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 famous locations of excavation sites of Herculaneum (the Collegio degli Augustali, Casa del Colonnato Tuscanico, Casa dello Scheletro and Casa del Gran Portale), were carried out. The use of infrared thermography allowed us to detect 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, especially of spore forming and mould. In fact, heterotrophic bacteria were prevalent in all wall paintings monitored, whereas fungi were also detected but at lower levels. Cultural–based methods allowed to obtain a total of 48 bacteria and 23 mould isolates molecularly identified by 16S and 26S rRNA partial sequence analysis. With this approach, Bacillus-related species (B. cereus/B. thuringiensis group, B. simplex/B.muralis group, B. megaterium and B. subtilis) were isolated in all sample points analysed with the exception of the Casa dello Scheletro in which Micrococcus luteus/Arthrobacter sp./Variovorax sp. group and Streptomyces fragilis were found. Mould isolates were closest related to different genera in which predominated Aspergillus, Penicillium and Fusarium together with the unusual genera as Microascus and Coprinus. Sequencing of the 16S ribosomal DNAs, selected on the basis of DGGE profiling, enabled detection of bacterial species closest related to Microbacterium groups in all sample points analysed, also associated with Brevibacterium, Streptomyces and Stenotrophomonas

Bio-Based Succinate Production from Arundo donax Hydrolysate with the New Natural Succinic Acid-Producing Strain Basfia succiniciproducens BPP7

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Biostimulant activity of azotobacter chroococcum and trichoderma harzianum in durum wheat under water and nitrogen deficiency

Biostimulants hold great potential for developing integrated sustainable agriculture systems. The rhizobacteria Azotobacter chroococcum strain 76A and the fungus Trichoderma harzianum strain T22, with demonstrated biostimulant activity in previous systems, were evaluated in Triticum durum cv Creso for their ability to enhance growth and tolerance to drought stress. Growth and drought tolerance were evaluated in conditions of low and high soil nitrogen, with two levels of water stress. T. harzianum increased plant growth (+16%) under control conditions and tolerance to moderate drought stress (+52%) under optimal fertilization, while A. chroococcum conferred a growth penalty (−28%) in well-watered conditions under suboptimal fertilization and increased tolerance only under extreme drought stress (+15%). This growth penalty was ameliorated by nitrogen fertilization. T. harzianum abundance was found to be positively correlated to extreme soil drying, whereas A. chroococcum-induced tolerance was dependent on soil nitrogen availability. These results indicate that while biostimulants may enhance growth and stress tolerance, nutrient availability soil and environmental conditions heavily influence these responses. These interactions should be considered when designing biostimulant products targeted to specific cultural conditions

Plant–Rhizobium symbiosis, seed nutraceuticals, and waste quality for energy production of Vicia faba L. as affected by crop management

Background: Broad bean fits sustainable agriculture model due to symbiosis with Rhizobium, the seeds being a good source of energy, proteins, polyphenols, and fiber. The large amount of broad bean biomass residues can be employed for biofuel production, thus valorizing the overall production process. This research was aimed to investigate on the effects of farming management, such as greenhouse cultivation and appropriate planting time on the qualities of broad bean seeds and residual biomass for conversion into biofuel. The related balances of energy gain associated to both ethanol yield and nitrogen fertilizer saving due to Rhizobium nitrogen fixation were assessed. Methods: Research was carried out on broad bean in Portici, province of Naples, southern Italy, based on the factorial combination of two farming systems (open field, greenhouse) and five planting times: 27 September and 11 October, to obtain early production; 25 October, which fell in the usual period for broad bean planting in the province area; and 8 November and 22 November, for late production. For each of these cultivation conditions, the quality of seeds, in terms of protein, fiber and antioxidant concentrations, and of crop residual biomass were determined. In addition, the energy yield as ethanol production from residual biomass and nitrogen fertilizer saving due to Rhizobium atmospheric fixation were assessed. Results and discussion: The highest plant nitrogen uptake was recorded under the fourth planting time in open field and the third in greenhouse, the average accumulation attaining 87% in residual biomass, 7.4% in pods, and 5.6% in seeds. Seed protein content was 12.6% higher in greenhouse than in open field and 16.2% higher under the latest planting time compared to the earliest one. Seed polyphenol concentration was higher in open field than in greenhouse and with the two earliest planting times. Greenhouse grown biomass showed higher values of lignin, hemicellulose and pectin, compared to open field, whereas the opposite trend was for cellulose. Lignin showed a decrease from the first to the last crop cycle, opposite to cellulose, and glucose was the most represented monosaccharide. Both the highest theoretical ethanol and overall energy production were highest with the fourth planting time. Conclusions: Greenhouse management enabled broad bean plants to accumulate higher proteins in seeds, but open field conditions resulted in better residual biomass quality for ethanol and Rhizobium-depending energy production

Effectiveness of Plant Beneficial Microbes: Overview of the Methodological Approaches for the Assessment of Root Colonization and Persistence

Issues concerning the use of harmful chemical fertilizers and pesticides that have large negative impacts on environmental and human health have generated increasing interest in the use of beneficial microorganisms for the development of sustainable agri-food systems. A successful microbial inoculant has to colonize the root system, establish a positive interaction and persist in the environment in competition with native microorganisms living in the soil through rhizocompetence traits. Currently, several approaches based on culture-dependent, microscopic and molecular methods have been developed to follow bioinoculants in the soil and plant surface over time. Although culture-dependent methods are commonly used to estimate the persistence of bioinoculants, it is difficult to differentiate inoculated organisms from native populations based on morphological characteristics. Therefore, these methods should be used complementary to culture-independent approaches. Microscopy-based techniques (bright-field, electron and fluorescence microscopy) allow to obtain a picture of microbial colonization outside and inside plant tissues also at high resolution, but it is not possible to always distinguish living cells from dead cells by direct observation as well as distinguish bioinoculants from indigenous microbial populations living in soils. In addition, the development of metagenomic techniques, including the use of DNA probes, PCR-based methods, next-generation sequencing, whole-genome sequencing and pangenome methods, provides a complementary approach useful to understand plant–soil–microbe interactions. However, to ensure good results in microbiological analysis, the first fundamental prerequisite is correct soil sampling and sample preparation for the different methodological approaches that will be assayed. Here, we provide an overview of the advantages and limitations of the currently used methods and new methodological approaches that could be developed to assess the presence, plant colonization and soil persistence of bioinoculants in the rhizosphere. We further discuss the possibility of integrating multidisciplinary approaches to examine the variations in microbial communities after inoculation and to track the inoculated microbial strains