Comparative genome analysis proposes three new Aureobasidium species isolated from grape juice.

Aureobasidium pullulans is the most abundant and ubiquitous species within the genus and is also considered a core component of the grape juice microflora. So far, a small number of other Aureobasidium species have been reported, that in contrast to A. pullulans, appear far more constrained to specific habitats. It is unknown whether grape juice is a reservoir of novel Aureobasidium species, overlooked in the course of conventional morphological and meta-barcoding analyses. In this study, eight isolates from grape juice taxonomically classified as Aureobasidium through ITS sequencing were subjected to whole-genome phylogenetic, synteny and nucleotide identity analyses, which revealed three isolates to likely represent newly discovered Aureobasidium species. Analyses of ITS and metagenomic sequencing datasets show that these species can be present in grape juice samples from different locations and vintages. Functional annotation revealed the Aureobasidium isolates possess the genetic potential to support growth on the surface of plants and grapes. However, the loss of several genes associated with tolerance to diverse environmental stresses suggest a more constrained ecological range than A. pullulans.

Broad Diversity of Fungi in Hospital Water.

INTRODUCTION: Some studies have reported the occurrence of microorganisms isolated from water. Considering these microorganisms, fungi are known to occur ubiquitously in the environment, including water, and some are pathogenic and may cause health problems, especially in immunocompromised individuals. The aim of this study was to identify fungi in hospital water samples and to correlate their presence with the concentration of free residual chlorine. METHODS: Water samples (100 mL) were collected from taps (n = 74) and water purifiers (n = 14) in different locations in a university hospital. Samples were filtered through a nitrocellulose membrane and placed on Sabouraud dextrose agar and incubated for 24 hours at 30°C. Fungi were identified according to established methods based on macroscopic and microscopic characteristics (filamentous) and physiological tests (yeasts). Free chlorine residual content was measured at the time of sample collection. RESULTS: Seventy species of fungi were identified in the water samples and about 56% of the water samples contained culturable fungi. Cladosporium oxysporum, Penicillium spinulosum, and Aspergillus fumigatus were the most common filamentous fungi. Aureobasidium pullulans and Candida parapsilosis were the most common yeasts. Chemical analyses revealed that free residual chlorine was present in 81.8% of the samples within recommended concentrations. Among samples from water purifiers, 92.9% showed low levels of free residual chlorine (<0.2 mg/L). There was no significant association between chlorine concentrations (either within or outside the recommended range) and the presence of filamentous fungi and yeasts. CONCLUSIONS: This study showed that hospital water can be a reservoir for fungi, some of which are potentially harmful to immunocompromised patients. Free residual chlorine was ineffective in some samples.

Antifungal Mechanism of Rhodotorula mucilaginosa and Aureobasidium sp. nov. Isolated from Cerbera manghas L. against the Growth of Destructive Molds in Post Harvested Apples.

BACKGROUND: Apples often experience postharvest damage due to being attacked by mold organisms. Several groups of molds such as Aspergillus sp., Penicilium expansum, Botrytis cinerea, and Venturia sp. can cause a serious postharvest disease exhibited as watery regions where areas of blue-green tufts of spores develop. Current methods using fungicides to control pathogenic fungi can cause resistance if applied in the long term. An alternative procedure using yeast as a biological agent has been found. OBJECTIVE: The aim of this study is to screen potential yeast, which has the ability to inhibit the growth of Aspergillus brasielensis (isolate A1) and Aspergillus flavus section flavi (isolate A17) isolated from apple fruits. METHODS: Antagonism test using YMA dual culture medium using in vitro assays and ITS rDNA identification were performed. RESULTS: The result showed that 3 out of 19 yeast isolated from Cerbera manghas L, T1, T3 and T4, demonstrated the potential ability as a biocontrol agent. ITS rDNA identification demonstrated that T1 has a similarity to Rhodotorula mucilaginosa while T3 and T4 were identified as Aureobasidium sp. nov. The 3 isolates exhibited the ability to reduce the growth of A. brasiliensis sensu lato better than dithane 0.3% with a Disease Incidence (DI) of 100% and a Disease Severity (DS) value of 45%. Only isolate T1 and T3 were able to reduce decay symptoms in apples inoculated with A. flavus sensu lato (with DO and DS were 100% and 25%, respectively) compared to dithane pesticides 0.3%. CONCLUSION: This study indicated that competition between nutrients occurs between pathogenic molds and under-yeast in vitro and in vivo conditions. However, further studies in the future might be able to elucidate the 'killer' activity and interaction with the pathogen cells and the bio-product production using Rhodotorula mucilaginosa and Aureoubasidium namibiae strains to control postharvest diseases.