Isolation Of Actinomycetes Research Articles

Antagonistic and Antioxidant Potential of Actinomycete Isolates from Sambhar Lake

Bacterial secondary metabolites contain a diverse spectrum of biologically active compounds, including antimicrobials and antioxidants. Harnessing these products has enabled humans to fight against various diseases. But due to the overuse of antibiotics over the past few decades, many resistant strains of microbes are emerging. Therefore, there is a need to identify new sources of antimicrobial compounds. Actinomycetes are a group of bacteria known to produce antimicrobial compounds. This investigation aimed to identify, isolate and characterize actinomycetes with antimicrobial and antioxidant activity against pathogens acquired from MTCC. Sambhar Lake has a very potential group of actinomycetes producing several secondary metabolites. The study reports the antimicrobial and antioxidant potential of different extracts of actinomycetes. The sections of the actinomycetes were tested for their antagonistic activity against five pathogenic microorganisms. Antibacterial activity was reported in all five actinomycete isolates against Bacillus subtilis-MTCC 441, Escherichia coli-MTCC-1885, and Salmonella typhi-MTCC 733 but almost negligible activity against Staphylococcus aureus-MTCC 737 and Pseudomonas aeruginosa- MTCC 424 except for ACT-14 and ACT- 11. ACT14 had the highest antibacterial activity compared to all other isolates. The antioxidant capacities of all isolated extracts were evaluated for total phenols, total antioxidant activity, total reducing power, DPPH, and ABTS assays. Section of Pseudonocardia Antarctica ACT14 showed the highest (23.89±0.96) free radical scavenging of 2, 2-diphenyl1-picrylhydrazyl (DPPH), phenolic activity (194 ± 6.05) activity. This study was conducted to identify novel actinomycetes with antimicrobial properties. The sample ACT14 was found to be a novel actinomycete (Pseudonocardia Antarctica), and this isolate showed antimicrobial activity against all the test pathogenic bacteria used in the study. The culture was optimized for antimicrobial compound production. Since many pathogens tend to acquire antibiotic resistance, this study is essential as a novel source of antimicrobials that will provide a new weapon in the fight against infectious pathogens. Further purification and characterization of this compound are underway.

Degradation of polyethylene plastic bags and bottles using microorganisms isolated from soils of Morogoro, Tanzania.

Plastics are of great significance in today's world due to their extensive use such as packaging food and carrying other goods, which have improved the quality of human life. However, plastics have low biodegradability and are persistent in the environment, becoming a major source of pollution. With regard to the current methods used in the management of plastic wastes, the degradation of plastics using beneficial soil microorganisms has recently gained attention due to their ability to degrade different types of plastics including polyethylene (PE) polymers. The study herein was conducted to isolate and identify microorganisms from agricultural soils capable of degrading plastics. Soil samples were inoculated into nutrient, potato dextrose, and starch-casein agar for the isolation of bacteria, fungi, and actinomycetes, respectively. During isolation, fungi and bacterial plates were incubated for 5 days and for 14 days, respectively. The population of bacteria ranged from 1 × 105 to 1.215 × 105 and that of fungi from 1.604 × 104 to 8.6 × 104 whereby actinomycetes ranged from 1.045 × 105 to 2.995 × 105 CFU/g of soil. However, the tested microorganisms showed significant (p ≤ 0.05) differences in the ability to degrade PE bags and bottles as depicted by the diameters of clear zones around the colonies. The diameters of clear zones ranged from 19.3 to 47.5 mm and 25.9 to 32.2 mm after 17 days for bacteria and actinomycetes, respectively, and those of fungi ranged from 30.0 to 66.3 mm after 13 days. Among the bacteria, actinomycetes, and fungi, unsequenced bacterial and actinomycete isolates B1 and A3 as well as Aspergillus sp. (F7) were the most efficient degraders of PE plastic bags. This retrospective study sheds light on our understanding and the need for the bioprospecting of agricultural soils, water bodies, and landfills containing plastic wastes that could lead to the identification of more efficient microbial species with the ability to degrade plastics.

Diversity of actinomycete and their metabolites isolated from Howz Soltan Lake, Iran.

Saline environments are largely unexplored sources of actinomycetes with the potential to produce biologically active secondary metabolites. A total of 34 actinomycete isolates from water, sediments and mostly rhizosphere (82%) were collected from different sites at Howz Soltan Lake in Iran. Based on phylogenetic analysis, the isolates belonged to the genera Streptomyces, Nocardia and Saccharomonospora. Cytotoxic assay revealed extract from isolate act9 as the most potent (19.716±5.72 µg/ml) against the MDA-MB-231 human breast cancer cell. Also, 38% of the isolates showed antimicrobial activity against some of the test microorganisms. The ethyl-acetate extract of isolate act18 showed the strongest antibacterial effect against Staphylococcus aureus and MRSA, and was further analyzed by GC/MS. Ar-tumerone (26.41%) and butyl isodecyl phthalate (21.77 %) were the main constituents detected in the extract. This is the first time Ar-tumerone is being detected in a prokaryote. Isolate act18 showed a high 16S rRNA sequence similarity to that of Streptomyces youssoufiensis DSM 41920. In addition, a number of the isolates produced different enzymes including lipase, amylase, protease, gelatinase, urease and lecithinase. Some of the isolates belonging to the genera Streptomyces and Nocardia exhibited plant growth promoting activity such as increased seed germination, stem length and the number of Echium leaves during the 20 days. Findings from this study indicated the diversity and biosynthetic potential of actinomycetes from saline environment.

CHARACTERIZATION OF MARINE ACTINOMYCETES SPECIES ISOLATED FROM AZHIMALA COASTAL REGION, KERALA AND IT’S EFFICACY AGAINST UROPATHOGENIC BACTERIA

Actinomycetes are virtually unlimited sources of novel compounds with many therapeutic applications and hold aprominent position due to their diversity and proven ability to produce novel bioactive compounds. The present study isaimed to prove the antagonistic activity of marine actinomycetes against uropathogens. 13 marine actinomycetes wereisolated from various marine sediment samples collected from different stations in the Azhimala coastal region, part ofthe Arabian Sea on the western coast of India. The sample collection and isolation of actinomycetes were done byfollowing the standard microbiological methods and the isolated colonies were characterized based on theirmorphological parameters. The morphologically distinct 13 isolates obtained in the present study, the isolates SD65,SD66, SD67, SD68, SD69, SD70, SD71, V66, V67, V68, V69,V70,V71 among them 3 isolates,V67,V68 and V70showed significant antagonism against selected uropathogens collected from a tertiary care center inThiruvananthapuram, Kerala. The results were promising and indicated that actinomycetes with distinctive biologicalactivity are abundant in the marine environment along Kerala's coast.

Biological control of potato bacterial wilt disease caused by Ralstonia solanacearum using actinomycetes isolates

Biological control of potato bacterial wilt disease caused by Ralstonia solanacearum using actinomycetes isolates

Isolation of actinomycetes from peatland to suppress the growth of Ganoderma boninense the causal agent of basal stem rot disease in oil palm

Abstract. Budi MBS, Giyanto, Tondok ET. 2022. Isolation of actinomycetes from peatland to suppress the growth of Ganoderma boninense the causal agent of basal stem rot disease in oil palm. Biodiversitas 23: 5914-5922. Basal stem rot is a major constrain in oil palm cultivation. The aim of this study was to obtain actinomycetes isolates that can suppress the growth of Ganoderma boninense. The research stages included rejuvenation of actinomycetes isolate stock cultures, observation of morphological characters, analysis of the potency of actinomycetes as biological control agents against G. boninense (antibiosis, volatile organic compound, effect of bioactive compounds in actinomycete culture supernatants and their concentration levels in suppressing G. boninense), physiological characterization and molecular identification was also done of selected actinomycetes. All actinomycetes colonies were grey and brown in color with rectiflexible and vertilicillate spore chain types. Three of the seven isolates tested, namely AKT19, AKT28, and AKT52, were able to suppress the growth of G. boninense up to 100% based on the dual culture test and the percent inhibition of G. boninense growth was 12.27; 17.50; and 23.23% by volatile organic compounds. At 10% concentration, the bioactive compounds of three actinomycetes isolates inhibited the growth of G. boninense, i.e., 89.17, 88.30 and 86.50%, respectively. Further results revealed that isolate AKT19 was the strongest suppressor (70.93) of G. boninense at a concentration of 0.5%, while isolates AKT 28 and 52 inhibited only 15.30 and 4.80%, respectively. All potential actinomycetes isolates produce chitinase, glucanase, cellulase, phosphatase enzymes, fixes nitrogen and secreted indole acetic acid growth hormone. Based on the analysis of 16S rRNA gene, it was noted that all potential isolates were identified as Streptomyces gelaticus.

1-(6-Methylsalicyloyl)glycerol from stony coral-derived Micromonospora sp.

A new natural product, 1-(6-methylsalicyloyl)glycerol (1) was isolated from the culture extract of the stony coral-derived Micromonospora sp. C029. The structure of 1 was determined by extensive analysis of 1D and 2D NMR spectroscopic data. The absolute configuration was determined to be S by comparison of specific rotation with synthetic (R)- and (S)-1. Compound 1 showed weak antimicrobial activity against Kocuria rizhophila. Structurally related benzoyl glycerol is not reported from actinomycetes, suggesting that isolation of actinomycetes from little studied environments should be important for the discovery of novel natural products.

Actinomycete Potential as Biocontrol Agent of Phytopathogenic Fungi: Mechanisms, Source, and Applications.

Synthetic fungicides have been the main control of phytopathogenic fungi. However, they cause harm to humans, animals, and the environment, as well as generating resistance in phytopathogenic fungi. In the last few decades, the use of microorganisms as biocontrol agents of phytopathogenic fungi has been an alternative to synthetic fungicide application. Actinomycetes isolated from terrestrial, marine, wetland, saline, and endophyte environments have been used for phytopathogenic fungus biocontrol. At present, there is a need for searching new secondary compounds and metabolites of different isolation sources of actinomycetes; however, little information is available on those isolated from other environments as biocontrol agents in agriculture. Therefore, the objective of this review is to compare the antifungal activity and the main mechanisms of action in actinomycetes isolated from different environments and to describe recent achievements of their application in agriculture. Although actinomycetes have potential as biocontrol agents of phytopathogenic fungi, few studies of actinomycetes are available of those from marine, saline, and wetland environments, which have equal or greater potential as biocontrol agents than isolates of actinomycetes from terrestrial environments.

Metabolomic Profiling, In Vitro Antimalarial Investigation and In Silico Modeling of the Marine Actinobacterium Strain Rhodococcus sp. UR111 Associated with the Soft Coral Nephthea sp.

Malaria is a persistent illness with a great public health concern. To combat this fatal disease, developing effective antimalarial medications has become a necessity. In the present study, we described the actinomycetes associated with the Red Sea soft coral Nephthea sp. and isolated a strain that was sub-cultured in three different media (M1, ISP2, and OLIGO). Actinomycete isolate's phylogenetic analysis of the 16S rRNA gene revealed that it belongs to the genus Rhodococcus. In vitro screening of the antimalarial activity for three extracts against Plasmodium falciparum was carried out. Non-targeted metabolomics for the chemical characterization of the isolated actinomycete species UA111 derived extracts were employed using high-resolution liquid chromatography-mass spectrometry (LC-HR-MS) for dereplication purposes. Additionally, statistical analysis of the vast LC-MS data was performed using MetaboAnalyst 5.0. Finally, an in silico analysis was conducted to investigate the potential chemical compounds that could be the source of the antimalarial potential. The results revealed that ISP2 media extract is the most effective against Plasmodium falciparum, according to antimalarial screening (IC50 8.5 µg/mL), in contrast, OLIGO media extract was inactive. LC-HRMS-based metabolomics identified a range of metabolites, mainly alkaloids, from the genus Rhodococcus. On the other hand, multivariate analysis showed chemical diversity between the analyzed samples, with ISP2 extract being optimal. The docking analysis was able to anticipate the various patterns of interaction of the annotated compounds with three malarial protein targets (P. falciparum kinase, P. falciparum cytochrome bc1 complex, and P. falciparum lysyl-tRNA synthetase). Among all of the test compounds, perlolyrine (11) and 3097-B2 (12) displayed the best docking profiles. In conclusion, this work demonstrated the value of the established method for the metabolic profiling of marine actinomycetes using the data from liquid chromatography-mass spectrometry (LC-MS), which helps to streamline the difficult isolation stages required for their chemical characterization. In addition, the antimalarial efficacy of this strain has intriguing implications for future pharmaceutical development.

Antibiofilm properties of bioactive compounds from Actinomycetes against foodborne and fish pathogens

In nature, bacteria can form biofilms, multi-layered structures that adhere microbial populations to solid surfaces by exopolysaccharides, proteins, and nucleic acids. In addition to causing foodborne infections, biofilms can be a major problem in aquaculture. Actinomycetes extracts have previously demonstrated antibiofilm activity against multiple foodborne and fish pathogens, and further characterization of these extracts is needed. In this study, we identified the chemical structures and antibiofilm properties of four extracts and determined the genetic similarity of the isolates to known Streptomyces isolates. We found that several extracts contained multiple antibiofilm compounds, and the antibiofilm activities of all extracts were most stable at pH 6. Furthermore, the antibiofilm inhibition and destruction activities of the isolates were stable at different temperatures. All of crude extracts demonstrated activity against biofilms formed by foodborne and fish pathogens on the surface of stainless-steel coupons as well as polystyrene that commonly used in industrial equipment. Using PCR 16S-rRNA gene and DNA sequencing analysis, the four Actinomycetes isolates were found to be 99% (1 AC), 97% (20 PM), 95% (16 PM), and 85% (18 PM) similar to Streptomyces. Biofilm structure were analyzed using Scanning Electron Microscopy coupled with Energy-Dispersive Spectrometry analysis. Coniine/(S)-2-propylpiperidine was the most active fraction of the crude extracts of the 1 AC, 20 PM, and 16 PM isolates, and piperidine, 2-(tetrahydro-2-furanyl) was most active in the 18 PM isolate.

Isolation and Characterization of a Novel Actinomycete Isolated from Marine Sediments and Its Antibacterial Activity against Fish Pathogens.

Marine habitats are especially complex, with a varied diversity of living organisms. Marine organisms, while living in such intense conditions, have developed great physiological and metabolic potential to survive. This has led them to produce several potent metabolites, which their terrestrial counterparts are unable to produce. Over the past few years, marine Actinomycetes have been considered one of the most abundant sources of diverse and novel metabolites. In this work, an attempt was made to isolate Actinomycetes from marine sediments in terms of their ability to produce several novel bioactive compounds. A total of 16 different Actinomycete colonies were obtained from marine sediment samples. Among the 16 Actinomycete isolates, 2 isolates demonstrated in vitro antibacterial activity against Aeromonas hydrophila and Vibrio parahemolyticus. However, among them, only one isolate was found to have potent antibacterial activity, and hence, was taken for further analysis. This isolate was designated as Beijerinickia fluminensis VIT01. The bioactive components obtained were extracted and later subjected to Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC-MS) analyses for identification. Several novel bioactive compounds were reported from the data obtained and were found to have potent antibacterial activity. Hence, they could be used as an alternative to antibiotics for treating several fish pathogens in the aquaculture industry.

Diversity and Bioactivity of Endophytic Actinobacteria Associated with Grapevines

Grapevine trunk diseases (GTDs) are a significant problem for New Zealand viticulture. Endophytic actinobacteria are of interest as potential biocontrol agents due to their ability to inhibit plant pathogens and improve plant growth. However, no studies have investigated the diversity of actinobacteria associated with grapevines in New Zealand vineyards and their bioactivity. Actinobacteria diversity in different ‘Sauvignon blanc’ vine tissues from three vineyards (conventional and organic management, and different vine ages) was assessed using different methods and media. Forty-six endophytic actinobacteria were isolated, with more isolates recovered from roots (n = 45) than leaves (n = 1) and shoot internodes (n = 0). More isolates were recovered from the organic (n = 21) than conventional (n = 8) vineyard, mature (25-year old; n = 21) than young (2-year old; n = 2) vines and using a tissue maceration technique (n = 40). Actinomycete Isolation Agar, International Streptomyces Project 2, and Starch Casein media were effective for actinobacteria isolation. Most of the isolates recovered belonged to Streptomyces, with one isolate identified as Mycolicibacterium. Forty isolates were assessed for antifungal activity and plant growth-promoting (PGP) characteristics. Of these, 13 isolates had antifungal activity against test GTD pathogens (Dactylonectria macrodidyma, Eutypa lata, Ilyonectria liriodendri, Neofusicoccum parvum, and N. luteum). Eighteen isolates exhibited more than one PGP trait; 25siderophore production (n = 25), phosphate solubilization (n = 6), and indole acetic acid production (n = 16). Two strains, Streptomyces sp. LUVPK-22 and Streptomyces sp. LUVPK-30, exhibited the best antifungal and PGP properties. This study revealed the diversity of culturable endophytic actinobacteria from grapevines in New Zealand vineyards and their biocontrol potential against GTD pathogens.

Biochemical And Physiological Characterization Of Actinomycetes Isolated From Rhizospheric Regions In The Soils Of Arachis Hypogea L. And Gossypium Herbaceum L. Near The Gir Wildlife Sanctuary

30 isolates of actinomycetes were collected from the soil samples of Arachis hypogea L. and Gossypium herbaceum L. near the fields located surrounding the Gir Wildlife Sanctuary area of Junagadh District,Gujarat State,India. All the isolates were subjected to serial dilution process. The present study aimed to identify and characterize these isolates using biochemical and physiological tests. From the morphological tests and gram staining procedures conducted prior to the biochemical and physiological tests, it was already observed that Actinomycetes are Gram positive , filamentous shaped bacteria. It was also observed that these bacteria contain hyphae, mycelium as well as sporangia which is able to release spores. It was able to produce yellow pigments, posses an earthy aroma and showed optimum growth under aerobic conditions at temperature about 28 ⁰C, pH 7 and 5% w/v NaCl Concentration. Therefore, it was considered as a mesophilic, basophilic and moderate Salt tolerant by nature. The isolates showed variations in carbon utilization but able to utilize almost all carbon sources. These bacteria were also able to give positive results in methyl red test, nitrate reduction tests, urea hydrolysis, citrate utilization tests etc. Altogether, the results indicated that these isolates i.e. Actinomycetes are able to utilize almost all nutrient sources available in the rhizosphere region of Arachis hypogea L. and Gossypium herbaceum L.

Novel biosynthesis of tellurium nanoparticles and investigation of their activity against common pathogenic bacteria

ObjectivesTellurium has received substantial attention for its remarkable properties. This study performed in vitro and in vivo testing of the antibacterial action of tellurium nanoparticles biosynthesized in actinomycetes against methicillin-resistant Staphylococcus aureus (MRSA), a common blood bacterial pathogen. MethodsNine actinomycete isolates were tested for their potential to reduce potassium tellurite (K2TeO3) and form tellurium nanoparticles (TeNPs). The most efficient actinomycete isolate in producing Tellerium nanoparticles was identified through molecular protocols. The generated TeNPs were characterized using UV, TEM, EDX, XRD and FTIR. The bacterial species implicated in bloodstream infections were detected at El Hussein Hospital. Bacterial identification and antibiotic susceptibility testing were performed using Vitek 2. An animal infection model was used to test the efficacy of the produced TeNPs against the most commonly isolated methicillin-resistant S.aureus using survival assays, colony counting, cytokine assessment and biochemical testing. ResultsThe most efficient actinomycete isolate was identified as Streptomyces graminisoli and given the accession number (OL773539). The mean particle size of the produced TeNPs was 21.4 nm, and rods and rosette forms were observed. Methicillin-resistant S.aureus (MRSA) was the main bacterium (60%) causing blood stream infections, and was followed by Escherichia coli (25%) and Klebsiella pneumoniae (15%). The produced TeNPs were tested against MRSA, the bacterium most frequently isolated from blood, and showed a promising action inhibition zone of 24 ± 0.7 mm and an MIC of 50 μg/ml. An animal infection model indicated the promise of TeNPs alone or in combination with standard drugs to combat MRSA in a rat intravenous infection model. ConclusionTeNPs combined with vancomycin have successive impact to combat bacteremia for further verification of results.

Morphological and molecular characterization of Actinomycetes isolates and their metabolite fingerprinting

Two actinomycetes isolates RK-302 and RK-320 obtained from limestone rock of Dehradun, Uttarakhand were characterized morphologically, biochemically and by using 16S rDNA sequencing at Jaypee Institute of Information Technology, Noida during 2017-18. Differences in morphological/biochemical features showed that the isolates differed from each other as well as from the nearest matching strains in the GenBank database. Variation in dimension for spore size of both isolates was observed through transmission electron microscopy. Both isolates, RK-302 and RK-320 showed activity against phytopathogenic fungi, Fusarium graminearum and Bipolaris maydis using agar plugs in vitro. Metabolite fingerprinting with GC-MS revealed the presence of 37 and 31 compounds, respectively from RK-302 and RK-320. Combined analysis of phenotypic, biochemical and molecular studies showed that the isolates differed at strain level. From the metabolite fingerprint and antimicrobial activity data, it was concluded that the antimicrobial compounds identified in present study may be useful in developing novel bio control agents for plant pathogens.

ISOLATION, IDENTIFICATION AND ANTAGONISTIC ACTIVITY OF MARINE ACTINOMYCETES FROM COASTAL REGIONS OF CUDDALORE DISTRICT, TAMILNADU

The chemical synthesized antibiotics used against different bacterial infectious disease .The prolonged usage of antibiotics had side effects. Actinomycetes are having lot of potential pharmaceutical applications. Bioactive compounds derived from marine actinomycetes having less side effects and having potential applications. Sediment samples collected from Pichavaram, TS pettai, Parangipettai, Ponanthittu and MGR Thittu coastal areas Chidambaram, Tamil Nadu. The collected samples were pretreated using calcium carbonate (CaCO3) and air dried for three to seven days. Samples are serially diluted for spread plate technique. In this technique, totally 25 actinomycetes isolated for further analysis. All the isolates were screened for antagonistic activity against disease-causing clinical bacterial pathogens such Klebsiella pneumonia, Shigella dysentriae, Salmonella typhi, Streptococcus pyogenes, Streptococcus pnemoniae, Salmonella paratyphi, Vibrio parahaemolyticus, Serratia marcescens, and Enterococcus harmaechei.Among this 25 isolates, the isolate TSP1 showing better antagonistic activity against all the bacterial pathogens. The potential strain TSP1 were identified by morphological, microscopical, biochemical, and SEM analytical characterization. Based on the results, the TSP1 isolate are identified as Streptomyces sp. The current research focuses on actinomycetes that have antagonistic activity and create bioactive secondary metabolites that cure several infectious diseases. The aim and objective of this present study is isolation of marine actinomycetes from sediment samples and evaluated antagonistic activity against bacterial pathogens.

SCREENING OF ACTINOMYCETES FROM Cystoseira barbata (Stackhouse) C. Agardh COMPOST FOR THEIR ENZYME AND ANTIBACTERIAL ACTIVITIES

Bacterial secondary metabolites play an essential role in biotechnological and biomedical applications. Actinomycetes are important bacterial sources of antibiotics and enzymes. Most of the antimicrobials known today have been isolated from actinomycetes, especially from the genus Streptomyces. In this study, actinomycete isolation was performed from Cystoseira barbata (Stackhouse) C. Agardh compost, collected from the Black Sea coast, by serial dilution method. A total of 73 actinomycetes isolates (BSC) were obtained from the compost samples. The ability of the isolates to produce different extracellular enzymes was investigated qualitatively. It was determined that 68.5% of the isolates have amylase, 100% cellulase, 47.9% chitinase, 94.5% pectinase, 98.6% protease and 96.3% lipase/esterase activity. Antibacterial activities of the isolates were investigated primarily using cross-streak method. Isolates showed high antibacterial activities, with 98.6 and 84.9 % against Staphylococcus aureus Rosenbach and Enterococcus faecalis (Andrewes & Horder) Schleifer & Kilpper-Bäl, respectively. Three out of six isolates (BSC-13, BSC-17, BSC-37, BSC-38, BSC-45, BSC-49) with high antibacterial activity, were screened secondarily for their antibacterial activities using double-layer method. At day 7, BSC-37 isolate showed a high inhibition (57 mm) against S. aureus. Furthermore, these six isolates were identified according to their morphological and physiological characteristics and 16S rDNA sequence analysis. 16S rDNA sequence analysis showed that the isolates with high antibacterial activity belong to Streptomyces genus. Results indicated that these isolates have great potential and may serve as a good source for the studies on bioactive natural products.

Antimicrobial and antioxidant activities of Streptomyces species from soils of three different cold sites in the Fez-Meknes region Morocco

The increasing demand for new bioactive compounds to combat the evolution of multi-drug resistance (MDR) requires research on microorganisms in different environments in order to identify new potent molecules. In this study, initial screening regarding the antimicrobial activity of 44 Actinomycetes isolates isolated from three soil samples from three different extremely cold sites in Morocco was carried out. Primary and secondary screening were performed against Candida albicans ATCC 60,193, Escherichia coli ATCC 25,922, Staphylococcus aureus ATCC 25,923, Bacillus cereus ATCC 14,579, other clinical MDR bacteria, and thirteen phytopathogenic fungi. Based on the results obtained, 11 active isolates were selected for further study. The 11microbial isolates were identified based on morphological and biochemical characters and their molecular identification was performed using 16S rRNA sequence homology. The UV–visible analysis of dichloromethane extracts of the five Streptomyces sp. Strains that showed high antimicrobial and antioxidant (ABTS 35.8% and DPPH 25.6%) activities revealed the absence of polyene molecules. GC–MS analysis of the dichloromethane extract of E23-4 as the most active strain revealed the presence of 21 volatile compounds including Pyrrolopyrazine (98%) and Benzeneacetic acid (90%). In conclusion, we studied the isolation of new Streptomyces strains to produce new compounds with antimicrobial and antioxidant activities in a cold and microbiologically unexplored region of Morocco. Furthermore, this study has demonstrated a significant (P < 0.0001) positive correlation between total phenolic and flavonoid contents and antioxidant capacity, paving the way for the further characterization of these Streptomyces sp. isolates for their optimal use for anticancer, antioxidant, and antimicrobial purposes.

Bioprospecting of endophytic actinobacterium associated with Aloe ferox mill for antibacterial activity

BackgroundThe emergence of drug resistance among pathogens has resulted in renewed interest in bioprospecting for natural microbial products.MethodsThis study aimed to bioprospecting endophytic actinobacterium associated with Aloe ferox Mill for its antibacterial activity. Endophytic actinomycetes were isolated from the gel of A. ferox Mill by surface sterilization technique using actinomycete isolation agar. The isolate with a promising antibacterial activity was identified using 16S rRNA sequence analysis. The minimum inhibitory concentration (MIC) of the extract was assessed by the micro-dilution method and its effect on the respiratory chain dehydrogenase (RCD) activity was ascertained by the iodonitrotetrazolium chloride (INT) assay. Fourier transform-infrared spectrophotometer (FTIR) and gas chromatography-mass spectrophotometry (GC-MS) were employed to identify functional groups and the chemical constituents, respectively.ResultsThe actinobacterium was found to be Streptomyces olivaceus CP016795.1. Its extract displayed noteworthy antibacterial activity (MIC ≤1 mg/mL) against Staphylococcus aureus (ATCC 25925), Bacillus cereus (ATCC 10102), and Escherichia coli (ATCC 25922); and showed an inhibitory effect on the RCD activity. FTIR spectrum displayed hydroxyl, amine, and aromatic groups, and the GC–MS revealed 5-Hydroxymethylfurfural as the main constituent (19.47%).ConclusionsS. olivaceus CP016795.1 can serve as a potential source of effective antibacterial compounds.

Bioprospecting of actinomycetes for anti-bacterial potential: A Review

Actinomycetes are gram-positive bacteria that have a high GC content compared to their counterparts. Actinomycetes were capable of producing a broad range of secondary metabolites and many of these were anti-bacterial agents. Antibiotics have been known to play a vital role in therapeutics and the clinical management of various diseases. Actinomycetes have contributed more than 70% of known antibiotics in the market today. Apart from antibiotics, actinomycetes also produce several enzymes, enzyme inhibitors, anticancer and anti-diabetic secondary metabolites. Currently, actinomycetes are being studied for medicinal, pharmaceutical, industrial, environmental and bioremediation applications. The current study focuses on a variety of antibacterial agents derived from actinomycetes and new antibiotics under clinical trial along with their mode of action. It also describes the genome mining methods for screening actinomycetes isolates for biosynthetic gene clusters and specific antibacterial secondary metabolites.