ABSTRACT: The impacts of continuous cropping of banana on soil microbiological and biochemical properties are little understood. In this study, we evaluated the variations in soil bacterial community abundance and diversity, microbial biomass carbon (MBC) and nitrogen (MBN) as well as soil enzyme activities involved in C, N and P cycles as affected by continuous cropping of banana. An initial increase in bacterial 16S rRNA copy and soil microbial biomass was observed in the second cropping and then decreased until the fourth cropping. The diversity of bacterial community showed a continuous decrease throughout the experiment. In addition, continuous cropping of banana caused shifts in bacterial community composition and structures. Soil urease and invertase exhibited the highest activities in the second cropping and then decreased gradually from the second to the fourth cropping. The phosphatase activity showed a gradual increase from the first to the third cropping. The bacterial 16S rRNA copy was positively correlated with the contents of MBN and urease activities. The results indicated that continuous cropping of banana was responsible for the disturbance of the bacterial community and that the effect on enzyme activity varies depending on the type of soil enzyme.
Chemical investigation on the cultures of the fungus Marasmiellus ramealis resulted in the first isolation of eleven compounds including two new eudesmane-type sesquiterpenoids 14(10→1)abeo-eudesmane-13-hydroxyl-11-ene, 14(10→1)abeo-eudesmane-11,13-diol, and the new mellein derivative (R)-(–)-5-ethoxycarbonyl mellein. The first two compounds were evaluated for their inhibitory activity against acetylcholinesterase (AChE), and proved to be active with a percentage inhibition of 29 and 41%, respectively, at a concentration of 100 μmol L-1.
A investigação química das culturas do fungo Marasmiellus ramealis resultou na primeira isolação de onze compostos incluindo dois novos sesquiterpenoides do tipo eudesmano 14(10→1)abeo-eudesmano-13-hidroxil-11-eno, 14(10→1)abeo-eudesmano-11,13-diol, e o novo derivado de meleína (R)-(–)-5-etoxicarbonil meleína. A atividade inibitória da aceticolinesterase (AChE) dos dois primeiros compostos foi avaliada, que mostraram ser ativos com uma porcentagem de inibição de 29 e 41%, respectivamente, em uma concentração de 100 μmol L-1.