Actinomycete Strain Research Articles

Antagonism and plant growth promoting traits of actinomycetes isolated from the rhizosphere of halophyte Atriplex halimus L.

Biocontrol is considered as an effective alternative to the application of agrochemicals, which are harmful to the environment, human, and animal health. In this study, twenty-six strains of actinomycetes were isolated from rhizospheric arid soil of the halophyte Atriplex halimus L. ῾Guettaf’ in Biskra province, Algeria. The six isolates that have inhibited at least three phytopathogenic fungi among the five tested (Fusarium oxysporum, Alternaria alternata, Fusarium solani, Aspergillus flavus and Botrytis cinerea) were selected, and have been tested in vitro against phytopathogenic bacteria (Pectobacterium carotovorum and Streptomyces scabies). They were also evaluated for their ability to hydrolyze phosphate, elaborate siderophores, produce indole-3-acetic acid (IAA), and to antagonize S. scabies in vivo (on radish seedlings). Based on the physicochemical analyses, soil samples were categorized as alkaline and extremely-saline. The antagonism results revealed varying antifungal potential among the selected isolates (Act11, Act16, Act17, Act18, Act23 and Act24), about 50% were able to inhibit the growth of F. solani and A. flavus, followed by 33.33% of those having antagonized F. oxysporum, while A. alternata was found to be the most sensitive. Only Act18 has antagonized S. scabies in vitro with an inhibition diameter zone of 19 ± 0.41 mm. However, in vivo trials showed that four isolates have counteracted S. scabies. Among them, Act18 and Act24 have significantly and positively affected the root surface (P = 0.0062) and prevented common scab. IAA was detected in all selected isolates with Act24 being the highest producer (77.45 μg mL−1). Additionally, degradation ability revealed that four isolates were able to hydrolyze phosphate while three exhibited the capacity of elaborating siderophores. The six isolates were assigned to Streptomyces genius according to their morphological, physiological and chemotaxonomical traits. Based on this study, Streptomyces sp. Act18 and Streptomyces sp. Act24 that tolerate 7.5% NaCl concentration, prevent common scab and exhibit some plant growth attributes, may be considered as promising biocontrol agents to be applied in arid and saline soils.

Antibacterial efficacy of synthesized silver nanoparticles of Microbacterium proteolyticum LA2(R) and Streptomyces rochei LA2(O) against biofilm forming meningitis causing microbes

Actinobacteria obtained from the least explored Indian regions were studied for their ability to suppress meningitis-causing bacteria in nanoparticle form. Drug-resistant bacteria and long-term treatment with different medications make meningitis control complicated. Thus, new meningitis drugs are required to combat MDR bacteria. In this study, secondary metabolites isolated from actinomycetes strains, Microbacterium proteolyticum LA2(R) and Streptomyces rochei LA2(O), were employed to synthesize silver nanoparticles (AgNPs) at 37 °C for seven days incubation. UV–Vis spectroscopy, TEM, FTIR, and HPLC studies were used for the confirmation of the synthesis of AgNPs. Furthermore, these NPs demonstrated antibacterial and antibiofilm activities against meningitis-causing bacteria. The average size of LA2(R) and LA2(O) isolated secondary metabolites mediated AgNPs was observed to be 27 ± 1and 29 ± 2 nm by TEM analysis. FTIR study of RAgNPs and OAgNPs revealed that presence of peaks with positions of 1637.17 cm1 and 1636.10 cm1 for C=O amide group appearances in the amide I linkage. These NPs were effective against bacterial pathogens such as S. pneumoniae, H. influenzae, and N. meningitidis and confirmed by their MICs, i.e., 109.4, 120.60, and 138.80 μg/ml of RAgNPs and 105.80, 114.40 and 129.06 μg/ml of OAgNPs, respectively. Additionally, the production of biofilms is impeded by these nanoparticles on S. pneumoniae, H. influenzae, and N. meningitidis by 73.14%, 71.89% and 64.81%, respectively. These findings confirm the potential role of synthesized AgNPs against biofilm forming meningitis causing Multidrug resistance (MDR) microbes.

Synergy between Genome Mining, Metabolomics, and Bioinformatics Uncovers Antibacterial Chlorinated Carbazole Alkaloids and Their Biosynthetic Gene Cluster from Streptomyces tubbatahanensis sp. nov., a Novel Actinomycete Isolated from Sulu Sea, Philippines.

In this study, a novel actinomycete strain, DSD3025T, isolated from the underexplored marine sediments in Tubbataha Reefs Natural Park, Sulu Sea, Philippines, with the proposed name Streptomyces tubbatahanensis sp. nov., was described using polyphasic approaches and characterized using whole-genome sequencing. Its specialized metabolites were profiled using mass spectrometry and nuclear magnetic resonance analyses, followed by antibacterial, anticancer, and toxicity screening. The S. tubbatahanensis DSD3025T genome was comprised of 7.76 Mbp with a 72.3% G+C content. The average nucleotide identity and digital DNA-DNA hybridization values were 96.5% and 64.1%, respectively, compared with its closest related species, thus delineating the novelty of Streptomyces species. The genome encoded 29 putative biosynthetic gene clusters (BGCs), including a BGC region containing tryptophan halogenase and its associated flavin reductase, which were not found in its close Streptomyces relatives. The metabolite profiling unfolded six rare halogenated carbazole alkaloids, with chlocarbazomycin A as the major compound. A biosynthetic pathway for chlocarbazomycin A was proposed using genome mining, metabolomics, and bioinformatics platforms. Chlocarbazomycin A produced by S. tubbatahanensis DSD3025T has antibacterial activities against Staphylococcus aureus ATCC BAA-44 and Streptococcus pyogenes and showed antiproliferative activity against colon (HCT-116) and ovarian (A2780) human cancer cell lines. Chlocarbazomycin A exhibited no toxicity to liver cells but moderate and high toxicity to kidney and cardiac cell lines, respectively. IMPORTANCE Streptomyces tubbatahanensis DSD3025T is a novel actinomycete with antibiotic and anticancer activities from Tubbataha Reefs Natural Park, a United Nations Educational, Scientific and Cultural Organization World Heritage Site in Sulu Sea and considered one of the Philippines' oldest and most-well-protected marine ecosystems. In silico genome mining tools were used to identify putative BGCs that led to the discovery of genes involved in the production of halogenated carbazole alkaloids and new natural products. By integrating bioinformatics-driven genome mining and metabolomics, we unearthed the hidden biosynthetic richness and mined the associated chemical entities from the novel Streptomyces species. The bioprospecting of novel Streptomyces species from marine sediments of underexplored ecological niches serves as an important source of antibiotic and anticancer drug leads with unique chemical scaffolds.

ISOLATION AND SCREENING OF INDIGENOUS MICROORGANISMS CAPABLE OF DEGRADING CELLULOSE TO TREAT HEMP HURD IN THANH HOA PROVINCE

Hemp Hurd has not yet found an optimal treatment method, therefore, in this paper, we isolated and screened native microorganisms with high cellulose-degradation capability for potentially effective treatment. Native microorganisms were isolated on Gauze I and Hans, media then CMC-as activity was determined. Next, the species names of screening microorganisms were determined by total DNA isolation, PCR and Sequencing. The results showed that 02 bacterial strains and 06 actinomycete strains were selected from 32 isolates. Then, we optimized the growing conditions of the screened microorganisms. Among actinomycetes strains PU1.1, PU2.1 gave the highest weight loss results, therefore they were selected for further study. Our results showed that TG2.1 and CM4.1 are Bacillus subtilis. PU1.1 is Streptomyces lilacs, while PU1.2 is Streptomyces Misiones. The selected microorganisms belong to risk group level 1 (safety group). Thus, these strains can be used for further experiments in the research and production of microorganism-derived bio-products to treat hemp hurd in Thanh Hoa province.

Three novel Actinoplanes species isolated by using polyaspartic acid as a water-retaining agent for the enrichment in situ.

Three novel actinomycete strains, designated TRM66264-DLMT, TRM88002T and TRM88003T, were isolated by using polyaspartic acid as a water-retaining agent for the enrichment in situ. The 16S rRNA gene sequence and phylogenetic analyses of three strains indicated that they belonged to the genus Actinoplanes. The phylogenetically closest strains of TRM66264-DLMT, TRM88002T and TRM88003T were Actinoplanes bogorensis LIPI11-2-Ac043T (98.4 %), Actinoplanes abujensis A4029T (98.0 %) and Actinoplanes ferrugineus IFO15555T (98.1 %), respectively. The major polar lipids of strains TRM66264-DLMT and TRM88002T were phosphatidylethanolamine and disphosphatidylglycerol, while strain TRM88003T only had phosphatidylethanolamine. The predominant menaquinones of strain TRM66264-DLMT were identified as MK-9(H4) and MK-9 (H6). Strains TRM88002T and TRM88003T had MK-9(H4). The cell-wall peptidoglycan of three strains contained meso-diaminopimelic acid. The whole-cell sugars of strain TRM66264-DLMT were identified as arabinose, glucose, galactose and xylose. Strains TRM88002T and TRM88003T mainly had arabinose and glucose. The DNA G+C content of strains TRM66264-DLMT, TRM88002T and TRM88003T were 70.48, 70.46 and 70.64 mol%, respectively. Genotypic and phenotypic analysis confirmed that all three strains sre new members of the genus Acinoplanes. Therefore, it is proposed that strains TRM66264-DLMT, TRM88002T and TRM88003T represent three novel species of the genus Actinoplanes, for which the names Actinoplanes polyasparticus sp. nov. (type strain TRM66264-DLMT=CCTCC AA 2021015T=LMG 32389T), Actinoplanes hotanensis sp. nov. (type strain TRM88002T=CCTCC AA 2021036T=LMG 32621T) and Actinoplanes aksuensis sp. nov. (type strain TRM88003T=CCTCC AA 2021037 T=LMG 32622T) are proposed.

Characterization of polyhydroxybutyrate (PHB) synthesized by newly isolated rare actinomycetes Aquabacterium sp. A7-Y

Polyhydroxyalkanoates (PHAs) as biodegradable plastics have attracted increasing attention due to its biodegradable, biocompatible and renewable advantages. Exploitation some unique microbes for PHAs production is one of the most competitive approaches to meet complex industrial demand, and further develop next-generation industrial biotechnology. In this study, a rare actinomycetes strain A7-Y was isolated and identified from soil as the first PHAs producer of Aquabacterium genus. Produced PHAs by strain A7-Y was identified as poly(3-hydroxybutyrate) (PHB) based on its structure characteristics, which is also similar with commercial PHB. After optimization of fermentation conditions, strain A7-Y can produce 10.2 g/L of PHB in 5 L fed-batch fermenter, corresponding with 54 % PHB content of dry cell weight, which is superior to the reported actinomycetes species. Furthermore, the phaCAB operon in stain A7-Y was excavated to be responsible for the efficient PHB production and verified in recombinant Escherichia coli. Our results indicate that strain A7-Y and its biosynthetic gene cluster are potential candidates for developing a microbial formulation for the PHB production.

Generation of a high quality library of bioactive filamentous actinomycetes from extreme biomes using a culture-based bioprospecting strategy.

Filamentous actinomycetes, notably members of the genus Streptomyces, remain a rich source of new specialized metabolites, especially antibiotics. In addition, they are also a valuable source of anticancer and biocontrol agents, biofertilizers, enzymes, immunosuppressive drugs and other biologically active compounds. The new natural products needed for such purposes are now being sought from extreme habitats where harsh environmental conditions select for novel strains with distinctive features, notably an ability to produce specialized metabolites of biotechnological value. A culture-based bioprospecting strategy was used to isolate and screen filamentous actinomycetes from three poorly studied extreme biomes. Actinomycetes representing different colony types growing on selective media inoculated with environmental suspensions prepared from high-altitude, hyper-arid Atacama Desert soils, a saline soil from India and from a Polish pine forest soil were assigned to taxonomically predictive groups based on characteristic pigments formed on oatmeal agar. One hundred and fifteen representatives of the colour-groups were identified based on 16S rRNA gene sequences to determine whether they belonged to validly named or to putatively novel species. The antimicrobial activity of these isolates was determined using a standard plate assay. They were also tested for their capacity to produce hydrolytic enzymes and compounds known to promote plant growth while representative strains from the pine forest sites were examined to determine their ability to inhibit the growth of fungal and oomycete plant pathogens. Comparative 16S rRNA gene sequencing analyses on isolates representing the colour-groups and their immediate phylogenetic neighbours showed that most belonged to either rare or novel species that belong to twelve genera. Representative isolates from the three extreme biomes showed different patterns of taxonomic diversity and characteristic bioactivity profiles. Many of the isolates produced bioactive compounds that inhibited the growth of one or more strains from a panel of nine wild strains in standard antimicrobial assays and are known to promote plant growth. Actinomycetes from the litter and mineral horizons of the pine forest, including acidotolerant and acidophilic strains belonging to the genera Actinacidiphila, Streptacidiphilus and Streptomyces, showed a remarkable ability to inhibit the growth of diverse fungal and oomycete plant pathogens. It can be concluded that selective isolation and characterization of dereplicated filamentous actinomyctes from several extreme biomes is a practical way of generating high quality actinomycete strain libraries for agricultural, industrial and medical biotechnology.

Isolation and antibacterial screening of actinomycetes with antibacterial properties from medicinal soil

Research on Actinomycetes has proven highly beneficial to society, particularly in the development of product-oriented solutions for disease cures through the utilization of their compounds, commonly known as drugs. This study focused on screening and identifying actinomycete strains derived from the root nodules of Cissus quadrangularis and Alpinia officinarum cultivated in Chennai. The research began with serial dilution and enumeration of soil samples, followed by screening and isolation procedures aimed at discovering novel species. The study yielded 13 Actinomycete strains identified based on Gram staining, colony morphology, and biochemical tests, all of which exhibited Gram-positive characteristics with varying colony morphologies and biochemical profiles. Primary screening determined antibacterial isolates and identified the range of microorganisms sensitive to the antibiotics. A secondary screening was conducted to validate the results. Both qualitative and quantitative approaches were employed to determine the sensitivity of microorganisms to potential antibiotics. The qualitative method determined the range of sensitive microorganisms, while the quantitative approach provided insights into the expected antibiotic yield when the organisms were cultured in ISP2 broth. All experimental measurements were conducted in triplicate, and the results were expressed as averages of three analyses. Among the isolates, I5, MS1005F, and MS1005E demonstrated high activity, while MS100E exhibited relatively lower activity against pathogenic bacterial strains. Notably, isolate I5 displayed the highest activity against MS1005F.

Бактерии-деструкторы дибутилфталата, выделенные из ризосферы мятлика лугового (Poa pratensis L.)

The ability of three bacterial strains of the class Actinomycetes, isolated from the rhizosphere of bluegrass (Poa pratensis L.) plants growing in the industrial development area of the Verkhnekamsk salt deposit (Perm krai), to grow on dibutyl phthalate (DBP) as the only source of carbon and energy was studied. Based on 16S rRNA gene analysis, it was shown that the strain Rh7bel showed similarity at 100% level with Rhodococcus wratislaviensis NBRC 100605T, and strains NKDBFbel and NKDBFgelt are phylogenetically close to two type strains of the species Pseudarthrobacter oxydans and Pseudarthrobacter polychromogenes (99.83% similarity). DBP-degrading strains are characterized by efficient growth on the key metabolite of DBP degradation, ortho-phthalic acid, and utilization of this metabolite. The strain Rhodococcus sp. Rh7bel demonstrated the highest rates of DBP utilization: the maximum specific substrate consumption rate was 0.018±0.002 h-1, substrate utili-zation was 70.7% in 72 hours (initial DBP concentration 0.2 g/L). Thus, rhizosphere DBP-degrading strains Rhodococcus sp. Rh7bel, Pseudarthrobacter spp. NKDBFbel and NKDBFgelt are promising for further study and development of technology for phytoremediation of soils contaminated with phthalates.

Antagonistic activity of pigment-forming streptomycets isolated from various anthropogenic zones of Tashkent, Uzbekistan

Actinomycetes play an important role in soil formation and soil fertility. Improvement of soils is connected with their activity. they transform and destroy complex organic compounds (cellulose, chitin, lignin, and others) that are inaccessible to many other microorganisms. Actinomycetes are of the greatest interest for biotechnology as producers of antibiotic substances. Antagonistic activity to phytopathogens of local strains of pigment-forming actinomycetes of the genus Streptomyces isolated from various anthropogenic zones of Tashkent was shown. Active strains with high antagonistic activity to plant pathogens were selected. The results showed that the significant was the antagonistic effect of Streptomyces sp.15 to the studied phytopathogens, while the zone of no growth of pathogens reached from 22 mm to 26 mm.

The characteristics of actinomyces strptomyces griseorubiginosus 83 – the effective biosorbent of silver

The bacteria bound about the same amount of silver at the time of inoculation and when added after 24 hours Fourier transform infrared spectroscopy (FT-IR) and measurements of the ζ- potential showed that several groups, mainly carboxy groups are involved in the binding and biotransformation of silver cations. Also, volatile organic compounds profiling for L. lactis, demonstrated the presence of many compounds in the free space of bacteria, which were typical products of bacterial metabolism. Finally, it can be stated that the combination of various instrumental methods used has opened up new possibilities for the interpretation of physicochemical phenomena occurring at the interface between bacteria-bacteria and bacteria-metals- bacteria. The ability of the biomass of cultures of various taxonomic groups to sorb metals is used both for purification of wastewater from metals and in the additional separation of valuable and environmentally significant metals from various wastes. In this work 48 strains of actinomycetes were isolated from various samples of desert soils of Uzbekistan under agricultural crops. As a result of screening, a strain of Streptomyces sp. 83, efficiently absorbs silver from solutions. The morphological-cultural and physiological-biochemical characteristics of the selected

Isolation, Identification and Screening of Saharan Actinomycete Strain Streptomyces fimbriatus AC31 Endowed with Antimicrobial Activity.

The increasing global public health concern of antimicrobial resistance (AMR) necessitates exploration of natural antimicrobial agents as potential alternatives. This study aimed to investigate antimicrobial activities of Saharan actinomycetes, with specific focus on the strain Streptomyces fimbriatus AC31, that holds promising potential as an alternative to combat AMR. In this context, 32 actinomycetes were isolated from El Atteuf (Ghardaïa), Algeria. Isolates obtained were characterized morphologically and biochemically. Screened isolate was identified by 16S rRNA gene sequencing. Classification of actinomycete isolates was carried out by UPGMA (Unweighted Pair Group Method with Arithmetic Mean). Then, they were screened for their antimicrobial activity by cross-streak method. Identification of 32 isolates revealed 5 genera: Streptomyces (65.63%), Nocardia (9.38%), Streptosporangium (9.38%), Nocardiopsis (9.38%) and Actinomadura (6.25%). According to the biochemical and physiological characteristics, UPGMA classified the isolates in 4 phenons. A number of 24 (75.00%) isolates were active against Gram-positive bacteria, 21 (65.63%) isolates were effective against Gram-negative bacteria, and 25 (78.13%) isolates inhibited Candida albicans. Screened strain Streptomyces fimbriatus AC31 showed highest antagonistic activity and revealed an inhibition zones of 41, 38, 41, 42, and 44 mm, against B. subtilis (ATCC 6633), E. coli (ATCC 8739), S. typhimurium (ATCC 13331), S. aureus (ATCC 6538) and C. albicans (ATCC 10231), respectively. Phylogenetic identification of the AC 31 isolate using 16S rRNA gene sequence showed similarity of 100% with Streptomyces fimbriatus NBRC 15411T. Actinomycete isolates characterized in this study were endowed with antimicrobial activity against various pathogenic microorganisms that could be used efficiently in developing new antimicrobial substances.

Isolation and screening antimicrobial activity of actinomycetes from marine organisms samples of the area Khanh Hoa, Vietnam

The marine environmental conditions are particularly different from terrestrial ones; recent studies have showed that marine actinomycetes might produce many novel compounds with good biological activity. The objective of this study is to isolate and screen actinomycetes strains from the marine environment with activity against pathogenic microorganisms. Fifty strains of actinomycetes were isolated from 40 samples including: sediments, sponges, soft corals, echinoderms... collected from Van Phong Bay area of Khanh Hoa province, Vietnam. The strains fermented in A+ medium and fermentation broths were extracted 5 times with ethyl acetate. The extracts were evaporated under reduced pressure to yield crude extracts. Quantitative assay was used to determine MIC (minimum inhibitory concentration) of extract against 7 test strains, including three Gram-negative bacteria (Escherichia coli ATCC25922, Pseudomonas aeruginosa ATCC27853, Salmonella enterica ATCC13076), three Gram-positive bacteria (Enterococcus faecalis ATCC29212, Staphylococcus aureus ATCC25923, Bacillus cereus ATCC 14579), and the yeast Candida albicans ATCC10231. The result of screening showed that: 18/50 strains have shown the antibacterial activities against at least 3 strains of tested microorganisms. In which, strains G650, G654, G657, G666, G675 inhibited three Gram-positive test microorganisms at MIC values from 8 to 64 µg/mL and C. albicans ATCC10231 with MIC values from 2 to 16 µg/mL. In addition, the two strains G657 and G666 had inhibitory effect on P. aeruginosa ATCC27853 và S. enterica ATCC13076 with MIC value 128 µg/mL. Morphological and phylogenetic investigations based on 16S rRNA gene sequences of the selected five strains showed that: strain G650 belonged to species Streptomyces ardesiacus and strain G666 high similarity to the genus Streptomyces; strain G654 showed the highest similarity to the Salinispora arenicola species; strain G657 highest similarity to the Micromonospora aurantiaca; whereas G675 belonged to the Nocardiopsis flavescens species.

Enzymatic and antibacterial activity of some actinomycete strains

The soil samples were collected from the Tuv provinces of Mongolia. Three cultures of actinomycetes were isolated and extracted bioactive crude extract with organic solvents, and their antimicrobial activity and some enzyme activities were determined. Actinomycetes 24-TSAND1, 21-TSB8, and 54-TSB4 had protease and amylase enzyme activities Cultures of actinomycetes 24-TSAND1, 21-TSB 8, and 54-TSB4 are highly active against pathogenic bacteria Staphylococcus aureus. However, 24-TSAND1 and 21-TSB 8 cultures were not effective against Escherichia coli pathogens, while 54-TSAND4 culture was moderately active. Also, the nucleotide sequence of the 16S rRNA gene of the actinomycete 24-TSAND1 culture was determined, and the phylogenetic analysis revealed that it depends on the species of Streptomyces microflavus. Зарим актиномицетийн нутгийн өсгөвөрүүдийн ферментийн болон бичил биетний эсрэг идэвх Төв аймгийн хөрснөөс ялгасан актиномицетийн 3 өсгөврийг сонгон органик уусгагчаар хандлан бичил биетний эсрэг идэвх болон зарим ферментийн идэвхийг тодорхойлов. Актиномицетийн 24-Цанд1, 21-ЦБ8 болон 54-ЦБ4 өсгөврүүд нь протеаза, амилаза ферментийн өндөр идэвхтэй байна. Актиномицетийн 24-Цанд1, 21- ЦБ8, 54-ЦБ4 нутгийн өсгөврүүд өвчин үүсгэгч S. aureus–ийн эсрэг идэвх өндөртэй байна. Харин E. coli өвчин үүсгэгчийн эсрэг 24-Цанд1, 21-ЦБ8 өсгөврүүд үйлчлээгүй бол 54-ЦБ4 өсгөвөр дунд зэргийн идэвхтэй байв. Мөн актиномицетийн 24-Цанд1 өсгөврийн 16S рРНХ генийн нуклеотидийн дарааллыг тогтоож, филогенетикийн анализ хийхэд Streptomyces microflavus-ийн төрөл зүйлд хамаарч байгааг тодорхойлов. Түлхүүр үгс: Актиномицет, 16S рРНХ ген, филогенетик, фермент, бичил биетний эсрэг идэвх

A New Method of Preparing Aurone by Marine Actinomycetes and Its Potential Application in Agricultural Fungicides.

A strain of marine actinomycetes was isolated from an intertidal zone and identified as Streptomyces cinereoruber. Through the fermentation of this strain, a compound with fungicidal activity was extracted and purified. Using mass spectrometry (MS) and nuclear magnetic resonance (NMR) data, the metabolite was determined to be an aurone. The toxicity of the aurone toward four kinds of tumor cells-SH-SY5Y, HepG2, A549, and HeLa cells-was verified by the MTT method, delivering IC50 values of 41.81, 47.19, 63.95, and 51.92 μg/mL, respectively. Greenhouse bioassay showed that the aurone exhibited a high fungicidal activity against powder mildew (Botrytis cinerea), cucurbits powder mildew (Sphaerotheca fuliginea (Schlecht ex Ff.) Poll), and rice blast (Pyricularia oryzae).

Optimization of Degenerate PCR Conditions for Reducing Error Rates in Detection of PKS and NRPS Gene groups in Actinomycetes.

The screen of Polyketide Synthase (PKS) and Nonribosomal Peptide Synthetase (NRPS) gene groups is a quick way to discover new therapeutic agents. However, errors in laboratory techniques cause a loss of touch with reality. This study aimed to evaluate the presence of PKS and NRPS gene groups in previously isolated strains by optimizing their specialized amplification by degenerate primers and indicating the evolutionary relationships with reference strains. PKS-I, II, and NRPS genes PCR amplification was performed using three degenerate primer sets for 22 actinomycete strains with antibacterial activity. Annealing temperature and the amount of template DNA and primers were optimized. PCR products of PKS-I, II, and NRPS from three strains were sequenced after TA cloning. Besides, strains with high antibacterial activity were identified by biochemical features and partial 16S rDNA sequencing and hypothetically classified by a phylogenetic tree. High frequencies of PKS-I (86.4%), PKS-II (81.8%), and NRPS (95.4%) genes were found among the strains after optimization. Fourteen strains (64%) contained all of the genes, and 100% of strains had at least two genes. These numbers are pretty distinct in comparison with the previous researches. All of the sequenced strains were members of Streptomyces genus. Our research showed that degenerate PCR strongly depends on the variation of annealing temperature and primer concentration, resulting in an unexpected shift in PCR outputs. The sequencing results confirmed the optimized conditions for specialized PCR of PKS-I, PKS-II, and NRPS gene groups.

Hemiactinomycin, an undescribed intermediate of actinomycin biosynthesis from an actinomycetes strain Streptomyces antibioticus H41-55

Hemiactinomycin (1), an intermediate derivative of actinomycin biosynthesis, together with three known actinomycins (2-4) , were isolated from the ethanolic extract of Streptomyces antibioticus H41-55 fermentation mycelium by using various column chromatography. The structure of the derivative was established by extensive spectroscopic analysis, including HRESIMS, 1D, and 2D NMR spectroscopy. In addition, the anti-inflammatory activities of all the isolates were tested. The derivative (1) showed inhibiting NO release activities in LPS-induced RAW 264.7 macrophages with the IC50 values of 15.41 ± 0.66 μM.

Soil-bacteria-mediated eco-friendly synthesis of ceramic nanostructure

Due to their magnetic and electrical properties, ceramic ferrite nanoparticles are a suitable option for use in various industries, including pharmaceutical, biomedical, food, and environmental. A total of 40 Gram-positive actinomycetes strains (named Ak1–40) were isolated from the soil and used to synthesize ceramic ferrite nanoparticles. To determine the identity of the isolated actinomycetes, its colonies were characterized morphologically using a scanning electron microscope (SEM). The PCR amplification (FD1 and RP2 primers) of 16 S rDNA gene was done to the genetically identification of the bacterial strain. Bacterial Streptomyces fulvissimus (isolate Ak10) was able to restore the production of ceramic ferrite nanoparticles. The characteristics of ceramic ferrite nanoparticles were examined through Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Vibrating Sample Magnetometry (VSM). The size of synthesized ceramic ferrite nanoparticles was less than 50 nm. This study is the first report on synthesizing ceramic ferrite nanoparticles by actinomycete soil bacteria. Using bacteria in synthesizing nanoparticles as nano-factories is a promising tool for the biological production of ceramic ferrite nanoparticles.

Exploring Micromonospora as Phocoenamicins Producers.

Over the past few years, new technological and scientific advances have reinforced the field of natural product discovery. The spirotetronate class of natural products has recently grown with the discovery of phocoenamicins, natural actinomycete derived compounds that possess different antibiotic activities. Exploring the MEDINA's strain collection, 27 actinomycete strains, including three marine-derived and 24 terrestrial strains, were identified as possible phocoenamicins producers and their taxonomic identification by 16S rDNA sequencing showed that they all belong to the Micromonospora genus. Using an OSMAC approach, all the strains were cultivated in 10 different media each, resulting in 270 fermentations, whose extracts were analyzed by LC-HRMS and subjected to High-throughput screening (HTS) against methicillin-resistant Staphylococcus aureus (MRSA), Mycobacterium tuberculosis H37Ra and Mycobacterium bovis. The combination of LC-UV-HRMS analyses, metabolomics analysis and molecular networking (GNPS) revealed that they produce several related spirotetronates not disclosed before. Variations in the culture media were identified as the most determining factor for phocoenamicin production and the best producer strains and media were established. Herein, we reported the chemically diverse production and metabolic profiling of Micromonospora sp. strains, including the known phocoenamicins and maklamicin, reported for the first time as being related to this family of compounds, as well as the bioactivity of their crude extracts. Although our findings do not confirm previous statements about phocoenamicins production only in unique marine environments, they have identified marine-derived Micromonospora species as the best producers of phocoenamicins in terms of both the abundance in their extracts of some major members of the structural class and the variety of molecular structures produced.

Characterizing corn-straw-degrading actinomycetes and evaluating application efficiency in straw-returning experiments.

Corn straw is an abundant lignocellulose resource and by-product of agricultural production. With the continuous increase in agricultural development, the output of corn straw is also increasing significantly. However, the inappropriate disposal of straw results in wasting of resources, and also causes a serious ecological crisis. Screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. For this purpose, our research group isolated three actinomycete strains with efficient lignocellulose degradation ability from soil in the cold region of China: Streptomyces sp. G1T, Streptomyces sp. G2T and Streptomyces sp. G3T. Their microbial properties and taxonomic status were assessed to improve our understanding of these strains. The three strains showed typical characteristics of the genus Streptomyces, and likely represent three different species. Genome functional annotation indicated that most of their genes were related to functions like carbohydrate transport and metabolism. In addition, a similar phenomenon also appeared in the COG and CAZyme analyses, with a large number of genes encoding carbohydrate-related hydrolases, such as cellulase, glycosidase and endoglucanase, which could effectively destroy the structure of lignocellulose in corn straw. This unambiguously demonstrated the potential of the three microorganisms to hydrolyze macromolecular polysaccharides at the molecular level. In addition, in the straw-returning test, the decomposing consortium composed of the three Streptomyces isolates (G123) effectively destroyed the recalcitrant bonds between the various components of straw, and significantly reduced the content of active components in corn straw. Furthermore, microbial diversity analysis indicated that the relative abundance of Proteobacteria, reportedly associated with soil antibiotic resistance and antibiotic degradation, was significantly improved with straw returning at both tested time points. The microbial diversity of each treatment was also dramatically changed by supplementing with G123. Taken together, G123 has important biological potential and should be further studied, which will provide new insights and strategies for appropriate treatment of corn straw.