Effects of dietary yeast Saccaromyces cerevisiae on the antioxidant system in the liver of juvenile sea bass Dicentrarchus labrax

The main goal of this work was to determine the effect of dietary live yeast Saccharomyces cerevisiae on the oxidative status of sea bass Dicentrarchus labrax juveniles. Fishes were fed on three diets: the GM group were fed a diet containing lyophilized yeast grown on grape must, the CS group were fed a diet containing lyophilized yeast grown on cornstarch, and the control group were fed a diet without yeast. The activity of the main antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, glutathione S-transferase (GST), and glutathione (GSH) content, as well as lipid peroxidation, was measured in the liver of sea bass juveniles 90?days after hatching. Supplementation of the diet with S. cerevisiae significantly reduced the SOD and CAT activity, increased the GST activity, decreased the GSH content, and had no effect on lipid peroxidation. The results support the already reported radical-scavenging properties of yeast and usefulness of its employment as antiperoxidative agent in fish.     

Multiple gene typing and phylogeny of avipoxvirus associated with cutaneous lesions in a stone curlew

Avipoxvirus (APV) infections have been observed in a wide variety of wild, captive and domestic avian hosts, recently including a range of island endemic and endangered species. However, not enough is known about genome diversity and phylogenetic relationships of APVs, as well as their host-range specificity. A wild stone curlew (Burhinus oedicnemus) was recovered in Sardinia (Italy), showing large wart-like lesions and nodules on both legs and toes, which resulted positive to poxvirus by PCR. Histopathological examination of the lesions showed ballooning degeneration and large intracytoplasmic inclusion bodies consistent with APV infection. A multiple gene sequencing approach was applied to highlight the phylogenetic relationships of this virus with a panel of selected APVs at the clade and subclade levels. This novel isolate was characterized by sequencing partial 4b core protein, P35 (locus fpv140) and DNA polymerase genes and phylogenetic analyses assigned it to clade A, (Fowlpox virus, FWPV), subclade A2. Conservation implications of avian pox presence in Sardinian stone curlews and possibly in other island bird species are discussed.     

Phytoremediation of a multi contaminated soil: mercury and arsenic phytoextraction assisted by mobilizing agent and plant growth promoting bacteria

Purpose

The possibility of using chemical and microbial additives to enhance the phytoextraction of mercury (Hg) and arsenic (As) from a multi-contaminated soil could be very effective, leading to a significant saving in terms of time and costs of the reclamation. The aim of this study was to evaluate the efficacy of the addition of (i) thiosulfate and (ii) metal-tolerant bacteria isolated from the polluted soil having plant growth promotion (PGP) potential to perform As and Hg phytoextraction by Brassica juncea and Lupinus albus.

Materials and methods

A collection of 13 bacterial isolates able to tolerate As and Hg was obtained from the contaminated soil, identified by partial 16S rRNA gene sequencing and tested in vitro for PGP activities. The most promising strains were further tested in vivo for the evaluation of plant growth ability and rhizocompetence on model plants. Pot experiments were conducted in microcosms, with polluted soil vegetated with B. juncea and L. albus. Ammonium thiosulfate and potassium dihydrogen phosphate were used as mobilizing agents, together with a bacterial consortium composed by the most promising PGP isolates.

Results and discussion

Thirteen indigenous metal-tolerant bacterial strains were isolated, and their in vitro characterization highlighted their great potential in assisting the phytoremediation process; most of them tolerated both trace elements and showed, at the same time, multiple PGP traits. The results were confirmed in vivo on model plants and lead to the selection of the most promising PGP strains to be applied in microcosm-scale phytoextraction experiments. Thiosulfate addition significantly increased the mobilization of both elements, promoting bioavailability and phytoextraction. When a selected bacterial consortium was supplemented in addition to thiosulfate, the efficacy of the phytoaccumulation was increased up to 85 % for As and up to 45 % for Hg.

Conclusions

The use of the common fertilizer thiosulfate appeared to have great potential in phytoextraction practices since it was able to facilitate the uptake by plants of both Hg and As. Moreover, the application of a consortium of indigenous PGP bacteria (PGPB) produced a further positive effect on the plant biomass, supporting and enhancing the phytoextraction strategy, thus demonstrating their potential in a microbe-assisted phytoremediation intervention.

     

The impact of adsorption on the exposure assessment of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> in the water-sediment system: a mathematical model approach

A model to assess the environmental fate of bacteria to be used as plant protection products or biocides is presented. The model, based on a black-box approach, takes into account the bacterial cell adsorption on the sediment phase and the degradation kinetics and allows the calculation of the expected environmental density of bacterial cells and the predicted environmental concentration of bacterial toxins in the water-sediment system. An example of calculation results is reported for the study cases of Bacillus thuringiensis subsp. aizawai strain GC-91, B. thuringiensis subsp. kurstaki strain ABTS-351, and B. thuringiensis subsp. tenebrionis strain NB 176, used as plant protection products, and B. thuringiensis subsp. israelensis strains AM 65–52 and SA3A, used as biocides. The calculation of expected environmental density and predicted environmental concentration for bacteria in soil-water systems allows to achieve an appropriate risk assessment of the environmental fate and of the impact of bacterial pest control agents or bacterial biocides on non-target organisms.     

Ecological and histopathological aspects of Didymodiclinus sp. (Trematoda: Didymozoidae) parasite of the dusky grouper,Epinephelus marginatus (Osteichthyes: Serranidae), from the western Mediterranean Sea

The dusky grouper Epinephelus marginatus (Lowe) is an ecologically and commercially important fish species of the Atlantic and Mediterranean coastal rocky habitats. Despite records of didymozoid infections in several grouper species, the identification and pathogenesis of these parasites in E. marginatus are lacking. The aim of this study is to characterize the didymozoids of E. marginatus, particularly their mechanisms of infection and histopathological features. Dusky groupers (n = 205) were caught off Majorca Island (western Mediterranean Sea) and examined for parasites. Of the fish sampled, 45% were infected with white and yellow didymozoid capsules and brown nodules, found on the gills and pseudobranchs. Parasite abundance had a strong positive relationship with the fish length; only fish larger than 20 cm were infected, suggesting infection via consumption of an intermediate host, for which E. marginatus size was a limiting factor. The capsules contained two convoluted viable adult trematodes, identified as Didymodiclinus sp., in close contact with host capillary vessels, with no evidence of the tissue inflammatory response. Conversely, nodules containing degraded parasites were surrounded by an intense inflammatory infiltrate. The findings suggest that Didymodiclinus sp. have the potential to evade the host's immune system by inhibiting the inflammatory response.     

Fusarium head blight evaluation in wheat transgenic plants expressing the maize <Emphasis Type="Italic">b-32</Emphasis> antifungal gene

The maize gene b-32, normally expressed in the maize (Zea mays) endosperm, encodes for a RIP (Ribosome Inactivating Protein) characterised by antifungal activity. Transgenic wheat plants were obtained via biolistic transformation, in which the b-32 gene is driven by the 35SCaMV promoter in association with the bar gene as a selectable marker. Plants were brought to homozygosity through genetic analysis of progeny and pathogenicity tests were performed on the fourth generation. Six homozygous b-32 wheat lines were characterised. All plants had a normal phenotype, not distinguishable from the control cv. Veery except for slightly smaller size, flowered and set seeds. Western blot analyses confirmed b-32 expression during the plant life cycle in the various tissues. Each line differed in the b-32 content in leaf protein extracts and the transgenic protein expression level was maintained at least up to 10 days after anthesis. Pathogenicity tests for Fusarium head blight (FHB) were performed on the b-32 transgenic wheat lines in comparison to the parental cv. Veery. Resistance to FHB was evaluated by the single floret injection inoculation method on immature spikes with spores of Fusarium culmorum. In all the transgenic lines, a similar reduction in FHB symptoms, not dependent on the level of b-32 protein, has been observed (20% and 30% relative to the control, respectively 7 and 14 days after inoculation). Percentage of tombstone kernels at maturity was also recorded; in all transgenic lines disease control for this parameter was around 25%. The data obtained indicate that maize b-32 was effective as in vivo antifungal protein reducing FHB symptoms in wheat lines expressing the maize RIP protein.     

Lactobacillus rhamnosus as additive for maize and sorghum ensiling

The effects of Lactobacillus rhamnosus AT195, a potential probiotic microorganism cultured in buffalo "scotta" whey, on chemical and microbiological composition in maize and sorghum ensiling were evaluated. Both crops were harvested, chopped, and treated or not with the selected strain prior to ensiling in fiberglass vertical silos; 90 days after ensiling, silages were sensorially evaluated and sampled. Different chemical components were evaluated both on fresh crops and silages: in particular, the water-soluble carbohydrates content was investigated by high-field NMR spectroscopy and the carbohydrate fermentation profile was performed by GC. Besides phenotypic identification and typing, microbiological studies included Lb. rhamnosus genotype typing by RAPD-PCR. All silages, inoculated or not, were well preserved, as their chemical and microbiological data along with the fermentation profiles showed. The selected strain used as inoculum influenced the lactic acid population of silages and evidenced a good survival performance during the ensiling process of both maize and sorghum. Moreover, the use of Lb. rhamnosus strain efficiently improved the quality of the multifactorial ensiling process by significantly reducing the ammonia nitrogen content of both maize and sorghum silages.