Starch Casein Agar Research Articles

Thioredoxin is involved in hexavalent chromium reduction in Streptomyces violaceoruber strain LZ-26-1 isolated from the Lanzhou reaches of the Yellow River

Hexavalent chromium [Cr(VI)] is one of the major environmental contaminants in the Lanzhou reaches of the Yellow River, and actinomycetes' Cr(VI) bioremediation within this area is still scarce. In the present study, twenty actinomycete strains were isolated from the Lanzhou reaches which could resist 1.2 mM Cr(VI) on Starch-Casein (SC) agar plates. Based on the 16S rRNA sequence data, sixteen strains belong to Streptomyces and four other strains belong to Gordonia, Nocardiopsis, Nocardia and Cellulosimicrobium. One strain named LZ-26-1 which is closely related to Streptomyces violaceoruber demonstrated a notable ability of Cr(VI) reduction. It could reduce 92.86% of the 0.6 mM Cr(VI) to trivalent chromium [Cr(III)] in SC liquid medium in 144 h. The optimum temperature and pH were 28 °C and 7.0 for Cr(VI) reduction. Transmission electron microscopy images showed that chromium was precipitated inside the cells. In resting cells and crude chromate reductase assays, strain LZ-26-1's Cr(VI) reduction was stimulated when NADPH was used as an electron donor and Cd2+ treatment inhibited Cr(VI) reduction. Furthermore, thioredoxin operon, which consists of three genes encoding a thioredoxin, thioredoxin reductase (NADPH) and a possible membrane protein, was upregulated by Cr(VI) treatment. These results suggested that LZ-26-1 might utilize a thioredoxin pathway to reduce Cr(VI).

Isolation, characterization and primary screening of soil actinomycetes from Kenyatta University arboretum grounds for antibacterial activities

Objective : Antimicrobial resistance has increased drastically in recent years in the developing countries, and it has leading public health concern. With almost all organisms becoming multidrug resistant to the commonly used antibiotics, there is a need to search for more drugs that are novel in order to address this challenge. Therefore, this study was aimed at isolating antimicrobial producing actinomyscetes and to evaluate their secondary metabolites against selected multidrug resistant bacteria isolates. Methodology: Half kg soil samples were collected 15cm below the ground. Starch Casein Agar (SCA) was used to isolate actinomycetes. Fifteen different actinomycetes identified as Is.1-Is.15 were isolated. They were differentiated based on the difference in appearance of the colony morphology and mycelial structure. Their metabolites were tested for antibiotic activities through the primary screening using the disk diffusion methods. Test bacteria were; Bacillus subtilis, E.coli, Klebsiella Pneumoniae, Staphylococcus aureus, Shigella sonei and Salmonella typhi. All the secondary metabolites from the isolated actinomycetes proved to posses the ability to inhibit bacterial growth by formation of different sized halo zones. Conclusion and application : Secondary metabolites produced by actinomycetes have the ability to inhibit growth of pathogenic bacteria. The ability of these metabolites to inhibit growth of test pathogenic bacteria has been attributed to the establishment of the fact that novel antibiotics can be manufactured from metabolites produced by actinomycetes. Large scale manufacture can be done through purification of these metabolites to ensure large scale production of novel drugs. This can serve help clear pathogenic bacteria that are ever developing

Isolation and characterization of novel alkali-halophilic actinomycetes from the Chilika brackish water lake, India

The current investigation deals with isolation and functional characterization of agriculturally important novel alkali-halophilic actinomycetes from water and sediment samples of three distinct niches, namely, central, south and sea mouth sectors of the Chilika brackish water lake. A total of 59 different morphotypes based on phenotypic characterization were isolated from different sectors of the lake. Among them, a total of twenty one isolates were screened as alkali-halophiles based on screening for salt and pH tolerance on starch casein agar medium amended with 10 % NaCl and at pH 9.0. Further characterization for plant growth promotion and biocontrol attributes revealed that the south sector harboured a maximum percentage of siderophore producers while the central sector had the highest indole 3-acetic acid as well as extracellular protease producers. The sea mouth sector had a higher portion of actinomycetes possessing nitrate reductase activity and some biocontrol attributes such as antimicrobial activity against fungal pathogens (Rhizoctonia solani, Fusarium udum and Fusarium oxysporum f. sp. ciceri) and production of chitinase enzyme. Identification including 16S rRNA gene sequences revealed that isolates belonged to the Streptomyces and Micromonospora genera, respectively.

Microorganisms associated particulate matter: A preliminary study

This study aims to determine the microbiological quality of particulate matter (PM) in an urban area in Jeddah, Saudi Arabia, during December 2012 to April 2013. This was achieved by the determination of airborne bacteria, fungi, and actinobacteria associated PM10 and PM2.5, as well as their relationships with gaseous pollutants, O3, SO2 and NO2, and meteorological factors (T°C, RH% and Ws). High volume samplers with PM10 and PM2.5 selective sizes, and glass fiber filters were used to collect PM10 and PM2.5, respectively. The filters were suspended in buffer phosphate and aliquots were spread plated onto the surfaces of trypticase soy agar, malt extract agar, and starch casein agar media for counting of bacteria, fungi and actinobacteria-associated PM, respectively. PM10 and PM2.5 concentrations averaged 159.9μg/m3 and 60μg/m3, respectively, with the ratio of PM2.5/PM10 averaged ~0.4. The concentrations of O3, SO2 and NO2 averaged 35.73μg/m3, 38.1μg/m3 and 52.5μg/m3, respectively. Fungi and actinobacteria associated PM were found in lower concentrations than bacteria. The sum of microbial loads was higher in PM10 than PM2.5, however a significant correlation (r=0.57, P≤0.05) was found between the sum of microbial loads associated PM10 and PM2.5. Aspergillus fumigatus and Aspergillus niger were the common fungal types associated PM. Temperature significantly correlated with both PM10 (r=0.44), and PM2.5 (r=0.5). Significant negative correlations were found between O3 and PM2.5 (r=−0.47), and between SO2 with PM10 (r=−0.48). Wind speed positively correlated with airborne microorganisms associated PM. The regression model showed that the inverse PM2.5 concentration (1/PM2.5) was a significant determinant of fungal count associated PM. Chemical processes and environmental factors could affect properties of PM and in turn its biological quality.

Exploration of Actinobacteria from Mangrove Ecosystems of Nizampatnam and Coringa for Antimicrobial Compounds and Industrial Enzymes

Aim: A study was made to examine the kinship between the seasonal distribution of actinobacteria and the physico-chemical properties of the mangrove sediments of Nizampatnam and Coringa located along the South East coast of Andhra Pradesh, India. Place and Duration of Study: Department of Botany and Microbiology, between April 2010 to February 2011. Methodology: Seasonal enumeration of actinobacteria from two different stations 1 (Nizampatnam) and 2 (Coringa) accorded by four different pre-treatments of soil sediments followed by plating onto three different media showed high incidence of actinobacteria in the month of February and least in December. Pretreatment with calcium carbonate and plating on starch casein agar yielded maximum number of actinobacteria. The strains were identified based on the morphological characteristics such as aerial mycelium, substrate mycelium, diffusible pigments and micro morphological features. Results: The present investigation revealed that majority of the mangrove actinobacteria Original Research Article British Biotechnology Journal, 4(2): 173-184, 2014 174 (69%) belongs to Streptomyces spp. Among the 55 isolates screened for antimicrobial compounds, 28 were found to be potential producers. The isolates could also produce commercially important enzymes such as L-asparaginase, cellulase and amylase. In addition the statistical study also revealed that positive correlation between the distribution of the actinomycetes and influence of physico-chemical parameters and the organic matter of the soil. Conclusion: Our study revealed that the unexplored regions like Nizampatnam and Coringa mangrove ecosystems are proved as potential sites for antimicrobial and industrial enzyme producing actinobacteria.

Isolation, characterization and antimicrobial activity of Streptomyces strains from hot spring areas in the northern part of Jordan

A total of 30 Streptomyces isolates (28 from soil and 2 from water) were isolated and purified from hot-springs areas in the northern part of Jordan. Four strains were thermopile. They grew at 45 and 55°C but not at 28°C. Strains were described morphologically on four different media: on glycerol yeast extract, oatmeal, yeast malt-extract and starch casein agar. White and grey color series were the most frequent series on all media. The results showed that glycerol yeast extract and starch casein were the best media for sporulation. And yeast malt-extract was the best medium for the production of soluble pigment. Physiological and biochemical tests showed that the highest number of Streptomyces isolates were able to hydrolyze tyrosine was 26 (87%). This was followed by 25 (83%) for starch, 24 (80%) for urea, 21 (70%) for casein and 10 (33%) for gelatin. Twenty two (73%) strains showed the ability to reduce nitrate and 8 (27%) strains produced melanin. Carbon source utilization showed that 26 (87%) strains were able to utilize L- arabinose, 25 (83%) strains were able to utilize meso-inositol, 8 (27%) strains were able to utilize D-sorbitol, 18 (60%) strains were able to utilize D-mannitol, 28 (93%) strains were able to utilize L-rhamnose and all isolates exhibited the ability to utilize D-fructose and D- glucose. The ability to exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus was detected among 20 and 26% of the isolates, respectively, while the ability to exhibit antifungal activity against Candida albicans was detected among 23% of the isolates. Molecular identification of the 8 antibiotics producers was carried out by PCR technique using two sets of primers specific to Streptomyces 16S rDNA gene sequences; strepB/strepE and strepB/strepF which amplified 520 and 1070 bp, respectively. All these antibiotic producer isolates showed positive results for the genus Streptomyces specific primers. Key words : Characterization, streptomyces , antimicrobial activity, hot springs, thermophile, PCR.

Antimicrobial and Antioxidant Potential of <i>Streptomyces sp</i>. RAMPP- 065 isolated from Kudremukh soil, Karnataka, India

Actinomycetes are among the industrially and therapeutically relevant microorganisms and are known to produce useful products such as antibiotics, enzymes, vitamins etc. Among actinomycetes, genus Streptomyces is known to produce a great array of products. In the present study, we have recovered a Streptomyces species RAMPP-065 from Western ghats soil of Kudremukh, Karnataka, India and determined its antimicrobial and antioxidant activity. The isolate was recovered on Starch casein agar and identified as Streptomyces species on the basis of cultural, microscopic, staining and biochemical characteristics. Fermentation was carried out in Starch casein broth for 7 days and filtered. The culture filtrate was extracted with ethyl acetate and the solvent was evaporated to get the extract. Antimicrobial activity of extract was tested against 8 bacteria and 2 fungi by agar well diffusion method. Gram positive bacteria were more sensitive to extract than Gram negative bacteria. Among fungi, susceptibility to extract was higher in Candida albicans than Cryptococcus neoformans. The extract showed a dose dependent scavenging of DPPH free radical as revealed by bleaching of DPPH radical color with increase in concentration of extract. In ferric reducing assay, the absorbance was found to increase with increase in extract concentration. Total phenolic content of extract, as estimated by Folin-Ciocalteau method, was 59mg Gallic acid equivalents/gram. The scavenging and reducing activity of extract were lesser when compared to reference compounds. The soils of Western ghats are rich sources for microorganisms with potent biological activities. To the best of our knowledge, this is the first report on bioactivity of Streptomyces species from Kudremukh soil. Further studiesare to be carried out to characterize the Streptomyces isolate and the active principles present in the extract.

Molecular characterization and its antioxidant activity of a newly isolated Streptomyces coelicoflavus BC 01 from mangrove soil

ObjectiveTo isolate and identify the biologically active strain of Streptomyces species from mangrove soil of Visakhapatnam region. Materials and methodsActinomycetes are isolated by using starch casein agar media and four potential strains were selected to evaluate the antioxidant activity by using the standard methods DPPH, FRAP and total antioxidant capacity. Further, significant antioxidant activity strain characterized by morphological, physiological, biochemical and molecular characterization. Results20 actinomycetes strains were isolated, among them four active isolates designated as BC 01, BC 02, BC 03 and BC 04 were studied for antioxidant activities. Of these four isolates, BC 01 showed a potent antioxidant activity when compared with other isolates. The morphological, biochemical and molecular characterization of the active isolate BC 01 belongs to the genus Streptomyces species. The phylogenetic tree was constructed and nucleotide blast in search indicated that the strain is 99.7% similarity with Streptomyces coelicoflavus. ConclusionThe results of the present investigation proven that actinomycetes isolated from mangroves are potent source of antioxidants. The strain BC 01 exhibited a potential in vitro antioxidant activity; studies of actinomycetes from mangrove soil can be useful in discovery of novel species to get novel drugs.

Metabolite profile of marine-derived endophytic Streptomyces sundarbansensis WR1L1S8 by liquid chromatography-mass spectrometry and evaluation of culture conditions on antibacterial activity and mycelial growth

This study was designed to investigate whether culture conditions (media, seawater concentration and pH) could lead Streptomyces sundarbansensis strain (isolated from marine brown algae Fucus sp. collected from Algerian coastline) to produce bioactive secondary metabolites. The most favourable condition for the production of anti-MRSA compound 1 [2-hydroxy-5-((6-hydroxy-4-oxo-4H-pyran-2-yl)methyl)-2-propylchroman-4-one] was determined. The profile of metabolites present in the crude extracts was carried out by HPLC analysis equipped with a diode array detector evaporative light scattering detection (DAD-ELSD) or online coupled to electrospray ionization-mass spectrometry (ESI-MS). Compound 1 was the most abundant secondary metabolite by culturing the strains on starch casein agar (SCA) medium in freshwater or 50% seawater at pH 7 or 9 using agar-state fermentation method. The study has shown the efficiency of HPLC/ESI-MS technique in the analysis of polyketides produced by the strain under investigation. It was possible to establish the best culture conditions for obtaining the most bioactive compound 1, previously isolated by the same strain. Marine algae-actinobacteria associations are a particularly promising renewable system for the production of new antibacterial metabolites. Based on the promising bioactivity of the chemically characterized compound 1, the analytical methodology here applied has resulted as an effective approach for establishing its optimized production.

Isolation and screening of antibiotic producing actinomycetes from soils in Gondar town, North West Ethiopia

ObjectiveTo isolate and screen antibiotic producing actinomycetes from potential soil samples of Gondar town, Ethiopia. MethodsFifteen soil samples were collected, serially diluted and spread on starch casein and oat meal agar supplemented with amoxicillin and cyclohexamide for inhibition of bacteria and fungi, respectively. Cross streak method was used to check antagonistic activity of isolated actinomycetes against test organisms. Solid state fermentation and crude extraction were used for the production of antibiotics from isolates. Agar well diffusion was used for antimicrobial activity of crude extracts against test organisms. ResultsThree isolates (Ab18, Ab28 and Ab43) have been shown high antagonistic activity during primary screening. Inhibition zones obtained from crude extracts showed significance differences when compared with standard antibiotics tested against test organisms (P<0.05). Inhibition zone of crude extracts from isolate Ab18 against Klebsiella pneumonia ATCC7000603 and Escherichia coli ATCC25922 were (14±1) mm and (35±1) mm, respectively which were strong active when compared to amoxicillin (0 mm) and tetracycline [(13±1) mm for Klebsiella pneumonia ATCC7000603 and (33±1) mm for Escherichia coli ATCC25922]. Crude extracts from isolate Ab18 showed (20±1) mm and (15±1) mm inhibition zones against methicillin resistant Staphylococcus aureus strains 2 (MRSA2) and MRSA4, respectively. Crude extract from isolate Ab43 has shown inhibition zones of (16±1) mm and (17±1) mm against MRSA2 and MRSA4, respectively. Combination of Ab18 and Ab43 has shown high antimicrobial activity (18±1) mm against MRSA2 and MRSA4. ConclusionsThere was not any scientific report on soil actinomycetes producing antibiotic in the study areas. Therefore, isolation and screening of actinomycetes from such areas in optimum condition may contribute the discovery of new antibiotics. Potent antibiotics from these actinomycetes could contribute a lot to fight against antibiotic resistant pathogens. Selected isolates have been shown strong antimicrobial activity against resistant pathogens. Further purification, structural elucidation and characterization are recommended to know the quality, novelty and commercial value of these antibiotics.

Isolation of rhizospheric and roots endophytic actinomycetes from Leguminosae plant and their activities to inhibit soybean pathogen, Xanthomonas campestris pv. glycine

In this study, actinomycetes from roots and rhizospheric soils of leguminous plants were isolated using starch casein agar supplemented with antifungal and antibacterial antibiotics. Three hundred and seventeen actinomycetes were isolated with 77 isolates obtained from plant roots and 240 isolates from rhizospheric soils. Analysis of whole-organism hydrolysates showed that 289 strains were rich in the LL-isomer of diaminopimelic acid, a result consistent with their assignment to the streptomycetes. The remaining 28 strains were assigned to non-streptomycetes based on the presence of meso-isomer of diaminopimelic acid in cell wall. Sixty-four isolates (20.2%) showed antagonistic activity against soybean pathogen Xanthomonas campestris pv. glycine by agar overlay method. Isolate RM 365 showed the highest activity with an inhibition ratio of 3.79, with no inhibitory activity on the growth of Rhizobium japonicum TISTR 079, Rhizobium sp. TISTR 061 and Rhizobium sp. TISTR 063. The 16S rRNA gene sequence analysis revealed that isolate RM 365 shared 99.28% similarity to Streptomyces caeruleatus GIMN4(T) (GQ329712). In addition, isolates which contained meso-DAP were also identified by 16S rRNA gene sequence analysis. The results showed that they were members of the genus Amycolatopsis, Isoptericola, Micromonospora, Microbispora, Nocardia, Nonomuraea, Promicromonospora and Pseudonocardia.

Nocardia aciditolerans sp. nov., isolated from a spruce forest soil

Actinomycetes growing on acidified starch-casein agar seeded with suspensions of litter and mineral soil from a spruce forest were provisionally assigned to the genus Nocardia based upon colonial properties. Representative isolates were found to grow optimally at pH 5.5, have chemotaxonomic and morphological features consistent with their assignment to the genus Nocardia and formed two closely related subclades in the Nocardia 16S rRNA gene tree. DNA:DNA relatedness assays showed that representatives of the subclades belong to a single genomic species. The isolates were distantly associated with their nearest phylogenetic neighbour, the type strain of Nocardia kruczakiae, and were distinguished readily from the latter based on phenotypic properties. On the basis of these data it is proposed that the isolates merit recognition as a new species, Nocardia aciditolerans sp. nov. The type strain is isolate CSCA68T (=KACC 17155T = NCIMB 14829T = DSM 45801T).Electronic supplementary materialThe online version of this article (doi:10.1007/s10482-013-9887-3) contains supplementary material, which is available to authorized users.

BIOCHEMICAL, NUTRIENT AND INHIBITORY CHARACTERISTICS OF &lt;i&gt;STREPTOMYCES&lt;/i&gt; CULTURED FROM A HYPERSALINE ESTUARY, THE LAGUNA MADRE (TEXAS)

Streptomyces are common soil bacteria that produce secondary metabolites, including several antibiotics; however, the characteristics of marine Streptomyces are largely unknown. Sediment samples were taken from 3 sites in the Laguna Madre to isolate marine Streptomyces . Sediment was diluted, spread onto synthetic seawater media to estimate the total bact erial density of the samples and spread onto starch casein agar to isolate Streptomyces . Isolated Streptomyces were tested for salinity tolerance and optimal gro wth pH. Isolates were assayed using API 20E ® test strips and BIOLOG ™ plates to construct biochemical profiles and assess nutrient utilization abilities of the ba cteria, respectively. Individual Streptomyces were tested for the ability to inhibit the growth of other isol ated Streptomyces (i.e., interference competition) and putatively identified by DNA sequencing. Results sh owed that there was no significant difference in microbial density in sediments from the 3 sampling sites. Eleven (11) Streptomyces pure cultures were obtained in total; most tolerated salinity up to 60 ppt and grew optimally at pH 7.5. Biochemical prof ile comparisons showed that the Streptomyces were only at least 74% similar; most (8/11) were > 90% similar. Isolates could use between 87-95 carbon so urces. Three (3) isolates displayed interference toward other isolates. Ten (10) isolates were ident ified as Streptomyces griseus by DNA sequencing. Laguna Madre Streptomyces organisms display some diverse characteristics wit h regards to their halotolerance, biochemical profiles, carbon source utilization and inhibition toward other organisms. Further investigations may yield greater understand ing of these organisms in this and other marine environments and may be a reservoir of novel microo rganisms and secondary metabolites.

Screening, isolation and purification of antibacterial agents from marine actinomycetes

As marine environmental conditions are extremely different from terrestrial ones, it is surmised that marine actinomycetes might produce novel bioactive compounds. Hence marine sediments, collected from the coastal areas of Gokharna and Muradeshwara of Karnataka state, were screened Seventeen isolates were obtained on starch-casein agar media by soil dilution technique. However, only six isolates namely ACT-A2, ACT-A3, ACT-A4, ACT-A5, ACT-A7 and ACT-A15 showed significant antibacterial activity against both gram-positive and gram-negative bacteria. Morphological, cultural and biochemical characterization indicated that the isolates belong to Streptomyces genus of Actinomycetes. Further studies were carried out with the most active ACT-A2. Optimization of media, temperature and pH by shake flask fermentation indicated starch-casein, 28°C and 7 to be suitable for ACT-A2. The production of antibiotics began after 24 h, reached maximum at 72 h and maintained at the same level up to 120 h. Ethyl acetate was used to extract antibacterial compounds from the culture filtrate. TLC was done on silica gel using ethyl acetate: methanol (6:4) and direct bioautography has shown the presence of two active substance, one with Rf 0.8 has more activity than the other with Rf 0.4. Further purification is done by column chromatography using a mixture of dicholoromethane and ethyl acetate. The findings from this investigation reveal that the strain ACT-A2 in order exhibited superior antimicrobial activities to other sediment isolates of actinomycetes.DOI: http://dx.doi.org/10.3329/icpj.v1i12.12448 International Current Pharmaceutical Journal 2012, 1(12): 394-402

Antibacterial and antifungal activities of Actinobacteria isolated from Rathnagiri hills

Article history: Received on: 18/08/2012 Revised on: 29/08/2012 Accepted on: 05/09/2012 Available online: 29/10/2012 This study was performed to isolate actinomycete colonies having antibacterial and antifungal activity from soil samples. A total of 27 actinomycete colonies were isolated in pure culture from five soil samples using Starch casein agar medium. Entire isolates were screened for their antimicrobial activity by agar plug method against five each of human pathogenic bacteria and fungi. Of this, 7 strains inhibits B. substilis, 3 strains inhibits Klebseilla sp, 6 strains inhibits B. cerus, 5 strains inhibits S. aureus and only 2 strains inhibits E. coli. Incase of fungi all the actinobateria has moderate activity with less fungal strains, only 1 strain (RA 5) inhibits entire fungus except Penicillium sp. The metabolites from potent strain was produced by fermentation, separated by centrifugation, it was tested for their antimicrobial activity against the test bacterial and fungal strains by well diffusion and disc diffusion method. In this study, the metabolites from RA5 (identified as Streptomyces sp.) have showed good antibacterial and antifungal activity. Since many isolates showed inhibitory activity against indicator bacteria, it is suggestive that Rathnagiri hill’s soil could be an interesting source to explore for antibacterial secondary metabolites.

Isolation of amylase producing aquatic actinomycetes from the sediments of mangrove forests in south of Iran

Recent researches have shown that aquatic actinomycetes can be important source to discover biological products including amylase. Amylase is one of the important enzymes in industry. In this study aquatic actinomycetes producing amylase were isolated from the sediments of mangrove forests in south of Iran and the rate of amylase activity was measured. The samples were collected from one hundred different places in mangrove forests of South of Iran. Collected samples were diluted then they were purified on the Starch (casein agar) culture and Woodruff. After that they were examined in terms of amylase production on agar- starch culture. The activity of the produced amylase by the isolated aquatic actinomycetes was measured by dinitrosalicylic acid (DNS) method. The results showed that aquatic actinomycetes were isolated from 86 per 100 places in spring (86%) and from 61 per 100 places in summer (61%). That the highest rate of producing enzyme was related to isolated samples in spring (62.97 U/ml). Biochemical and Bergey’s book tests showed that the most isolated aquatic actinomycetes belonged toStreptomyces genus. As regards this, it is economical and easy to isolate the aquatic actinomycetes which produce amylase that is used in different industries in Iran from the sediments of mangrove forests of South of Iran. So the isolated strains in this study can be suitable candidates for amylase production after genetic manipulation. Key words: Streptomyces, amylase, mangrove forests, dinitrosalicylic acid method.

Characterization and phylogenetic analysis of novel polyene type antimicrobial metabolite producing actinomycetes from marine sediments: Bay of Bengal India

ObjectiveTo isolate and indentify the promising antimicrobial metabolite producing Streptomyces strains from marine sediment samples from Andrapradesh coast of India. MethodsAntagonistic actinomycetes were isolated by starch casein agar medium and modified nutrient agar medium with 1% glucose used as a base for primary screening. Significant antimicrobial metabolite producing strains were selected and identified by using biochemical and 16S rDNA level. Minimum inhibitory concentrations of the organic extracts were done by using broth micro dilution method. ResultsAmong the 210 actinomycetes, 64.3% exhibited activity against Gram positive bacteria, 48.5 % showed activity towards Gram negative bacteria, 38.8% exhibited both Gram positive and negative bacteria and 80.85 % isolates revealed significant antifungal activity. However, five isolates AP-5, AP-18, AP-41 and AP-70 showed significant antimicrobial activity. The analysis of cell wall hydrolysates showed the presence of LL-diaminopimelic acid and glycine in all the isolates. Sequencing analysis indicated that the isolates shared 98.5%-99.8% sequence identity to the 16S rDNA gene sequences of the Streptomyces taxons. The antimicrobial substances were extracted using hexane and ethyl acetate from spent medium in which strains were cultivated at 30°C for five days. The antimicrobial activity was assessed using broth micro dilution technique. Each of the culture extracts from these five strains showed a typical polyene-like property. The lowest minimum inhibitory concentrations of ethyl acetate extracts against Escherichia coli and Curvularia lunata were 67.5 and 125.0 μg/mL, respectively. ConclusionIt can be concluded that hexane and ethyl acetate soluble extracellular products of novel isolates are effective against pathogenic bacteria and fungi.

A new approach to isolating siderophore-producing actinobacteria

This study was conducted to investigate the application of 2,2'-dipyridyl as a new approach to isolating siderophore-producing actinobacteria. Isolation of actinobacteria from soil was conducted by a soil dilution plate technique using starch-casein agar. Iron starvation was fostered by the incorporation of the iron chelator 2,2'-dipyridyl in the isolation medium. Pretreatment of the samples at an elevated temperature (40°C) ensured that the majority of nonsporulating bacteria were excluded. The survivors of this treatment were largely actinobacteria. Of the viable cultures grown in the presence of 2,2'-dipyridyl, more than 78-88% (average of three separate studies) were reported to produce siderophore-like compounds compared to 13-18% (average of three separate studies) when grown on the basic media in the absence of the chelating agent. The most prolific producers as assessed by the chrome azurol sulphate (CAS) assay were further characterized and found to belong to the genus Streptomyces. Selective pressure using 2,2'-dipyridyl as an iron-chelating agent in starch-casein media increased the isolation of siderophore-producing actinobacteria compared to the unamended medium. The study described represents a new approach to the isolation of siderophore-producing actinobacteria using a novel procedure that places a selection on cell population based upon the incorporation of a chelating agent in the medium.

Isolation of Hg and Cu resistant Streptomyces from marine sediments in different regions of the Caspian Sea

Expansion of industrial activities; mining and metal plating could cause release of high amount of heavy metals into seawater and marine sediment resulting in heavy metal resistant microorganisms. Due to the important role of Streptomyces in production of secondary metabolites, the reduction ability of enzymes and elements was used to study the resistance exhibited by Streptomyces in the isolation of heavy metals (copper and mercury) from marine sediments and coastal waters of the Caspian Sea. Marine sediments samples were collected from coastal locations aseptically. The media of Starch Casein agar (SCA), and Kusters agar (KUA) were used for the isolation of Streptomyces and biochemical testes like lipid, casein, starch and gelatin hydrolysis and etc. was carried out for identification of this bacteria and determination of heavy metals (Hg, Cu) resistant strains was performed with well diffusion assay and for detection of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) Micro dilution assay was used. Also, amounts of heavy metals in different parts of coastal waters were measured with atomic absorption spectrophotometry assay. A total of 41 Streptomyces were isolated from coastal locations 7 strains (17.07%) showed copper resistant to 1000 mg/L, 4 strains (9.75%) showed mercury resistant. The strains C9, D11 and E16 to 20 mg/L and C2 to 40 mg/L were mercury resistant. Due to existence of heavy metals (Hg, Cu) resistant Streptomyces in the Caspian Sea, researcher can use them as well suited agents for Bioremediation.

Diversity and Antibacterial Screening of Actinomycetes from Javadi Hill Forest Soil, Tamilnadu, India

Actinomycetes from diverse environments are known to produce novel antibacterial and antifungal substances. Herein we report isolation of antibiotic producing actinomycetes from forest soil of ancient human inhabited Javadi hill, Tamilnadu, India, an environment that is under explored. Thirty six isolates were obtained from five soil samples using nalidixic acid and nystatin supplemented starch casein agar and actinomycete isolation agar medium. These colonies NLO were characterized based on their mycelium structure, colour and arrangement of spores on the mycelium. Further they were evaluated for their antimicrobial activity against a range of pathogenic resistant bacteria including Escherichia coli (MTCC 739), Bacillus cereus (MTCC 1272), Staphylococcus aureus (MTCC 1144), Pseudomonas aeruginosa (MTCC 1688), Pro- teus mirabilis (MTCC 1425) and Klebsiella pneumonia (MTCC 109) adopting agar plug method and confirmed by cross streak method.