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Biological nitrogen fixation (BNF) is a key process for the N input in agriculture, with outstanding economic and environmental benefits from the replacement of chemical fertilizers. However, not all symbioses are equally effective in fixing N2, and a major example relies on the high contribution associated with the soybean (Glycine max), contrasting with the low rates reported with the common bean (Phaseolus vulgaris) crop worldwide. Understanding these differences represents a major challenge that can help to design strategies to increase the contribution of BNF, and next-generation sequencing (NGS) analyses of the nodule and root microbiomes may bring new insights to explain differential symbiotic performances. In this study, three treatments evaluated in non-sterile soil conditions were investigated in both legumes: (i) non-inoculated control; (ii) inoculated with host-compatible rhizobia; and (iii) co-inoculated with host-compatible rhizobia and Azospirillum brasilense. In the more efficient and specific symbiosis with soybean, Bradyrhizobium presented a high abundance in nodules, with further increases with inoculation. Contrarily, the abundance of the main Rhizobium symbiont was lower in common bean nodules and did not increase with inoculation, which may explain the often-reported lack of response of this legume to inoculation with elite strains. Co-inoculation with Azospirillum decreased the abundance of the host-compatible rhizobia in nodules, probably because of competitiveness among the species at the rhizosphere, but increased in root microbiomes. The results showed that several other bacteria compose the nodule microbiomes of both legumes, including nitrogen-fixing, growth-promoters, and biocontrol agents, whose contribution to plant growth deserves further investigation. Several genera of bacteria were detected in root microbiomes, and this microbial community might contribute to plant growth through a variety of microbial processes. However, massive inoculation with elite strains should be better investigated, as it may affect the root microbiome, verified by both relative abundance and diversity indices, that might impact the contribution of microbial processes to plant growth.

Introduction. Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides spp. As the disease is known to affect mostly men over 40 years old who previously worked handling soil, some cities of agricultural economy in endemic regions may have more cases of paracoccidioidal infection. Gap statement. The true frequency of PCM cannot be established in Brazil because it is not a disease of mandatory reporting. The detection of paracoccidioidal infection may assist in the planning of health services, in order to provide early detection of the disease and to prevent its worsening or even progression to death. In addition, little is described about sera reactivity with antigens from different species of Paracoccidiodes, especially P. lutzii. Aim. Current research was conducted in an inland municipality of southern Brazil, in order to assess infection rate within this endemic region of PCM disease. Methodology. ELISA was employed to evaluate 359 sera from random volunteers from Guarapuava, Paraná, Brazil, to detect IgG against cell-free antigens (CFA) from P. restrepiensis B339, P. americana LDR3 and P. lutzii LDR2. Confirmatory ELISA employed gp43 from B339. Reduction of cross-reactions was sought by treatment with sodium metaperiodate (SMP-CFA, SMP-gp43). Immunoblot was performed with 37 selected sera among those reactive in ELISA. Epidemiological profile was assessed by questionnaire. Results. ELISA reactivity was: CFA/SMP-CFA in general 37.3/17.8 %, B339 25.3/14.5 %, LDR3 24.5/1.4 %, LDR2 8.3/5.8 %; gp43/SMP-gp43 7.2/4.7 %. There were sera reactive with multiple CFAs. In immunoblot, five sera showed the same reaction profile with P. lutzii’s antigens as PCM disease sera. Rural residence and soil-related professions were risk factors for paracoccidioidal infection. Conclusion. The low prevalence is in accordance with previous reports of lower PCM disease endemicity in Guarapuava than in other areas of Paraná. Although P. brasiliensis seems to be the prevalent strain of the region, 21 sera from people who only lived in Guarapuava reacted with P. lutzii LDR2. CFA-ELISA with whole antigens seems a good option for serological screening in epidemiological surveys.

Arthrographis kalrae é um fungo dimórfico, patógeno humano oportunista. Os modelos experimentais em camundongos Swiss e BALBc infectados pelo fungo A. kalrae tem demonstrado lesões em diversos órgãos (rins, fígado, pulmões, baço, cérebro) e. efeito neurológico com alteração de comportamento. Neste trabalho foi proposto analisar alteração comportamental, grau de infecção e resposta imune humoral em camundongos C57BL/6, infectados com A. kalrae, bem como avaliar o efeito da infecção concomitante de A. kalrae com o fungo patogênico Paracoccidioides brasiliensis. Trinta e seis camundongos C57BL/6, machos, foram divididos em seis grupos (n=6). Cada Grupo recebeu 100µL de PBS contendo ou não fungo por via endovenosa: Grupo 1 (controle) PBS estéril, Grupo 2 P. brasiliensis (1x106 ), Grupo 3 A. kalrae (1x106 ), Grupo 4 A. kalrae (1x107 ), Grupo 5 A. kalrae (1x106 ) e P. brasiliensis (1x106 ) e Grupo 6 A. kalrae (1x10 7 ) e P. brasiliensis, (1x106 ). Após 21 dias, foi determinado o grau de infecção por Unidade Formadora de Colônia (UFC) em amostras de homogeneizado de órgãos (baço, cérebro, coração, fígado, pulmão, rim) e adicionalmente de algumas amostras de urinas. Parte das amostras de órgãos foram utilizadas para o exame histológico. Para avaliação da resposta humoral foi determinado o nível sérico de IgG anti-A. kalrae utilizando Elisa. Os resultados obtidos demonstraram UFC positiva para baço, cérebro, coração, fígado, pulmão e rim, porém sem diferença significativa entre os grupos (p > 0,05). Duas amostras de urina demonstraram positividade em UFC, apresentando características morfológicas de A. kalrae. Nenhum camundongo infectado com A. kalrae demonstrou alteração comportamental. A histologia comprovou a presença de A. kalrae e A. kalrae + P. brasiliensis nos órgãos de camundongos mono e com infecção associada, respectivamente. Elisa resultou em nível significativamente elevado de IgG anti A.kalrae no grupo infectado com A. kalrae 1x107 em relação ao 1x106 (p < 0,05) porém sem diferença significativa em relação aos grupos concomitantemente infectados (p > 0,05). Em conclusão, camundongo da linhagem C57BL/6 é susceptível à infecção sistêmica com A. kalrae; porém resistente quanto à alteração comportamental. A resposta imune humoral anti-A. kalrae em camundongos C57BL/6 é dependente da concentração de A. kalrae inoculado, mas não é influenciado pela infecção concomitante com P. brasiliensis. Este trabalho demonstra pela primeira vez a presença de A. kalrae em urina de camundongo infectado, evidenciando a possibilidade de ocorrer eliminação do referido fungo via urinária. Arthrographis kalrae is a dimorphic fungus and an opportunistic human pathogen. The experimental models of infection with A. kalrae of Swiss and BALBc mice have demonstrated lesion in many organs (kidneys, liver, lungs, spleen and brain) and neurologic effect with behavior changes. Current research aimed to analyze behavior changes, level of infection and the humoral immune response of C57BL/6 mice, infected with A. kalrae, and also to evaluate the effect of coinfection of A. kalrae and the pathogenic fungus Paracoccidioides brasiliensis. Thirty-six C57BL/6 male mice were divided in six groups (n=6). Each group received, endovenously, 100 µL of PBS, with or without the fungi: Group 1 (control) sterile PBS; Group 2 P. brasiliensis (1x106 ), Group 3 A. kalrae (1x106 ); Group 4 A. kalrae (1x107 ); Group 5 A. kalrae (1x106 ); and P. brasiliensis (1x106 ); Group 6 A. kalrae (1x107 ) and P. brasiliensis, (1x106 ). After 21 days, the level of infection was evaluated by Colony Forming Units (CFU) of homogenates of organs (spleen, brain, heart, liver, lung, kidney) and additionally of some urine samples. Samples of the organs were histologically examined. The evaluation of humoral response was by the serum level of IgG anti-A. kalrae by ELISA. There were positive UFC in spleen, brain, heart, liver, lung and kidney, though without significant difference between groups (p > 0.05). Two urine samples had positive UFC, with morphological characteristics of A. kalrae. No mouse infected with A. kalrae presented behavior changes. Histology confirmed the presence of A. kalrae and A. kalrae + P. brasiliensis in the organs of mice mono and coinfected, respectively. ELISA resulted in a significantly higher level of IgG anti-A. kalrae in the group infected with A. kalrae 1x107 in comparison to 1x106 (p < 0.05), but without difference to the coinfected groups (p > 0.05). In conclusion, the C57BL/6 mouse is susceptible to the systemic infection with A. kalrae; notwithstanding, it is resistant to the behavior changes. The humoral immune response anti-A. kalrae in C57BL/6 mice depends on the concentration of the inoculated A. kalrae, but it is not affected by the coinfection with P. brasiliensis. Current research demonstrates, for the first time, the presence of A. kalrae in the urine of infected mice, which indicates the possible elimination of the fungus through the urinary tract.