Fatty acid based antimicrobials from Streptomyces sp. SORS-24, an endophyte isolated from Sonchus oleraceus.

Due to the rise in bacterial resistance towards various therapeutic agents, interest is now developing towards fatty acid based antimicrobials because of their non-specific mode of action. A strain SORS 24 isolated from Sonchus oleraceus (Sow thistle) showed significant activity against Escherichia coli ATCC 25922 (25 mm), Chlorella vulgaris (20 mm), Bacillus subtilis DSM 10 (ATCC 6051) and Pseudomonas sp. (15 mm). It displayed an LC50 value of 10 µg/ml against Artemia salina (Brine shrimp) nauplii and an EC50 value of 0.8 µg/ml in the (DPPH) diphenylpicrylhydrazyl antioxidant assay. The strain also displayed genotoxicity against a PolA deficient strain, E. coli K-12 AB 3027 (15 mm). Mass spectrometry (HPLC-MS) showed that the strain produced oleamide (9-Octadecenamide) and erucamide (13-Docosenamide). Both of the purified fatty acid amides showed prominent activity against B. subtilis DSM 10 (ATCC 6051) (20 mm) and E. coli ATCC 25922 (15 mm). Significant genotoxicity was observed against E. coli K-12 AB 3027 (15 mm). The 16S gene sequencing revealed that the strain belonged to species, Streptomyces tanashiensis. As far as our understanding, this is the first report of this species producing these fatty acid based antimicrobials.

Ancylobacter sonchi sp. nov., a novel methylotrophic bacterium frоm roots of Sonchus arvensis L.

An aerobic facultatively methylotrophic bacterium was isolated from roots of Sonchus arvensis L. and designated strain OsotT The cells of this strain were Gram-stain-negative, asporogenous, motile short rods multiplying by binary fisson. They utilized methanol, methylamines and a variety of polycarbon compounds as the carbon and energy sources. Methanol was assimilated after sequential oxidation to formaldehyde and CO2 via the ribulose bisphosphate pathway. The organism grew optimally at 22-29 °C and pH 7.5-8.0. The dominant phospholipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol and diphosphatidylglycerol (cardiolipin). The major cellular fatty acids of strain OsotT cells grown in R2A medium were C18 : 1ω7c (49.0 %), C19 : 0ω8c cyclo (38.3 %) and C16 : 0 (8.4 %). The major ubiquinone was Q-10. The DNA G+C content of strain OsotT was 66.1 mol% (Tm). On the basis of 16S rRNA gene sequence analysis strain OsotT is phylogenetically related to the members of genus Ancylobacter (97.1-98.8 % sequence similarity). Based on 16S rRNA gene sequence analysis and DNA-DNA relatedness (27-29 %) with type strains of the genus Ancylobacter, the novel isolate is classified as a new species of this genus and named Ancylobacter sonchi sp. nov.; the type strain is OsotT (=VKM B-3145T=JCM 32039T).

Restoration of red mud deposits by naturally growing vegetation.

Disposal of red mud (RM) poses serious environmental problems such as wind erosion, air and water pollution. To overcome these problems, effective restoration of the disposal land through naturally growing vegetation is a sustainable and economical approach. The present study involved estimation of frequency (F), density (D), abundance (Ab), and important value index (IVI) of natural flora on abandoned RM sites in order to assess their metal toxicity tolerance capacity. Based on visual observations and highest IVI, S. Asper and S. punicea were identified as effective ecological tools for the restoration of barren RM sites. From the study, remarkable differences were observed between non-rhizospheric and rhizospheric RM of both species. These rhizospheric RM analyses confirm the ability of S. asper and S. punicea for enhancing the biological activities of abandoned RM. Translocation factor (TF) of iron was maximum (2.58) in S. asper, and bioconcentration factor (BCF) was found maximum (1.25) in S. punicea, but both TF (2.58) and BCF (1.35) were high in S. asper. Therefore, this plant could be reported as an iron hyperaccumulator plant. These results suggest that these plant species can be exploited for effective restoration of RM deposited land without any inputs or maintenance.

Verrucosispora sonchi sp. nov., a novel endophytic actinobacterium isolated from the leaves of common sowthistle (Sonchus oleraceus L.).

A novel actinobacterium, designated strain NEAU-QY3T, was isolated from the leaves of Sonchus oleraceus L. and examined using a polyphasic taxonomic approach. The organism formed single spores with smooth surface on substrate mycelia. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the strain had a close association with the genus Verrucosispora and shared the highest sequence similarity with Verrucosispora qiuiae RtIII47T (99.17 %), an association that was supported by a bootstrap value of 94 % in the neighbour-joining tree and also recovered with the maximum-likelihood algorithm. The strain also showed high 16S rRNA gene sequence similarities to Xiangella phaseoli NEAU-J5T (98.78 %), Jishengella endophytica 202201T (98.51 %), Micromonospora eburnea LK2-10T (98.28 %), Verrucosispora lutea YIM 013T (98.23 %) and Salinispora pacifica CNR-114T (98.23 %). Furthermore, phylogenetic analysis based on the gyrB gene sequences supported the conclusion that strain NEAU-QY3T should be assigned to the genus Verrucosispora. However, the DNA-DNA hybridization relatedness values between strain NEAU-QY3T and V. qiuiae RtIII47T and V. lutea YIM 013T were below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA-DNA hybridization results, strain NEAU-QY3T was readily distinguished from its most closely related strains and classified as a new species, for which the name Verrucosispora sonchi sp. nov. is proposed. The type strain is NEAU-QY3T (=CGMCC 4.7312T=DSM 101530T).

Rare actinomycetes Nocardia caishijiensis and Pseudonocardia carboxydivorans as endophytes, their bioactivity and metabolites evaluation.

Two strains identified as Nocardia caishijiensis (SORS 64b) and Pseudonocardia carboxydivorans (AGLS 2) were isolated as endophytes from Sonchus oleraceus and Ageratum conyzoides respectively. The analysis of their extracts revealed them to be strongly bioactive. The N. caishijiensis extract gave an LC50 of 570 µg/ml(-1) in the brine shrimp cytotoxicity assay and an EC50 of 0.552 µg/ml(-1) in the DPPH antioxidant assay. Antimicrobial activity was observed against Methicillin resistant Staphlococcus aureus (MRSA) and Escherichia coli ATCC 25922 (14 mm), Klebsiella pneumoniae ATCC 706003 (13 mm), S. aureus ATCC 25923 (11 mm) and Candida tropicalis (20 mm). For the extract of P. carboxydivorans the EC50 was 0.670 µg/ml(-1) and it was observed to be more bioactive against Bacillus subtilis DSM 10 ATCC 6051 (21 mm), C. tropicalis (20 mm), S. aureus ATCC 25923 (17 mm), MRSA (17 mm), E. coli K12 (W1130) (16 mm) and Chlorella vulgaris (10 mm). The genotoxicity testing revealed a 20 mm zone of inhibition against the polA mutant strain E. coli K-12 AB 3027 suggesting damage to the DNA and polA genes. The TLC and bioautography screening revealed a diversity of active bands of medium polar and nonpolar compounds. Metabolite analysis by HPLC-DAD via UV/vis spectral screening suggested the possibility of stenothricin and bagremycin A in the mycelium extract of N. caishijiensis respectively. In the broth and mycelium extract of P. carboxydivorans borrelidin was suggested along with α-pyrone. The HPLC-MS revealed bioactive long chained amide derivatives such as 7-Octadecenamide, 9, 12 octadecandienamide. This study reports the rare actinomycetes N. caishijiensis and P. carboxydivorans as endophytes and evaluates their bioactive metabolites.

Plantactinospora sonchi sp. nov., an actinobacterium isolated from the leaves of common sowthistle (Sonchus oleraceus L.).

A novel actinobacterium, designated strain NEAU-QY2T, was isolated from the leaves of Sonchus oleraceus L. specimen, collected from Wuchang, Heilongjiang Province, China. A polyphasic study was carried out to establish the taxonomic position of this strain. The organism formed single spores with rough surfaces on substrate mycelia. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-QY2T belonged to the genus Plantactinospora and formed a monophyletic clade with its closest related strains Plantactinospora endophytica YIM 68255T (99.2 % 16S rRNA gene sequence similarity), Plantactinospora veratri NEAU-FHS4T (98.8 %) and Plantactinospora mayteni YIM 61359T(98.7 %), an association that was supported by a bootstrap value of 90 % in the neighbor-joining tree and also recovered with the maximum-likelihood algorithm. However, DNA-DNA hybridization values between strain NEAU-QY2T and the three closely related strains were below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA-DNA hybridization results, strain NEAU-QY2T was distinguished from closely related strains and is classified as representing a novel species of the genus Plantactinospora, for which the name Plantactinospora sonchi sp. nov. is proposed. The type strain is NEAU-QY2T (=CGMCC4.7216T=JCM 30345T).

Streptosporangium sonchi sp. nov. and Streptosporangium kronopolitis sp. nov., two novel actinobacteria isolated from a root of common sowthistle (Sonchus oleraceus L.) and a millipede (Kronopolites svenhedind Verhoeff).

Two novel actinobacteria, designated strains NEAU-QS7(T) and NEAU-ML10(T), were isolated from a root of Sonchus oleraceus L. and a Kronopolites svenhedind Verhoeff specimen, respectively, collected from Wuchang, Heilongjiang Province, China. A polyphasic study was carried out to establish the taxonomic positions of these strains. The two strains were observed to form abundant aerial hyphae that differentiated into spherical spore vesicles. The phylogenetic analysis based on the 16S rRNA gene sequences of strains NEAU-QS7(T) and NEAU-ML10(T) showed that the two novel isolates exhibited 99.7 % 16S rRNA gene sequence similarity with each other and that they are most closely related to Streptosporangium shengliense NEAU-GH7(T) (99.1, 99.0 %) and Streptosporangium longisporum DSM 43180(T) (99.1, 99.0 %). However, the DNA-DNA hybridization value between strains NEAU-QS7(T) and NEAU-ML10(T) was 46.5 %, and the values between the two strains and their closest phylogenetic relatives were also below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA-DNA hybridization results, the two strains can be distinguished from each other and their closest phylogenetic relatives. Thus, strains NEAU-QS7(T) and NEAU-ML10(T) represent two novel species of the genus Streptosporangium, for which the names Streptosporangium sonchi sp. nov. and Streptosporangium kronopolitis sp. nov. are proposed. The type strains are NEAU-QS7(T) (=CGMCC 4.7142(T) =DSM 46717(T)) and NEAU-ML10(T) (=CGMCC 4.7153(T) =DSM 46720(T)), respectively.

Influence of habitat and climate variables on arbuscular mycorrhizal fungus community distribution, as revealed by a case study of facultative plant epiphytism under semiarid conditions.

In semiarid Mediterranean ecosystems, epiphytic plant species are practically absent, and only some species of palm trees can support epiphytes growing in their lower crown area, such as Phoenix dactylifera L. (date palm). In this study, we focused on Sonchus tenerrimus L. plants growing as facultative epiphytes in P. dactylifera and its terrestrial forms growing in adjacent soils. Our aim was to determine the possible presence of arbuscular mycorrhizal fungi (AMF) in these peculiar habitats and to relate AMF communities with climatic variations. We investigated the AMF community composition of epiphytic and terrestrial S. tenerrimus plants along a temperature and precipitation gradient across 12 localities. Epiphytic roots were colonized by AMF, as determined by microscopic observation; all of the epiphytic and terrestrial samples analyzed showed AMF sequences from taxa belonging to the phylum Glomeromycota, which were grouped in 30 AMF operational taxonomic units. The AMF community composition was clearly different between epiphytic and terrestrial root samples, and this could be attributable to dispersal constraints and/or the contrasting environmental and ecophysiological conditions prevailing in each habitat. Across sites, the richness and diversity of terrestrial AMF communities was positively correlated with rainfall amount during the most recent growing season. In contrast, there was no significant correlation between climate variables and AMF richness and diversity for epiphytic AMF communities, which suggests that the composition of AMF communities in epiphytic habitats appears to be largely determined by the availability and dispersion of fungal propagules from adjacent terrestrial habitats.

Identification and utilization of a sow thistle powdery mildew as a poorly adapted pathogen to dissect post-invasion non-host resistance mechanisms in Arabidopsis.

To better dissect non-host resistance against haustorium-forming powdery mildew pathogens, a sow thistle powdery mildew isolate designated Golovinomyces cichoracearum UMSG1 that has largely overcome penetration resistance but is invariably stopped by post-invasion non-host resistance of Arabidopsis thaliana was identified. The post-invasion non-host resistance is mainly manifested as the formation of a callosic encasement of the haustorial complex (EHC) and hypersensitive response (HR), which appears to be controlled by both salicylic acid (SA)-dependent and SA-independent defence pathways, as supported by the susceptibility of the pad4/sid2 double mutant to the pathogen. While the broad-spectrum resistance protein RPW8.2 enhances post-penetration resistance against G. cichoracearum UCSC1, a well-adapted powdery mildew pathogen, RPW8.2, is dispensable for post-penetration resistance against G. cichoracearum UMSG1, and its specific targeting to the extrahaustorial membrane is physically blocked by the EHC, resulting in HR cell death. Taken together, the present work suggests an evolutionary scenario for the Arabidopsis-powdery mildew interaction: EHC formation is a conserved subcellular defence evolved in plants against haustorial invasion; well-adapted powdery mildew has evolved the ability to suppress EHC formation for parasitic growth and reproduction; RPW8.2 has evolved to enhance EHC formation, thereby conferring haustorium-targeted, broad-spectrum resistance at the post-invasion stage.

Paenibacillus sonchi sp. nov., a nitrogen-fixing species isolated from the rhizosphere of Sonchus oleraceus.

A nitrogen-fixing bacterium, designated strain X19-5(T), was isolated from rhizosphere soil of Sonchus oleraceus. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain X19-5(T) was a member of the genus Paenibacillus. Strain X19-5(T) showed the highest 16S rRNA gene sequence similarity (98.8 %) with Paenibacillus graminis RSA19(T) and below 97 % similarity with other recognized members of the genus. The level of DNA-DNA relatedness between strain X19-5(T) and P. graminis RSA19(T) was 45.7 %. The DNA G+C content of strain X19-5(T) was 46.8 mol%. The major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). On the basis of its phenotypic characteristics and the level of DNA-DNA hybridization, strain X19-5(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sonchi sp. nov. is proposed. The type strain is X19-5(T) (=CCBAU 83901(T)=LMG 24727(T)).

Relation between in vitro production of ascosonchine and virulence of strains of the potential mycoherbicide Ascochyta sonchi: a method for its quantification in complex samples.

The potential of the fungus Ascochyta sonchi as a mycoherbicide for the biocontrol of the perennial weeds Sonchus arvensis and Cirsium arvense that occur throughout temperate regions of the world is under evaluation. Ascosonchine, a newly discovered enol tautomer of 4-pyridylpyruvic acid with potential herbicidal properties, is the main phytotoxin produced by this fungus. A simple and sensitive method has been developed for the rapid quantitative analysis of ascosonchine based on HPLC with UV detection. The toxin content in culture filtrates of different strains of A. sonchi was measured. The strains tested produced up to 2.7 mg/L when grown in static conditions. Toxin production was compared with the virulence on the host plant of each strain to determine if the most virulent strains could be simply selected by choosing the best toxin producers. The results obtained do not support this approach. The same HPLC method was also applied to quantify toxin production under different fungal growth conditions, in order to achieve the highest toxin production. The most productive strain synthesised more than 8 mg/L when grown for 8 weeks in static conditions.