Enhanced photoprotection for photo-labile compounds using double-layer coated corn oil-nanoemulsions with chitosan and lignosulfonate.

With the aim to establish a novel nanocarrier system with relatively high payload and high photoprotection capacity for photo-labile active compounds, in this work, deltamethrin (photo-labile compound) was encapsulated into corn oil-nanoemulsions (NE) by a hot high pressure homogenization technique followed by coating with chitosan as the first coating layer (CH-NE) and lignosulfonate as the second coating layer to form a double-layer coated NE (L-CH-NE). The optimal conditions for preparation of NE, chitosan coating and lignosulfonate coating were investigated. The results indicate that polymer coating and the number of coating layers significantly affected the release profile and photoprotection capacity of nanocarriers. In particular, after coating, the release rate became slower and photoprotection capacity became higher. Moreover, in the case of L-CH-NE after 24h of UV exposure in direct photolysis and 2.5h of UV exposure in indirect photolysis, the non-degraded amount of deltamethrin was approximately 4.5 times and 2.1 times, respectively, higher than that of the free-from deltamethrin. In the future, this novel nanocarrier system will show great potential and be widely applied to many fields related to protection of photo-labile compounds against photo-degradation.

Photoprotection for deltamethrin using chitosan-coated beeswax solid lipid nanoparticles.

BACKGROUND: In the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan-coated beeswax solid lipid nanoparticles (CH-BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient. RESULTS: Under optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH-BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free-form deltamethrin. In addition, in indirect photolysis, in the case of CH-BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free-form deltamethrin. CONCLUSION: CH-BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well.

Identification and biocontrol efficacy of Streptomyces miharaensis producing filipin III against Fusarium wilt.

A number of bacterial strains were isolated from the internal tissue of Trapa japonica. Of these, strain KPE62302H, which had a 16S rDNA sequence identical to that of Streptomyces miharaensis showed antifungal activity against several plant pathogens. Treatment of seeds with strain KPE62302H induced a significant reduction in the incidence of Fusarium wilt in tomato plants compared with untreated controls. An antifungal substance (FP-1) was purified from the culture extract of strain KPE62302H using C18 flash and Sephadex LH-20 column chromatography and reverse phase HPLC. Extensive spectrometric analysis using MS and NMR identified this as filipin III. FP-1 inhibited the mycelial growth of plant pathogenic fungi such as Alternaria mali, Aspergillus niger, Colletotrichum gloeosporioides, C. orbiculare, Cylindrocarpon destructans, Diaporthe citiri, Fusarium oxysporum at 1-10 µg ml(-1) and also markedly inhibited the development of Fusarium wilt caused by F. oxysporum f.sp. lycopersici in tomato plants by treatment with 10 µg ml(-1) under greenhouse conditions. The efficacy of FP-1 against Fusarium wilt was comparable to that of the synthetic fungicide benomyl. An egfp -tagged strain of KPE62302H confirmed its ability to colonize tomato plants.

Disease control effect of strevertenes produced by Streptomyces psammoticus against tomato fusarium wilt.

During screening of microorganisms producing antifungal metabolites, Streptomyces psammoticus strain KP1404 was isolated. The culture extract of this strain showed potent disease control efficacy against Fusarium wilt on tomato plants. The antifungal metabolites ST-1 and ST-2 were isolated from the culture extract using a variety of chromatographic procedures. On the basis of MS and NMR spectrometric analysis, the structures of the antifungal active compounds ST-1 and ST-2 were determined to be the polyene antibiotics strevertene A and strevertene B, respectively. In vitro, strevertenes A and B showed inhibitory effects against the mycelial growth of Alternaria mali , Aspergillus oryzae , Cylindrocarpon destructans , Colletotrichum orbiculare , Fusarium oxysporum f.sp. lycopersici, and Sclerotinia sclerotiorum , even at concentrations of 4-16 µg/mL. Fusarium wilt development on tomato plants was strongly retarded by treatment with 1 µg/mL of these strevertenes. The disease control efficacies of strevertenes on Fusarium wilt were as remarkable as that of benomyl.

Acinetobacter antiviralis sp. nov., from Tobacco plant roots.

Acinetobacter strain KNF2022T was isolated from tobacco plant roots during the screening of antiviral substances having inhibitory effects on Tobacco mosaic virus (TMV) and examined by phenotypic, chemotaxonomic, and genetic characterization. It was a nonmotile, Gram-negative bacterium. This strain contained Q-9 as the main respiratory quinone. The major cellular fatty acids of the isolate were 16:0, 18:1 w9c, and 16:1 w7c/15 iso 2OH. The DNA base composition was 44 mol%. Phylogenetic analysis based on the 16S rRNA sequence revealed that the isolate formed an evolutionary lineage distinct from other Acinetobacter species. Based on the evaluation of morphologic, physiologic, and chemotaxonomic characteristics, DNA-DNA hybridization values, and 16S rRNA sequence comparison, we propose the new species Acinetobacter antiviralis sp. nov., the type strain of which is KNF2022T(=KCTC0699BPT).

Proteomic analysis of parasitized Plutella xylostella larvae plasma.

Insects use their innate immunity to defend themselves against foreign invaders, such as microorganisms, nematodes and parasites. Cotesia plutellae, an endoparasitoid wasp that parasitizes the diamondback moth Plutella xylostella, uses several strategies to attack the host immune system, such as injection of viruses, venom, and serosal membrane-derived cells denoted teratocytes. However, the proteome profiles related to these immune deficiency systems have yet to be clearly defined. In this study, we investigate differences in protein expression patterns in parasitized P. xylostella larvae, with a view to identifying parasitism-specific factors. Using 2D polyacrylamide gel electrophoresis, proteins in the host plasma were assessed every 48 h after parasitism by C. plutellae. A large number of protein spots (350 in total) were detected, and approximately 50 spots were differentially expressed in the parasitized P. xylostella larvae every 48 h. In total, 26 potential candidates, including P. xylostella Serpin 2 (pxSerpin 2), translationally controlled tumor protein, signal transduction histidine kinase, apolipophorin-III, and fatty-acid binding protein were identified through quadrupole time-of-flight tandem mass spectrometry and sequence homology analysis. These proteins were classified into the following functional groups: immunity, signaling, lipid metabolism, energy metabolism, amino acid/nucleotide metabolism, and others. The pxSerpin 2 gene was cloned, and its expression profile investigated during the course of parasitism. Real-time PCR analysis of pxSerpin 2 revealed a poor correlation between the mRNA level and protein abundance. Our results clearly suggest that parasitism-specific proteins participate in suppression of the host immune response.

Description of Streptomyces neopeptinius sp. nov., an actinobacterium with broad spectrum antifungal activities.

A streptomycete strain producing broad-spectrum antifungal substances was taxonomically characterized. The strain, designated KNF 2047(T) (= SH-09(T) = KCTC 10586BP(T)), was found to form extensively branching aerial and substrate mycelia, and produce spiny-ornamented spores with loose spiral chains. The whole cell hydrolyzates contained major amount of LL-diaminopimelic acid. The major fatty acids of the phospholipids were saturated and branched fatty acids containing 14~17 carbons, and the major isoprenoid quinones were hexa-and octa-hydrogenated menaquinones with 9 isoprene units. The phylogenetic analysis using the 16S rRNA gene indicated that the strain belongs to the genus Streptomyces but forms an independent phyletic line. These results clearly demonstrate that strain KNF2047(T) forms a new center of taxonomic variation within Streptomyces, for which the name Streptomyces neopeptinius sp. nov. is proposed.

Biological evaluation of neopeptins isolated from a Streptomyces strain.

BACKGROUND: Microbial secondary metabolites are a rich source of antifungal agents and have merit as alternatives to synthetic fungicides. To develop disease control agents against powdery mildew, the lipopeptide antibiotic neopeptins were identified from the culture broth of a Streptomyces sp., and in vivo control efficacy of the compounds was evaluated on cucumber plants under glasshouse conditions. RESULTS: The Streptomyces sp. KNF2047 antagonistic against powdery mildew development in cucumber plants was isolated from a soil sample. Antifungal compounds were purified from the culture broth and identified as neopeptin A and B. In vitro microtitre assays revealed the inhibitory activities of the compounds in the range 128-512 microg mL(-1) against the mycelial growth of Alternaria mali, Botrytis cinerea, Cladosporium cucumerinum, Colletotrichum lagenarium, Didimella bryoniae and Magnaporthe grisea. Although neither compound showed remarkable in vitro antifungal activity against other plant pathogenic fungi, a mixture of neopeptins (484 mg of neopeptin A and 290 mg of neopeptin B per gram of partially purified powder) showed potent protective and curative activity against cucumber powdery mildew in vivo. The disease control activity of the neopeptins at a concentration of 2.4 mg L(-1) was 92.1%, which was similar to that of the commercial fungicide fenarimol (89.3% at 63 mg L(-1)) and that of the commercial biocontrol agent Actinovate (67.4% at 2 x 10(7) cfu L(-1)). CONCLUSION: Neopeptin mixtures isolated from Streptomyces sp. KNF2047 showed potent disease control activity against powdery mildew development on cucumber plants. .