Potential for biocontrol of melanized fungi by actinobacteria isolated from intertidal region of Ilha Do Mel, Paraná, Brazil

Abstract Actinobacteria occur in many environments and have the capacity to produce secondary metabolites with antibiotic potential. Identification and taxonomy of actinobacteria that produce antimicrobial substances is essential for the screening of new compounds, and sequencing of the 16S region of ribosomal DNA (rDNA), which is conserved and present in all bacteria, is an important method of identification. Melanized fungi are free-living organisms, which can also be pathogens of clinical importance. This work aimed to evaluate growth inhibition of melanized fungi by actinobacteria and to identify the latter to the species level. In this study, antimicrobial activity of 13 actinobacterial isolates from the genus Streptomyces was evaluated against seven melanized fungi of the genera Exophiala, Cladosporium, and Rhinocladiella. In all tests, all actinobacterial isolates showed inhibitory activity against all isolates of melanized fungi, and only one actinobacterial isolate had less efficient inhibitory activity. The 16S rDNA region of five previously unidentified actinobacterial isolates from Ilha do Mel, Paraná, Brazil, was sequenced; four of the isolates were identified as Streptomyces globisporus subsp. globisporus, and one isolate was identified as Streptomyces aureus. This work highlights the potential of actinobacteria with antifungal activity and their role in the pursuit of novel antimicrobial substances.

Potential for biocontrol of melanized fungi by actinobacteria isolated from intertidal region of Ilha Do Mel, Paraná, Brazil.

Actinobacteria occur in many environments and have the capacity to produce secondary metabolites with antibiotic potential. Identification and taxonomy of actinobacteria that produce antimicrobial substances is essential for the screening of new compounds, and sequencing of the 16S region of ribosomal DNA (rDNA), which is conserved and present in all bacteria, is an important method of identification. Melanized fungi are free-living organisms, which can also be pathogens of clinical importance. This work aimed to evaluate growth inhibition of melanized fungi by actinobacteria and to identify the latter to the species level. In this study, antimicrobial activity of 13 actinobacterial isolates from the genus Streptomyces was evaluated against seven melanized fungi of the genera Exophiala, Cladosporium, and Rhinocladiella. In all tests, all actinobacterial isolates showed inhibitory activity against all isolates of melanized fungi, and only one actinobacterial isolate had less efficient inhibitory activity. The 16S rDNA region of five previously unidentified actinobacterial isolates from Ilha do Mel, Paraná, Brazil, was sequenced; four of the isolates were identified as Streptomyces globisporus subsp. globisporus, and one isolate was identified as Streptomyces aureus. This work highlights the potential of actinobacteria with antifungal activity and their role in the pursuit of novel antimicrobial substances.

Qualidade microbiológica da água e dialisato em clínicas de hemodiálise do Sul do Brasil / Microbiological quality of water and dialysate from haemodialysis units in Southern Brazil

Infectious diseases in renal patients may be associated with the dialysis water quality, which may be contaminated with microorganisms. In Brazil, the water quality is evaluated by analyzing total coliforms, heterotrophic bacteria, and bacterial endotoxin, but not Pseudomonas sp. and fungi. Water samples from haemodialysis units in Curitiba/PR were investigated on their conformity with the standard established by the Brazilian Health Ministry. Total coliforms, heterotrophic bacteria,P. aeruginosa and fungi counts were performed according to APHA, and LAL methodology for detecting bacterial endotoxin. All of the samples showed the total coliforms counts ≤1.1 MPN/100 mL,and ≥ 95 % of analyzed samples complied with the standards for heterotrophic bacteria counting.P. aeruginosa was recovered from 4 % of samples. In 15 % of samples, bacterial endotoxin was detected in values above the limit established by legislation. Yeasts were isolated from 26 % samples and filamentous fungi from 58 %, being 46 % characterized as melanized fungi. The fungi genera were Cladosporium spp., Penicillium spp., Beauveria spp., Exophiala spp., Fusarium spp., Aspergillus spp., Trichoderma spp, Acremonium spp. and Rinocladiella spp.. The study highlights the significance ofP. aeruginosa and fungi detection in those systems, as these microorganisms are potentially pathogenic to immunocompromised patients...

Black yeasts-like fungi isolated from dialysis water in hemodialysis units.

Hemodialysis in patients with chronic renal failure promotes the removal of toxic substances, water, and minerals from the body and often takes place in specialized clinics. Microbial contamination of dialysis fluid is a serious problem in therapy. One of the sources of contamination is the water used to prepare the dialysate. In Brazil, legislation regulating the microbiological quality of water for dialysis does not cover waterborne microbes such as Pseudomonas, mycobacteria, and fungi. The aim of the present study was to quantify, isolate, and identify fungi present in water systems in six hemodialysis units in Curitiba, Paraná state, Brazil. Fungi were analyzed by surface plating and membrane filtration. Isolates were identified by morphology, while the dematiaceous fungi were identified by sequencing the rDNA ITS region. It was found that 66 % of the samples presented fungi, while black fungi were present in 46 % of all samples. Twenty-eight isolates from treated water for dialysis and dialysate were identified by sequencing and were found to be Exophiala pisciphila, E. cancerae, E. equina, and Rhinocladiella similis. The presence of dematiaceous fungi may pose a risk for debilitated hospitalized patients.