Atacama desert actinomycetes: taxonomic analysis, drought tolerance and plant growth promoting potential.

This study was designed to recover representative culturable actinomycetes from the Atacama Desert, and to detect their ability to promote plant growth under drought conditions. Environmental samples were taken from three Atacama Desert habitats, namely, from the Aguas Calientes, Lomas Bayas and Yungay core regions. With one exception higher actinomycete counts were obtained when isolation media were inoculated with mineral particles than with corresponding aliquots of serial dilution. Comparative 16S rRNA gene sequencing showed that representative isolates belonged to thirteen genera including putative novel Blastococcus, Kocuria, Micromonospora, Pseudonocardia, Rhodococcus and Streptomyces species. Representative isolates produced indole-3-acetic acid, siderophore and solubilized phosphate as well as displaying an ability to grow under drought conditions. In conclusion, the current findings open up exciting prospects for the promising potential of actinomycetes from the Atacama Desert to be used as bioinoculants to promote plant growth in arid and semi-arid biomes.

Actinomycins from Soil-Inhabiting Streptomyces as Sources of Antibacterial Pigments for Silk Dyeing.

Actinobacteria produce a broad spectrum of bioactive substances that are used in the pharmaceutical, agricultural, and biotechnology industries. This study investigates the production of bioactive substances in Streptomyces, isolated from soil under five tropical plants, focusing on their potential as natural antibacterial dyes for silk fabrics. Out of 194 isolates, 44 produced pigments on broken rice as a solid substrate culture. Eight antibacterial pigmented isolates from under Magnolia baillonii (TBRC 15924, TBRC 15927, TBRC 15931), Magnolia rajaniana (TBRC 15925, TBRC 15926, TBRC 15928, TBRC 15930), and Cinnamomum parthenoxylon (TBRC 15929) were studied in more detail. TBRC 15927 was the only isolate where all the crude extracts inhibited the growth of the test organisms, Staphylococcus epidermidis TISTR 518 and S. aureus DMST 4745. The bioactive compounds present in TBRC 15927 were identified through LC-MS/MS analysis as belonging to the actinomycin group, actinomycin D (or X1), X2, and X0ß. Also, the ethyl acetate crude extract exhibited non-toxicity at an IC50 value of 0.029 ± 0.008 µg/mL on the mouse fibroblast L-929 assay. From the 16S rRNA gene sequence analysis, TBRC 15927 had 100% identity with Streptomyces gramineus JR-43T. Raw silk dyed with the positive antimicrobial TBRC 15927 extract (8.35 mg/mL) had significant (>99.99%) antibacterial properties. Streptomyces gramineus TBRC 15927 is the first actinomycin-producing strain reported to grow on broken rice and shows promise for antibacterial silk dyeing.

Biotechnological and Ecological Potential of Micromonospora provocatoris sp. nov., a Gifted Strain Isolated from the Challenger Deep of the Mariana Trench.

A Micromonospora strain, isolate MT25T, was recovered from a sediment collected from the Challenger Deep of the Mariana Trench using a selective isolation procedure. The isolate produced two major metabolites, n-acetylglutaminyl glutamine amide and desferrioxamine B, the chemical structures of which were determined using 1D and 2D-NMR, including 1H-15N HSQC and 1H-15N HMBC 2D-NMR, as well as high resolution MS. A whole genome sequence of the strain showed the presence of ten natural product-biosynthetic gene clusters, including one responsible for the biosynthesis of desferrioxamine B. Whilst 16S rRNA gene sequence analyses showed that the isolate was most closely related to the type strain of Micromonospora chalcea, a whole genome sequence analysis revealed it to be most closely related to Micromonospora tulbaghiae 45142T. The two strains were distinguished using a combination of genomic and phenotypic features. Based on these data, it is proposed that strain MT25T (NCIMB 15245T, TISTR 2834T) be classified as Micromonospora provocatoris sp. nov. Analysis of the genome sequence of strain MT25T (genome size 6.1 Mbp) revealed genes predicted to responsible for its adaptation to extreme environmental conditions that prevail in deep-sea sediments.

Performance of Actinobacteria isolated from rhizosphere soils on plant growth promotion under cadmium toxicity.

This work aimed to evaluate the potential use of plant growth-promoting actinobacteria (PGPA) for enhanced cadmium (Cd) phytoremediation and plant growth. Forty-two actinobacteria were isolated from rhizosphere soils in Thailand. Among isolates tested, only Streptomyces phaeogriseichromatogenes isolate COS4, showed the high ability to produce siderophores as a plant growth stimulant and had a strong Cd tolerance potential. The significance of siderophores production and Cd tolerance ability under different Cd concentrations suggests the potential of isolate COS4 to work effectively. Plant culture revealed that the significant increase in root length, root to tip length, and total dried weight of sunflower were obtained after 2 h incubation of sunflower seeds with isolate COS4. The efficiency of Cd uptake was found to range between 42.3 and 61.3%. Translocation factor results confirmed that plant growth promoting S. phaeogriseichromatogenes isolate COS4-assisted phytoremediation can be considered as Cd absorbents for the restoration of polluted sites due to high translocation values.

Nonomuraea antri sp. nov., an actinomycete isolated from cave soil in Thailand.

A novel actinobacterium, designated strain NN258T, was isolated from a cave soil sample collected from a karst cave at Khao No-Khao Kaeo, Nakhon Sawan province, Thailand. The morphological, chemotaxonomic and phylogenetic characteristics were consistent with its classification in the genus Nonomuraea. Strain NN258T showed the highest 16S rRNA gene sequence similarity values to Nonomuraea candida HMC10T, Nonomuraea mesophila 6K102T, Nonomuraea rubra DSM 43768T, Nonomuraea diastatica KC712T and Nonomuraea helvata IFO 14681T. The strain formed an extensively branched substrate and aerial mycelia. The whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, with glucose, madurose, mannose and ribose as the whole-cell sugars. The polar lipids were diphosphatidylglycerol, phosphotidylmethylethanolamine, phosphatidylethanolamine, hydroxy-phosphatidylmonomethylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, two unidentified phospholipids, three unidentified sugar-containing phosphoaminolipids, an unidentified glycolipid and two unidentified lipids. The predominant menaquinone was MK-9(H4), with minor amounts of MK-9(H0), MK-9(H2) and MK-9(H6). Major cellular fatty acids (>10%) were iso-C16 : 0 and 10-methyl-C17 : 0. The G+C content of the genomic DNA was 71.0 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain NN258T and the reference strains were 79.9-80.9 % and 26.1-27.0 %, respectively. On the basis of phenotypic, genotypic and phylogenetic data, strain NN258T represents a novel species of the genus Nonomuraea, for which the name Nonomuraea antri sp. nov. is proposed. The type strain is NN258T (=TBRC 11478T=NBRC 114269T).

Amycolatopsis eburnea sp. nov., an actinomycete associated with arbuscular mycorrhizal fungal spores.

A novel actinomycete, designated strain GLM-1T, was isolated from arbuscular mycorrhizal fungal spores from Funneliformis mosseae RYA08, collected from Aquilaria crassna Pierre ex Lec. rhizosphere soil in Klaeng, Rayong Province, Thailand. Morphological characteristics of this strain included long chains of rod-like cells and squarish elements. The cell-wall composition of this novel isolate contained meso-diaminopimelic acid. The whole-cell diagnostic sugars were arabinose and galactose. The predominant menaquinone was MK-9(H4). The major fatty acids were iso-C16 : 0 and iso-C15 : 0. Only phosphatidylethanolamine was detected as a polar lipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain GLM-1T was closely related to Amycolatopsis rhabdoformis SB026T (99.11 %) with a low DNA-DNA hybridization value of 22.6-34.7 %. Genome sequencing revealed a genome size of 10 Mbp. There were obvious distinctions in the average nucleotide identity values between stain GLM-1T and its closely related strains at around 86-93 % (ANIb) and 89-94 % (ANIm). The digital DNA-DNA hybridization values between strain GLM-1T and type strains of phylogenetically related species were 34-55 %. The G+C content of the genomic DNA was 71.8 mol%. Based on these data, strain GLM-1T is considered to represent a novel species of the genus Amycolatopsis, for which the name Amycolatopsiseburnea sp. nov. is proposed. The type strain is GLM-1T (=TBRC 9315T=NBRC 113658T).

Streptomyces venetus sp. nov., an actinomycete with a blue aerial mycelium.

A Gram-positive bacterium, designated CMU-AB225T, was isolated from rhizosphere soil of an oil palm (Elaeis guineensis). The strain exhibited a blue aerial spore mass and a light cream to moderate yellow substrate mycelium and formed chains of spiny spores. Whole-cell hydrolysates consisted of ll-diaminopimelic acid, glucose, ribose, mannose and galactose. The predominant menaquinones were MK-9(H6), MK-9(H8) and MK-9(H4). The polar lipids profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol-mannoside, four unidentified lipids, two unidentified aminolipids and an unidentified glycolipid. The major cellular fatty acids (>10 %) were iso-C16 : 0, C16 : 0, anteiso-C15 : 0 and iso-C15 : 0. The G+C content of genomic DNA was 69.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CMU-AB225T was a member of the genus Streptomyces and formed a distinct phyletic line which was most closely related to Streptomyces koyangensis JCM 14915T, Streptomyces misionensis JCM 4497T and Streptomyces aurantiogriseus JCM 4346T. Multilocus sequence analysis (MLSA) using five housekeeping genes (atpD, gyrB, recA, rpoB and trpB) showed that the MLSA distances of strain CMU-AB225T to phylogenetically related species were greater than the 0.007 threshold. Moreover, the low values of DNA-DNA relatedness and phenotypic differences, especially a blue aerial mycelium, enabled strain CMU-AB225T to be distinguished from its closely related species. It is thus proposed that strain CMU-AB225T represents a novel species, namely Streptomyces venetus sp. nov. The type strain is CMU-AB225T (=JCM 31290T=TBRC 2001T).

Amycolatopsis oliviviridis sp. nov., a novel polylactic acid-bioplastic-degrading actinomycete isolated from paddy soil.

A novel bioplastic-degrading actinomycete, strain SCM_MK2-4T, was isolated from paddy soil in Thailand. The 16S rRNA gene sequence showed that strain SCM_MK2-4T belonged to the genus Amycolatopsis, with the highest sequence similarity to Amycolatopsisazurea JCM 3275T (99.4 %), and was phylogenetically clustered with this strain along with Amycolatopsislurida JCM 3141T (99.3 %), A. japonica DSM 44213T (99.2 %), A. decaplanina DSM 44594T (99.0 %), A. roodepoortensis M29T (98.9 %), A. keratiniphilasubsp. nogabecina DSM 44586T (98.8 %), A. keratiniphilasubsp. keratiniphila DSM 44409T (98.5 %), A. orientalis DSM 40040T (98.4 %) and A. regifaucium GY080T (98.3 %). A combination of DNA-DNA hybridization results ranging from 42.8±3.2 to 66.2±1.4 % with the type strains of A. azurea and A. lurida and some different phenotypic characteristics indicated that the strain could be distinguished from its closest phylogenetic neighbours. Whole-cell hydrolysates of the strain were shown to contain meso-diaminopimelic acid, arabinose, galactose, glucose, ribose, mannose, rhamnose and xylose. The predominant menaquinone was MK-9(H4). The major cellular fatty acid profile consisted of iso-C15 : 0, iso-C16 : 0, summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2OH) and C16 : 0. The polar lipid composition of the strain consisted of phosphatidyl-N-methylethylethanolamine, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylglycerol, aminophospholipids, an unidentified phospholipid and two unidentified glycolipids. The G+C content of the genomic DNA was 68.2 mol%. On the basis of phylogenetic analyses, DNA-DNA hybridization experimentation and the phenotypic characteristics, it was concluded that strain SCM_MK2-4T represents a novel species of the genus Amycolatopsis, for which the name Amycolatopsis oliviviridis sp. nov. is proposed. The type strain is SCM_MK2-4T (=TBRC 7186T=JCM 32134T).

Amycolatopsis vastitatis sp. nov., an isolate from a high altitude subsurface soil on Cerro Chajnantor, northern Chile.

The taxonomic position of a novel Amycolatopsis strain isolated from a high altitude Atacama Desert subsurface soil was established using a polyphasic approach. The strain, isolate H5T, was shown to have chemical properties typical of members of the genus Amycolatopsis such as meso-diaminopimelic acid as the diamino acid in the cell wall peptidoglycan, arabinose and galactose as diagnostic sugars and MK-9(H4) as the predominant isoprenologue. It also has cultural and morphological properties consistent with its classification in the genus, notably the formation of branching substrate hyphae which fragment into rod-like elements. 16S rRNA gene sequence analyses showed that the strain is closely related to the type strain of Amycolatopsis mediterranei but could be distinguished from this and other related Amycolatopsis strains using a broad range of phenotypic properties. It was separated readily from the type strain of Amycolatopsis balhymycina, its near phylogenetic neighbour, based on multi-locus sequence data, by low average nucleotide identity (92.9%) and in silico DNA/DNA relatedness values (51.3%) calculated from draft genome assemblies. Consequently, the strain is considered to represent a novel species of Amycolatopsis for which the name Amycolatopsis vastitatis sp. nov. is proposed. The type strain is H5T (= NCIMB 14970T = NRRL B-65279T).

Pseudonocardia thailandensis sp. nov., an actinomycete isolated from a subterranean termite nest.

A novel Gram-stain-positive bacterium designated CMU-NKS-70T was isolated from a subterranean termite nest and characterized using a polyphasic approach. The strain exhibited branching, pinkish-cream aerial mycelium and cream-brown substrate mycelium, and formed chains of rod-like spores. The 16S rRNA gene sequence analyses indicated that strain CMU-NKS-70T belonged to the genus Pseudonocardia, showing high similarity with Pseudonocardia oroxyli D10T (98.9 % 16S rRNA gene sequence similarity), Pseudonocardia xishanensis YIM 63638T (98.9 %) and Pseudonocardia kujensis A4038T (98.5 %). However, DNA-DNA relatedness values between strains CMU-NKS-70T and the closest phylogenetically related species ranged from 40.5±2.9 to 48.6±0.7 %. Whole-cell hydrolysates of strain CMU-NKS-70T consisted of meso-diaminopimelic acid, glucose, galactose, arabinose, mannose, ribose and rhamnose. The predominant menaquinone was MK-8(H4). The major cellular fatty acids (>10 %) were iso-C16 : 0, C16 : 0, C16 : 1ω7c and/or iso-C15 : 0 2-OH and 10-methyl C16 : 0. The polar lipids detected were phosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, three unidentified glycolipids and two unidentified phospholipids. The G+C content of genomic DNA was 71.9 mol%. The physiological and biochemical properties also supported the phenotypic distinction of strain CMU-NKS-70T from its closely related species. On the basis of evidence from this study using a polyphasic approach, strain CMU-NKS-70T represents a novel species of the genus Pseudonocardia for which the name Pseudonocardia thailandensis sp. nov. is proposed. The type strain is CMU-NKS-70T (=JCM 31292T=TBRC 2000T).

Effective enhancement of polylactic acid-degrading enzyme production by Amycolatopsis sp. strain SCM_MK2-4 using statistical and one-factor-at-a-time approaches.

This study aims to find the optimal medium and conditions for polylactic acid (PLA)-degrading enzyme production by Amycolatopsis sp. SCM_MK2-4. Screening of the most effective components in the enzyme production medium by Plackett-Burman design revealed that the silk cocoon and PLA film were the most significant variables enhancing the PLA-degrading enzyme production. After an response surface methodology, a maximum amount of PLA-degrading enzyme activity at 0.74 U mL-1 was predicted and successfully validated at 95% after 0.39% (w/v) silk cocoon and 1.62% (w/v) PLA film were applied to the basal medium. The optimal initial pH value, temperature, and inoculum size were evaluated by a method considering one-factor-at-a-time. The values were recorded at an initial pH in the range of 7.5-9.0, a temperature of 30-32°C, and an inoculum size of 4-10%. The highest activity of approximately 0.95 U mL-1 was achieved after 4 days of cultivation using the optimized medium and under optimized conditions in a shake flask. Upscaling to the use of a 3-L stirred tank fermenter was found to be successful with a PLA-degrading activity of 5.53 U mL-1; which represents a 51-fold increase in the activity compared with that obtained from the nonoptimized medium and conditions in the shake flask.

Actinopolyspora salinaria sp. nov., a halophilic actinomycete isolated from solar saltern soil.

The taxonomic position of the halophilic actinobacterial strain, HS05-03T, isolated from solar saltern soil, was determined using a polyphasic approach. Phylogenetic analysis based on the 16S rRNA gene sequence of the strain showed that it formed a distinct evolutionary lineage in the genus Actinopolyspora. The organism was most closely related to the type strains of the species Actinopolyspora xinjiangensis (98.0% similarity), Actinopolyspora righensis (97.9% similarity), Actinopolyspora lacussalsi (97.9% similarity) and Actinopolyspora erythraea (97.8% similarity). The whole-organism hydrolysates contained meso-diaminopimelic acid, arabinose, galactose and ribose. The predominant menaquinones were found to be MK-9(H4) and MK-10(H4). The acyl type of the peptidoglycan was N-acetyl. The diagnostic phospholipid detected was phosphatidylcholine. The predominant cellular fatty acids were iso-C16 : 0, anteiso-C17:0 and iso-C15:0. The G+C content of the genomic DNA was 69.9 mol%. DNA-DNA hybridization values between strain HS05-03T and the type strains of the most closely related species were below the 70 % threshold. On the basis of the phenotypic and genotypic data, it is proposed that strain HS05-03T represents a novel species of the genus Actinopolyspora, with the name Actinopolyspora salinaria sp. nov. The type strain is HS05-03T (=BCC 51286T=NBRC 109078T).

Streptomyces palmae sp. nov., isolated from oil palm (Elaeis guineensis) rhizosphere soil.

Actinomycete strain CMU-AB204T was isolated from oil palm rhizosphere soil collected in Chiang Mai University (Chiang Mai, Thailand). Based on morphological and chemotaxonomic characteristics, the organism was considered to belong to the genus Streptomyces. Whole cell-wall hydrolysates consisted of ll-diaminopimelic acid, glucose, ribose and galactose. The predominant menaquinones were MK-9(H4), MK-9(H6), MK-9(H2) and MK-8(H4). The fatty acid profile contained iso-C15 : 0, iso-C16 : 0 and anteiso-C15 : 0 as major components. The principal phospholipids detected were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The DNA G+C content of strain CMU-AB204T was 70.9 mol%. Based on 16S rRNA gene sequence similarity, strain CMU-AB204T was closely related to Streptomyces orinoci JCM 4546T (98.7 %), Streptomyces lilacinus NBRC 12884T (98.5 %), Streptomyces abikoensis CGMCC 4.1662T (98.5 %), Streptomyces griseocarneus JCM 4905T (98.4 %) and Streptomyces xinghaiensis JCM 16958T (98.3 %). Phylogenetic trees revealed that the new strain had a distinct taxonomic position from closely related type strains of the genus Streptomyces. Spiny to hairy spores clearly differentiated strain CMU-AB204T from the five most closely related Streptomyces species, which produced smooth spores. On the basis of evidence from this polyphasic study, it is proposed that strain CMU-AB204T represents a novel species of the genus Streptomyces, namely Streptomyces palmae sp. nov. The type strain is CMU-AB204T (=JCM 31289T=TBRC 1999T).

Jiangella mangrovi sp. nov., isolated from mangrove soil.

An aerobic, Gram-stain-positive actinomycete, designated strain 3SM4-07T, was characterized using a polyphasic taxonomic approach. The strain produced branching mycelium which fragmented into short or elongated rods. The whole-cell hydrolysates contained ll-2,6-diaminopimelic acid as the diagnostic diamino acid, with glucose and ribose as the main sugars. The predominant cellular fatty acids were anteiso-C15  :  0, iso-C15  :  0 and iso-C16  :  0.The predominant menaquinone was MK-9(H4). Phospholipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol and phosphatidylinositol mannoside. Mycolic acids were absent. The DNA G+C content was 72.3 mol%. Strain 3SM4-07T formed a phylogenetic line within the genus Jiangella and its 16S rRNA gene sequence was related most closely to Jiangella alkaliphila D8-87T (99.0% similarity), Jiangella muralis 15-Je-017T (98.8%), Jiangella alba YIM 61503T (98.6%) and Jiangella gansuensis YIM 002T (98.6%). However, mean DNA-DNA hybridization values revealed that strain 3SM4-07T differed from the closest species previously described in this genus. Data from phenotypic, chemotaxonomic and molecular analyses between strain 3SM4-07T and recognized species of the genus Jiangella indicate that strain 3SM4-07T is a representative of a novel species of the genus Jiangella, for which the name Jiangella mangrovi sp. nov. is proposed. The type strain is 3SM4-07T ( = BCC 60398T = NBRC 109648T).

Streptomyces ferrugineus sp. nov., isolated from mangrove soil in Thailand.

Bacterial strain HV38(T) was isolated from mangrove soil, which was collected from Thailand. Chemotaxonomic and morphological characteristics were found to be typical of members of the genus Streptomyces. The strain was found to form a distinct phyletic line in the Streptomyces 16S rRNA gene tree and to be closely associated with the type strains of Streptomyces coeruleofuscus CGMCC 4.1667(T) (98.84 % sequence similarity), Streptomyces chromofuscus CGMCC 4.1451(T) (98.63 %) and Streptomyces albidoflavus CGMCC 4.1291(T) (98.56 %). The major menaquinones were identified as MK-9(H8) and MK-9(H10). Its major cellular fatty acids were found to be iso-C14:0, iso-C15:0, anteiso-C15:0, iso-C16:1ω8c, C16:0, anteiso-C16:1ω8c, iso-C16:0 and anteiso-C16:0. The DNA-DNA hybridization values between strain HV38(T) with S. coeruleofuscus CGMCC 4.1667(T), S. chromofuscus CGMCC 4.1451(T) and S. albidoflavus CGMCC 4.1291(T) were 32.7 ± 0.9, 21.8 ± 0.3 and 19.9 ± 0.9 %, respectively, which clearly supported the conclusion that they belong to separate genomic species. Cumulatively, the data indicated that strain HV38(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces ferrugineus sp. nov. is proposed. The type strain is HV38(T) (=CCTCC AA2014009(T )= DSM 42152(T)).

Melanogenic actinomycetes from rhizosphere soil-antagonistic activity against Xanthomonas oryzae and plant-growth-promoting traits.

A total of 210 melanogenic actinomycetes were isolated from 75 rhizospheric soils using ISP6 and ISP7 agar supplemented with antifungal and antibacterial agents. Their morphological characteristics and the presence of ll-diaminopimelic acid in whole-cell hydrolyzates revealed that all isolates belonged to the genus Streptomyces. Their ability to inhibit the growth of 2 pathogenic rice bacteria, Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola, was observed using the agar overlay method. The results indicated that 61.9% of the isolates could inhibit at least one of the tested rice pathogens. Among these, isolate TY68-3 showed the highest antibacterial activity and siderophore production. The 16S rRNA gene sequence analysis of 46 representative isolates revealed that isolates with high similarity to Streptomyces bungoensis were frequently found. The present study indicated the potential of melanogenic actinomycetes for use as biocontrol agents against X. oryzae as well as their diversity in rhizospheric soils.

Isolation and screening of biopolymer-degrading microorganisms from northern Thailand.

Forty agricultural soils were collected from Chiang Mai and Lampang provinces in northern Thailand. Bacteria, actinomycetes and fungi were isolated and screened for their ability to degrade polylactic acid (PLA), polycaprolactone (PCL) and poly(butylene succinate) (PBS) by the agar diffusion method. Sixty-seven actinomycetes, seven bacteria and five fungal isolates were obtained. The majority of actinomycetes were Streptomyces based on morphological characteristic, chemotaxonomy and 16S rRNA gene data. Seventy-nine microorganisms were isolated from 40 soil samples. Twenty-six isolates showed PLA-degradation (32.9 %), 44 isolates showed PBS-degradation (55.7 %) and 58 isolates showed PCL-degradation (73.4 %). Interestingly, 16 isolates (20.2 %) could degrade all three types of bioplastics used in this study. The Amycolatopsis sp. strain SCM_MK2-4 showed the highest enzyme activity for both PLA and PCL, 0.046 and 0.023 U/mL, respectively. Moreover, this strain produced protease, esterase and lipase on agar plates. Approximately, 36.7 % of the PLA film was degraded by Amycolatopsis sp. SCM_MK2-4 after 7 days of cultivation at 30 °C in culture broth.

Allokutzneria oryzae sp. nov., isolated from rhizospheric soil of Oryza sativa L.

The taxonomic status of a rhizospheric soil actinomycete, designated R8-39(T), was established using a polyphasic approach. The organism had phenotypic and morphological characteristics consistent with its classification in the genus Allokutzneria. Phylogenetic analysis based on an almost complete 16S rRNA gene sequence showed that the strain formed a monophyletic clade with the type strains of members of the genus Allokutzneria. Strain R8-39(T) displayed the highest levels of 16S rRNA gene sequence similarity to Allokutzneria albata DSM 44149(T) (98.8%) and Allokutzneria multivorans YIM 120521(T) (98.3%). However, the DNA-DNA hybridization values between strain R8-39(T) and A. albata and A. multivorans were clearly below the 70% threshold. The organism was found to have chemical characteristics consistent with its classification in the genus Allokutzneria. Whole-cell hydrolysates contained meso-diaminopimelic acid, arabinose, galactose, glucose, mannose, rhamnose and ribose. The main menaquinone was MK-9(H4). No mycolic acid was detected. The G+C content of the genomic DNA was 71.8 mol%. In addition, strain R8-39(T) had a phenotypic profile that readily distinguished it from recognized representatives of the genus Allokutzneria. It is evident from the combined genotypic and phenotypic properties that strain R8-39(T) represents a novel species of the genus Allokutzneria. The proposed name for this species is Allokutzneria oryzae sp. nov.; the type strain is R8-39(T) ( = BCC 60399(T) = NBRC 109649(T)).

Biodecolorization of a food azo dye by the deep sea Dermacoccus abyssi MT1.1(T) strain from the Mariana Trench.

This study reports the characterization of the ability of Dermacoccus spp. isolated from the deepest point of the world's oceans for azo dye decolorization. A detailed investigation of Dermacoccus abyssi MT1.1(T) with respect to the azoreductase activity and enzymatic mechanism as well as the potential role of the bacterial strain for biocleaning of industrial dye baths is reported. Resting cells with oxygen-insensitive azoreductase resulted in the rapid decolorization of the polysulfonated dye Brilliant Black BN (BBN) which is a common food colorant. The highest specific decolorization rate (vs) was found at 50 °C with a moderately thermal tolerance for over 1 h. Kinetic analysis showed the high rates and strong affinity of the enzymatic system for the dye with a Vmax = 137 mg/g cell/h and a Km = 19 mg/L. The degradation of BBN produces an initial orange intermediate, 8-amino-5-((4-sulfonatophenyl)diazenyl)naphthalene-2-sulfonic acid, identified by mass spectrometry which is later converted to 4-aminobenzene sulfonic acid. Nearly 80% of the maximum vs is possible achieved in resting cell treatment with the salinity increased up to 5.0% NaCl in reaction media. Therefore, this bacterial system has potential for dye decolorization bioprocesses occurring at high temperature and salt concentrations e.g. for cleaning dye-containing saline wastewaters.

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

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