Potential of yeasts as biocontrol agents against Fusarium graminearum in vitro and on corn.

AIMS: The antifungal effect of the yeast species Kluyveromyces marxianus, Meyerozyma caribbica, and Wickerhamomyces anomalus was evaluated against two Fusarium graminearum strains (FRS 26 and FSP 27) in vitro and on corn seeds. METHODS AND RESULTS: The antifungal effect of the yeasts against F. graminearum was evaluated using scanning electron microscopy and extracellular chitinase and glucanase production to further elucidate the biocontrol mode of action. In addition, the germination percentage and vigor test were investigated after applying yeast on corn seeds. All the yeast strains inhibited fungal growth in vitro (57.4%-100.0%) and on corn seeds (18.9%-87.2%). In co-culture with antagonistic yeasts, F. graminearum showed collapsed hyphae and turgidity loss, which could be related to the ability of yeasts to produce chitinases and glucanases. The three yeasts did not affect the seed corn germination, and W. anomalus and M. caribbica increased corn seed growth parameters (germination percentage, shoot and root length, and shoot dry weight). CONCLUSION: Meyerozyma caribbica and W. anomalus showed satisfactory F. graminearum growth inhibition rates and did not affect seed growth parameters. Further studies are required to evaluate the application of these yeasts to the crop in the field.

Lactic acid bacteria and Bacillus spp. as fungal biological control agents.

Fungal pathogens are one of the most important agents affecting crop production and food safety, and agrochemical application is one of the main approaches to reduce phytopathogenic fungi contamination in agricultural products. However, excessive and inadequate use can cause environmental damage, human and animal hazard, and increased phytopathogen resistance to fungicides. Biological control using lactic acid bacteria (LAB) and Bacillus spp. is an environmentally friendly strategy for phytopathogenic fungi management. Several molecules produced by these bacteria indeed affect fungal growth and viability in different plant crops. In this article, the activity spectra are reviewed along with the antifungal effect and antifungal compounds produced by LAB (e.g. organic acids, peptides, cyclic dipeptides, fatty acids, and volatile compounds) and Bacillus spp. (e.g. peptides, enzymes, and volatile compounds).

Leptospirose no estado do Paraná, Brasil: uma abordagem de saúde única / Leptospirosis in the state of Paraná, Brazil: A One Health Approach

Leptospirose é uma doença endêmica no Brasil. Sua ocorrência é relacionada a diversos fatores de vulnerabilidade social e exposição ocupacional, sendo sua cadeia epidemiológica complexa, envolvendo o homem, animais e meio ambiente. Foi realizado um estudo transversal descritivo dos casos novos de leptospirose confirmados no estado do Paraná entre os anos de 2007-2017. A incidência média para o período foi de 2,98 casos por 100.000 habitantes com letalidade média de 10,53 óbitos por 100 casos. A maior parcela da população afetada foi do sexo masculino (84,4%), cor branca (72,9%) habitantes do perímetro urbano (56,2%) que se infectaram no domicilio (40,4%), sendo em sua maioria confirmados por análises laboratoriais (93,3%). A doença apresentou aumento em comparação à sua incidência no período de 1993 a 2001 no estado do Paraná, com distribuição sazonal ao longo do ano. (AU)

Leptospirosis is an endemic disease in Brazil. Its occurrence is related to several factors of social vulnerability and occupational exposure, with its complex epidemiological chain involving man, animals, and environment. A descriptive cross-sectional study of new confirmed leptospirosis cases in the State of Paraná between 2007-2017 was performed. The average incidence for the period was 2.98 cases per 100,000 inhabitants with an average lethality of 10.53 deaths per 100 cases. The largest portion of the affected population was male (84.4%), white (72.9%) living in the urban perimeter (56.2%) and infected at home (40.4%). In addition, most of the cases were confirmed by laboratory analysis (93.3%). The disease showed an increase when compared to its incidence in the period from 1993 to 2001 in the state of Paraná, with seasonal distribution throughout the year. (AU)

Extended low-resolution structure of a Leptospira antigen offers high bactericidal antibody accessibility amenable to vaccine design.

Pathogens rely on proteins embedded on their surface to perform tasks essential for host infection. These obligatory structures exposed to the host immune system provide important targets for rational vaccine design. Here, we use a systematically designed series of multi-domain constructs in combination with small angle X-ray scattering (SAXS) to determine the structure of the main immunoreactive region from a major antigen from Leptospira interrogans, LigB. An anti-LigB monoclonal antibody library exhibits cell binding and bactericidal activity with extensive domain coverage complementing the elongated architecture observed in the SAXS structure. Combining antigenic motifs in a single-domain chimeric immunoglobulin-like fold generated a vaccine that greatly enhances leptospiral protection over vaccination with single parent domains. Our study demonstrates how understanding an antigen's structure and antibody accessible surfaces can guide the design and engineering of improved recombinant antigen-based vaccines.