Improving control of storage diseases on apple by combining biological and physical post-harvest methods

Post-harvest non-chemical treatments consists of a large range of different approaches, including strengthening of the commodity’s natural defence mechanisms, thermotherapy, application of antagonistic microorganisms and natural antimicrobial substances. NEX0101 is a promising antagonistic biocontrol agent containing the yeast Candida oleophila as the active ingredient. NEX0101 was developed by Bionext, a spin-off from the laboratory of Dr. H. Jijakli, and is currently evaluated for commercial use. The product contains a yeast strain isolated from apple fruit and was originally developed for the control of post-harvest diseases on apple. The antifungal effectiveness of this antagonist can be increased by addition of calcium salts. As the mode of action of this yeast is based on the colonisation of wounds, the mean targets of NEX0101 are blue mould, caused by Penicillium expansum, and grey mould, caused by Botrytis cinerea. Facing possible latent infections, thermotherapy by using hot water treatments could provide an advanced control towards lenticelrot (Gloeosporium spp.). A combination of both physical and biological treatment techniques could broaden the spectrum to all key pathogens on apple and pear. The use of NEX0101 for the control of P. expansum was examined in combination with calcium gluconate. According to the results the combination NEX0101 with calcium gluconate provides an advanced mould control towards P. expansum The best results were achieved using NEX0101 in combination with post-harvest dipping by thermotherapy. The hot water treatment alone was clearly inefficient towards wound parasite P. expansum, on the contrary thermotherapy stimulates the decay caused by this postharvest pathogen. For the future a combination of biological and physical treatments could offer a worthy non-chemical alternative for organic and integrated fruit growers towards fruit rot decay, although more research is necessary to implement these methods in practice

Exploring bacterial communities in aquaponic systems

Aquaponics is a production system based on the dynamic equilibrium between fish, plants, and microorganisms. In order to better understand the role of microorganisms in this tripartite relationship, we studied the bacterial communities hosted in eight aquaponic and aquaculture systems. The bacterial communities were analyzed by 16S rRNA gene deep sequencing. At the phylum level, the bacterial communities from all systems were relatively similar with a predominance of Proteobacteria and Bacteroidetes. At the genus level, however, the communities present in the sampled systems were more heterogeneous. The biofilter samples harbored more diverse communities than the corresponding sump samples. The core microbiomes from the coupled and decoupled systems shared more common operational taxonomic units than with the aquaculture systems. Eventually, some of the taxa identified in the systems could have beneficial functions for plant growth and health, but a deeper analysis would be required to identify the precise functions involved in aquaponics

Molecular features of new Peach Latent Mosaic Viroid variants suggest that recombination may have contributed to the evolution of this infectious RNA.

peer reviewe

Production and partial characterization of chitinase from a halotolerant Planococcus rifitoensis strain M2-26

peer reviewedThis paper is the first to investigate the production and partial characterization of the chitinase enzyme from a moderately halophilic bacterium Planococcus rifitoensis strain M2-26, earlier isolated from a shallow salt lake in Tunisia. The impact of salt, salinity concentration, pH, carbon and nitrogen sources on chitinase production and activity have been determined. This is the first report on a high salt-tolerant chitinase from P. rifitoensis, since it was active at high salinity (from 5 to 30% NaCl) as well as in the absence of salt. This enzyme showed optimal activity at 70 C and retained up to 82 and 66% of its original activity at 80 or 90 C, respectively. The activity of the enzyme was also shown over a wide pH range (from 5 to 11). For characterization of the enzyme activity, the chitinase secreted in the culture supernatant was partially purified. The preliminary study of the concentrated dialysed supernatant on native PAGE showed at least three chitinases produced by strain M2-26, with highest activity approximately at 65 kDa. Thus, the thermo-tolerant and high salt-tolerant chitinases produced by P. rifitoensis strain M2-26 could be useful for application in diverse areas such as biotechnology and agro-industry

Desarrollo de Agentes de Biocontrol: Oportunidades y descubrimientos para sus aplicaciones prácticas

The relevance of biocontrol agents in plant pathology is still limited in spite of the great enthusiasm generated by research on biopesticides. Most of scientific reports are focused on selection of strains and basic biochemical studies. Priority issues as mass production formulation of biocontrol agents, toxicological and environmental safety and integration into other control strategies are not completely developed.Aunque el control biológico de fitopatógenos, como alternativa de control sostenible, ha despertado considerable entusiasmo en los últimos tiempos, la mayor parte de la investigación reportada hasta ahora, refleja más un interés académico que práctico desde el punto de vista de su aplicación. Es así como la mayoría de reportes hechos en la literatura científica están enfocados hacia la selección de cepas con potencial para el biocontrol y al estudio de sus mecanismos de acción. Sin embargo, temas prioritarios tales como la producción masiva, la formulación, la seguridad toxicológica y medioambiental, y la integración con otras formas de control, han presentado escaso desarrollo