups of secondary metabolite producers and are very important from an industrial point of view. Many representatives of the order Actinomycetales are prolific producers of thousands of biologically active secondary metabolites. Actinobacteria from terrestrial sources have been studied and screened since the 1950s, for many important antibiotics, anticancer, antitumor and immunosuppressive agents. However, frequent rediscovery of the same compounds from the terrestrial actinobacteria has made them less attractive for screening programs in the recent years. At the same time, actinobacteria isolated from the marine environment have currently received considerable attention due to the structural diversity and unique biological activities of their secondary metabolites. They are efficient producers of new secondary metabolites that show a range of biological activities including antibacterial, antifungal, anticancer, antitumor, cytotoxic, cytostatic, anti-inflammatory, anti-parasitic, anti-malaria, antiviral, antioxidant, anti-angiogenesis, etc. In this review, an evaluation is made on the current status of research on marine actinobacteria yielding pharmaceutically active secondary metabolites. Bioactive compounds from marine actinobacteria possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens. With the increasing advancement in science and technology, there would be a greater demand for new bioactive compounds synthesized by actinobacteria from various marine sources in future.
Pub.: 21 Aug '13, Pinned: 26 Aug '17
Abstract: Poultry waste is an abundant renewable source for the recovery of several value-added metabolites with potential industrial applications. This study describes the production of protease on poultry waste, with the subsequent use of the same poultry waste for the extraction of antioxidants. An extracellular protease-producing strain was isolated from Cuddalore coast, India, and identified as Streptomyces sp. MAB18. Its protease was purified 17.13-fold with 21.62% yield with a specific activity of 2398.36 U/mg and the molecular weight was estimated as 43 kDa. The enzyme was optimally active at pH 8-10 and temperature 50-60 ° C and it was most stable up to pH 12 and 6-12% of NaCl concentration. The enzyme activity was reduced when treated with Hg(2+), Pb(2+), and SDS and stimulated by Fe(2+), Mg(2+), Triton X-100, DMSO (dimethyl sulfoxide), sodium sulphite, and β-mercaptoethanol. Furthermore, the antioxidant activities of protease were evaluated using in vitro antioxidant assays, such as DPPH radical-scavenging activity, O2 scavenging activity, NO scavenging activity, Fe(2+) chelating activity, and reducing power. The enzyme showed important antioxidant potential with an IC50 value of 78 ± 0.28 mg/mL. Results of the present study indicate that the poultry waste-derived protease may be useful as supplementary protein and antioxidant in the animal feed formulations.
Pub.: 31 Aug '13, Pinned: 26 Aug '17
Abstract: Marine environment is largely an untapped source for deriving actinobacteria, having potential to produce novel, bioactive natural products. Actinobacteria are the prolific producers of pharmaceutically active secondary metabolites, accounting for about 70% of the naturally derived compounds that are currently in clinical use. Among the various actinobacterial genera, Actinomadura, Actinoplanes, Amycolatopsis, Marinispora, Micromonospora, Nocardiopsis, Saccharopolyspora, Salinispora, Streptomyces and Verrucosispora are the major potential producers of commercially important bioactive natural products. In this respect, Streptomyces ranks first with a large number of bioactive natural products. Marine actinobacteria are unique enhancing quite different biological properties including antimicrobial, anticancer, antiviral, insecticidal and enzyme inhibitory activities. They have attracted global in the last ten years for their ability to produce pharmaceutically active compounds. In this review, we have focused attention on the bioactive natural products isolated from marine actinobacteria, possessing unique chemical structures that may form the basis for synthesis of novel drugs that could be used to combat resistant pathogenic microorganisms.
Pub.: 25 Jun '14, Pinned: 26 Aug '17
Abstract: Carbapenems are potent β-lactam antibiotics with a broad spectrum of activity against both Gram positive and Gram negative bacteria. As naturally produced metabolites, they have been isolated from species of Streptomyces, Erwinia and Serratia. The latter two members of the Enterobacteriaceae have proved to be genetically amenable and a growing body of research on these organisms now exists concerning the genes responsible for carbapenem biosynthesis and the regulatory mechanisms controlling their expression. A cluster of nine carbapenem (car) genes has been identified on the chromosome of Erwinia carotovora. These genes encode the enzymes required for construction of carbapenem and the proteins responsible for a novel β-lactam resistance mechanism, conferring carbapenem immunity in the producing host. Although sharing no homology with the well known enzymes of penicillin biosynthesis, two of the encoded proteins are apparently similar to enzymes of the clavulanic acid biosynthetic pathway implying a common mechanism for construction of the β-lactam ring. In addition, a transcriptional activator is encoded as the first gene of the carbapenem cluster and this allows positive expression of the remaining downstream genes in response to a quorum sensing, N-acyl homoserine lactone, signalling molecule.
Pub.: 01 Feb '99, Pinned: 24 Aug '17
Abstract: Arnica montana L. is a medical plant of the Asteraceae family and grows preferably on nutrient poor soils in mountainous environments. Such surroundings are known to make plants dependent on symbiosis with other organisms. Up to now only arbuscular mycorrhizal fungi were found to act as endophytic symbiosis partners for A. montana. Here we identified five Streptomyces strains, microorganisms also known to occur as endophytes in plants and to produce a huge variety of active secondary metabolites, as inhabitants of A. montana. The secondary metabolite spectrum of these strains does not contain sesquiterpene lactones, but consists of the glutarimide antibiotics cycloheximide and actiphenol as well as the diketopiperazines cyclo-prolyl-valyl, cyclo-prolyl-isoleucyl, cyclo-prolyl-leucyl and cyclo-prolyl-phenylalanyl. Notably, genome analysis of one strain was performed and indicated a huge genome size with a high number of natural products gene clusters among which genes for cycloheximide production were detected. Only weak activity against the Gram-positive bacterium Staphylococcus aureus was revealed, but the extracts showed a marked cytotoxic activity as well as an antifungal activity against Candida parapsilosis and Fusarium verticillioides. Altogether, our results provide evidence that A. montana and its endophytic Streptomyces benefit from each other by completing their protection against competitors and pathogens and by exchanging plant growth promoting signals with nutrients.
Pub.: 04 Jun '15, Pinned: 24 Aug '17