Bacterial community associated with the ambrosia beetle Platypus cylindrus on declining Quercus suber trees in the Alentejo region of Portugal

In Portugal, the oak pinhole borer Platypus cylindrus and its mycobiota have been associated with cork oak (Quercus suber) death, but no knowledge exists regarding the associated bacterial community. However, it is known that some bacteria are important for ambrosia beetle symbiosis and play a role in oak tree health. To explore the bacteria associated with this beetle and its host, with the ultimate goal of highlighting potential roles in oak decline, this study used a culture-dependent approach for strain isolation and phylogenetic identification using 16S rRNA gene sequencing and multilocus sequence analysis (MLSA). The bored galleries of different cork oak trees from a cork stand in Alentejo, together with the body and mycangia of adult beetles, were investigated. The samples revealed a diverse community comprising 500 isolates with 64 distinct types of bacterial colonies. Sixty-eight strains were selected for sequencing and used for phylogenetic analysis, 40 from wood galleries and 28 from beetles. Thirty-two genera of bacteria were identified, 18 of which were described for the first time within oak–beetle interactions. Major taxonomic groups were Actinobacteria in beetles and Enterobacterales in wood galleries. Although specific oak bacterial pathogens were not detected, a group of distinct strains detected in wood galleries, potentially belonging to a new Pectobacteriaceae species, were able to produce mild symptoms on cork oak plantlets. This study reports for the first time the biodiversity of culturable bacteria associated with the Q. suber–P. cylindrus interaction, their relevance to both organisms and the possible contribution to oak decline.     

Microbial dynamics after adding bovine manure effluent together with a nitrification inhibitor (3,4 DMPP) in a microcosm experiment

The application of animal manure effluents in agriculture in combination with nitrification inhibitors should be beneficial for nutrient recycling, soil quality, plant productivity, and greenhouse gas emission and offer economic advantages to make them an alternative to conventional fertilizers. The present study aims to estimate the effects of the addition of bovine manure effluent alone or together with a nitrification inhibitor (3,4-dymethylpyrazol-phosphate (3,4 DMPP)) on the microbial community dynamics in a Mediterranean soil in an incubation experiment over 28 days. The application of the bovine manure effluent increased respiration, microbial biomass carbon, fungal and bacterial growth, and enzyme activities and changed the microbial community structure evaluated by the phospholipid fatty acid pattern. Adding the bovine manure effluent together with the nitrification inhibitor, although partly negating the positive effect of the effluent on soil microbial activity, still resulted in higher or similar growth and activity as in the control. Our results indicate that the addition of the nitrification inhibitor 3,4 DMPP together with a bovine manure effluent could be a promising solution to control the animal manure effluent application effects on soil microbiological properties and microbial dynamics, as well as counteracting direct inhibiting effects of 3,4 DMPP on the soil heterotrophic community.     

Map- vs. homology-based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew

The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one cleaved amplified polymorphic sequence (CAPS) marker which are linked to the resistance locus and co-dominantly inherited. Aiming to provide a base for ol-2 positional cloning, we used a large segregating F₂ population to merge these markers with all the ol-2 linked amplified fragment length polymorphism (AFLP^®) markers previously identified in an integrated genetic map. By screening a tomato bacterial artificial chromosome (BAC) library, we detected two BAC clones containing two expressed sequence tags (ESTs) homologous to the gene mlo, responsible for powdery mildew resistance in barley, as well as an ol-2-linked marker. Chromosomal mapping by Fluorescence in situ Hybridization (FISH) revealed major signals of the two BAC DNAs in the pericentromeric heterochromatin of the short arm of chromosome 4, in the same region where the ol-2 gene was previously mapped. The genetic and cytogenetic co-localisation between ol-2 and tomato mlo-homologue(s), in addition to the similarity of ol-2 and mlo resistances for both genetic and phytopathological characteristics, suggests that ol-2 is likely a mlo-homologue. Thus, a homology-based cloning approach could be more suitable than positional cloning for ol-2 isolation.     

Biochemical Characterization of Cassiopea andromeda (Forsskål, 1775), Another Red Sea Jellyfish in the Western Mediterranean Sea

Increasing frequency of native jellyfish proliferations and massive appearance of non-indigenous jellyfish species recently concur to impact Mediterranean coastal ecosystems and human activities at sea. Nonetheless, jellyfish biomass may represent an exploitable novel resource to coastal communities, with reference to its potential use in the pharmaceutical, nutritional, and nutraceutical Blue Growth sectors. The zooxanthellate jellyfish Cassiopea andromeda, Forsskål, 1775 (Cnidaria, Rhizostomeae) entered the Levant Sea through the Suez Canal and spread towards the Western Mediterranean to reach Malta, Tunisia, and recently also the Italian coasts. Here we report on the biochemical characterization and antioxidant activity of C. andromeda specimens with a discussion on their relative biological activities. The biochemical characterization of the aqueous (PBS) and hydroalcoholic (80% ethanol) soluble components of C. andromeda were performed for whole jellyfish, as well as separately for umbrella and oral arms. The insoluble components were hydrolyzed by sequential enzymatic digestion with pepsin and collagenase. The composition and antioxidant activity of the insoluble and enzymatically digestible fractions were not affected by the pre-extraction types, resulting into collagen- and non-collagen-derived peptides with antioxidant activity. Both soluble compounds and hydrolyzed fractions were characterized for the content of proteins, phenolic compounds, and lipids. The presence of compounds coming from the endosymbiont zooxanthellae was also detected. The notable yield and the considerable antioxidant activity detected make this species worthy of further study for its potential biotechnological sustainable exploitation.     

Microstructure, fundamental rheology and baking characteristics of batters and breads from different gluten-free flours treated with a microbial transglutaminase

Gluten is a fundamental component for the overall quality and structure of breads. The replacement of the gluten network in the development of gluten-free cereal products is a challenging task for the cereal technologist. The functionality of proteins from gluten-free flours could be modified in order to improve their baking characteristics by promoting protein networks. Transglutaminase (TGase) has been successfully used in food systems to promote protein cross-linking. In this study, TGase was investigated for network forming potential on flours from six different gluten-free cereals (brown rice, buckwheat, corn, oat, sorghum and teff) used in breadmaking. TGase was added at 0, 1 or 10 U/g of proteins present in the recipe. The effect of TGase on batters and breads was evaluated by fundamental rheological tests, Texture Profile Analysis and standard baking tests. Three-dimensional elaborations of Confocal Laser Scanning Microscopy (CLSM) images were performed on both batters and breads to evaluate the influence of TGase on microstructure. Fundamental rheological tests showed a significant increase in the pseudoplastic behaviour of buckwheat and brown rice batters when 10 U of TGase were used. The resulting buckwheat and brown rice breads showed improved baking characteristics as well as overall macroscopic appearance. Three-dimensional CLSM image elaborations confirmed the formation of protein complexes by TGase action. On the other side, TGase showed negative effects on corn flour as its application was detrimental for the elastic properties of the batters. Nevertheless, the resulting breads showed significant improvements in terms of increased specific volume and decreased crumb hardness and chewiness. Under the conditions of this study, no effects of TGase could be observed on breads from oat, sorghum or teff. Overall, the results of this study show that TGase can be successfully applied to gluten-free flours to improve their breadmaking potentials by promoting network formation. However, the protein source is a key element determining the impact of the enzyme.     

Activity of Berberis aetnensis root extracts on Candida strains

The antifungal activity of methanolic extract and alkaloidal fraction of Berberis aetnensis against Candida species was investigated. The crude extract was active against Candida species, this activity being higher than that of the alkaloidal fraction and berberine.     

Antiproliferative activity of Citrus juices and HPLC evaluation of their flavonoid composition

The antiproliferative activity of fresh fruit juices extracted from Citrus sinensis (cv. Washington Navel and cv. Sanguinello), C. deliciosa cv. Avana, C. clementina cv. Nules, C. aurantium subsp. myrtifolia , was evaluated against K562 (human chronic myelogenous leukemia), HL-60 (human leukemia) and MCF-7 (human breast adenocarcinoma) cell lines. All the juices tested showed antiproliferative activity. Moreover, the pattern of the main flavanone compounds in the juices has been determined by HPLC analysis.     

Detritus accumulation and decomposition in a coastal lake (Acquatina–southern Italy)

• 1. Knowledge about processes and dynamics underlying organic matter accumulation in transitional waters is crucial for the protection of these ecologically important coastal habitats. This study investigated the relationship between large particle accumulation and decomposition in a coastal lake included in a Site of Community Interest (SCI) using sediment trap and litterbag techniques.
• 2. Two sets of sediment traps were deployed at five sites along the longitudinal axis of the lake. One set was emptied once a month for 12 months, and the other twice a year. The contents of the monthly and the 6‐monthly traps and the superficial sediments were then compared to estimate the organic matter accumulation and loss. To determine the mass loss rate of the three major allochthonous sources of detritus (the reed Phragmites australis, the cordgrass Spartina juncea, and the seagrass Posidonia oceanica), litterbags were placed near the sediment traps at three out of the five sites at the beginning of each 6‐month period and retrieved monthly.
• 3. The amount of annual particulate organic matter (POM) deposition in the traps was 1320.2±58.5 g m^?2 y^?1 and consisted of 25% large particles (CPOM). Allochthonous litter comprised an important fraction of CPOM, and its breakdown rate changed with the plant species, site and season. Loss rate of CPOM accumulated at the lake bottom was significantly related with the mass loss rate of reed and cordgrass litter, but not with that of seagrass.
• 4. Due to slow litter breakdown and tidal landward advection, the lake acted as a sediment trap for allochthonous matter, especially from Posidonia. The important role of marine‐derived litter in organic matter sedimentation suggests addressing conservation strategies of the lake functioning towards the selective control of allochthonous CPOM inputs, in particular at the mouth where the incoming tide brings suspended material and salinity decelerates matter flow to the sea and decomposition. This study supports the hypothesis that sedimentation and decomposition dynamics are important factors for coastal lake evolution, and shows litterbag and sediment trap techniques as simple useful investigation tools in management strategies aiming at conserving transitional waters.

Copyright © 2008 John Wiley & Sons, Ltd.