Isolation of Actinomycetes from Arachis hypogaea L. and Gossypium herbaceum L. for Screening Antibacterial and Antifungal Activities

The principal objective of the present study was to check the antimicrobial activity of Actinomycetes isolated from soil samples collected from the fields of Arachis hypogea L. and Gossipium herbaceum L. against different plant pathogenic strains. Various soil samples were isolated from fields located near the Junagadh district, Gujarat, India. Isolation was followed by a serial dilution process which was later plated on Actinomycete Isolation Agar (AIA) media. Potential colonies were subjected to screening, purification, and storage in glycerol stock. Morphological and Biochemical characterization of the isolates was performed. Isolated candidates were subjected to extraction for the production of the antimicrobial compound. The antimicrobial activity of the purified extract of isolates was tested. Total 30 actinomycete isolates were evaluated for antagonistic activity against pathogenic microorganisms. Isolates C-25, C-15, and G-1 showed the best results in the decreasing order of their potency against fungal pathogens, and C-5, C-25, C-14, and C-13 showed the best results in decreasing order of potency against bacterial pathogens. 3 isolates inhibited all 4 test fungi. 10 isolates inhibited 3 test fungi. 11 isolates inhibited 2 test fungi. 6 isolates did not inhibit any test fungi. 4 isolates show potent inhibition. 15 inhibited Macrophomina. C-10 showed a 1 cm inhibition zone & G-1 showed a 0.8 cm zone of inhibition. 12 isolates gave 0.2-0.6 cm zone and 15 isolates gave negative results against Macrophomina. C-10 showed a very potent zone of inhibition of 0.7 cm. 9 isolates showed a 0.1-0.5 cm zone of inhibition. 20 isolates did not show inhibition against Fusarium. 1 isolate C-11(a) gave the 1cm potent zone of inhibition. 15 isolates gave the 0.7-0.2cm inhibition of the growth. 14 isolates gave negative results against Alternaria fungus. From these results, it was concluded that isolates had antibacterial and antifungal activities and could be used in the development of new antibiotics for pharmaceutical or agricultural purposes.

Advances in the biosynthesis of cyclodipeptide type natural products derived from actinomycetes / 生物工程学报

Cyclodipeptide (CDP) composed of two amino acids is the simplest cyclic peptide. These two amino acids form a typical diketopiperazine (DKP) ring by linking each other with peptide bonds. This characteristic stable ring skeleton is the foundation of CDP to display extensive and excellent bioactivities, which is beneficial for CDPs' pharmaceutical research and development. The natural CDP products are well isolated from actinomycetes. These bacteria can synthesize DKP backbones with nonribosomal peptide synthetase (NRPS) or cyclodipeptide synthase (CDPS). Moreover, actinomycetes could produce a variety of CDPs through different enzymatic modification. The presence of these abundant and diversified catalysis indicates that actinomycetes are promising microbial resource for exploring CDPs. This review summarized the pathways for DKP backbones biosynthesis and their post-modification mechanism in actinomycetes. The aim of this review was to accelerate the genome mining of CDPs and their isolation, purification and structure identification, and to facilitate revealing the biosynthesis mechanism of novel CDPs as well as their synthetic biology design.

Actinomycotic osteomyelitis in the maxilla and the zygomatic bone: a case report and literature review / 口腔疾病防治

Objective@# To investigate the clinical features, diagnosis and treatment of osteomyelitis of the jaw caused by an actinomycotic infection and to provide a reference for clinical diagnosis and treatment.@*Methods@#A case of osteomyelitis in the bilateral maxilla and the left zygomatic bone and arch caused by a mixed bacterial infection dominated by Actinomycetes was reviewed and analyzed in combination with the literature. @*Results @#The patient had left upper posterior tooth pain with repeated left facial swelling for 7 months. The patient's left face was swollen before surgery, the left maxillary alveolar bone was necrotic, and the upper palate showed fistula discharge. A maxillofacial magnetic resonance imaging scan excluded tumors and other space-occupying lesions. According to CBCT images, the initial diagnoses were left infraorbital space infection and osteomyelitis of the bilateral maxillary, the left zygomatic bone, the left zygomatic arch and the lateral orbital wall. Necrosis of the left maxilla and the zygomatic bone was excised, the focus was cleared and the focal tooth was extracted under general anesthesia. Histopathological results confirmed osteomyelitis and actinomycotic infection. Anti-inflammatory therapy with penicillin sodium was given before surgery, and piperacillin sodium and tazobactam sodium, dexamethasone sodium phosphate, tranexamic acid and mecobalamine were given after surgery. The patients' 6-month follow-up results showed that the maxillofacial shape was basically symmetrical; no ulceration, pus or abnormal secretion was found in the skin or intraoral mucosa; and the surgical area showed good recovery. A review of the relevant literature showed that Actinomyces is an opportunistic pathogen, and factors such as trauma and dental infection have been implicated in the pathogenesis of osteomyelitis. In addition to surgery, antibiotics are used to treat the disease and multidisciplinary symptomatic treatment combined with supportive treatment is required to achieve a better prognostic effect. @*Conclusion @# Actinomycotic osteomyelitis occurring in the maxilla and the zygomatic bone is an extremely rare disease that can be diagnosed by clinical manifestations, bacteriological examination and biopsy. Appropriate and effective penicillin drugs should be given at the initial stage of treatment, more sensitive antibiotics should be selected according to the results of the drug sensitivity test, and the lesions should be surgically removed when the patient's condition improves. Active symptomatic and supportive treatment should be performed during the treatment period.

Development and application of ribosomal engineering in actinomycetes / 生物工程学报

Ribosomal engineering is a technique that can improve the biosynthesis of secondary metabolites in the antibiotics-resistant mutants by attacking the bacterial RNA polymerase or ribosome units using the corresponding antibiotics. Ribosomal engineering can be used to discover and increase the production of valuable bioactive secondary metabolites from almost all actinomycetes strains regardless of their genetic accessibility. As a consequence, ribosomal engineering has been widely applied to genome mining and production optimization of secondary metabolites in actinomycetes. To date, more than a dozen of new molecules were discovered and production of approximately 30 secondary metabolites were enhanced using actinomycetes mutant strains generated by ribosomal engineering. This review summarized the mechanism, development, and protocol of ribosomal engineering, highlighting the application of ribosomal engineering in actinomycetes, with the aim to facilitate future development of ribosomal engineering and discovery of actinomycetes secondary metabolites.

Genome analysis and plant growth promoting activity of Pseudonocardia strain DR1-2 from the root of Dendrobium christyanum Rchb.f

Aims@#The objective of this study was to analyze the genome of endophytic actinomycete associated with orchids and evaluate its plant hormone activities, including phytohormone, siderophore, ammonia production, zinc and phosphate solubilization.@*Methodology and results@#Strain DR1-2 isolated from the roots of the Thai orchid, Dendrobium christyanum Rchb.f., was closely related to Pseudonocardia alni DSM 44104T, P. antarctica DSM 44749T and P. carboxydivorans Y8T (99.93-100% similarity) based 16S rRNA gene sequence. This strain exhibited IAA production (294.10 ± 12.17 μg/mL), phosphate solubilization (2.20 ± 0.08 solubilization Index, SI), positive for siderophore production and ammonia production (36.99 ± 2.24 μg/mL). It showed a maximum IAA of 489.73 ± 8.90 μg/mL, when optimized using 0.5% Ltryptophan, pH 6 and incubated at 30 °C for 7 days. The IAA of strain enhanced the root length, shoot length, number of roots and fresh weight of rice seedlings (Oryza sativa L. cv. RD49). The draft genome of strain DR1-2 was 6,077,423 bp in 23 contigs with G+C content of 74.6%. The average nucleotide identity-Blast (ANIb) and average nucleotide identity-MUMmer (ANIm) values of strain DR1-2 and related type strains were 95.81 to 97.25% and the digital DNA-DNA hybridization (dDDH) values were 72.60 to 74.00%, respectively. Genomic analysis of strain DR1-2 revealed that the gene encodes the enzyme involved in the phytohormones biosynthesis and gene clusters involved in the biosynthesis of bioactive metabolites.@*Conclusion, significance and impact of study@#Endophytic actinomycete, Pseudonocardia strain DR1-2 from Thai orchid, D. christyanum Rchb.f., exhibited significant IAA production and affected the growth of the plant, which was the potential source of plant hormones for agricultural applications.

Novel angucycline/angucyclinone family of natural products discovered between 2010 and 2020 / 生物工程学报

Angucyclines/angucyclinones are a large group of polycyclic aromatic polyketides and their producers are widely distributed in nature. This family of natural products attracts great attention because of their diverse biological activities and unique chemical structures. With the development of synthetic biology and the exploitation of the actinomycetes from previously unexplored environments, angucyclines/angucyclinones-like natural products with new skeletons were continuously discovered, thus enriching the structural diversity of this family. In this review we summarize the new angucyclines/angucyclinones analogues discovered in the last decade (2010-2020) by using different strategies, such as changing cultivation conditions, genetic modification, genome mining, bioactivity-guided compound isolation, and fermentation of actinomycetes from underexplored environments. We also discuss the role of synthetic biology in the discovery and development of new compounds of the angucycline/angucyclinone family.

Exploring Biodiversity for Prevention and Control of Cancer and other Non-Communicable Diseases using Indigenous Environmental Resources: An Interdisciplinary Research

Background: An interdisciplinary research of public health, biomedical and pharmaceutical sciences is neededfor integrating qualitative and quantitative researches undertaken. It hence requires focus on public beneficencefor non-communicable diseases. Purpose: To study anticancer activities of soil samples of Central India andits stability for applied public health use. Material and Methods: Screening on Actinomycetes isolates obtainedfrom rural and urban farm soils illustrating arginase production was conducted from equated soil samples ofgeo-representative localities and adjoining areas of Bhopal, India. Enrichment Technique (CDSEA) was usedfor detection of extracellular production of L-arginase and their anticancer activities using MTT 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay along with characterization and probioticproperties of selected isolate. Results: L-Arginase activity quantified by ornithine (21.06-117.92 U/mg) wasfound in isolates BRD-21, KAR-73, BHA-162, BAR-199, ARH-210, HAB-228. Urea release (15.88 – 59.79 U/mg protein) depicted L- arginase activity in crude enzyme samples. It shows noticeable anticancer activity.Morphological and biochemical characterization of these isolates revealed metabolic diversity. Isolate KAR 73produced collagenase (specific activity 57.8 U/mg), L-asparaginase (specific activity 116 U/mg) and L-arginasewith tolerance to higher temperature (45°C) and salt concentration (2-8% w/v). Equal concentrations ofcrude L- arginase from these isolates inhibited growth and proliferation of colorectal adenocarcinoma celllines (19.99%-38.65%) under in-vitro conditions. Conclusion: Arginine depletion through arginase activity isevidenced for potential effectiveness in cancer treatment especially adenocarcinomas and squamous cellcarcinoma. It is useful for wider public health purposes

Isolation and characterization of aerobic actinomycetes with probiotic properties in Nile tilapia

This study scoped the isolation of aerobic actinomycetes with probiotic properties against bacterial pathogens in Niletilapia. Eleven rhizosphere soil samples were collected from the agricultural sites in three provinces (Chanthaburi,Nan, and Chachoengsao) of Thailand. A total of 157 actinomycete-like colonies were successfully isolated. Theantibacterial testing against four tested bacteria (Streptococcus agalactiae 2809, Aeromonas jandaei 1929, Aeromonasveronii 1930, and Edwardsiella ictaluri 2234) was carried out by a modified cross-streaked method. The results showedthat 108 strains possessed antibacterial activity against at least one of the bacterial pathogens. Seventeen active isolateswere identified in the actinomycetes by the analysis of the partial 16S ribosomal rRNA gene, and the phylogeneticrelationships of the isolates and their closely related strains were confirmed by the neighbor-joining method. IsolatesLNW002 and YNW004 survived in the liquid cultivation with International Streptomyces Project 2 at pH 2 and thepresence of 0.3% bile salt for 2 hours, which mimics the gastric acidity and bile salt in the gastrointestinal tract of Niletilapia in vitro. In conclusion, these strains might be further investigated for their efficacy as probiotics in Nile tilapia.This study is the first to report on anti-E. ictaluri activity in streptomycetes.

Antiviral activity of geldanamycin and its derivatives against influenza virus

Two new geldanamycin derivatives such as 17-(tryptamine)-17-demethoxygeldanamycin (2) andC17 methoxyl of geldanamycin (1). Their antiviral activity was evaluated based on influenza virus propagation inembryonated chicken eggs and viral absorption by hemagglutination (HA) inhibition test. The findings indicatedthat these compounds inhibited viral propagation at a concentration of 12.5 µg/ml. For the viral absorption, onlycompounds 2 and 3 inhibited HA at a concentration of 50 µg/ml. The solubility of compounds 2 and 3 in waterwas 290 and 306 µM, higher than that of compound 1 about 1.91 and 2.01 times, respectively. The compounds 2and 3 showed a moderate cytotoxic activity on LLC-MK2 and Vero cells with IC50 values of >200.00 µg/ml. Theseresults demonstrated the invention of tryptamine-geldanamycin hybrids to prevent influenza virus infection in viralabsorption and viral propagation steps.

Effect of Polygonum multiflorum-Andrographis paniculata intercropping system on rhizosphere soil actinomycetes community structure and diversity of P. multiflorum / 中国中药杂志

To investigate the effect of Polygonum multiflorum-Andrographis paniculata intercropping system on rhizosphere soil actinomycetes of P. multiflorum, the community structure and diversity of soil actinomycetes were studied by using the original soil as the control group and the rhizosphere soil actinomycetes communities of P. multiflorum under monoculture and intercropping systems as the experimental group. In this study 655 221 effective sequences were obtained with an average length of 408 bp. OTU coverage and rarefaction curve showed that the sequencing could represent the real situation of soil actinomycetes. According to the results of alpha diversity analysis, the diversity soil actinomycetes varied as follows: original soil>intercropping soil>monoculture soil. The soil actinomycetes community structure and the relative abundance of dominant genera were significantly changed by both monoculture and intercropping, especially monoculture. OTU clustering and PCA analysis of soil samples showed that all the soil samples were divided into three distinct groups and the original soil was more similar to intercropping soil. In addition, intercropping increased the relative abundance of some beneficial actinomyces, such as Kitasatospora and Mycobacterium, which was beneficial to maintain soil health and reduce the occurrence of soil-borne diseases. The results show that, P. multiflorum-A. paniculata intercropping reduced the change of community structure and the decrease of diversity of soil actinomycetes caused by P. multiflorum monoculture, and made the actinomycete community in rhizosphere soil of P. multiflorum close to the original soil.

Growth and antioxidant response of juvenile oysters Crassostrea sikamea and Crassostrea corteziensis treated with Streptomyces strains / Crescimento e resposta oxidative de ostras jovens Crassostrea sikamea e Crassostrea corteziensis tratadas com cultura Streptomyces

The effect of three Streptomyces strains (N7, RL8 and V4) and a mixture of Bacillus (BMix) on the growth (Weight, Size) and superoxide dismutase activity (SOD) in hatchery-reared juvenile oysters Crassostrea corteziensis and Crassostrea sikamea was investigated to determine their probiotic potential. Microorganisms were added to culture water at 1×106 CFU/ml once a day during 30 days and all oysters fed daily a microalgae mix. Juveniles of C. sikamea treated with strains N7, RL8 and V4 had a significant weight gain compared to the control group. C. corteziensis juveniles treated with strains RL8 and BMix showed a significantly higher weight gain than the control group. No significant size increase was observed in any treated group for both oyster species. SOD activity significantly increased in C. sikamea treated with RL8 and with RL8, N7 and BMix in C. corteziensis. Streptomyces strains RL8 and N7 emerge as promising probiotic agents to cultivate C. sikamea and C. corteziensis and may also be useful to other molluscs and marine invertebrates .(AU)

O efeito de três culturas Streptomyces (N7, RL8 e V4) e uma mistura de Bacillus (BMix) sobre o cresimento (Peso, Tamanho) e atividade superóxido dismutase (SOD) em ostras jovens Crassostrea corteziensis e Crassostrea sikamea cultivadas artificalmente foi investigado para determinar seu potencial probiótico. Microorganismos foram adicionados à água de cultura a 1×10 6 CFU/ml uma vez por dia durante 30 dias e todas as ostras foram alimentadas diariamente com uma mistura de microalgas. Jovens C. sikamea tratados com culturas N7, RL8 e V4 tiveram ganho de peso significativo quando comparado ao grupo de controle. Jovens C. corteziensis tratados com culturas RL8 e BMix demonstraram peso significativamente mais algo que o grupo de controle. Nenhum aumento em tamanho foi observado em grupos tratados em ambas espécies. A atividade SOD foi significamente aumentada em C. sikamea treatado com RL8 e com RL8, N7 e BMix em C. corteziensis. Culturas Streptomyces RL8 e N7 surgem como agentes probióticos promissores para o cultivo de C. sikamea e C. corteziensis e podem ser úteis para outros moluscos animais marinhos invertebrados.(AU)

Sand Dune Streptomyces Jb66 Native To The Great Indian Thar Desert Inhibits Multidrug-Resistant Pathogens

The efficacy of an actinomycete strain JB66 recovered from a sand dune soil from the Bikaner district of the Thar desert in inhibiting the growth of various bacterial pathogens was studied. The type strains Staphylococcus aureus, Shigella flexneri, Klebsiella pneumoniae and the clinical isolates Escherichia coli, multidrug-resistant S. aureus and P. vulgaris were included in the antimicrobial assays. Polyphasic characterization of JB66 isolate revealed its identity as Streptomyces (MH762010). It showed 88.99-89.24% sequence similarity with the other members of this genus and share the maximum (88.89%) similarity with Streptomyces sp. ATSC13. The strain JB66 was found to produce a high amount of extracellular L-asparaginase, catalase, gelatinase, protease, tyrosinase and urease enzymes. The partial chemical categorization of the methanolic crude extract of the JB66 strain led to the preliminary identification of various metabolic compounds. The thin-layer chromatography fractionation revealed the presence of prodigiosin pigment or chandramycin, cephalosporin or zeatin, daidzein, demethoxy rapamycin, 4,6-dihydroxy-7-methoxyisoflavone, munumbicins and amiclenomycin like compounds. Bio-autography revealed that the metabolites localized at the Rf values of 0.40, 0.46 and 0.53 in TLC profile had the actual bioactive fractions. UV-VIS spectrum absorbance maxima at 288 nm revealed the presence of an aromatic nucleus.

An Implication Of Actinomycetes On Human Well-Being: A Review

This review conceptualizes about the actinomycetes and its contribution to human health by playing a key role as bioactive secondary metabolites, such as enzymes, antibiotics and pigments, leading to their diverse applications and use in various industries. These searches have been uncommonly successful, and around 66% of naturally happening antibiotics, including many medically important, have been isolated from actinomycetes. The speedy occurrence of antimicrobial resistance among pathogens has led to a renewed interest to search for novel antimicrobial agents, but these antibiotics are not enough for the treatment of all diseases because there is a berserk requirement for a novel actinomycetes to combat against the antibiotic-resistant strains of pathogenic microorganisms, which are quickly expanding bit by bit. Actinomycetes are the important providers to the pharmaceutical and other industries and are well known for their capacity to produce secondary metabolites many of which are active against pathogenic microorganisms.

Distribution and antimicrobial activity of Thai marine actinomycetes

A total of 41 actinomycetes were isolated from marine samples collected in Thailand. On the basis of morphology,chemotaxonomy, and 16S rRNA gene sequence analysis, they were identified as Salinispora (13 isolates),Micromonospora (11 isolates), Nocardia (1 isolate), Verrucosispora (2 isolates), and Streptomyces (14 isolates).The antimicrobial activity screening revealed that two Micromonospora isolates, 12 Salinispora isolates and 10Streptomyces isolates showed activity against Staphylococcus aureus ATCC 25923, Kocuria rhizophila ATCC 9341,Bacillus subtilis ATCC 6633, Escherichia coli NIHJ KC213, Candida albicans KF1, and Mucor racemosus IFO 4581.Based on this study, the production media and strains were the main factors that influenced the antimicrobial activity

Endophytic Actinomycetes as Potential Producers of Hemicellulases and Related Enzymes for Plant Biomass Degradation

Abstract Tailor made enzymatic preparation must be design to hydrolyze efficiently plant biomass, once that each plant biomass possesses a distinct cell wall composition. Most of actinomycetes used for plant cell wall degradation are focused on the cellulases and xylanases production. However, a wide range of enzymes must be produced for an efficient degradation of lignocellulose materials. During the last decade several unusual environments were studied to obtain strains that produce glycohydrolases with innovator characteristics. In this context, the present work concerned the selection of endophytic actinomycetes as producers of hemicellulases and related enzymes with different enzymatic profiles, for use in the deconstruction of lignocellulosic biomass. A total of 45 Brazilian actinomycetes previously isolated from plants (endophytics) and soil were prospected for hemicellulases and β-glucosidase production. Four strains highlighted for hemicellulase production (DR61, DR63, DR69 and DR66) and were selected for cultivation under other inductors substrates (xylan and pectin). All strains belong to Streptomyces genera and have their extracts tested for degradation of several hemicellulolytic substrates. The strains presented different glicohydrolyse enzymes profiles mainly for xylans and glucans that can be used for specific formulations of enzymes applied on the biomass deconstruction, principally on sugar cane bagasse.

Nocardiosis Associated with Novel Agents at Relapsed Multiple Myeloma: Case Series

Nocardiosis is a gram positive bacterial infection caused by aerobicactinomycetes. It抯 nonspesific presentation and radiographic findings usually make it undiagnosed with highly fatal outcomes. The patients with intracelluler defects are prone to nocardiosis. Multiplemyelom(MM) itself is a mainly humoral deficiency disorder because of defective antibodies but recent drugs such as proteasome inhibitors and immuno modulatory drugs also cause cellular deficiency. Here we presented two definite and oneprobable pulmonary nocardiosis patients who have a diagnosis of MM, autologou shematopoetic stem cell transplant history in their past and anti myeloma therapy presently.

Research on rhizospheric and endophytic actinomycetes in medicinal tree peony(Paeonia suffruticosa) from five producing regions / 中国中药杂志

In this study, Paeonia suffruticosa roots and rhizospheric soil in five geographic regions which were harvested in October were utilized as experimental materials, then the diversity of endophytic and rhizospheric actinomycetes were investigated by High-throughput sequencing technique. The 1 754 operational taxonomic units (OTUs) were obtained from 129 954 high quality sequences, 1 311 OTUs were detected in rhizospheric actinomycetes and belonged to four classes, four orders, twenty-seven families and ninety-seven genera, thirty-three genera such as Ilumatobacter were found in the five regions rhizospheric soil while three genera such as Longispora were only detected in the Dao-di regions, the dominant genera were Mycobacterium, Nocardioides, Streptomyces. 443 OTUs were obtained in roots and distributed in three classes, three orders, twenty-four families and fifty genera, thirteen genera such as Cryptosporangium were found in the five regions roots while Planosporangium, Luteococcus were only detected in the Dao-di regions, the dominant genera were Nocardioides. Alpha diversity analysis showed that the Shannon and Chao1 index in rhizospheric actinomycetes in Bozhou, Tongling and Nanling region were higher than Heze and Luoyang. Based on principal co-ordinates analysis (PCoA) analysis, the rhizospheric actinomycetes formations were similar in Tongling and Nanling region, at the same in Tongling and Luoyang endophytic actinomycetes. According to heatmap analysis, Bozhou, Tongling and Nanling region rhizospheric actinomycetes showed a close similarity in actinomycetes community structures on phylogenetic analysis, while Tongling, Luoyang and Nanling endophytic actinomycetes showed the same. Our results not only suggested that the rich and diverse actinomycetes resources in P. suffruticosa roots and rhizospheric soil but also revealed rhizospheric actinomycetes in the Dao-di regions had high similarity.

Secondary metabolites of co-culture of Alternaria alternate YX-25 and Streptomyces exfoliatus YX-32 / 中草药

Objective To study the secondary metabolites of the co-culture of fungus Alternaria alternata YX-25 and Streptomyces exfoliatus YX-32 isolated from mangrove mud in Yunxiao Country of Fujian Province. Methods The compounds were purified by silica gel and Sephadex LH-20, followed by semi-preparative chromatography. The structures of the compounds were determined by MS and NMR. Results Nine compounds were isolated from the crude extract, which were identified as gliotoxin (1), 12,13-dihydroxy-fumitremorgin C (2), fumitremorgin (3), bisdethiobis(methylthio)gliotoxin (4), demethoxyfumitremorgin C (5), vermistatin (6), cyclo-(L-Trp-L-Pro) (7), 6-methoxyspirotryprostatin B (8), and citrinolactone D (9). Conclusion Nine compounds were isolated for the first time from co-culture of the fungus Alternaria alternata YX-25 and Streptomyces exfoliates YX-32, including indole diketopiperazines, polyketides, and cyclopeptides. The co-cultivation method can be as a new method for enrichment of secondary metabolites.

Isolation of actinomycetes with antibacterial activity against multi-drug resistant bacteria

@#Aims: To isolate and characterise actinomycetes from various sources of soil samples (fruit orchard, dipterocarp forest and oil palm plantation) and to screen these isolates forantibacterial activity against multi-drug resistant bacteria.Methodology and results: A total of 158 fast-growing actinomycete isolates with different colony morphologywere subjected to primary cross-streak and secondary well diffusion screening. Six isolates (OP1E, OP7A, OP2A-C, MG1A, UT9C1 and UT7E)were found to inhibit atleast one of the seven multi-drug resistant (MDR) bacteria. MG1A exhibited the strongest and broadest spectrum of antibacterial activity against 6 MDR bacteria tested. These isolates were identified as Streptomyces species based on 16S rRNA gene sequence analysis. Further morphological and biochemical analysis revealed that MG1A was highly similar to S. griseocarneus (98.36%)whereas OP1E and OP2A-C were similar to S. parvulus(99.93% and 99.51% respectively). Preliminary identification using LCMS/MS and database search revealed that the major compound in the extract of OP2A-C could be dactinomycin (1255.4170 g/mol). Other antibacterial compounds in the extracts remain to be identified. Conclusion, significance and impact of study: Soil actinomycetes with antibacterial activity against MDR bacteria were isolated not only from undisturbed natural soils but cultivated soils. These isolates were characterised, identified and the antibacterial compounds were extracted for further study. The isolates could serveas a potential source for the development of new and sustainable compounds against MDR bacteria.

Screening and Evaluation of Streptomyces Species as a Potential Biocontrol Agent against a Wood Decay Fungus, Gloeophyllum trabeum

Two-hundred and fifty-five strains of actinomycetes isolated from soil samples were screened for their antagonistic activities against four well-known wood decay fungi (WDF), including a brown rot fungus, Gloeophyllum trabeum and three white rot fungi Donkioporia expansa, Trametes versicolor, and Schizophyllum commune. A dual culture assay using culture media supplemented with heated or unheated culture filtrates of selected bacterial strains was used for the detection of their antimicrobial activity against four WDF. It was shown that Streptomyces atratus, S. tsukiyonensis, and Streptomyces sp. greatly inhibited the mycelial growth of the WDF tested compared with the control. To evaluate the biocontrol efficacy of S. atratus, S. tsukiyonensis, and Streptomyces sp., wood blocks of Pinus densiflora inoculated with three selected Streptomyces isolates were tested for weight loss, compression strength (perpendicular or parallel to the grain), bending strength, and chemical component changes. Of these three isolates used, Streptomyces sp. exhibited higher inhibitory activity against WDF, especially G. trabeum, as observed in mechanical and chemical change analyses. Scanning electron microscopy showed that cell walls of the wood block treated with Streptomyces strains were thicker and collapsed to a lesser extent than those of the non-treated control. Taken together, our findings indicate that Streptomyces sp. exhibits the potential to be used as a biocontrol agent for wood decay brown rot fungus that causes severe damage to coniferous woods.