Effects of Temperature and Humidity on Fungal Occurrence in Dried Red Pepper during Storage

Dried red peppers are frequently contaminated with mycotoxins during storage. To determine the effect of storage environments on fungal occurrence and subsequent mycotoxin accumulation in dried red peppers, we monitored red pepper powder and whole fruit samples for fungal occurrence under various temperatures and relative humidity (RH) conditions during 340 days. Fungal occurrences fluctuated in both pepper forms throughout the storage but they were higher in pepper powder than whole one, higher under low temperatures (-20°C, 0°C, or 4°C) than others (10°C, 25°C, or 30°C), and higher under RH 93% than RH 51% and 69% in both peppers. The samples exhibiting high fungal occurrences were associated mainly with dominant species such as Aspergillus sydowii, Penicillium solitum, P. roqueforti, P. polonicum, or P. chrysogenum. Mycotoxigenic species, including A. flavus, A. ochraceus, A. westerdijkiae, A. tubingensis, and P. citrinum, were also detected throughout the samples. Although mycotoxins were not detected in the samples, mycotoxigenic potential of A. flavus, A. ochraceus, and A. westerdijkiae isolates were confirmed. These results show that low temperatures (-20°C, 0°C, or 4°C) and/or high surrounding RH (>93%) are not safe environments for storage of dried red peppers as fungal growth can occur under these conditions.

Endoglucanase Activity of Novel Aspergillus sydowii Isolate WIU-01 and Application for Hydrophyte Degradation

<p>Many eutrophic lakes contain rapidly growing hydrophytes. Overgrown biomass is usually me-chanically harvested and thrown away, leading to resource waste and secondary environmental pollution. Microbial degradation is an economically and environmentally friendly approach for managing hydrophytic waste, fuelling the search for efficient biomass degraders. Here, we present isolation and characterization of Aspergillus sydowii WIU-01, a novel cellulolytic fungus. Strain WIU-01 was isolated from air. The degradation rate (29.75 vs. 21.95%) and endoglucanase activi-ty (0.31 vs. 0.16 U mL–1) of the fungus were higher in Canna indica (emergent plant) medium than in Hydrilla verticillata (submerged plant) medium, accordingly. Further, fungal endoglucanase ac-tivity was significantly positively correlated with the degradation rate, neutral detergent fiber con-tent, and acid detergent fiber content of hydrophyte powder. Fungal biomass was significantly negatively correlated with reducing sugar and cellulose content of hydrophyte medium, but was significantly positively correlated with hemicellulose, acid detergent lignin, and ash content of the medium. Collectively, these observations indicate that A. sydowii decomposes emergent and sub-merged plant mass without acid–base sample pretreatment, albeit its endoglucanase activity is rela-tively low. This highlights the role of cellulolytic microorganisms in the natural environment and the notion that the environment can be a source of cellulolytic microorganisms for potential envi-ronmentally friendly applications.</p>

Keratinases Produced by Aspergillus stelliformis, Aspergillus sydowii, and Fusarium brachygibbosum Isolated from Human Hair: Yield and Activity

Twenty fungal strains belonging to 17 species and isolated from male scalp hair were tested for their capacity to hydrolyze keratinous material from chicken feather. The identification of the three most efficient species was confirmed by sequencing of the internal transcribed spacer (ITS) region of rDNA. Activities of fungal keratinases produced by Aspergillus stelliformis (strain AUMC 10920), A. sydowii (AUMC 10935), and Fusarium brachygibbosum (AUMC 10937) were 113, 120, and 130 IU mg−1 enzymes, respectively. The most favorable conditions were at pH 8.0 and 50 °C. Keratinase activity was markedly inhibited by EDTA and metal ions Ca+2, Co+2, Ni+2, Cu+2, Fe+2, Mg+2, and Zn+2, with differences between the fungal species. To the best of our knowledge, this is the first study on the activity of keratinase produced by A. stelliformis, A. sydowii, and F. brachygibbosum. F. brachygibbosum keratinase was the most active, but the species is not recommended because of its known phytopathogenicty. Aspergillus sydowii has many known biotechnological solutions and here we add another application of the species, as producer of keratinases. We introduce A. stelliformis as new producer of active fungal keratinases for biotechnological solutions, such as in the management of keratinous waste in poultry industry.

Osmolyte Signatures for the Protection of Aspergillus sydowii Cells under Halophilic Conditions and Osmotic Shock

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.

Fungus-mediated green synthesis of nano-silver using Aspergillus sydowii and its antifungal/antiproliferative activities

Due to the increasing demand for eco-friendly, cost-effective and safe technologies, biosynthetic metal nanoparticles have attracted worldwide attention. In this study, silver nanoparticles (AgNPs) were extracellularly biosynthesized using the culture supernatants of Aspergillus sydowii. During synthesis, color change was preliminarily judge of the generation of AgNPs, and the UV absorption peak at 420 nm further confirms the production of AgNPs. Transmission electron microscopy and X-ray diffraction were also used to identify the AgNPs. The results shows that AgNPs has crystalline cubic feature and is a polydisperse spherical particle with size between 1 and 24 nm. Three main synthesis factors (temperature, pH and substrate concentration) were optimized, the best synthesis conditions were as follows 50 °C, 8.0 and 1.5 mM. In the biological application of AgNPs, it shows effective antifungal activity against many clinical pathogenic fungi and antiproliferative activity to HeLa cells and MCF-7 cells in vitro. Our research finds a new path to biosynthesis of AgNPs in an eco-friendly manner, and bring opportunity for biomedical applications in clinic.

Avaliação microbiológica de ovos revestidos com nanobiopolímero a base de isolado proteico de soro

O ovo é um alimento proteico barato e acessível, mas que está sujeito a contaminação microbiológica, acarretando perigo potencial aos consumidores, principalmente se Salmonella estiver presente. Fungos também representam sério problema para a qualidade de ovos, podendo levar à rejeição pelo consumidor. Visando solucionar este problema, desenvolveu-se um revestimento a base de isolado proteico de soro de leite (IPS) com nanopartículas de montmorilonita adicionado do agente antimicrobiano metabissulfito de sódio. A pesquisa objetivou avaliar a atividade antimicrobiana do revestimento contra Salmonella Enteritidis, Aspergillus sydowii e Penicillium paxilli quando aplicado em ovos brancos. Não houve diferença significativa (p > 0,05) entre as populações de S. Enteritidis das cascas revestidas e sem revestimento. A. sydowii e P. paxilli apresentaram crescimento tanto nas cascas de ovos sem revestimento quanto nas cascas de ovos revestidos, evidenciando que o revestimento não foi capaz de inibi-los nas condições testadas. Conclui-se que o revestimento desenvolvido não apresenta atividade antimicrobiana contra S. Enteritidis, A. sydowii e P. paxilli nas condições testadas.

Genome sequence analysis of deep sea Aspergillus sydowii BOBA1 and effect of high pressure on biodegradation of spent engine oil

A deep-sea fungus Aspergillus sydowii BOBA1 isolated from marine sediment at a depth of 3000 m was capable of degrading spent engine (SE) oil. The response of immobilized fungi towards degradation at elevated pressure was studied in customized high pressure reactors without any deviation in simulating in situ deep-sea conditions. The growth rate of A. sydowii BOBA1 in 0.1 MPa was significantly different from the growth at 10 MPa pressure. The degradation percentage reached 71.2 and 82.5% at atmospheric and high pressure conditions, respectively, within a retention period of 21 days. The complete genome sequence of BOBA1 consists of 38,795,664 bp in size, comprises 2582 scaffolds with predicted total coding genes of 18,932. A total of 16,247 genes were assigned with known functions and many families found to have a potential role in PAHs and xenobiotic compound metabolism. Functional genes controlling the pathways of hydrocarbon and xenobiotics compound degrading enzymes such as dioxygenase, decarboxylase, hydrolase, reductase and peroxidase were identified. The spectroscopic and genomic analysis revealed the presence of combined catechol, gentisate and phthalic acid degradation pathway. These results of degradation and genomic studies evidenced that this deep-sea fungus could be employed to develop an eco-friendly mycoremediation technology to combat the oil polluted marine environment. This study expands our knowledge on piezophilic fungi and offer insight into possibilities about the fate of SE oil in deep-sea.