Selection and Characterization of Microorganisms Utilizing Thaxtomin A, a Phytotoxin Produced by Streptomyces scabies

Thaxtomin A is the main phytotoxin produced by Streptomyces scabies, a causal agent of potato scab. Thaxtomin A is a yellow compound composed of 4-nitroindol-3-yl-containing 2,5-dioxopiperazine. A collection of nonpathogenic streptomycetes isolated from potato tubers and microorganisms recovered from a thaxtomin A solution were examined for the ability to grow in the presence of thaxtomin A as a sole carbon or nitrogen source. Three bacterial isolates and two fungal isolates grew in thaxtomin A-containing media. Growth of these organisms resulted in decreases in the optical densities at 400 nm of culture supernatants and in 10% reductions in the thaxtomin A concentration. The fungal isolates were identified as a Penicillium sp. isolate and a Trichoderma sp. isolate. One bacterial isolate was associated with the species Ralstonia pickettii, and the two other bacterial isolates were identified as Streptomyces sp. strains. The sequences of the 16S rRNA genes were determined in order to compare thaxtomin A-utilizing actinomycetes to the pathogenic organism S. scabies and other Streptomyces species. The nucleotide sequences of the γ variable regions of the 16S ribosomal DNA of both thaxtomin A-utilizing actinomycetes were identical to the sequence of Streptomyces mirabilis ATCC 27447. When inoculated onto potato tubers, the three thaxtomin A-utilizing bacteria protected growing plants against common scab, but the fungal isolates did not have any protective effect.     

In Vitro and In Vivo Plant Growth Promoting Activities and DNA Fingerprinting of Antagonistic Endophytic Actinomycetes Associates with Medicinal Plants

Endophytic actinomycetes have shown unique plant growth promoting as well as antagonistic activity against fungal phytopathogens. In the present study forty-two endophytic actinomycetes recovered from medicinal plants were evaluated for their antagonistic potential and plant growth-promoting abilities. Twenty-two isolates which showed the inhibitory activity against at least one pathogen were subsequently tested for their plant-growth promoting activities and were compared genotypically using DNA based fingerprinting, including enterobacterial repetitive intergenic consensus (ERIC) and BOX repetitive elements. Genetic relatedness based on both ERIC and BOX-PCR generates specific patterns corresponding to particular genotypes. Exponentially grown antagonistic isolates were used to evaluate phosphate solubilization, siderophores, HCN, ammonia, chitinase, indole-3-acetic acid production, as well as antifungal activities. Out of 22 isolates, the amount of indole-3-acetic acid (IAA) ranging between 10–32 μg/ml was produced by 20 isolates and all isolates were positive for ammonia production ranging between 5.2 to 54 mg/ml. Among 22 isolates tested, the amount of hydroxamate-type siderophores were produced by 16 isolates ranging between 5.2 to 36.4 μg/ml, while catechols-type siderophores produced by 5 isolates ranging from 3.2 to 5.4 μg/ml. Fourteen isolates showed the solubilisation of inorganic phosphorous ranging from 3.2 to 32.6 mg/100ml. Chitinase and HCN production was shown by 19 and 15 different isolates, respectively. In addition, genes of indole acetic acid (iaaM) and chitinase (chiC) were successively amplified from 20 and 19 isolates respectively. The two potential strains Streptomyces sp. (BPSAC34) and Leifsonia xyli (BPSAC24) were tested in vivo and improved a range of growth parameters in chilli (Capsicum annuum L.) under greenhouse conditions. This study is the first published report that actinomycetes can be isolated as endophytes from within these plants and were shown to have antagonistic and plant growth promoting abilities. These results clearly suggest the possibility of using endophytic actinomycetes as bioinoculant for plant growth promotion, nutrient mobilization or as biocontrol agent against fungal phytopathogens for sustainable agriculture.     

Toxic-Metabolite-Producing Bacteria and Fungus in an Indoor Environment

Toxic-metabolite-emitting microbes were isolated from the indoor environment of a building where the occupant was suffering serious building-related ill-health symptoms. Toxic substances soluble in methanol and inhibitory to spermatozoa at <10 μg (dry weight) ml⁻¹ were found from six bacterial isolates and one fungus. The substances from isolates of Bacillus simplex and from isolates belonging to the actinobacterial genera Streptomyces and Nocardiopsis were mitochondriotoxic. These substances dissipated the mitochondrial membrane potential (Δψ) of boar spermatozoa. The substances from the Streptomyces isolates also swelled the mitochondria. The substances from isolates of Trichoderma harzianum Rifai and Bacillus pumilus damaged the cell membrane barrier function of sperm cells.     

Cellulose-degrading bacteria associated with the invasive woodwasp Sirex noctilio

Sirex noctilio is an invasive wood-feeding wasp that threatens the world''s commercial and natural pine forests. Successful tree colonization by this insect is contingent on the decline of host defenses and the ability to utilize the woody substrate as a source of energy. We explored its potential association with bacterial symbionts that may assist in nutrient acquisition via plant biomass deconstruction using growth assays, culture-dependent and -independent analysis of bacterial frequency of association and whole-genome analysis. We identified Streptomyces and γ-Proteobacteria that were each associated with 94% and 88% of wasps, respectively. Streptomyces isolates grew on all three cellulose substrates tested and across a range of pH 5.6 to 9. On the basis of whole-genome sequencing, three Streptomyces isolates have some of the highest proportions of genes predicted to encode for carbohydrate-active enzymes (CAZyme) of sequenced Actinobacteria. γ-Proteobacteria isolates grew on a cellulose derivative and a structurally diverse substrate, ammonia fiber explosion-treated corn stover, but not on microcrystalline cellulose. Analysis of the genome of a Pantoea isolate detected genes putatively encoding for CAZymes, the majority predicted to be active on hemicellulose and more simple sugars. We propose that a consortium of microorganisms, including the described bacteria and the fungal symbiont Amylostereum areolatum, has complementary functions for degrading woody substrates and that such degradation may assist in nutrient acquisition by S. noctilio, thus contributing to its ability to be established in forested habitats worldwide.     

Production of B-group vitamins by mycorrhizal fungi and actinomycetes isolated from the root zone of pine (Pinus sylvestris L.)

Summary Studies were carried out on synthesis of B-group vitamins by mycorrhizal fungi and actinomycetes (Streptomyces sp.) derived from soil, rhizosphere and mycorrhizosphere of pine.None of the fungal isolates produced biotin. The vitamin produced in largest amounts by the mycorrhizal fungi was thiamin.In general more actinomycetes isolated from the rhizosphere than from the root free soil produced B-group vitamins. This was particularly true for thiamin.The amount of vitamins produced was higher in actinomycetes than the amounts produced by the mycorrhizal fungi.This research was carried out under problem MR.II. 16 coordinated by the Institute of Dendrology, Polish Academy of Sciences.     

Exploring the Antibacterial and Antifungal Potential of Jellyfish-Associated Marine Fungi by Cultivation-Dependent Approaches

Fungi isolated from marine invertebrates are of considerable importance as new promising sources of unique secondary metabolites with significant biomedical potential. However, the cultivable fungal community harbored in jellyfish was less investigated. In this work, we seek to recover symbiotic fungi from different tissues of jellyfish Nemopilema nomurai. A total of seven morphotypes were isolated, which were assigned into four genera (Aspergillus, Cladosporium, Purpureocillium, and Tilletiopsis) from two phyla (Ascomycota and Basidiomycota) by comparing the rDNA-ITS sequences with the reference sequences in GenBank. The most fungi were found in the inner tissues of subumbrella. Two of the cultivation-independent procedures, changing media type and co-cultivation, were employed to maximize the complexity of metabolites. Thus, thirteen EtOAc gum were obtained and fingerprinted by High Performance Liquid Chromatography (HPLC) equipped with a photodiode array (PDA) detector. Antibacterial and antifungal activities of these complex mixtures were tested against a panel of bacterial and fungal pathogens. The antimicrobial results showed that all of the 13 EtOAc extracts displayed different levels of antibacterial activity, three of which exhibited strong to significant antibacterial activity to the bacterial pathogens Staphylococcus aureus and Salmonella entrica. Antifungal activity indicated that the EtOAc extracts from pure culture of Aspergillus versicolor and co-culture of A. versicolor and Tilletiopsis sp. in rice media were promising for searching new compounds, with the maximal mycelial growth inhibition of 82.32% ± 0.61% for Rhizoctonia solani and 48.41% ± 11.02% for Botrytis cinerea at 200 μg/ml, respectively. This study is the first report on the antibacterial and antifungal activity of jellyfish-associated fungi and allows the first sight into cultivable fungal community residing in jellyfish. Induced metabolites by cultivation-dependent approaches provides a new reservoir for drug discovery from jellyfish-derived fungi.     

Survey of Tall-Fescue Pasture: Correlation of Toxicity of Fusarium Isolates to Known Toxins

Several aspects of fescue foot in cattle suggest that this disease is caused by fungi growing on fescue grass. Certain fungi isolated from winter pasture yield toxins when grown on synthetic medium. Most of these toxin producers belong to the genus Fusarium. All but 1 of the 21 toxic and 7 questionably toxic Fusarium isolates produce either 4-acetamido-4-hydroxy-2-butenoic acid γ-lactone, or 4β, 15-diacetoxy-8α-(3-methylbutyryloxy)-12, 13-epoxytrichothec-9-en-3α-ol, or both.     

Actinomycetes and fungi isolated from plant-parasitic nematode infested soils: screening of the effective biocontrol potential,indole-3-acetic acid and siderophore production

Root-knot nematodes are serious pathogens that severe damage to major crops. They damage plant root system that caused significant yield losses. Moreover, the predisposition of nematode-infected plants is secondary infection from fungal plant pathogen that additional adverse effects on plant growth. Our target is to find the antagonist for control nematode, and secondary infection agents and stimulate plant growth. Twenty-three plant-parasitic nematode infested soils were taken from some provinces in the northern and center of Thailand and actinomycetes and fungi were isolated. Eighty-three isolates belong to actinomycete and 67 isolates were fungi. The predominant actinomycete taxa was Streptomyces (97.6%). The predominant fungal taxa were Penicillium (37.3%) and Fusarium (32.8%). All actinomycete and fungal isolates were subjected for primary screening in vitro for their effects on egg hatching and juvenile mortality of Meloidogyne incognita. Secondary screening was evaluated for antagonist effect on plant pathogenic fungi collected from nematode-infected plant, plant growth hormone (indole-3-acetic acid; IAA) and siderophore production. From primary screening, 7 actinomycete and 10 fungal isolates reduced egg hatching and kill juveniles of M. incognita after 7 days incubation. In secondary screening, 10 nematophagous microbes produced IAA and 9 isolates produced hydroxamate siderophore. Streptomyces sp. CMU-MH021 was selected as a potential biocontrol agent. It reduced egg hatching rate to 33.1% and increased juvenile mortality rate to 82% as contrasted to the control of 79.6 and 3.6%, respectively. This strain had high activity to against tested fungi and high ability on IAA (28.5 μg ml⁻¹) and siderophore (26.0 μg ml⁻¹) production.     

Diversity of Culturable Bacteria Isolated from Highland Barley Cultivation Soil in Qamdo,Tibet Autonomous Region

The soil bacterial communities have been widely investigated. However, there has been little study of the bacteria in Qinghai-Tibet Plateau, especially about the culturable bacteria in highland barley cultivation soil. Here, a total of 830 individual strains were obtained at 4°C and 25°C from a highland barley cultivation soil in Qamdo, Tibet Autonomous Region, using fifteen kinds of media. Seventy-seven species were obtained, which belonged to 42 genera and four phyla; the predominant phylum was Actinobacteria (68.82%), followed by Proteobacteria (15.59%), Firmicutes (14.29%), and Bacteroidetes (1.30%). The predominant genus was Streptomyces (22.08%, 17 species), followed by Bacillus (6.49%, five species), Micromonospora (5.19%, four species), Microbacterium (5.19%, four species), and Kribbella (3.90%, three species). The most diverse isolates belonged to a high G+C Gram-positive group; in particular, the Streptomyces genus is a dominant genus in the high G+C Gram-positive group. There were 62 species and 33 genera bacteria isolated at 25°C (80.52%), 23 species, and 18 genera bacteria isolated at 4°C (29.87%). Meanwhile, only eight species and six genera bacteria could be isolated at 25°C and 4°C. Of the 77 species, six isolates related to six genera might be novel taxa. The results showed abundant bacterial species diversity in the soil sample from the Qamdo, Tibet Autonomous Region.     

Richness and bioactivity of culturable soil fungi from the Fildes Peninsula,Antarctica

Since the discovery of penicillin, fungi have been an important source of bioactive natural products. However, as a specific resource, the bioactive potentiality and specificity of fungal metabolites from the Antarctic region have had little attention. In this paper, we investigated the diversity patterns and biological activities of cultivable fungi isolated from soil samples in Fildes Peninsula, King George Island, Antarctica. Fungal communities showed low abundance and diversity; a total of 150 cultivable fungi were isolated from eight soil samples. After being dereplicated by morphological characteristics and chemical fingerprints, 47 fungal isolates were identified by ITS-rDNA sequencing. We confirmed that these isolates belonged to at least 11 different genera and clustered into nine groups corresponding to taxonomic orders in the phylogenetic analysis. Using two different fermentation conditions, 94 crude extracts acquired from the abovementioned different metabolite characteristic isolates were screened by bioactivity assay and 18 isolates produced biologically active compounds. Compared with HPLC–DAD–UV fingerprint analysis of culture extracts and standard compounds, two bioactive components secalonic acid and chetracins were identified. Our research suggests that the abundance and diversity of Antarctic cultivable fungal communities exhibit unique ecological characteristics and potential producers of novel natural bioactive products.     

Host-Pathogen Interactions: I. A Correlation Between alpha-Galactosidase Production and Virulence

Resistance or susceptibility of Red Kidney, Pinto and Small White beans (Phaseolus vulgaris) to the alpha, beta, and gamma strains of Colletotrichum lindemuthianum was either confirmed or established. These fungal strains secrete α-galactosidase, β-galactosidase and β-xylosidase when grown on cell walls isolated from the hypocotyls of any of the above bean varieties. These enzymes effectively degrade cell walls isolated from susceptible 5-day old hypocotyls but degrade only slightly the walls isolated from resistant 18-day old hypocotyls. The amounts of the β-galactosidase and β-xylosidase secreted by the 3 fungal strains are relatively low and are approximately equivalent. The secretion of these 2 enzymes is not dependent upon the bean variety from which the hypocotyl cell walls used as a carbon source were isolated. However, the fungal strains secrete greater amounts of α-galactosidase when grown on hypocotyl cell walls isolated from susceptible plants than when grown on walls from resistant plants. Virulent isolates of the fungus, when grown on hypocotyl cell walls isolated from a susceptible plant, secrete more α-galactosidase than do attenuated (avirulent) isolates of the same fungal strain grown under the same conditions. The α-galactosidase secreted by each of the fungal strains is capable of removing galactose from the hypocotyl cell walls of each bean variety tested. Galactose is removed from the cell walls of each variety at the same rate regardless of whether the cell walls were isolated from a susceptible or resistant plant.     

Experimental evidence of bark beetle adaptation to a fungal symbiont

The importance of symbiotic microbes to insects cannot be overstated; however, we have a poor understanding of the evolutionary processes that shape most insect–microbe interactions. Many bark beetle (Coleoptera: Curculionidae, Scolytinae) species are involved in what have been described as obligate mutualisms with symbiotic fungi. Beetles benefit through supplementing their nutrient‐poor diet with fungi and the fungi benefit through gaining transportation to resources. However, only a few beetle–fungal symbioses have been experimentally manipulated to test whether the relationship is obligate. Furthermore, none have tested for adaptation of beetles to their specific symbionts, one of the requirements for coevolution. We experimentally manipulated the western pine beetle–fungus symbiosis to determine whether the beetle is obligately dependent upon fungi and to test for fine‐scale adaptation of the beetle to one of its symbiotic fungi, Entomocorticium sp. B. We reared beetles from a single population with either a natal isolate of E. sp. B (isolated from the same population from which the beetles originated), a non‐natal isolate (a genetically divergent isolate from a geographically distant beetle population), or with no fungi. We found that fungi were crucial for the successful development of western pine beetles. We also found no significant difference in the effects of the natal and non‐natal isolate on beetle fitness parameters. However, brood adult beetles failed to incorporate the non‐natal fungus into their fungal transport structure (mycangium) indicating adaption by the beetle to particular genotypes of symbiotic fungi. Our results suggest that beetle–fungus mutualisms and symbiont fidelity may be maintained via an undescribed recognition mechanism of the beetles for particular symbionts that may promote particular associations through time.     

Biodiversity,Anti-Trypanosomal Activity Screening,and Metabolomic Profiling of Actinomycetes Isolated from Mediterranean Sponges

Marine sponge–associated actinomycetes are considered as promising sources for the discovery of novel biologically active compounds. In the present study, a total of 64 actinomycetes were isolated from 12 different marine sponge species that had been collected offshore the islands of Milos and Crete, Greece, eastern Mediterranean. The isolates were affiliated to 23 genera representing 8 different suborders based on nearly full length 16S rRNA gene sequencing. Four putatively novel species belonging to genera Geodermatophilus, Microlunatus, Rhodococcus and Actinomycetospora were identified based on a 16S rRNA gene sequence similarity of < 98.5% to currently described strains. Eight actinomycete isolates showed bioactivities against Trypanosma brucei brucei TC221 with half maximal inhibitory concentration (IC₅₀) values <20 μg/mL. Thirty four isolates from the Milos collection and 12 isolates from the Crete collection were subjected to metabolomic analysis using high resolution LC-MS and NMR for dereplication purposes. Two isolates belonging to the genera Streptomyces (SBT348) and Micromonospora (SBT687) were prioritized based on their distinct chemistry profiles as well as their anti-trypanosomal activities. These findings demonstrated the feasibility and efficacy of utilizing metabolomics tools to prioritize chemically unique strains from microorganism collections and further highlight sponges as rich source for novel and bioactive actinomycetes.     

Antimicrobial properties of endophytic actinomycetes isolated from <Emphasis Type="Italic">Combretum latifolium</Emphasis> Blume,a medicinal shrub from Western Ghats of India

Endophytic actinomycetes were isolated from Combretum latifolium Blume (Combretaceae),Western Ghats of Southern India and identified by its characteristic culture morphology and molecular analysis of 16S rRNA gene sequences. In this survey of endophytic actinomycetes, a total of 117 isolates representing 9 different genera of endophytic actinomycetes were obtained using four different isolation media and several of them seemed to be novel taxa. Streptomyces genera (35%) was the most frequently isolated strains, followed by Nocordiopsis (17%) and Micromonospora (13%). ISP-4 medium recovered more isolates (47%) when compared to rest of the media used. Preliminary antibacterial activity of the isolates was carried out by confrontation test. Ethyl acetate fraction of selected isolates in disc diffusion assay exhibited broad spectrum antimicrobial activity against test human pathogens. All Streptomyces spp. strains displayed significant antimicrobial activity against test pathogens. Strain CLA-66 and CLA-68 which are Nocordipsis spp. inhibited both bacterial and fungal pathogens where as other isolates inhibited atleast three test human pathogens in disc diffusion assay. Antimicrobial screening of endophytic actinomycetes from this host may represent a unique potential niche for antimicrobial compounds of industrial and pharmaceutical applications. This work is the first comprehensive report on incidence of potential endophytic actinomycetes inhabiting C. latifolium Blume.     

Characterization and identification of actinomycetes isolated from ‘fired plots’ under shifting cultivation in northeast Himalaya, India

A total of 35 actinomycetes was isolated from soil samples collected after fire operations at agricultural sites under shifting cultivation in northeast India. More than one-half of these isolates were observed in viable but nonculturable (VBNC) state. Five isolates were always seen embedded with slimy bacteria during subculture; 11 morphologically distinct and cultivable isolates were subjected to characterization and identification. The isolates developed circular to irregular colonies of between 3 and 6 mm on tryptone yeast extract agar plates at 28 °C following 7 days of incubation. The isolates could survive at temperatures between 4 and 50 °C (optimum 28 °C), and pH 5–11 (optimum 8). The isolates varied in cell morphology, utilization of carbon sources, sensitivity to antibiotics, and salt tolerance. Based on 16S rRNA sequencing, the isolates revealed maximum similarity to the genus Streptomyces (9), and to Kitasatospora and Nocardia (1 each). Several isolates were found to be positive for production of lytic (chitinase and glucanase) and industrially important (amylase, lipase, and protease) enzymes. The occurrence of actinomycetes in VBNC state and embedded with bacteria was attributed to coping mechanisms associated with these organisms under stress (high temperature) conditions. The cultivable cultures extend the opportunity for further investigations on ecological resilience during fire operations.     

Biodiversity of Actinomycetes Associated with Caribbean Sponges and Their Potential for Natural Product Discovery

Marine actinomycetes provide a rich source of structurally unique and bioactive secondary metabolites. Numerous genera of marine actinomycetes have been isolated from marine sediments as well as several sponge species. In this study, 16 different species of Caribbean sponges were collected from four different locations in the coastal waters off Puerto Rico in order to examine diversity and bioactive metabolite production of marine actinomycetes in Caribbean sponges. Sediments were also collected from each location, in order to compare actinomycete communities between these two types of samples. A total of 180 actinomycetes were isolated and identified based on 16S rRNA gene analysis. Phylogenetic analysis revealed the presence of at least 14 new phylotypes belonging to the genera Micromonospora, Verruscosispora, Streptomyces, Salinospora, Solwaraspora, Microbacterium and Cellulosimicrobium. Seventy-eight of the isolates (19 from sediments and 59 from sponges) shared 100 % sequence identity with Micromonospora sp. R1. Despite having identical 16S rRNA sequences, the bioactivity of extracts and subsequent fractions generated from the fermentation of both sponge- and sediment-derived isolates identical to Micromonospora sp. R1 varied greatly, with a marked increase in antibiotic metabolite production in those isolates derived from sponges. These results indicate that the chemical profiles of isolates with high 16S rRNA sequence homology to known strains can be diverse and dependent on the source of isolation. In addition, seven previously reported dihydroquinones produced by five different Streptomyces strains have been purified and characterized from one Streptomyces sp. strain isolated in this study from the Caribbean sponge Agelas sceptrum.     

Actinomycetes isolated from medicinal plant rhizosphere soils: diversity and screening of antifungal compounds,indole-3-acetic acid and siderophore production

A total of 445 actinomycete isolates were obtained from 16 medicinal plant rhizosphere soils. Morphological and chemotaxonomic studies indicated that 89% of the isolates belonged to the genus Streptomyces, 11% were non-Streptomycetes: Actinomadura sp., Microbispora sp., Micromonospora sp., Nocardia sp, Nonomurea sp. and three isolates were unclassified. The highest number and diversity of actinomycetes were isolated from Curcuma mangga rhizosphere soil. Twenty-three Streptomyces isolates showed activity against at least one of the five phytopathogenic fungi: Alternaria brassicicola, Collectotrichum gloeosporioides, Fusarium oxysporum, Penicillium digitatum and Sclerotium rolfsii. Thirty-six actinomycete isolates showed abilities to produce indole-3-acetic acid (IAA) and 75 isolates produced siderophores on chrome azurol S (CAS) agar. Streptomyces CMU-PA101 and Streptomyces CMU-SK126 had high ability to produced antifungal compounds, IAA and siderophores.     

Study on the communities of endophytic fungi and endophytic actinomycetes from rice and their antipathogenic activities in vitro

The populations of endophytic fungi and actinomycetes from four rice cultivars in the Panyu district (Site 1) and Wushan district (Site 2) in Guangdong province, South China, were studied. The preponderant endophytic fungi and actinomycetes isolated belonged to Fusarium and Streptomyces respectively. The incidence of Streptomycetes griseofuscus ranged from 36.1 to 69% out of all the different rice cultivars from the two sites. It is the commonest population of endophytic actinomycetes, and constituted the greatest part of all the antagonistic communities. The distributions of endophytic fungi and actinomycetes in roots and leaves were different, endophytic fungi from leaves were diverse, some were organ-specific. More diverse endophytic actinomycetes were isolated from roots than from leaves. The endophytic fungi isolated from rice in Site 2 were more diverse than that in Site 1. The diversity of the endophytic actinomycetes, however, was less than that in Site 1. Acid soil in Site 2 is ideal for the growth and colonization of fungi while the alkaline soil in Site 1 is better for the growth and colonization of actinomycetes. The results suggested that differences in the chemical composition of soil could influence the endophytic microbial communities of rice plants. The endophytic fungi and actinomycetes isolated from poor-growing seedlings and susceptible rice cultivars were more abundant than that the disease-resistant counterparts. In the dual culture and activity detection of the metabolites, 41.2% of all the isolated endophytic fungi showed antagonism to rice pathogens. Fifty percent of all the isolated endophytic actinomycetes were antagonistic to those pathogens. The percentage of Streptomyces griseofuscus and hygroscopicus reached 55.4 and 21.4% of all the active actinomycetes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chitinolytic Activity of Cold Tolerant Antagonistic Species of <Emphasis Type="Italic">Streptomyces</Emphasis> Isolated from Glacial Sites of Indian Himalaya

Seventy-eight isolates of actinomycetes were isolated from the soil samples collected from alpine zones of Pindari glacier region in Indian Himalaya. Following a plate based rapid screening using two test fungi, five efficient isolates (nos. HA1, HA2, HA6, HA40, and HA142) were selected for further characterization with special reference to their antagonistic properties. Based on phenotypic and genotypic characters, the isolates were identified up to species level. All the isolates belonged to the genus Streptomyces. The isolate nos. HA1 and HA2 were S. sampsonii and HA6, HA40 and HA142 were S. griseobrunneus, S. aurantiacus, and S. griseoluteus, respectively. The isolates showed strong antifungal properties against phytopathogenic test fungi in plate assays. All the isolates hydrolyzed glycol–chitin as a substrate in denaturing conditions showing variable amount of different isoforms.     

Isolation and characterization of wastewater sand filter actinomycetes

One hundred twenty-two different actinomycete strains were isolated from sample collected from several depths of the Marrakech wastewater infiltration-percolation system. To evaluate the antimicrobial effect of the different actinomycetes recovered, eleven wastewater-associated micro-organisms known as human potential pathogens were used. Results showed that 44 isolates had an in vitro inhibitory effect toward at least seven of the indicator microorganisms while only five active strains inhibited all these pathogens. All five selected active isolates belonged to the genus Streptomyces. Three were identified as Streptomyces violaceorubidus. These isolates showed the broad activity spectrum against a wastewater-associated pathogenic yeast (Candida albicans), Gram-negative (Salmonella sp. CCMM B₁₇) and Gram-positive (Staphylococcus aureus CCMM B₃). These findings indicate the potential involvement of antagonistic actinomycetes in the removal of wastewater-associated pathogens.