Growth and mycotoxin production by <Emphasis Type="Italic">Chaetomium globosum</Emphasis>

Chaetomium globosum, the most common species within this genus, produces chaetoglobosins A and C when cultured on building material. Relatively low levels of these compounds have been shown to be lethal to various tissue culture cell lines. This study had two major objectives: (1) to determine the frequency at which Chaetomium species are isolated in water-damaged buildings and (2) to examine the production of chaetoglobosins A and C in isolates of C. globosum obtained from different buildings. Out of 794 water-damaged buildings, Chaetomium species were isolated in 49% of these structures. C. globosum ATCC 16021 was grown on four different media: oatmeal agar (OA), potato dextrose agar (PDA), corn meal agar (CMA), and malt extract agar (MEA). After 4 weeks, fungal growth was evaluated based on colony diameter and the quantity of spores produced on agar plates. In addition, production of chaetoglobosin A and C was monitored using high performance liquid chromatography. Colony diameter, spore production, and mycotoxin production by C. globosum were the highest on OA. Out of 30 C. globosum isolates cultured on OA for 4 weeks, 16 produced detectable amounts of chaetoglobosin A and every isolate produced chaetoglobosin C.     

Mycotoxin-producing potential of fungi isolated from red kidney beans

The predominant fungi present in samples of reject and retail red kidney beans were Aspergillus glaucus, Penicillium spp. and Alternaria spp. Together with A. ochraceus, A. flavus, Fusarium spp., and Trichoderma, these isolates from the reject beans were screened for numerous mycotoxins by TLC. The most consistently produced mycotoxins were penicillic acid (from A. ochraceus and Penicillium spp.) and Alternaria toxins (tenuazonic acid and alternariol). A. glaucus strains were tested for cytotoxicity in three tissue culture cell lines with positive results.     

Production of extracellular proteins,cellulases and antifungal metabolites by Chaetomium globosum Kunze ex. Fr.

Chaetomium globosum has been well-known potential antagonist of several seed and soilborne fungus. Eight isolates of C. globosum were obtained from different sources and were identified by morphological characters. C. globosum isolates examined for the presence of extra cellular proteins, cellulases and antifungal metabolites in culture filtrate by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), thin-layer chromatography and high-performance liquid chromatography. Variation in the mycelial protein of C. globosum isolates was noted in the SDS-PAGE analysis. Different C. globosum isolates that showed more number of bands in protein profile was further screened for the production of cellulases in culture filtrate. Cellulase activity of C. globosum isolates revealed that maximum activity was observed in the isolate Cg-6 after 11?days of incubation, while Cg-2 had least activity. C. globosum isolates were tested for antibiotic production, among which three isolates viz. Cg-6, Cg-7 and Cg-5 were found to produce the antibiotic Chaetoglobosin A in the culture filtrate. The antibiotic Chaetoglobosin A appeared blue colour under UV spectrum with a wavelength of 250?nm.     

Tolerance of pesticides and antibiotic resistance in bacteria isolated from wastewater-irrigated soil

A total of 64 bacterial isolates (40 Pseudomonas spp., 12 Azotobacter and 12 Rhizobium spp.) were characterized on the basis of morphological, cultural and biochemical characteristics. All the isolates were tested for their tolerance to the pesticides endosulfan, carbofuran, and malathion. 12.5% of the Pseudomonas isolates from soil tolerated concentrations of 1600 g malathion ml whereas 7.5% of isolates tolerated the same concentration of carbofuran. However, Pseudomonas isolates demonstrated a tolerance limit to endosulfan at a concentration of 800 g/ml. Asymbiotic N₂-fixers (Azotobacter) and symbiotic N₂-fixers (Rhizobium spp.) were also able to tolerate concentrations of pesticides up to 1600 g/ml. All the isolates were further tested for their antibiotic susceptibility against seven different antibiotics, nalidixic acid, cloxacillin, chloramphenicol, tetracycline, amoxycillin, methicillin, doxycycline. 100% of the Pseudomonas isolates were resistant to cloxacillin and 57.5% were resistant to methicillin. 7.5% of the isolates exhibited multiple resistance to five different antibiotics in three different combinations whereas 25% of the isolates showed multiple resistance to four different antibiotics in seven different combinations. Some of the resistant isolates were also screened for plasmid DNA and found to harbour a single plasmid.     

Enzyme profiles and genotyping of Chaetomium globosum isolates from various substrates

The genus Chaetomium is a rich source of novel and bioactive secondary metabolites of great importance. To date, a variety of more than 200 secondary metabolites belonging to diverse structural types have been discovered. Fungal enzymes are used in food, beverages, confectionaries, textiles, and leather industries to simplify the processing of raw materials. They are often more stable than enzymes derived from other sources. Ten isolates of Chaetomium globosum recovered and designated as TUCg1 to TUCg10 were identified by morphological and molecular biology means and submitted to the GenBank. These isolates were screened for extracellular enzymes such as amylase, cellulase, laccase, lipase, pectinases, protease and chitinase on solid media. All Chaetomium globosum isolates screened for potential enzymes showed amylolytic, cellulolytic, and proteolytic activities; six isolates were chitinolytic and laccase producers; and five and three isolates showed pectinolytic and lipolytic activities, respectively. The produced array of enzymes differed among isolates. Molecular techniques such as internal transcribed spacer (ITS) region sequencing and specific genes random primers polymerase chain reaction (SGRP-PCR) have shown high DNA polymorphism of Chaetomium globosum. In conclusion, SGRP-PCR is a rapid and valuable tool for assessment and characterization of genetic diversity of Chaetomium globosum, which suggests the use of this technique for identification of different fungal isolates.     

Onychomycoses in a Military Population in Brazil

Purpose of Review

This study aimed to isolate and characterize filamentous fungi onychomycosis agents in a military population assisted at a hospital outpatient clinic.

Recent Findings

In onychomycosis, the fungi colonize the subungual region causing thickening, discoloration, or cracking of the nail bed. Samples were collected from patients with clinical sights of onychomycosis.

Summary

Among 80 samples collected, 50 (62.5%) had positive culture. Isolated dermatophytes (86%) were Trichophyton rubrum (21; 42%), T. mentagrophytes var. interdigitale (19; 38%), and Microsporum gypseum (3; 6%) and non-dermatophyte molds were Fusarium spp. (1; 2%), Scytalidium spp. (1; 2%), and Chaetomium globosum (5; 10%). Minimal inhibitory concentrations (mg/L) of terbinafine, itraconazole, and fluconazole necessary to inhibit 50/90% of the isolates were respectively 0.015/0.06, 0.06/0.12, and 32/32. Etiological agents of onychomycosis in a military hospital are similar as reported in studies for the general population. High prevalence of non-dermatophytic agents was observed, especially for Chaetomium globosum.

     

Fibrinolytic and collagenolytic activity of extracellular proteinases of the strains of micromycetes <Emphasis Type="Italic">Aspergillus ochraceus</Emphasis> L-1 and <Emphasis Type="Italic">Aspergillus ustus</Emphasis> 1

It was shown that extracellular proteinases produced by the strains of micromycetes A. ochraceus L-1 and A. ustus 1 differ by the activity at various pH as well as by the intensity of the effect on fibrillar proteins. It was revealed that the proteinases of A. ochraceus L-1 demonstrated maximum activity during the growth of the producer in the nitrate-free growth medium (the pH of enzyme reaction was 8.0), whereas those of A. ustus 1 showed maximal activity during the growth of the micromycete in the medium containing sodium nitrate (the pH of enzyme reaction was 6.0). Values of specific fibrinolytic and collagenolytic activities of A. ochraceus L-1 were 2.2 and 1.6 times higher than those of A. ustus 1. At the same time, A. ustus 1 showed very low values of total proteolytic (caseinolytic) activity and had a high ratio of fibrinolytic activity to total proteolytic (caseinolytic) activity (6.92). It makes the strain a promising producer of proteinases, which hydrolyze fibrin and collagen.     

Occurrence of Indole Alkaloids among Secondary Metabolites of Soil Aspergillus Spp.

The occurrence of indole alkaloids among secondary fungal metabolites was studied in species of the genus Aspergillus, isolated from soils that were sampled in various regions of Russia (a total of 102 isolates of the species A. niger, A. phoenicis, A. fumigatus, A. flavus, A. versicolor, A. ustus, A. clavatus, and A. ochraceus). Clavine alkaloids were represented by fumigaclavine B, which was formed by A. fumigatus. -Cyclopiazonic acid was formed by isolates of A. fumigatus, A. flavus, A. versicolor, A. phoenicis, and A. clavatus. The occurrence of indole-containing diketopiperazine alkaloids was documented for isolates of A. flavus, A. fumigatus, A. clavatus, and A. ochraceus. No indole-containing metabolites were found among the metabolites of A. ustus or A. niger.     

PCR amplification of four genes coding for aminoglycoside-modifying enzymes in bacteria of clinical isolates from Jordan University Hospital

Three species of Gram-negative G(–) bacteria were chosen for this study: Escherichia spp. (29 isolates), Pseudomonas spp. (16 isolates) andEnterobacter spp. (17 isolates), utilizing colony PCR to detect genes coding for aminoglycoside-modifying enzymes. The 62 isolates were purified and cultured on nutrient broth media supplemented with 50 g kanamycin/ml. Only 17 out of the 62 isolates were resistant to kanamycin and were subjected to colony PCR protocol using 20 l cell lysate and eight sets of primers with each isolate. Sizing of the amplified fragments was carried out in order to determine the specificity of PCR. The 17 isolates were shown to carry the rrs, aacC2, aacA-aphD and aphA3 genes.     

Identification of a Unique Azaphilone Produced by Chaetomium globosum Isolated from Polygonatum sibiricum

A new azaphilone, chaephilone E, eight azaphilone derivatives, and three chaetoglobosins were isolated from endophytic fungi Chaetomium globosum. The structures of the compounds were elucidated by 1D and 2D NMR as well as HR‐ESI‐MS data, and the absolute configuration of chaephilone E was established on the basis of electronic circular dichroism and NOESY spectrum. The activity of chaephilone E was evaluated via the cytotoxic assay (human hepatoma cell lines HepG‐2) and brine shrimp (Artemia salina) bioassay.     

Seabed photography,environmental assessment and evidence for deep-water trawling on the continental margin west of the Hebrides

Little is known about marine filamentous fungi and yeasts, almost nothing about their life and metabolism under deep sea conditions. Data on growth and metabolic activity give insight into the role of organisms in the marine habitat. Degradation studies on pollutants, such as polymeric thermoplasts, provide information about the self-cleaning capacity of a habitat. Therefore, recently isolated fungal strains from the deep sea and our newly developed methods and apparatus for investigation of fungi under simulated deep sea conditions were used to study fungal growth and degradation of a commercially produced thermoplastic polymer (poly--hydroxybutyric acid = PHB). Two deep sea isolates, a filamentous fungus (Aspergillus ustus) and one yeast (Rhodosporidium sphaerocarpum), and for comparison, two marine surface yeast isolates (Candida guilliermondii, Debaryomyces hansenii) and one terrestrial isolate of Aspergillus ustus were investigated. Growth (colony-forming units, dry weight), physiological parameters (oxygen saturation of the hydraulic fluid as oxygen reservoir, pH and consumption of total carbohydrate) and PHB degradation (clearing test: clearing of PHB-turbid agar medium; spectrophotometric test: PHB depolymerase activity) were followed after incubation in high-pressure autoclaves in artificial seawater medium at 27 °C and pressures of 0.1 MPa (= atmospheric pressure), 5 MPa, 10 MPa, 20 MPa, 30 MPa, 45 or 50 MPa and 100 MPa ( 10000 m water depth) for a maximum of 21 days (yeasts) and 28 days (filamentous fungi), respectively. Irrespective of the marine or terrestrial origin of the isolates, growth decreased with increasing pressure with a limit between 30 MPa and 50 MPa for filamentous fungi and yeasts. Metabolic activity (consumption of medium components) started to decrease from 20 MPa, ceasing at growth-limiting pressures. Under atmospheric conditions, all strains degraded PHB in solid medium, in liquid medium degradation was less and decreased further and/or was delayed with increasing hydrostatic pressure; beyond 30 MPa, no PHB degradation could be observed. In summary, it could be shown that growth, metabolism and degradation of pollutants such as PHB by marine fungal isolates was impaired with increasing pressure, showing one aspect of the reduced self-cleaning capacity of the deep sea habitat.Dedicated to Prof. Dr Jan Kohlmeyer, Morehead City, USA, on the occasion of his 70th anniversary     

Endophytic fungi from Musa acuminata leaves and roots in South China

One hundred and sixty-three endophytic fungal cultures were isolated from 200 leaf samples of Musa acuminata trees, which were soaked in 36% formaldehyde solution for surface sterilization. They belonged to the genera of Gloeosporium musae (45%), Myxosporium spp. (11%), Deightoniella torulosa (8.5%), Alternaria tenuis (7.9%), Sphaceloma spp. (7.4%), Aureobasidium spp. (4.3%), Melida spp. (1.8%), Uncinula spp. (1.8%), Penicillium spp. (1.8%), Aspergillus spp. (1.2%), Sarcinella spp. (1.2%), Cladosporium sp. (0.6%), Cephalosporium sp. (0.6%) and sterile mycelium (6.7%). Sixty-eight endophytic fungal cultures were isolated from 100 root samples. They respectively belonged to the genera of Aspergillus spp. (31%), Paecilomyces spp. (16%), Penicillium spp. (15%), Fusarium spp. (10%), Gloeosporium musae (6%), yeast (3%), Deightoniella torulosa (3%), Spicaria sp. (1.4%), Cephalosporrium sp. (1.4%), Meliola sp. (1.4%) and sterile mycelium (10%). Water agar (containing 50 g chloramphenicol ml^–1 and 50 g streptomycin ml^–1) seemed to be a better medium for isolation of endophytic fungi than potato-dextrose agar (PDA, containing 50 g chloramphenicol ml^–1 and 50 g streptomycin ml^–1).     

Screening tomato-associated bacteria for biological control of grey mold on tomato

Aiming at discovering effective biocontrol agents (BCAs) against grey mold on tomato caused by Botrytis cinerea Pers., we selected 819 bacterial isolates from the surface as well as the interior of the roots, stems, and leaves of tomato plants grown in B. cinerea-infested fields. In a dual-culture assay, 116 isolates (14.16%) showed antagonism against B. cinerea and fewer ones against five additional tomato-associated fungal pathogens – Pythium ultimum, Phytophthora capsici, Fusarium oxysporum f. sp. lycopersici, Sclerotinia sclerotiorum and Ralstonia solanacearum. Thirty-one isolates with antagonism to B. cinerea and at least one of the five additional pathogens were assessed for their efficacy in controlling grey mold on tomato in a greenhouse test. Thirteen of them attained the efficacy over 50% and were subjected to the second greenhouse test, in which 12 isolates consistently accomplished the biocontrol efficacy over 50%, with isolates ABc28 and ABc22 achieving the efficacy of 66.71% and 64.90%, respectively. Under greenhouse conditions, the above two as well as isolates ABc2, ABc11 and ABc17 increased tomato biomass by more than 20% in comparison with the control. The 12 antagonistic isolates accomplishing the biocontrol efficacy over 50% in both greenhouse tests were considered potential BCAs against grey mold, which were identified as Pseudomonas spp., Pantoea spp., Bacillus spp. and Chryseobacterium spp. Ten of them were found to produce at least one of the three hydrolytic enzymes (protease, cellulase and chitinase) and/or siderophore, which might be involved in their mechanisms of suppressing the disease. Based on the origin of these 12 strains, the leaf tissue, especially the leaf interior, of tomato plants grown in a B. cinerea-infested field appears to be a good source of potential BCAs against grey mold.     

Insecticidal and nematicidal properties of microbial metabolites

Summary Metabolites from 942 microbial isolates were screened for insecticidal and nematicidal properties. The isolates included 302 streptomycetes, 502 novel actinomycetes including representatives of 18 genera, 28 unidentified aerobic actinomycetes, 70 fungi and 40 bacteria other than actinomycetes. When diluted 10-fold, the metabolites from 55 isolates caused nearly 100% mortality in mosquito larvae (Aedes aegypti) within 24 h. These isolates included 27 isolates ofStreptomyces, four ofActinoplanes, three isolates each ofActinomadura andStreptoverticillium, two isolates each ofMicromonospora, Bacillus andPaecilomyces, and one isolate each ofMicropolyspora, Nocardiopsis, Streptosporangium, Oerskovia, Thermomonospora, Chainia, Pseudomonas, Fusarium, Monilia andSyncephalestrum. Two fungal isolates could not be identified to the generie level. Extracts from the culture broth of 18 isolates caused 100% mortality in mosquito larvae within 15 min to 24 h at a concentration of 1000 ppm. The LC₅₀ of partially purified products from two isolates was 1–2.5 ppm and that of the semipurified preparations from four other isolates was 50 ppm. Valinomycin was identified as an active component in the culture broth from one isolate. The culture broth from 15 isolates of aerobic actinomycetes and 4 of fungi were toxic toPanagrellus redivivus (Nematoda); these included 12 isolates with selective nematicidal properties.Michigan Agriculture Experiment Station, Journal Article No. 12321.     

Antibiotic resistance profiles of coagulase-positive and coagulase-negative staphylococci from pit latrine fecal sludge in a peri-urban South African community

The aim of this study was to assess pit latrine samples from a peri-urban community in KwaZulu-Natal (South Africa) for the presence of multidrug-resistant (MDR) Staphylococcus spp. Standard procedures were used to isolate Staphylococcus spp. from pit latrine fecal sludge samples, with confirmation at genus level by polymerase chain reaction (PCR). Sixty-eight randomly selected pit latrine Staphylococcus spp. isolates were further characterized by using established disk diffusion procedures. An average Staphylococcus spp. count of 2.1?×?10⁵ CFU per g fecal material was established using two randomly selected pit latrine samples. Of the 68-selected Staphylococcus spp. pit latrine isolates, 49% were identified as coagulase positive, 51% as coagulase negative and 65% (12 coagulase positive, 32 coagulase negative isolates) were categorized as MDR. The majority (66/68) of Staphylococcus spp. isolates displayed resistance to fusidic acid while only 5/68 isolates displayed resistance to chloramphenicol. The pit latrine samples analyzed in this study are a source of MDR Staphylococcus spp., highlighting the need for proper hygiene and sanitation regimes in rural communities using these facilities.     

The Production of Reactive Oxygen Species in Intact Isolated Nerve Terminals Is Independent of the Mitochondrial Membrane Potential

Dependence on mitochondrial membrane potential (m) of hydrogen peroxide formation of in situ mitochondria in response to inhibition of complex I or III was studied in synaptosomes. Blockage of electron flow through complex I by rotenone or that through complex III by antimycin resulted in an increase in the rate of H₂O₂ generation as measured with the Amplex red assay. Membrane potential of mitochondria was dissipated by either FCCP (250nM) or DNP (50mM) and then the rate of H₂O₂ production was followed. Neither of the uncouplers had a significant effect on the rate of H₂O₂ production induced by rotenone or antimycin. Inhibition of the F₀F₁-ATPase by oligomycin, which also eliminates m in the presence of rotenone and antimycin, respectively, was also without effect on the ROS formation induced by rotenone and only slightly reduced the antimycin-induced H₂O₂ production. These results indicate that ROS generation of in situ mitochondria in nerve terminals in response to inhibition of complex I or complex III is independent of m. In addition, we detected a significant antimycin-induced H₂O₂ production when the flow of electrons through complex I was inhibited by rotenone, indicating that the respiratory chain of in situ mitochondria in synaptosomes has a substantial electron influx distal from the rotenone site, which could contribute to ROS generation when the complex III is inhibited.     

Fungi pathogenic to ryegrass seedlings

Summary Fungi borne on or in ryegrass (Lolium spp.) seeds or invading ryegrass seedlings grown on field soils were isolated and identified. Selected isolates were tested to determine their pathogenicity to ryegrass seedlings. Seed-borne fungi were generally weakly virulent or non-pathogenic to ryegrass seedlings. Pathogenic seed-borne fungi includedChaetomium globosum Kunze: Fr.,Curvularia trifolii (Kauffm.) Boedijn, and species ofPenicillium Link andAspergillus Mich. ex Link. Species of fungi isolated from seedlings grown on field soils de pended on soil and temperature. Soil-borne fungi pathogenic to seedlings includedFusarium avenaceum (Fr.) Sacc.,F. culmorum (W. G. Smith) Sacc.,F. equiseti (Corda) Sacc.,F. oxysporum Schlecht.: Fr.,F. solani (Mart.) Sacc.,Pythium afertile Kanouse and Humphrey,P. debaryanum auct. non Hesse,P. irregulare Buisman,P. ultimum Trow, a sphaerosporangiatePythium sp.,Chaetomium globosum, Thanatephorus cucumeris (Frank) Donk,Trichoderma koningii Oudem., and aPhomopsis sp. Individual isolates of fungi differed in virulence to ryegrass seedlings, and ryegrass cultivars differed in susceptibility to seedling pathogens.     

Onychomycosis caused by Chaetomium globosum Kunze

In this paper we report a case of onychomycosis caused by Chaetomium globosum. The patient had lesions of the fingernails of the left hand. The direct microscopical examination of the nails showed light-brown hyphae with thick-walled cells. The histopathological examination revealed thick aggregated hyphal element in the nail plate. Amongst the antimycotics tested oxiconazole with MIC values of 0.3 g/ml^–1 was found to be most effective in vitro against Chaetomium globosum.     

Nematicidal activity of <Emphasis Type="Italic">Paecilomyces</Emphasis> spp. and isolation of a novel active compound

Many species of Paecilomyces are entomogenous fungi and several are efficacious toward nematodes. To study the potential of Paecilomyces species in controlling nematodes, fungal extracts of 40 Paecilomyces spp. were evaluated for their nematicidal activity against Bursaphelenchus xylophilus and Panagrellus redivivus. The extracts of six Paecilomyces spp. exhibited the nematicidal activity against P. redivivus, and 11 species exhibited the nematicidal activity against B. xylophilus. The methanol extract of strain 1.01761 incubating on Czapek solid medium killed more than 95% P. redivivus in 24 h at 5 mg/ml, and the filtrate of strain 1.01788 cultured in Sabouraud’s broth medium resulted in 90% mortality of B. xylophilus in 24 h at 5 mg/ml. A novel nematicidal compound 4-(4′-carboxy-2′-ethyl-hydroxypentyl)-5,6-dihydro-6-methylcyclobuta[b]pyridine-3,6-dicarboxylic acid, was isolated from Paecilomyces sp. YMF1.01761. The LD₅₀ value of the compound within 24 h against P. redivivus was 50.86 mg/L, against Meloidogyne incognita was 47.1 mg/L, and against B. xylophilus was 167.7 mg/L.     

Biofungicides as alternative to synthetic fungicide control of grey mould (Botrytis cinerea) – prospects and challenges

Botrytis cinerea is one of the most destructive pathogens of ve?getables and fruits both in the field and storage. There have been several research activities focused on developing biocontrol strategies for the pathogen due to its resistance to the commonly used synthetic fungicides. Additionally, concerns have been raised over residual effect of current synthetic fungicides used for its control. Most of these research activities have focused on Trichoderma spp., Ulocladium spp., Bacillus subtilis, plant extracts and their essential oils with some commercial products available on the market for the control of B. cinerea disease. This review summarises some of the current published information on the use of biocontrol agents and plant-based compounds for B. cinerea control. Some limitations and future prospects were also mentioned.