Deuteromicets de la Fam. Melanconiacies parasits de les plantes a Catalunya

S¿han déterminat més de 30 espècies de fongs fitoparàsits a partir de les anàlisis realitzades en unes 40 espècies de patrons. Entre aquests fongs s'inclouen tant espècies parasites de fulles com de tubercles, de l'escorça de branques o d'arrels etc. Les mostres recol.lectades a diferents localitats de Catalunya foren analitzades directament en el laboratori i si el cas ho requeria es procedia a l'aïllament de l'espècie infectant seguint les tècniques de E. Hellmers modificades. Els patògens observats pertanyen a la Fam. Melanconiàcies de l'O. Melanconials.

Alleviating abiotic and biotic soil constraints by combining Arbuscular Mycorrhizal Fungi with banana and plantain micropropagation systems

The objectives of Participant 4 were: - Establishment and maintenance of a representative collection of AM fungal species in vivo on trap plant cultures. - Study of the effects of early mycorrhizal inoculation in the growth and health of in vitro plantlets and their subsequent behaviour in the nursery. - Effect of the mycorrhization of in vitro produced bananas and plantains on plant growth and health, under biotic stress conditions (nematode and fungi)

Lactic acid bacteria from fresh fruit and vegetables as biocontrol agents of phytopathogenic bacteria and fungi

This study evaluated the efficacy of lactic acid bacteria (LAB) isolated from fresh fruits and vegetables as biocontrol agents against the phytopathogenic and spoilage bacteria and fungi, Xanthomonas campestris, Erwinia carotovora, Penicillium expansum, Monilinia laxa, and Botrytis cinerea. The antagonistic activity of 496 LAB strains was tested in vitro and all tested microorganisms except P. expansum were inhibited by at least one isolate. The 496 isolates were also analyzed for the inhibition of P. expansum infection in wounds of Golden Delicious apples. Four strains (TC97, AC318, TM319, and FF441) reduced the fungal rot diameter of the apples by 20%; only Weissella cibaria strain TM128 decreased infection levels by 50%. Cell-free supernatants of selected antagonistic bacteria were studied to determine the nature of the antimicrobial compounds produced. Organic acids were the preferred mediators of inhibition but hydrogen peroxide was also detected when strains BC48, TM128, PM141 and FF441 were tested against E. carotovora. While previous reports of antifungal activity by LAB are scarce, our results support the potential of LAB as biocontrol agents against postharvest rot. [Int Microbiol 2008; 11(4):231-236]

Interactions of bacteria and fungi on decomposing litter: differential extracellular enzyme activities

Fungi and bacteria are key agents in plant litter decomposition in freshwater ecosystems. However, the specific roles of these two groups and their interactions during the decomposition process are unclear. We compared the growth and patterns of degradativeenzymes expressed by communities of bacteria and fungi grown separately and in coexistence on Phragmites leaves. The two groups displayed both synergistic and antagonistic interactions. Bacteria grew better together with fungi than alone. In addition, there was a negative effect of bacteria on fungi, which appeared to be caused by suppression of fungal growth and biomass accrual rather than specifically affecting enzyme activity. Fungi growing alone had a high capacity for the decomposition of plant polymers such as lignin, cellulose, and hemicellulose. In contrast, enzyme activities were in general low when bacteria grew alone, and the activity of key enzymes in the degradation of lignin and cellulose (phenol oxidase and cellobiohydrolase) was undetectable in the bacteria-only treatment. Still, biomass-specific activities of most enzymes were higher in bacteria than in fungi. The low total activity and growth of bacteria in the absence of fungi in spite of apparent high enzymatic efficiency during the degradation of many substrates suggest that fungi provide the bacteria with resources that the bacteria were not able to acquire on their own, most probably intermediate decomposition products released by fungi that could be used by bacteria

Avaluació del creixement del fong ligninolític Trametes versicolor sobre diferents suports sòlids per a l'aplicació en tractaments de bioremediació

Els fongs de podridura blanca (WRF - de l'anglès: White-rot fungi) són de gran interès en l'àmbit de la bioremediació per la seva capacitat de degradar la lignina. La lacasa, un dels enzims extracel·lulars que aquests fongs excreten per degradar la lignina, pot ser utilitzada per degradar els contamiants presents en una matriu donada. Trametes versicolor ha estat estudiat per la seva capacitat de produïr aquest enzim en rersidus agrícoles com a substrats. Un primer triatge basat en la producció de CO2, la mesura de l'activitat lacasa i la quantificació de l'ergosterol han permés seleccionar els substrats on es donava un major poder oxidatiu dels cultius inoculats amb T. versicolor. Els posteriors experiments de colonització de sòls, on es monitoritzava l'activitat lacasa i l'ergosterol, han mostrat que T. vesicolor és capaç de colonitzar sòls i que té una major activitat lacasa en condicions no estèrils. També h'ha provat, mitjançant el test ND24, que T. versicolor és capaç de degradar un contaminant emergent, el naproxè, en sòls estèrils i no estèrils esmenats amb residus agrícoles.

Probiotic microorganisms: 100 years of innovation and efficacy. Modes of action

AbstractArticle StructureFigures and TablesReferences Benefits from probiotic micro-organisms have been recognised for over 100 years, and as being useful in poultry for 50 years. Fuller (1989) redefined probiotics as ‘a live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance’. Benefits derived from this improved intestinal microbial balance could be reflected in performance or prevention of pathogen colonisation. Probiotic micro-organisms use in poultry production has been widely accepted and new opportunities arose from the 2006 EU ban on antimicrobial growth promoters. The majority of microbial products for compound feeds are made up from a relatively small number of micro-organisms that are normally present in the GI tract. They include non-sporulated bacteria, sporulated bacteria, fungi or yeasts; and presented from single to multi-strain products. A review on the proposed modes of action is presented including recent approaches to quorum sensing interference