Enhancement of Trichoderma harzianum CFAM-422 for cellulase and hemicellulase production by deletion of the carbon catabolite repressor gene cre1.

Carbon catabolite repression (CCR) is a mechanism by which microorganisms can utilize preferably highly energetic compounds over those of difficult degradation. For Trichoderma reesei, the protein that acts as repressor in the presence of glucose is CRE1. In this project, we aim to delete cre1 gene in Trichoderma harzianum CFAM-422 and obtain mutants with enhanced production of biomass degrading enzymes. Disruption of cre1 in T. harzianum CFAM-422 was performed by gene replacement of cre1 for hph (hygromycin B phosphotransferase) via homologous recombination. Hygromycin resistant mutants and parental strains enzyme production was evaluated in both inductive and repressive conditions in four different carbon sources. Enzymatic indexes (EI) were determined and compared. All genetically stable transformants showed increased enzymatic index under inductive conditions and modest inhibition under repressive conditions for most carbon sources, indicating that the deletion of cre1 in T. harzianum can be beneficial to cellulase and hemicellulase production with reduced product inhibition.SINAFERM; SHEB. 3 a 6 de setembro. Seção Trabalhos. Ref. 59019

Recent updates and perspectives on approaches for the development of vaccines against visceral leishmaniasis

All rights reserved. Visceral leishmaniasis (VL) is one of the most important tropical diseases worldwide. Although chemotherapy has been widely used to treat this disease, problems related to the development of parasite resistance and side effects associated with the compounds used have been noted. Hence, alternative approaches for VL control are desirable. Some methods, such as vector control and culling of infected dogs, are insufficiently effective, with the latter not ethically recommended. The development of vaccines to prevent VL is a feasible and desirable measure for disease control, for example, some vaccines designed to protect dogs against VL have recently been brought to market. These vaccines are based on the combination of parasite fractions or recombinant proteins with adjuvants that are able to induce cellular immune responses, however, their partial efficacy and the absence of a vaccine to protect against human leishmaniasis underline the need for characterization of new vaccine candidates. This review presents recent advances in control measures for VL based on vaccine development, describing extensively studied antigens, as well as new antigenic proteins recently identified using immuno-proteomic techniquesThis work was supported by grants from Instituto Nacional de Ciência e Tecnologia em Nano-Biofarmacêutica, Rede Nanobiotec/Brasil-Universidade Federal de Uberlândia/CAPES, PRONEX-FAPEMIG (APQ-01019-09), FAPEMIG (CBB-APQ-00819-12 and CBB-APQ-01778-2014), and CNPq (APQ-482976/2012-8, APQ-488237/2013-0, and APQ-467640/2014-9). EAFC and LRG are recipients of the grant from CNPq. MACF is the recipient of grants from FAPEMIG/CAPE

Resistance des sols aux maladies : XIII. - Role des fusarium oxysporum non pathogenes dans les mecanismes de resistance d'un sol de Noirmoutier aux fusarioses vasculaires

National audienceThe high level of suppressiveness of a soil from Noirmoutier (Western France) has been established, using the standardized method to evaluate the level of soil receptivity to fusarium wilts. This suppressiveness was destroyed by heat treatment of the soil and was restored by mixing 10 % of suppressive soil into the steamed suppressive soil, indicating that the suppressiveness is based on microbiological interactions. Introduction of high populations of fluorescent Pseudomonas isolated from this soil did not establish suppressiveness in steamed soil. Addition of Fe E.D.T.A. at 200 μg/g soil did not reduce the high level of suppressiveness of the suppressive soil. Thus, the role of fluorescent Pseudomonas competing for iron seems to be of low importance in this suppressive soil. On the other hand, addition of non-pathogenic strains of Fusarium oxysporum induced a high level of suppressiveness in steamed soil. As the addition of glucose slightly reduced the level of suppressiveness it could be assumed that the mechanism of suppression is similar to that previously described in the suppressive soil from Châteaurenard. Thirty strains of each species F. oxysporum, F. roseum and F. solani were compared for their ability to induce suppressiveness in steamed soil. Overall, F. oxysporum were more effective than F. roseum and F. solani. Thus, non-pathogenic F. oxysporum seemed to be involved in this mechanism of suppression but their mode of action is not known. There was no clear relationship between the level of soil colonization or root colonization by different strains of F. oxysporum and their ability to induce suppressiveness. Furthermore, some strains were able to produce cross-protection in tomatoes indicating that these non-pathogenic F. oxysporum could be active through different modes of action.L’emploi de la méthode standardisée d’évaluation du niveau de réceptivité des sols aux fusarioses vasculaires a permis de mettre en évidence le très fort niveau de résistance d’un sol maraîcher de Noirmoutier. Cette résistance, détruite par traitement thermique du sol (60 °C, 30 mn) et transmissible par simple mélange à un autre sol, est fondamentalement de nature microbiologique. L’introduction de fortes populations de Pseudomonas fluorescents ne permet pas de rétablir la résistance dans le sol traité à la chaleur et l’apport de Fe E.D.T.A. est sans effet sur le niveau de résistance de ce sol. Il est donc permis de conclure que les Pseudomonas fluorescents entrant en compétition pour le fer ne jouent qu’un rôle négligeable dans les mécanismes de résistance de ce sol. Au contraire, l’apport de Fusarium oxysporum non pathogènes suffit à induire un niveau élevé de résistance dans le sol traité à la chaleur. Comme l’addition de glucose induit une faible baisse du niveau de résistance du sol, il est vraisemblable que les mécanismes de résistance sont en relation avec des phénomènes de compétition nutritive comme dans le cas du sol résistant de Châteaurenard. Trente souches de chacune des espèces F. oxysporum, F. roseum et F. solani ont été comparées pour leur aptitude à induire la résistance dans le sol traité à la chaleur. Globalement les F. oxysporum sont nettement plus efficaces, mais il n’existe pas de relation claire entre l’aptitude des souches à coloniser le sol ou la racine des plantes et leur aptitude à rendre le sol résistant. De plus, certaines souches ont permis d’induire des réactions de prémunition chez la tomate. Il est donc vraisemblable que les F. oxysporum non pathogènes disposent de différents mécanismes d’induction de résistance

La réceptivité des sols aux fusarioses vasculaires : rapports entre résistance et microflore autochtone avec référence particulière aux Fusarium non pathogènes (*)

L'estimation du niveau de réceptivité aux fusarioses vasculaires de 4 échantillons de sols provenant de l'Italie du Nord a permis de montrer que 3 d'entre eux sont résistants à la fusariose du lin, le quatrième étant beaucoup plus sensible. Dans tous les cas, le traitement thermique à la vapeur détruit la résistance de ces sols qui est donc de nature microbiologique. L'isolement d'une collection de souches de Fusarium spp à partir de ces 4 échantillons de sols et leur introduction dans un sol traité à la chaleur montrent qu'une forte proportion de souches de F oxysporum est capable d'induire la résistance dans ce sol désinfecté. Le rôle de F oxysporum dans les mécanismes de résistance apparaît plus important que celui des F solani et des F roseum. L'aptitude des souches de F oxysporum à diminuer l'incidence de la maladie se manifeste de manière similaire dans les différents types de sols traités à la chaleur. Cette aptitude n'est pas corrélée à la capacité des souches à se multiplier saprophytiquement dans ces sols.Soil-suppressiveness to Fusarium-wilt: relationship between suppressiveness and indigenous microflora of the soil with special emphasis on the non-pathogenic Fusarium. The microbiological nature of the suppressiveness to Fusarium-wilt was established by comparative research carried out in Northern Italy, on 4 different soil samples collected whose physico-chemical and cultural features are summarized in table I. Both microbial populations (table II) and suppressiveness to Fusarium-wilt of flax (fig 1) is the soils from Albenga, Carmagnola and Santena were at higher levels than those in the soil from Donnas. A large proportion of the strains of Fusarium spp isolated from these soils were able to induce suppressiveness to Fusarium-wilt of flax in steamed soil. Among the non-pathogenic Fusaria, F oxysporum appeared to be more involved than F solani and F roseum in the mechanisms of the suppression (fig 2). Soil suppressiveness was conditioned not only by the density but also by the composition of the population of non-pathogenic F oxysporum present in each soil (fig 3). There was no relationship between the ability of non-pathogenic strains of F oxysporum to colonize the steamed soil (table III) and to induce suppressiveness (table IV, V). Moreover the activity of non-pathogenic strains of F oxysporum was not influenced by the physical and chemical characteristics of the tested soil samples