Antifungal peptides produced by Bacillus amyloliquefaciens AG1 active against grapevine fungal pathogens
Abstract Antifungal metabolites produced by Bacillus amyloliquefaciens AG1, previously isolated from wood of grapevine with “esca syndrome”, were studied. The crude protein extract (CPE) obtained from culture supernatant fluid by precipitation with ammonium sulfate was assayed against many grapevine fungal pathogens. B. amyloliquefaciens strain AG1 showed a broad spectrum of antifungal activity, inhibiting mycelial growth in vitro of all tested fungal microorganisms. The metabolites contained in CPE were heat stable and remained active over a wide pH range (2–10). Their activity was not affected by proteolytic or glycolytic enzymes. Tricine- SDS-polyacrylamide gel electrophoresis revealed a…
Study of green Sicilian table olive fermentations through microbiological, chemical and sensory analyses.
The production of five different green table olive cultivars was studied by a combined strategy consisting of chemical, microbiological and sensory analyses. Cultivable microflora of samples collected during processing was monitored by plate counts on seven synthetic culture media. In all samples Enterobacteriaceae, Pseudomonaceae, staphylococci, lactic acid bacteria and spore-forming bacteria were undetectable. Yeasts and moulds were countable from the day 42 (2 log CFU/ml) till the end of fermentation (6 log CFU/ml). The use of three different approaches for microorganism detection, including a culture-independent methodology, revealed the presence of barely three yeast species during the…
Characterization in the archaeological excavation site of heterotrophic bacteria and fungi of deteriorated wall painting of Herculaneum in Italy
Microbiological characterization of frescos in four different locations (Collegio degli Augustali, Casa del Colonnato Tuscanico, Casa dello Scheletro and Casa del Gran Portale) of excavation sites of Herculaneum was carried out. The use of infrared thermography allowed detecting sample points on frescos with greatest moisture not visible to the naked eye, resulting in structural damage. The microclimatic conditions provided perfect habitat for bacteria and fungi, particularly of spore forming and mould. In fact, heterotrophic bacteria were prevalent in all wall paintings monitored (ranging from 18 +/- 2 CFU 100 cm(-2) to 68 +/- 4 CFU 100 cm(-2)), whereas fungi were also detected but at lowe…
Microbial dynamics during green Sicilian table olive fermentations
The production of green table olives is traditionally a spontaneous fermentation carried out by indigenous microflora. Variability of microbial raw material may result in changes in the qualitative aspects of final products (Silvestri et al., 2009). Table olives of five different green table olive cultivars (four Sicilian Brandofino, Castriciana, Nocellara del Belice and Passalunara and the Spanish Manzanilla) were produced according to a semi-industrial technology, in which lactic acid bacteria (LAB) role is partially replaced by lactic acid addiction. Transformation processes were studied by a combined strategy consisting of chemical, microbiological and sensory analyses. Yeasts harboured…
Response to salinity stress of Rhizobium leguminosarum bv. viciae strains in the presence of different legume host plants
We investigated the effect of residual salts from the previous summer’s irrigation on two non-irrigated cover crops—broad bean and common vetch—and on their rhizobial symbiontics. Before sowing, seeds were inoculated with a salt-tolerant strain and a salt-sensitive strain of Rhizobium leguminosarum biovar viciae. An increase in the electrical conductivity of the saturated-soil extract from 2.0 dS m−1 to 6.0 dS m−1 caused a severe reduction of broad bean biomass, while growth of common vetch was almost unaffected by the salinity level. Our results clearly indicate that common vetch as a cover crop may increase the availability of nitrogen in soil more than broad bean also in saline environme…
Changes in soil mineral N content and abundances of bacterial communities involved in N reactions under laboratory conditions as predictors of soil N availability to maize under field conditions.
Proper management of soil fertility requires specific tools for predicting N availability for crops as a consequence of different fertilization strategies. More information is required, especially for organic fertilizers, depending on their mineralization rate, composition, and processing (i.e., fresh or composted manure), as well as their effects on soil properties. Laboratory soil incubations were used as a proxy for understanding plant–soil N dynamics under field conditions. Chemical and microbiological measurements as contents of mineral N, potentially mineralizable N and the abundance of key genes regulating the overall N cycle were used as predictors of mineral N availability to maize…
Impact of Innovative Agricultural Practices of Carbon Sequestration on Soil Microbial Community.
This chapter deals with the impact on soil microbiology of innovative management techniques for enhancing carbon sequestration. With in the MESCOSAGR project, the effect of different field treatments was investigated at three experimental sites differing in pedo-climatic characteristics. Several microbiological parameters were evaluated to describe the composition of soil microbial communities involved in the carbon cycle, as well as to assess microbial biomass and activity. Results indicated that both compost and catalyst amendments to field soils under maize or wheat affected microbial dynamics and activities, though with out being harmful to microbial communities.
Response of Soil Microbial Communities to Iron-Porphyrin Catalytic Amendments.
Intensive agricultural practices strongly increase CO2 emission from soil. Synthetic metal-porphyrins were shown to significantly decreased CO2 emission from soil due to an in-situ catalysis of oxidative polymerization of soil organic matter. This research aimed to assess the effects of iron-porphyrin (POR) amendments on soil microbial communities in three arable soils under wheat and maize cropping located in Naples, Turin and Piacenza, characterized by different pedological and climatic conditions. Bulk-soil and rhizo-soil were sampled during 4 years and the microbial groups directly involved in organic matter (OM) mineralization and in key processes of the nitrogen cycle were examined. M…