Plant triterpenoid saponins function as susceptibility factors to promote the pathogenicity of Botrytis cinerea.

The gray mold fungus Botrytis cinerea is a necrotrophic pathogen that causes diseases in hundreds of plant species, including high-value crops. Its polyxenous nature and pathogenic success are due to its ability to perceive host signals in its favor. In this study, we found that laticifer cells of Euphorbia lathyris are a source of susceptibility factors required by B. cinerea to cause disease. Consequently, poor-in-latex (pil) mutants, which lack laticifer cells, show full resistance to this pathogen, whereas lot-of-latex mutants, which produce more laticifer cells, are hypersusceptible. These S factors are triterpenoid saponins, which are widely distributed natural products of vast structural diversity. The downregulation of laticifer-specific oxydosqualene cyclase genes, which encode the first committed step enzymes for triterpene and, therefore, saponin biosynthesis, conferred disease resistance to B. cinerea. Likewise, the Medicago truncatula lha-1 mutant, compromised in triterpenoid saponin biosynthesis, showed enhanced resistance. Interestingly, the application of different purified triterpenoid saponins pharmacologically complemented the disease-resistant phenotype of pil and hla-1 mutants and enhanced disease susceptibility in different plant species. We found that triterpenoid saponins function as plant cues that signal transcriptional reprogramming in B. cinerea, leading to a change in its growth habit and infection strategy, culminating in the abundant formation of infection cushions, the multicellular appressoria apparatus dedicated to plant penetration and biomass destruction in B. cinerea. Taken together, these results provide an explanation for how plant triterpenoid saponins function as disease susceptibility factors to promote B. cinerea pathogenicity.

Untargeted Metabolomic to Access Chemical Differences Induced by Dual Endophyte Cultures Isolated from Euphorbia Umbellata.

Endophytic fungi live asymptomatically inside vegetal tissues, and such uncommon habitat contributes to their exceptional chemical diversity. Isolating natural products from endophytic fungi could fail due to silent biosynthetic gene clusters under ordinary in vitro culture conditions, and co-culturing has been assayed to trigger their metabolism. We carried out single and dual cultures with 13 endophyte strains isolated from Euphorbia umbellata leaves. Multivariate statistics applied to untargeted metabolomics compared the chemical profiles of all endophyte cultures. PCA analysis guided the selection of the Aspergillus pseudonomiae J1 - Porogramme brasiliensis J9 dual culture for its most significant chemical differentiation: Five compounds were putatively annotated in the J1-J9 culture according to UHPLC-HRMS data, kojic acid, haliclonol and its diastereoisomer, caffeic acid, and 2-(3,4-dihydroxyphenyl)acetaldehyde. Analysis by PLS-DA using VIP score showed that kojic acid displayed the most significative importance in discriminating single and dual J1-J9 cultures.

Multiphasic investigations imply transfer of orange-/red-pigmented strains of the bean pathogen Curtobacterium flaccumfaciens pv. flaccumfaciens to a new species as C. aurantiacum sp. nov., elevation of the poinsettia pathogen C. flaccumfaciens pv. poinsettiae to the species level as C. Poinsettiae sp. nov., and synonymy of C. albidum with C. citreum.

Curtobacterium flaccumfaciens (Microbacteriaceae), a plant-pathogenic coryneform species includes five pathovars with valid names and a number of proposed - but unvalidated - new members. In this study, phenotypic features and DNA similarity indexes were investigated among all C. flaccumfaciens members. Results showed that the C. flaccumfaciens pv. poinsettiae strains causing bacterial canker of Euphorbia pulcherrima in the USA as well as the orange-/red-pigmented strains of C. flaccumfaciens pv. flaccumfaciens pathogenic on dry beans in Iran are too distinct from each other and from the type strain of the species to be considered members of C. flaccumfaciens. Hence, the latter two groups were elevated at the species level as C. poinsettiae sp. nov. (ATCC 9682T = CFBP 2403T = ICMP 2566T = LMG 3715T = NCPPB 854T as type strain), and C. aurantiacum sp. nov. (50RT = CFBP 8819T = ICMP 22071T as type strain). Within the emended species C. flaccumfaciens comb. nov., yellow-pigmented strains causing bacterial wilt of dry beans and those causing bacterial canker of Euphorbia pulcherrima in Europe were retained as C. flaccumfaciens pv. flaccumfaciens and C. flaccumfaciens pv. poinsettiae, respectively; while taxonomic position of the sugar beet pathogen C. flaccumfaciens pv. beticola ATCC BAA144PT was confirmed. The newly described onion pathogen C. allii was also reclassified as C. flaccumfaciens pv. allii with the pathotype strain LMG 32517PT. Furthermore, C. flaccumfaciens pv. basellae causing bacterial leaf spot of malabar spinach (Basella rubra) was transferred to C. citreum pv. basellae with ATCC BAA143PT as pathotype.

Expression Level of a Phenylalanine Ammonia-Lyase Gene in Poinsettia Is Negatively Correlated with Poinsettia Branch-Inducing Phytoplasma Titer.

Poinsettia is an important ornamental cultivated worldwide. Commercial poinsettias are almost universally infected with a pathogen known as the poinsettia branch-inducing phytoplasma (PoiBI), which can increase the level of branching in host plants and make the plants more desirable to consumers. Despite PoiBI's crucial role in poinsettia production, little is known about PoiBI-poinsettia interactions in regard to the pathogen's in planta population dynamics. The expression profiles of a phenylalanine ammonia-lyase gene (Euphorbia pulcherrima PAL [EpPAL]) and the PoiBI titers in poinsettia tissues were investigated. Differential gene expression analyses using quantitative PCR (qPCR) showed that EpPAL expression levels differed significantly across tissue types. The highest expression levels were detected in stems, followed by root. Lower EpPAL expression levels were detected in leaf tissues, particularly in source leaves closer to the base; the average expression level in these leaves was only one-seventh of that detected in stems. Phytoplasma concentrations in source leaves close to the base were significantly greater than the other tissue types; the average value was 7.6-fold of that detected in stem tissues, which had the lowest phytoplasma titers. A negative correlation between EpPAL expression level and PoiBI load was detected, suggesting that the products of EpPAL-associated pathways or other genes indirectly associated with EpPAL may interfere with PoiBI's growth. While additional studies are needed to validate these interpretations, the results from this work provide new insights into PoiBI-poinsettia interaction and showed that correlations between pathogen load and defense-related genes could be detected in phytoplasma-associated pathosystems. IMPORTANCE Phytoplasma-plant interactions are interesting subjects for fundamental and applicative research. Although many studies have characterized molecular interplays between these pathogens and hosts, knowledge on relationships between phytoplasmas' in planta population dynamics and host gene expression remains scarce. By using the poinsettia branch-inducing phytoplasma (PoiBI) and poinsettia as a model system, a negative correlation was observed between the expression level of a plant defense-related gene and the pathogen's titer. The findings provide potential explanations to PoiBI's distribution patterns in the plant and highlight the importance of studying phytoplasma-plant interactions in regard to the pathogen's population dynamics in other pathosystems.

Latex Metabolome of Euphorbia Species: Geographical and Inter-Species Variation and its Proposed Role in Plant Defense against Herbivores and Pathogens.

Based on the hypothesis that the variation of the metabolomes of latex is a response to selective pressure and should thus be affected differently from other organs, their variation could provide an insight into the defensive chemical selection of plants. Metabolic profiling was used to compare tissues of three Euphorbia species collected in diverse regions. The metabolic variation of latexes was much more limited than that of other organs. In all the species, the levels of polyisoprenes and terpenes were found to be much higher in latexes than in leaves and roots of the corresponding plants. Polyisoprenes were observed to physically delay the contact of pathogens with plant tissues and their growth. A secondary barrier composed of terpenes in latex and in particular, 24-methylenecycloartanol, exhibited antifungal activity. These results added to the well-known role of enzymes also present in latexes, show that these are part of a cooperative defense system comprising biochemical and physical elements.

Endophytic fungi from the medicinal herb Euphorbia geniculata as a potential source for bioactive metabolites.

Many researchers proved that plant endophytes manage successful issues to synthesize active chemicals within plant cells. These bioactive compounds might support a range of plant defense mechanism against many pathogenic microorganisms. In this study, a total of 22 isolates representing 21 fungal species belonging to 15 fungal genera in addition to one variety were isolated and identified for the first time from Euphorbia geniculate plants. The genus Aspergillus was the most common fungus isolated from the studied plant. The fungus Isaria feline was recorded in both leaves and stem, while Aspergillus flavus, A. ochraceus, A. terreus var. terreus, Emercilla nidulans var. acristata, Macrophomina phaseolina colonized both stem and root. The isolated fungi showed antagonistic activities against six strains of plant pathogenic fungi viz., Eupenicillium brefeldianum, Penicillium echinulatum, Alternaria phragmospora, Fusarium oxysporum, Fusarium verticilloid, and Alternaria alternata in dual culture assay. The highest antagonistic activity fungal species (Aspergillus flavus, A. fumigatus, and Fusarium lateritium) and the lowest (Cladosprium herbarum, F. culomrum, and Sporotrichum thermophile) showed twining in their secondary metabolites especially terpens and alkaloids with that of their host E. geniculata. Three concentrations of (0.5, 1.0, and 2.0 mg/ml) of these secondary metabolites extracted by ethyl acetate and n-butanol from the above six endophytic fungal species were tested against three pathogenic fungi isolated from infected tomato plant (E. brefeldianum-EBT-1, P. echinulatum-PET-2, and A. phragmospora-APT-3), whereas these pathogens showed promising sensitivity to these fungal secondary metabolites. In conclusion, this is the first report on the isolation of endophytic fungi from E. geniculata and evaluation of their antifungal activity.

[A new phenolic compound from endophytic fungus Aspergillus fumigatus of Euphorbia royleana].

This research was carried out to study the secondary metabolites of endophytic fungus Aspergillosis fumigatus from Euphorbia royleana. The endophytic fungus A. fumigatus was fermented by solid fermentation,and purified by various chromatographic methods after extraction. The structures of the compounds were identified by1 H-NMR,13 C-NMR and HSQC,HMBC spectra and physicchemical properties. Three compounds were isolated and their structures were identified as 3-( 3,4-dihydroxybenzoyl)-5-( 3,4-dihydroxyphenyl)-6-methyl-5,6-dihydro-2 H-pyran-2-one( 1),hydroxysydonic acid( 2) and 11-hydroxysydonic acid( 3). Compound 1 is a new compound.

A new phenolic compound from endophytic fungus Aspergillus fumigatus of Euphorbia royleana / 中国中药杂志

This research was carried out to study the secondary metabolites of endophytic fungus Aspergillosis fumigatus from Euphorbia royleana. The endophytic fungus A. fumigatus was fermented by solid fermentation,and purified by various chromatographic methods after extraction. The structures of the compounds were identified by1 H-NMR,13 C-NMR and HSQC,HMBC spectra and physicchemical properties. Three compounds were isolated and their structures were identified as 3-( 3,4-dihydroxybenzoyl)-5-( 3,4-dihydroxyphenyl)-6-methyl-5,6-dihydro-2 H-pyran-2-one( 1),hydroxysydonic acid( 2) and 11-hydroxysydonic acid( 3). Compound 1 is a new compound.

Fitness Attributes of Pythium aphanidermatum with Dual Resistance to Mefenoxam and Fenamidone.

Pythium aphanidermatum is the predominant species causing Pythium root rot on commercially grown poinsettias in North Carolina. Resistance to mefenoxam is common in populations of P. aphanidermatum but resistance to fenamidone and other quinone outside inhibitor fungicides has only just been reported in greenhouse floriculture crops. The in vitro sensitivity to the label rate of mefenoxam (17.6 µl active ingredient [a.i.]/ml) and fenamidone (488 µl a.i./ml) was determined for 96 isolates of P. aphanidermatum. Isolates were assigned to four fungicide phenotypes: mefenoxam-sensitive/fenamidone-sensitive (MefS, FenS), mefenoxam-sensitive/fenamidone-insensitive (MefS, FenR), mefenoxam-insensitive/fenamidone-sensitive (MefR, FenS), and mefenoxam-insensitive/fenamidone-insensitive (MefR, FenR). In all, 58% of isolates were insensitive to one (MefR, FenS = 36% and MefS, FenR = 16%) or both fungicides (MefR, FenR = 6%). A single point mutation in the cytochrome b gene (G143A) was identified in fenamidone-insensitive isolates. Mycelial growth rate at three temperatures (20, 25, and 30°C), in vitro oospore production, and aggressiveness on poinsettia were evaluated to assess relative fitness of sensitive and insensitive isolates. Isolates with dual insensitivity to mefenoxam and fenamidone had reduced radial hyphal growth at 30°C and produced fewer oospores than isolates sensitive to one or both fungicides. Isolates sensitive to both fungicides produced greater numbers of oospores. Aggressiveness on poinsettia varied by isolate but fungicide phenotype was not a good predictor of aggressiveness. These results suggest that populations of P. aphanidermatum with dual resistance to mefenoxam and fenamidone may be less fit than sensitive populations under our imposed experimental conditions but populations of P. aphanidermatum should continue to be monitored in poinsettia production systems for mefenoxam and fenamidone insensitivity.

Euphorbia milii-native bacteria interactions under airborne formaldehyde stress: Effect of epiphyte and endophyte inoculation in relation to IAA, ethylene and ROS levels.

Better understanding of plant-bacteria interactions under stress is of the prime importance for enhancing airborne pollutant phytoremediation. No studies have investigated plant-epiphyte interactions compared to plant-endophyte interactions under airborne formaldehyde stress in terms of plant Indole-3-acetic acid (IAA), ethylene, reactive oxygen species (ROS) levels and pollutant removal efficiency. Euphorbia milii was inoculated with native plant growth-promoting (PGP) endophytic and epiphytic isolates individually to investigate plant-endophyte compared to plant-epiphyte interactions under continuous formaldehyde fumigation. Under airborne formaldehyde stress, endophyte interacts with its host plant closely and provides higher levels of IAA which protected the plant against formaldehyde phytotoxicity by lowering intracellular ROS, ethylene levels and maintaining shoot epiphytic community; hence, higher pollutant removal. However, plant-epiphyte interactions could not provide enough IAA to confer protection against formaldehyde stress; thus, increased ROS and ethylene levels, large decrease in shoot epiphytic population and lower pollutant removal although epiphyte contacts with airborne pollutant directly (has greater access to gaseous formaldehyde). Endophyte-inoculated plant synthesized more tryptophan as a signaling molecule for its associated bacteria to produce IAA compared to the epiphyte-inoculated one. Under stress, PGP endophyte interacts with its host closely; thus, better protection against stress and higher pollutant removal compared to epiphyte which has limited interactions with the host plant; hence, lower pollutant removal.

Euphorbia milii-Endophytic Bacteria Interactions Affect Hormonal Levels of the Native Host Differently Under Various Airborne Pollutants.

This study was conducted to assess the effect of plant-native endophytic bacteria interactions on indole-3-acetic acid (IAA), ethylene levels, and hormonal balance of Euphorbia milii under different airborne pollutants. IAA levels and airborne formaldehyde removal by E. milii enhanced when inoculated with endophytic isolates. However, one isolate, designated as root endophyte 4, with the highest levels of IAA production individually, declined gaseous formaldehyde removal of plant, since it disturbed hormonal balance of E. milii, leading to IAA levels higher than physiological concentrations, which stimulated ethylene biosynthesis and stomatal closure under light conditions. However, plant-root endophyte 4 interactions favored airborne benzene removal, since benzene was more phytotoxic and the plant needed more IAA to protect against benzene phytotoxicity. As trimethylamine (TMA) was not toxic, it did not affect plant-endophyte interactions. Therefore, IAA levels of root endophyte 4-inoculated E. milii was not significantly different from a noninoculated one. Under mixed-pollutant stress (formaldehyde, benzene, TMA), root endophyte 4-inoculated E. milii removed benzene at the lowest rate, since benzene was the most phytotoxic pollutant with the greatest molecular mass. However, TMA (with greater molecular mass) was removed faster than formaldehyde due to higher phytotoxicity of formaldehyde. Plant-endophyte interactions were affected differently under various airborne pollutants.

Effect of endophytic Bacillus cereus ERBP inoculation into non-native host: Potentials and challenges for airborne formaldehyde removal.

Phytoremediation could be a cost-effective, environmentally friendly approach for the treatment of indoor air. However, some drawbacks still dispute the expediency of phytotechnology. Our objectives were to investigate the competency of plant growth-promoting (PGP) endophytic Bacillus cereus ERBP (endophyte root blue pea), isolated from the root of Clitoria ternatea, to colonize and stabilize within Zamioculcas zamiifolia and Euphorbia milii as non-native hosts without causing any disease or stress symptoms. Moreover, the impact of B. cereus ERBP on the natural shoot endophytic community and for the airborne formaldehyde removal capability of non-native hosts was assessed. Non-native Z. zamiifolia was effectively inoculated with B. cereus ERBP through soil as the most efficient method of endophyte inoculation. Denaturing gradient gel electrophoresis profiling of the shoot endophytic community verified the colonization and stability of B. cereus ERBP within its non-native host during a 20-d fumigation period without interfering with the natural shoot endophytic diversity of Z. zamiifolia. B. cereus ERBP conferred full protection to its non-native host against formaldehyde phytotoxicity and enhanced airborne formaldehyde removal of Z. zamiifolia whereas non-inoculated plants suffered from formaldehyde phytotoxicity because their natural shoot endophytic community was detrimentally affected by formaldehyde. In contrast, B. cereus ERBP inoculation into non-native E. milii deteriorated airborne formaldehyde removal of the non-native host (compared to a non-inoculated one) as B. cereus ERBP interfered with natural shoot endophytic community of E. milii, which caused stress symptoms and stimulated ethylene biosynthesis. Non-native host inoculation with PGP B. cereus ERBP could bear potentials and challenges for airborne formaldehyde removal.

Endophytic fungi associated with Sudanese medicinal plants show cytotoxic and antibiotic potential.

In this study, we isolated 15 endophytic fungi from five Sudanese medicinal plants. Each fungal endophytic strain was identified by sequencing of internal transcribed spacer (ITS) regions of rDNA. Ethyl acetate extracts were prepared from each endophyte cultivated in vitro and tested for their respective antibacterial activities and antiproliferative activities against human cancer cells. Antibacterial screening was carried out against two bacterial strains: Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus, by the broth dilution method. Cell viability was evaluated by the MTT procedure after exposure of MCF7 breast cancer cells and HT29 or HCT116 human colon adenocarcinoma cells to each endophytic extract. Of interest, Byssochlamys spectabilis isolated from Euphorbia prostata showed cytotoxicity (IC50 = 1.51 ± 0.2 µg mL(-1)) against MCF7 cells, but had a low effect against HT29 or HCT116 cells (IC50 > 20 µg mL(-1)). Cladosporium cladosporioides 2, isolated from Vernonia amygdalina leaves, showed antiproliferative activities against MCF7 cells (IC50 = 10.5 ± 1.5 µg mL(-1)) only. On the other hand, B. spectabilis and Alternaria sp. extract had antibacterial activities against the S. aureus strain. The findings of this work revealed that endophytic fungi associated with medicinal plants from Sudan could be considered as an attractive source of new therapeutic compounds.

Euphorbia plant latex is inhabited by diverse microbial communities.

PREMISE OF THE STUDY: The antimicrobial properties and toxicity of Euphorbia plant latex should make it a hostile environment to microbes. However, when specimens from Euphorbia spp. were propagated in tissue culture, microbial growth was observed routinely, raising the question whether the latex of this diverse plant genus can be a niche for polymicrobial communities. METHODS: Latex from a phylogenetically diverse set of Euphorbia species was collected and genomic microbial DNA extracted. Deep sequencing of bar-coded amplicons from taxonomically informative gene fragments was used to measure bacterial and fungal species richness, evenness, and composition. KEY RESULTS: Euphorbia latex was found to contain unexpectedly complex bacterial (mean: 44.0 species per sample; 9 plants analyzed) and fungal (mean: 20.9 species per sample; 22 plants analyzed) communities using culture-independent methods. Many of the identified taxa are known plant endophytes, but have not been previously found in latex. CONCLUSIONS: Our results suggest that Euphorbia plant latex, a putatively hostile antimicrobial environment, unexpectedly supports diverse bacterial and fungal communities. The ecological roles of these microorganisms and potential interactions with their host plants are unknown and warrant further research.

The composition of arbuscular mycorrhizal fungal communities in the roots of a ruderal forb is not related to the forest fragmentation process.

Land-use changes and forest fragmentation have strong impact on biodiversity. However, little is known about the influence of new landscape configurations on arbuscular mycorrhizal fungal (AMF) community composition. We used 454 pyrosequencing to assess AMF diversity in plant roots from a fragmented forest. We detected 59 virtual taxa (VT; phylogenetically defined operational taxonomic units) of AMF - including 10 new VT - in the roots of Euphorbia acerensis. AMF communities were mainly composed of members of family Glomeraceae and were similar throughout the fragmented landscape, despite variation in forest fragment size (i.e. small, medium and large) and isolation (i.e. varying pairwise distances). AMF communities in forest fragments were phylogenetically clustered compared with the global, but not regional and local AMF taxon pools. This indicates that non-random community assembly processes possibly related to dispersal limitation at a large scale, rather than habitat filtering or biotic interactions, may be important in structuring the AMF communities. In this system, forest fragmentation did not appear to influence AMF community composition in the roots of the ruderal plant. Whether this is true for AMF communities in soil and the roots of other ecological groups of host plants or in other habitats deserves further study.

Development and application of a loop-mediated isothermal amplification assay for rapid detection of Pythium helicoides.

Root rot of poinsettia, caused by Pythium helicoides at high temperatures in hydroponic cultures, has become a serious problem in many parts of the world. We have developed a species-specific, loop-mediated isothermal amplification (LAMP) assay for the rapid diagnosis of this pathogen. The primers were designed using the ribosomal DNA internal transcribed spacer sequence. Primer specificity was established using 40 Pythium species including P. helicoides, 11 Phytophthora species, and eight other soil-borne pathogens. A sensitivity test was carried out using genomic DNA extracted from P. helicoides, and the detection limit was c. 100 fg which is comparable to that of the polymerase chain reaction (PCR). In addition, we tested the ease of pathogen detection in poinsettia roots. The LAMP results were consistent with those from the conventional plating method and showed more sensitivity than the PCR results. Consequently, the LAMP method developed in this study is effective for the rapid and easy detection of P. helicoides.

Assessment of the applicability of a "toolbox" designed for microbially assisted phytoremediation: the case study at Ingurtosu mining site (Italy).

The paper describes the fieldwork at the Italian test site of the abandoned mine of sphalerite and galena in Ingurtosu (Sardinia), with the aim to assess the applicability of a "toolbox" to establish the optimized techniques for remediation of soils contaminated by mining activities. A preliminary characterization-including (hydro)geochemistry, heavy metal concentration and their mobility in soil, bioprospecting for microbiology and botany-provided a data set for the development of a toolbox to deliver a microbially assisted phytoremediation process. Euphorbia pithyusa was selected as an endemic pioneer plant to be associated with a bacterial consortium, established with ten selected native strains, including metal-tolerant bacteria and producers of plant growth factors. The toolbox was firstly assessed in a greenhouse pot experiment. A positive effect of bacterial inoculum on E. pithyusa germination and total plant survival was observed. E. pithyusa showed to be a well-performing metallophyte species, and only inoculated soil retained a microbial activity with a high functional diversity, expanding metabolic affinity also towards root exudates. These results supported the decision to proceed with a field trial, investigating different treatments used singly or in combination: bioaugmentation with bacterial consortia, mycorrhizal fungi and a commercial mineral amendment. Microbial activity in soil, plant physiological parameters and heavy metal content in plants and in soil were monitored. Five months after the beginning, an early assessment of the toolbox under field conditions was carried out. Despite the cold season (October-March), results suggested the following: (1) the field setup as well as the experimental design proved to be effective; (2) plant survival was satisfactory; (3) soil quality was increased and bioaugmentation improved microbial activity, expanding the metabolic competences towards plant interaction (root exudates); and (4) multivariate analysis supported the data provided that the proposed toolbox can be established and the field trial can be carried forward.

Action of chitosan against Xanthomonas pathogenic bacteria isolated from Euphorbia pulcherrima.

The antibacterial activity and mechanism of two kinds of chitosan were investigated against twelve Xanthomonas strains recovered from Euphorbia pulcherrima. Results indicated that both chitosans markedly inhibited bacterial growth based on OD loss. Furthermore, the release of DNA and RNA from three selected strains was increased by both chitosans. However, the release of intracellular proteins was inhibited by both chitosans at different concentration and incubation times, except chitosan A at 0.1 mg/mL for 0.5 h incubation and 0.2 mg/mL for 2.0 h incubation increased the release of proteins, indicating the complexity of the interaction and cell membranes, which was affected by incubation time, bacterial species, chitosan type and concentration. Transmission electron microscopic observations revealed that chitosan caused changes in protoplast concentration and surface morphology. In some cells, the membranes and walls were badly distorted and disrupted, while other cells were enveloped by a thick and compact ribbon-like layer. The contrary influence on cell morphology may explain the differential effect in the release of material. In addition, scanning electron microscope and biofilm formation test revealed that both chitosans removed biofilm biomass. Overall, this study showed that membrane and biofilm play an important role in the antibacterial mechanism of chitosan.

The obesity and fatty liver are reduced by plant-derived Pediococcus pentosaceus LP28 in high fat diet-induced obese mice.

We evaluated the effect of an oral administration of a plant-derived lactic acid bacterium, Pediococcus pentosaceus LP28 (LP28), on metabolic syndrome by using high fat diet-induced obese mice. The obese mice were divided into 2 groups and fed either a high fat or regular diet for 8 weeks. Each group was further divided into 3 groups, which took LP28, another plant-derived Lactobacillus plantarum SN13T (SN13T) or no lactic acid bacteria (LAB). The lean control mice were fed a regular diet without inducing obesity prior to the experiment. LP28 reduced body weight gain and liver lipid contents (triglyceride and cholesterol), in mice fed a high fat diet for 8 weeks (40%, 54%, and 70% less than those of the control group without LAB, and P = 0.018, P<0.001, and P = 0.021, respectively), whereas SN13T and the heat treated LP28 at 121°C for 15 min were ineffective. Abdominal visceral fat in the high fat diet mice fed with LP28 was also lower than that without LAB by 44%, although it was not significant but borderline (P = 0.076). The sizes of the adipocytes and the lipid droplets in the livers were obviously decreased. A real-time PCR analyses showed that lipid metabolism-related genes, such as CD36 (P = 0.013), SCD1 encoding stearoyl-CoA desaturase 1 (not significant but borderline, P = 0.066), and PPARγ encoding peroxisome proliferator-activated receptor gamma (P = 0.039), were down-regulated by taking LP28 continuously, when compared with those of the control group. In conclusion, LP28 may be a useful LAB strain for the prevention and reduction of the metabolic syndrome.

New species of Gondwanamyces from dying Euphorbia trees in South Africa.

Gondwanamyces and its Custingophora anamorphs were first described from Protea infructescences in South Africa. Subsequently these unusual fungi were also found on Cecropia in Central America. During an investigation into the decline and death of native Euphorbia trees in South Africa, several fungal isolates resembling the anamorph state of Gondwanamyces were obtained from diseased tissues. In this study these isolates are identified based on morphology and comparisons of DNA sequences. Two previously unknown Gondwanamyces species were identified, both were associated with damage caused by beetles (Cossonus sp.). Inoculation studies showed that the new species of Gondwanamyces are pathogenic on Euphorbia ingens and may contribute to the decline of these trees.