Aspergillus Ruber Research Articles

Bioturbation effect of high - Yield pyrazine strain on the microbial community and flavour metabolites of fortified Daqu

In order to comprehensively explore the regulatory effect of bioturbation on the assembly and overall metabolic characteristics of Daqu microbial community. This study used metatranscriptomics and metabolomics to investigate the composition of the microbial community, physicochemical properties, and overall metabolic profile of Daqu before and after bioturbation by Bacillus velezensis. The results demonstrated that the acidity, moisture, amino acid nitrogen, and starch content of Daqu exhibited a significant increase following bioturbation. The symbol microorganisms of Daqu have also changed significantly, from the original Aspergillus chevalieri, Rasamsonia emersonii, Aspergillus ruber, Aspergillus glaucus, Aspergillus wentii and Aspergillus cristatus to Paecilomyces varioti, Trichomonascus ciferrii and Staphylococcus gallinarum. Correlation analyses and integration pathways indicated that altered microbial community abundance also promoted the metabolism of starch, ethanol, fatty acids, and pyrazine, resulting in a significant enhancement of Daqu's saccharification and liquefaction power, as well as the content of some volatile and non-volatile metabolites, with pyrazines increased by 24.50%. The application of fortified Daqu to Baijiu fermentation can significantly enhance the content of various pyrazines in Baijiu. These results are helpful to elucidate the mechanism of biochemical changes, microbial assembly and flavor production of Daqu after biodisturbance.

Re-identification of Strains from Aspergillus Section Aspergillus and Description of Three Unrecorded Species from Korea

The section Aspergillus includes xerophilic fungi that are economically significant and broadly distributed in natural settings as well as human habitats and are recognized for their sustenance on substrates with low water activity. Accurate identification of fungal species is essential for any reliable advances in mycological research. In this study, 108 strains from the section Aspergillus, originating from Korea and conserved at the Korean Agricultural Culture Collection, were subjected to re-identification using a combined dataset that included partial sequences of β-tubulin (BenA), Calmodulin (CaM), and RNA polymerase II second largest subunit (RPB2) genes, along with their morphological characteristics. We confirmed the presence of 12 species among the 108 strains originally isolated from Korea. Of them, nine species have been formerly reported in Korea (Aspergillus chevalieri, Aspergillus cibarius, Aspergillus cumulatus, Aspergillus glaucus, Aspergillus montevidensis, Aspergillus proliferans, Aspergillus pseudoglaucus, Aspergillus ruber, and Aspergillus tonophilus), and 3 species (Aspergillus aurantiacoflavus, Aspergillus intermedius, and Aspergillus niveoglaucus) were found to be previously unreported to be isolated from Korea. Here, the detailed characteristic features of these three unexplored species are presented, including specific morphological traits, genetic variations, and ecological niches in Korea.

Insight into the Relationship between the Causes of Off-Odour and Microorganism Communities in Xuanwei Ham.

To expound on the correlation between the microorganism communities and the formation of off-odour in Xuanwei ham, the microorganism communities and volatile compounds were investigated in the biceps femoris (BF) and semimembranosus (SM) of Xuanwei ham with different quality grades (normal ham and spoiled ham). The single molecule real-time sequencing showed that differential bacteria and fungi were more varied in normal hams than in spoiled hams. Headspace solid-phase microextraction-gas chromatography (HS-SPME-GC-MS) results indicated that aldehydes and alcohols were significantly higher in spoiled hams than those in normal hams (p < 0.05). The off-odour of spoiled hams was dominated by ichthyic, malodourous, sweaty, putrid, sour, and unpleasant odours produced by compounds such as trimethylamine (SM: 13.05 μg/kg), hexanal (BF: 206.46 μg/kg), octanal (BF: 59.52 μg/kg), methanethiol (SM: 12.85 μg/kg), and valeric acid (BF: 15.08 μg/kg), which are positively correlated with Bacillus cereus, Bacillus subtilis, Bacillus licheniformis, Pseudomonas sp., Aspergillus ruber, and Moraxella osloensis. Furthermore, the physicochemical property and quality characteristics results showed that high moisture (BF: 56.32 g/100 g), pH (BF: 6.63), thiobarbituric acid reactive substances (TBARS) (SM: 1.98 MDA/kg), and low NaCl content (SM: 6.31%) were also responsible for the spoilage of hams with off-odour. This study provided a deep insight into the off-odour of Xuanwei ham from the perspective of microorganism communities and a theoretical basis for improving the flavour and overall quality of Xuanwei hams.

Pathogenic bacteria and fungi in bioaerosols from specialized hospitals in Shandong province, East China

Bacteria and fungi are abundant and ubiquitous in bioaerosols in hospital environments. Understanding the distribution and diversity of microbial communities within bioaerosols is critical for mitigating their detrimental effects. Our knowledge on the composition of bacteria or fungi in bioaerosols is limited, especially the potential pathogens present in fine particulate matter (PM2.5) from specialized hospitals. Thirty p.m.2.5 filter samples were collected from five hospitals (i.e., oral, dermatology, chest, eye, and general hospitals) in Shandong Province, East China. The diversity of bacteria and fungi was analyzed at the species level using single-molecule real-time sequencing of the 16 S and internal transcribed spacer 1 (ITS) ribosomal genes, respectively. Significant differences were detected across sampling sites in terms of microbial diversity and community composition in PM2.5 as well as pollution concentrations. The range of PM2.5 concentrations observed in hospital halls was higher, ranging from 39.0 to 46.2 μg/m3, compared to the wards where the concentrations ranged from 10.7 to 25.2 μg/m3. Furthermore, microbial variations in PM2.5 bioaerosols were associated with hospital type. The most dominant pathogens identified were Vibrio metschnikovii, Staphylococcus epidermidis, Staphylococcus haemolyticus, Fusarium pseudensiforme, and Aspergillus ruber. Among these, A. ruber was identified as an opportunistic fungus in a hospital setting for the first time. Nine potentially novel strains of F. pseudensiforme, showing 84.5%–92.0% ITS sequence similarity to known Fusarium isolates, were identified in PM2.5 samples from all hospitals (excluding an eye hospital). This study highlights the importance of hospital environments in shaping microbial aerosol communities. To the best of our knowledge, this is the first study to provide insights into the bacterial and fungal biodiversity of PM2.5 in specialized hospitals, enriching research in healthcare environmental microbiology and carrying significant public health implications.

Growth/no-growth models of propionic and sorbic acid for bread and cake moulds

Propionic and sorbic acid are very effective weak-organic acid preservatives in bakery products. Their pH-dependent antifungal activity, the role of undissociated acid and the importance of the aqueous phase was studied. Besides looking for new natural preservation techniques the gain of further knowledge on their activity is still highly relevant to tackle the problem of food waste. In this study, the susceptibility of spoilage moulds for propionic (PA) and sorbic acid (SA) was tested in-vitro and in bread and cake. Aspergillus niger, Aspergillus montevidensis, Aspergillus ruber, Cladosporium ramotenellum, Penicillium brevicompactum and Penicillium roqueforti were subjected to PA and SA, both through macrodilution on malt extract agar (MEA) plates with adjusted aw (0.93, 0.95, 0.97), pH (5, 5.5, 6.0), acid (max. 2000 mg/L MEA), and through validation in wheat bread (max. 2901 mg PA/kg) and (lemon) cake (max. 1988 mg SA/kg). The undissociated acid concentrations (CHA) were estimated using either the Henderson-Hasselbalch (HH) equation or two modified HH equations. The influence of the food matrix (liquid oil, water, pH, aw), partitioning coefficient of the acids and spoilage fungi were evaluated and results were compared with in-vitro predictive models. In bread, the regular HH eq. proved to have good predictive power of CHA, whereas in cake a modified HH eq. (model 2) had better performance due to the inclusion of potential loss of CHA in the oil phase of complex food systems. The minimal inhibitory concentration (MIC) of PA in bread, after 30 days, was higher than 2901 mg/kg bread due to the strong resistance of P. brevicompactum, P. roqueforti and A. montevidensis. MIC of SA in lemon cake was 1429 mg SA/kg (pH 5.2), whereas in standard cake with pH 7.2, the max. level of 1988 mg SA/kg was insufficient for postponing mould growth to 30 days. The pH of cake had no influence on MIC of SA against A. niger and A. rubrum, whereas this effect was seen for C. ramotenellum, P. brevicompactum and P. roqueforti.

A Pair of New Spirocyclic Alkaloid Enantiomers with TrxR Inhibitory Activities Were Isolated from Marine-Derived Aspergillus ruber TX-M4-1

A Pair of New Spirocyclic Alkaloid Enantiomers with TrxR Inhibitory Activities Were Isolated from Marine-Derived Aspergillus ruber TX-M4-1

Friend or Foe? The Endophytic Fungus Alternaria tenuissima Might Be a Major Latent Pathogen Involved in Ginkgo Leaf Blight

Ginkgo leaf blight, one of the most economically important ginkgo diseases, has become very prevalent in many places in China. Flavonoids and endophytes are both considered important in ginkgo plant functioning. However, little is known about the potential relationships among ginkgo leaf blight pathogens, flavonoid accumulation profiles in infected leaves, and ginkgo leaf endophytes. In this study, the flavonoid accumulation profiles in infected leaves, pathogens of ginkgo leaf blight, and the endophytes of healthy ginkgo leaves were characterized. The levels of total flavonoids in the healthy parts of the infected leaves were significantly higher than those in the healthy leaves. Furthermore, Alternaria tenuissima, Botryosphaeria dothidea, and Dothiorella gregaria were identified as pathogens of ginkgo leaf blight; among them, A. tenuissima was the major pathogen. The in vitro experiments showed that flavonoids (apigenin, luteolin, and kaempferol) could significantly inhibit the growth of one or more pathogens at a concentration of 10 mg/L. Furthermore, fifty-six ginkgo leaf endophytic fungi (GLEF) from healthy ginkgo plants were isolated and characterized. Among them, Alternaria spp. were the most abundant, and GLEF55 shared the same ITS sequence with the pathogen Alternaria tenuissima. Thereafter, four flavonoid-producing endophytes were selected and their effects on the growth of pathogens were evaluated. The extracts of GLEF55 could significantly inhibit the growth of the pathogens B. dothidea and D. gregaria simultaneously in vitro, but not the growth of the pathogen A. tenuissima. Furthermore, the dual cultures of the candidate GLEF and ginkgo leaf blight pathogens revealed that GLEF55 had a similar growth rate to that of A. tenuissima and D. gregaria, but its growth rate was significantly slower than that of B. dothidea. Finally, the GLEF exhibited variable roles when facing pathogens in ginkgo leaves. Among them, GLEF55 showed similar pathogenicity as the pathogen A. tenuissima when they were dually cultured in ginkgo leaves. By contrast, GLEF17 (an uncultured soil fungus) could significantly counteract the pathogenic effects of A. tenuissima and D. gregaria, but it dramatically exacerbated the pathogenic effects of B. dothidea. Larger lesion areas were observed on the side of ginkgo leaves where GLEF39 (Alternaria sp.) or GLEF54 (Aspergillus ruber) and pathogens were simultaneously inoculated, which suggested that the pathogenicity of specific endophytic fungi occurred when plants were wounded. Overall, A. tenuissima, a major pathogen of ginkgo leaf blight, might lurk inside the plants as a friendly endogenous fungus and convert into a hostilely pathogenic mode at a particular time. This study proposed a possible cause of ginkgo leaf blight and provided potential theoretical guidance for its prevention.

Fungal aerosols in rabbit breeding environment: Metagenetic insight into PM2.5 based on third-generation sequencing technology

Fungal aerosols are a vital environmental hazard factor impeding the development of the rabbit breeding industry and threatening public health. This study aimed to determine fungal abundance, diversity, composition, diffusion, and variability in aerosols in rabbit breeding environments. Twenty PM2.5 filter samples were collected from five sampling sites (i.e. En5, In, Ex5, Ex15, and Ex45) in a modern rabbit farm in Linyi City, China. Fungal component diversity at the species level was analyzed in all samples using third-generation sequencing technology. Results revealed that fungal diversity and community composition in PM2.5 significantly differed across different sampling sites, and different pollution levels. The highest concentrations of PM2.5 and fungal aerosols (i.e., 102.5 μg/m3 and 18.8 × 103 CFU/m3, respectively) were found at Ex5, and these concentrations were found to decrease as the distance from the exit increased. However, no significant correlation was observed between the internal transcribed spacer (ITS) gene abundance and overall PM2.5 levels, except for Aspergillus ruber and Alternaria eichhorniae. Although most fungi are not pathogenic to humans, zoonotic pathogenic microorganisms that cause pulmonary aspergillosis (e.g., Aspergillus ruber) and invasive fusariosis (e.g., Fusarium pseudensiforme) were observed. The relative abundance of A. ruber was higher at Ex5 than that at In, Ex15, and Ex45 (p < 0.01), and the relative abundance of the fungal species decreased with an increase in distance from the rabbit houses. Moreover, four potential novel strains of Aspergillus ruber were discovered, with 82.9%–90.3% of the nucleotide and amino acid sequences similar to those of reference strains. This study highlights the importance of rabbit environments as a source in shaping fungal aerosol microbial communities. To the best of our knowledge, this is the first study to uncover the initial characteristics of fungal biodiversity and dispersion of PM2.5 in rabbit breeding environments, contributing to infectious disease control and prevention in rabbits.

SG-APSIC1085: Microbiological analysis concerning antimicrobial effect of atomized ionless hypochlorous acid water in a hospital environment

Objectives: We evaluated the disinfecting efficacy of atomized ionless hypochlorous acid water (CLFine) against pathogenic microorganisms in an isolation room. Methods: The study was conducted in an isolation room of Kurume University Hospital. CLFine with available chlorine concentrations of 40 ppm and 300 ppm as test substances and purified water as control were atomized with an ultrasonic atomizer (CLmistL). The 40 ppm and 300 ppm of CLFine were atomized at the atmospheric available chlorine concentrations of ~0.03 ppm and 0.1~0.2 ppm, respectively, and purified water was atomized in the same manner as CLFine. Petri dishes with Staphylococcus aureus, Bacillus cereus spores, Bacillus subtilis spores and Aspergillus ruber were allocated in the room, then CLFine or purified water was atomized. Sampling was performed at 3 and 5 hours after the start of atomization, and the bacterial counts were measured. The study was carried out either with air conditioning turned “on” or “off” because atmospherically available chlorine concentration is affected by ventilation. Results: When the air conditioning was turned on, purified water showed a slight reduction of bacterial counts by 0.9 log or less at 5 hours after the atomization. When CLFine was used, 40 ppm greatly reduced the counts of Staphylococcus aureus by 5.1~5.4 logs reduction at 5 hours after the atomization, but no distinctive efficacy was observed against other microorganisms. On the other hand, 300 ppm caused a significant reduction of the bacterial counts for all the microorganisms at 5 hours after the atomization (P &lt; .001 vs purified water). The same results were observed in the environment with the air conditioning turned off. Conclusions: Our data suggest that CLFine effectively disinfects pathogenic microorganisms and can contribute to maintaining the hygienic environment of hospital rooms. This study was funded as contracted research by NIPRO Corporation with the approval of the ethics committee (study no. 21229).

Bacterial and fungal communities in indoor aerosols from two Kuwaiti hospitals.

The airborne transmission of COVID-19 has drawn immense attention to bioaerosols. The topic is highly relevant in the indoor hospital environment where vulnerable patients are treated and healthcare workers are exposed to various pathogenic and non-pathogenic microbes. Knowledge of the microbial communities in such settings will enable precautionary measures to prevent any hospital-mediated outbreak and better assess occupational exposure of the healthcare workers. This study presents a baseline of the bacterial and fungal population of two major hospitals in Kuwait dealing with COVID patients, and in a non-hospital setting through targeted amplicon sequencing. The predominant bacteria of bioaerosols were Variovorax (9.44%), Parvibaculum (8.27%), Pseudonocardia (8.04%), Taonella (5.74%), Arthrospira (4.58%), Comamonas (3.84%), Methylibium (3.13%), Sphingobium (4.46%), Zoogloea (2.20%), and Sphingopyxis (2.56%). ESKAPEE pathogens, such as Pseudomonas, Acinetobacter, Staphylococcus, Enterococcus, and Escherichia, were also found in lower abundances. The fungi were represented by Wilcoxinia rehmii (64.38%), Aspergillus ruber (9.11%), Penicillium desertorum (3.89%), Leptobacillium leptobactrum (3.20%), Humicola grisea (2.99%), Ganoderma sichuanense (1.42%), Malassezia restricta (0.74%), Heterophoma sylvatica (0.49%), Fusarium proliferatum (0.46%), and Saccharomyces cerevisiae (0.23%). Some common and unique operational taxonomic units (OTUs) of bacteria and fungi were also recorded at each site; this inter-site variability shows that exhaled air can be a source of this variation. The alpha-diversity indices suggested variance in species richness and abundance in hospitals than in non-hospital sites. The community structure of bacteria varied spatially (ANOSIM r2 = 0.181–0.243; p < 0.05) between the hospital and non-hospital sites, whereas fungi were more or less homogenous. Key taxa specific to the hospitals were Defluvicoccales, fungi, Ganodermataceae, Heterophoma, and H. sylvatica compared to Actinobacteria, Leptobacillium, L. leptobacillium, and Cordycipitaceae at the non-hospital site (LefSe, FDR q ≤ 0.05). The hospital/non-hospital MD index > 1 indicated shifts in the microbial communities of indoor air in hospitals. These findings highlight the need for regular surveillance of indoor hospital environments to prevent future outbreaks.

Pathogenicity test of sengon (Falcataria moluccana) seed-borne endophytic fungus

The sengon (Falcataria moluccana) is one of the high-economic and highly cultivated industrial plants in Indonesia. Attacks by pests and diseases can affect quality and quantity and thus require effective control. One of the rare sengon plant fungus explorations has been developed. This study aims to find out the pathogenicity of 13 seed-borne endophytic fungi from sengon seeds. The result shows that seven endophytic fungi were pathogenic (Daldinia sp, Curvularia lunata, Sardiomycetes sp. Eremothecium ashbyi, Annulohypoxylon stygium. Arthrinium malaysianum, Annulohypoxylon nitens) and six non-pathogenic (Onchroconis humicola, Cladophialophora boppii, Aspergillus ruber, Aspergillus chevalieri, Ascotricha sp., and not identified fungi). Thus the isolated endophytic fungi mainly were potentially pathogenic. Among the six species of non-pathogenic endophytic fungi, O. humicola is better able to increase the increase of plumules, radicals, cotyledons, and leaves higher than six other isolates

Mycobiome in the Middle Ear Cavity with and Without Otitis Media with Effusion.

Objective:No data have yet been published revealing the composition and the diversity of fungal communities (mycobiome) in the human middle ear cavity. The presented study investigated the mycobiome in the middle ear cavities of individuals with healthy middle ears and patients with otitis media with effusion.Methods:A total of 77 middle ear and four adenoid samples were collected from 47 individuals (35 children and 12 adults) in Group 1 and from 20 children in Group 2. The mycobiome profile was analyzed with nuclear ribosomal internal transcribed spacer 2 (ITS2) based metabarcoding using an Illumina MiSeq metagenomics kit.Results:ITS2-based metabarcoding detected 14 different genera and 17 different species with a mean relative abundance of ≥1% in the samples analyzed. Mycobiome profile was similar between the adenoid tissue and the middle ear cavity, between Groups 1 and Group 2, and between children and adults. Fusarium, Stemphylium, Candida, and Cladosporium were the most abundant genera detected in all samples. The mean relative abundances of the genera Candida and Fusarium were remarkably higher in Group 2 compared to Group 1.Conclusion:The species Candida glaebosa, Candida cretensis, Aspergillus ruber, Penicillium desertorum, and Rhizopus arrhizus were significantly more abundant in patients with otitis media with effusion (OME), raising the possibility that they affect the pathogenesis of OME.

An Updated Review on the Secondary Metabolites and Biological Activities of Aspergillus ruber and Aspergillus flavus and Exploring the Cytotoxic Potential of Their Isolated Compounds Using Virtual Screening.

The secondary metabolites and biological activities of Aspergillus ruber and Aspergillus flavus were comprehensively reported. About 70 compounds were isolated from both species that belong to different classes using conventional and advanced chromatographic techniques and unambiguously elucidated employing one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) and high resolution mass spectrometry (HRMS). Some of them displayed promising antiviral, anti-inflammatory, and antioxidant activities. In silico studies were conducted on human cyclin-dependent kinase 2 (CDK-2), human DNA topoisomerase II (TOP-2), and matrix metalloprotinase 13 (MMP-13) in an effort to explore the cytotoxic potential of the diverse compounds obtained from both Aspergillus species. 1,6,8-Trihydroxy-4-benzoyloxy-3-methylanthraquinone (23) revealed the most firm fitting with the active pockets of CDK-2 and MMP-13; meanwhile, variecolorin H alkaloid (14) showed the highest fitting within TOP-2 with ∆G equals to −36.51 kcal/mole. Thus, fungal metabolites could offer new drug entities for combating cancer. Relevant data about both Aspergillus species up to August 2020 were gathered from various databases comprising Scifinder (https://scifinder.cas.org/scifinder/login) for secondary metabolite-related studies; meanwhile, for biology-related articles, data were collected from both PubMed (http://www.ncbi.nlm.nih.gov/pubmed/) and Web of Knowledge (http://www.webofknowledge.com) as well.

Prenylation and Dehydrogenation of a C2-Reversely Prenylated Diketopiperazine as a Branching Point in the Biosynthesis of Echinulin Family Alkaloids in Aspergillus ruber.

The echinulin family alkaloids can be grouped into three series depending on the number of the exo double bonds adjacent to the diketopiperazine core structure. Heterologous expression of the putative echinulin biosynthetic gene cluster from Aspergillus ruber in Aspergillus nidulans led to accumulation of echinulin without a double bond and neoechinulin A with one double bond (Δ10) as major products. Their analogues with a different number of prenyl moieties were detected as minor products. Neoechinulin B and analogues with two double bonds (Δ10,14) were not observed. Feeding experiments confirmed that the cytochrome P450 enzyme EchP450 only catalyzes the formation of the double bond between C10 and C11. Coincubation and substrate concentration dependent assays with the prenyltransferase EchPT2 revealed that the reversely C2-prenylated preechinulin without a double bond is a much better substrate than neoechinulin A. These results prove that preechinulin serves as a common substrate for the formation of echinulin by two regiospecific prenylation steps with EchPT2 or for EchP450 to introduce one double bond and subsequent prenylations with low regioselectivity.

Biological control of mites by xerophile Eurotium species isolated from the surface of dry cured ham and dry beef cecina

The aim of this article is to study the possible biological control of mites by fungi that form part of the normal microbiota of these meat products. Some yellow/orange pigmented fungi growing on the ham surface decreased the proliferation of mites; therefore, we isolated from ham and cecina xerophilic yellow/orange coloured fungal strains that were identified as members of the genus Eurotium (recently reclassified as Aspergillus section Aspergillus). Using molecular genetic tools, we have identified 158 strains as Eurotium rubrum (Aspergillus ruber), Eurotium repens (Aspergillus pseudoglaucus) and Eurotium chevalieri (Aspergillus chevalieri). Two strains, E. rubrum C47 and E. rubrum C49, showed strong miticidal activity. The toxic compound(s) are associated with the formation of cleistothecia. In synchronized mite development experiments, we observed that all stages of the mite lifecycle were inhibited by the E. rubrum C47 strain. In addition, we searched for miticidal activity in 13 culture collection Eurotium strains isolated from different habitats, and found that only one, Eurotium cristatum NRRL 4222 (Aspergillus cristatus) has a strong miticidal activity. These fungal strains have proliferated on the surface of ham and cecina for decades, and possibly have acquired miticidal activity as a resistance mechanism against fungivores. Biological control of infecting mites by favouring growth of E. rubrun C47, in place of the normal mixed population of Aspergillus and Penicillium, is an attractive approach to control mite infestations.

Alkaloids including two rare variecolortides from the fungus Aspergillus ruber

Three new alkaloids, namely, (−)-(S)-variecolortide D (1a), (+)-(R)-variecolortide D (1b) and brevicompanine I (3), along with three known alkaloids (2, 4 and 5) were isolated from Aspergillus ruber WH4-1. Variecolortide D (1) is a racemic natural product composed of anthraquinone and isoechinulin alkaloid, separation of 1 by chiral HPLC, provided two optically pure enantioners (1a and 1b). The structures of all compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. 2 showed weak inhibitory activity against the production of NO in RAW264.7 cells stimulated by lipopolysaccharide (LPS), with inhibitory rate of 53.2 ± 3.8% at 30 μM.

Biosynthesis of the Prenylated Salicylaldehyde Flavoglaucin Requires Temporary Reduction to Salicyl Alcohol for Decoration before Reoxidation to the Final Product.

The biosynthetic pathway of the prenylated salicylaldehyde flavoglaucin and congeners in Aspergillus ruber was elucidated by genome mining, heterologous expression, precursor feeding, and biochemical characterization. The polyketide skeleton was released as alkylated salicyl alcohols, which is a prerequisite for consecutive hydroxylation and prenylation, before reoxidation to the final aldehyde products. Our results provide an excellent example for a highly programmed machinery in natural product biosynthesis.

Feeding Interactions Between Microorganisms and the House Dust Mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Astigmata: Pyroglyphidae)

The feeding interactions between house dust mites (HDM) and microorganisms are key factors in the survival of mites in human environments. The suitability of different microbes for HDM is not known. Here, microbial species isolated from HDM cultures were offered to HDM in food preference tests under laboratory conditions. The microbial species were added to the rearing diet of mites to reach 7% of Saccharomyces cerevisiae and 10% of each tested microorganism. The suitability of each microbe-supplemented diet for Dermatophagoides pteronyssinus and Dermatophagoides farinae was compared in terms of mite population growth and mite preference in a cafeteria test. The effect of mite feeding on the respiration of microorganisms in the diet was observed in microcosms. HDM were able to feed and reproduce on some bacterial and fungal species, but the suitability of microbial species differed. Increasing the yeast Sa. cerevisiae in the diet from 7 to 17% appeared the most suitable for both mite species. Staphylococcus spp. bacteria were preferred for D. farinae and were suitable for reproduction. The population growth and feeding preferences of D. pteronyssinus and D. farinae with respect to microorganisms indicate that D. farinae can develop on a diet with bacterial (Staphylococcus nepalensis and Staphylococcus kloosii) additions, whereas D. pteronyssinus was successful on a diet with fungal (Aspergillus jensenii and Aspergillus ruber) additions. The bacteria Kocuria rhizophila and Bacillus cereus decreased population growth in D. pteronyssinus, whereas the yeasts Hyphopichia pseudoburtonii, Hyphopichia burtonii, and Candida ciferrii decreased population growth in D. farinae. These results indicate that some microorganisms are an important food source for HDM.

Secondary Metabolites Isolated from the Gorgonian-Derived Fungus Aspergillus ruber and Their Antiviral Activity

Secondary Metabolites Isolated from the Gorgonian-Derived Fungus Aspergillus ruber and Their Antiviral Activity

Convenient synthetic approach for tri- and tetraprenylated cyclodipeptides by consecutive enzymatic prenylations.

The prenyltransferases EchPT1 and EchPT2 from Aspergillus ruber are responsible for the consecutive prenylations of cyclo-L-Trp-L-Ala, leading to the formation of the triprenylated echinulin as the predominant product. In this study, we demonstrate that EchPT1 also accepts all stereoisomers of cyclo-Trp-Ala and cyclo-Trp-Pro and catalyses regiospecific reverse C2-prenylation at the indole nucleus. EchPT1 products were well accepted by EchPT2 for multiple consecutive prenylations, with conversion yields of 84 to 98% for six of the eight substrates. C2-, C5- and C7-triprenylated derivatives are identified as major enzyme products, with product yields of 40 to 86% in seven cases. High product yields of 25-36%, i.e. approximate 30% of the total enzyme products, were observed for tetraprenylated derivatives in the four reaction mixtures with one D- and one L-configured amino acid residues. To the best of our knowledge, enzymatic preparation of tetraprenylated cyclodipeptides with such high efficacy has not been reported prior to this study.