RESUMO
Aspergillus sydowii is a moderate halophile fungus extensively studied for its biotechnological potential and halophile responses, which has also been reported as a coral reef pathogen. In a recent publication, the transcriptomic analysis of this fungus, when growing on wheat straw, showed that genes related to cell wall modification and cation transporters were upregulated under hypersaline conditions but not under 0.5 M NaCl, the optimal salinity for growth in this strain. This led us to study osmolyte accumulation as a mechanism to withstand moderate salinity. In this work, we show that A. sydowii accumulates trehalose, arabitol, mannitol, and glycerol with different temporal dynamics, which depend on whether the fungus is exposed to hypo- or hyperosmotic stress. The transcripts coding for enzymes responsible for polyalcohol synthesis were regulated in a stress-dependent manner. Interestingly, A. sydowii contains three homologs (Hog1, Hog2 and MpkC) of the Hog1 MAPK, the master regulator of hyperosmotic stress response in S. cerevisiae and other fungi. We show a differential regulation of these MAPKs under different salinity conditions, including sustained basal Hog1/Hog2 phosphorylation levels in the absence of NaCl or in the presence of 2.0 M NaCl, in contrast to what is observed in S. cerevisiae. These findings indicate that halophilic fungi such as A. sydowii utilize different osmoadaptation mechanisms to hypersaline conditions.
RESUMO
BACKGROUND: Avian coccidiosis is a disease caused worldwide by several species of parasite Eimeria that causes significant economic losses. This disease affects chickens development and production, that most of times is controlled with anticoccidial drugs. Although efforts have been made to address this disease, they have been made to control Eimeria sporozoites, although enteric stages are often vulnerable, however; the parasite oocyst remains a problem that must be controlled, as it has a resistant structure that facilitates dispersion. Despite some commercial products based on chemical compounds have been developed as disinfectants that destroy oocysts, the solution of the problem remains to be solved. RESULTS: In this work, we assessed in vitro anticoccidial activity of a compound(s) secreted by yeast isolated in oocysts suspension from infected chickens. The yeast was molecularly identified as Meyerozyma guilliermondii, and its anticoccidial activity against Eimeria tenella oocysts was assessed. Here, we report the damage to oocysts walls caused by M. guilliermondii culture, supernatant, supernatant extract and intracellular proteins. In all cases, a significant decreased of oocysts was observed. CONCLUSIONS: The yeast Meyerozyma guilliermondii secretes a compound with anticoccidial activity and also has a compound of protein nature that damages the resistant structure of oocyst, showing the potential of this yeast and its products as a feasible method of coccidiosis control.
