Assessment of the antifungal activity of the violacein-forming strain Janthinobacterium sp. B-3515 against the mould fungus Alternaria brassicicola F-1864

A study of antifungal properties of violacein-forming strain Janthinobacterium sp. B-3515 as well as its secondary metabolite, violacein, against Alternaria brassicicola F-1864 is presented. Regardless of the presence of bacteria, mycelium growth in the first two days proceeded at the same rate. The effect of the bacterial strain was manifested after the third day of incubation. In general, during co-culture, the bacterial strain statistically significantly reduced the average growth of the mycelium of the mould fungus by 10%. The average growth of A. brassicicola F-1864 was decreased in the presence of an aqueous solution of violacein in the nutrient medium (1%, 3%, and 5%). The pigment in 5% concentration had the greatest effect, as the difference between the average growth of the control group and the experimental group was 18%. The mycostatic activity of bacteria of genus Janthinobacterium and violacein against mould fungus Alternaria brassicicola F-1864 was shown for the first time.

SORPTION OF HEAVY METALS BY MOLD FUNGUS ASPERGILLUS CARBONARIUS MELANIZING CARDBOARD

It has been shown that the mould fungus Aspergillus carbonarius, which synthesizes extracellular melanin, is able to develop due to the degradation of cellulose inside the cardboard under conditions of low water availability. The maximum yield of melanin was noted in a slightly alkaline medium, but in the presence of copper ions, a high level of pigmentation of the medium is also observed at low pH values. Melanized mycelium and exomelanin are characterized by a high sorption capacity in relation to heavy metal ions present in printing pigments of waste paper. In the process of growth A. carbonarius decreases acidity from neutral values to pH 2.8–3.1, increases the mobility of heavy metals immobilized on cellulose fibers and binds them by functional groups via ionic or chelating pathways. The sorption capacity of biomass with respect to copper, zinc, and nickel ions increased in the order of viable mycelium < inactivated mycelium < exomelanin. Lead ions were most actively bound by inactivated mycelium. The extracellular pigment accumulated copper better than other metals. The distribution coefficient in the system melanin – Cu2+ reached 1390 ml/g.

Sooty bark disease of maples: the risk for hypersensitivity pneumonitis by fungal spores not only for woodman

In the middle of the twentieth century, the from North America sooty bark disease (SBD) of maples was first discovered in England and has spread in the last decades in Central Europe, in particular. The trigger of SBD is the mould fungus Cryptostroma (C.) corticale. The most common infested maple is the sycamore, Acer pseudoplatanus, a common tree in woods and parks. The disease is characterised by peeling of the outer layer of the bark and brownish-black spores under the peeled off bark. These spores can cause maple bark disease (MBD) in humans, a hypersensitivity pneumonitis (HP) with similar symptoms like COPD, allergic asthma, influenza or flu-like infections and interstitial pneumonia. Persons who have intensive respectively occupational contact with infested trees or wood, e.g., woodman, foresters, sawyers or paper mill workers, are at risk in particular. Since C. corticale favours hot summers and host trees weakened by drought, SBD will increasingly spread in the future due to ongoing climate change. Consequently, the risk of developing MBD will increase, too. As with all HPs, e.g., farmer’s lung and pigeon breeder’s disease, the diagnosis of MBD is intricate because it has no clear distinguishing characteristics compared to other interstitial lung diseases. Therefore, the establishment of consistent diagnosis guidelines is required. For correct diagnosis and successful therapy, multidisciplinary expertise including pulmonologists, radiologists, pathologists and occupational physicians is recommended. If MBD is diagnosed in time, the removal of the triggering fungus or the infested maple wood leads to complete recovery in most cases. Chronic HP can lead to lung fibrosis and a total loss of lung function culminating in death. HP and, thus, MBD, is a disease with a very high occupational amount. To avoid contact with spores of C. corticale, persons working on infested wood or trees have to wear personal protective equipment. To protect the public, areas with infested maples have to be cordoned off, and the trees should be removed. This is also for impeding further spreading of the spores.

First Report of Wilt of Rubber Tree Caused by Chalaropsis thielavioides in China

Rubber tree (Hevea brasiliensis (Willd. ex Adr. Juss) Müll. Arg.) is used for the extraction of natural rubber and is an economically and socially important estate crop commodity in many Asian countries such as Indonesia, Malaysia, Thailand, India, Sri Lanka, China and several countries in Africa (Pu et al, 2007). Xishuangbanna City and Wenshan City are the main rubber cultivation areas in Yunnan Province, China. In November 2012, rubber tree showing typical wilt symptoms (Fig. 1 A) and vascular stains (Fig. 1 B) were found in Mengla County, Xishuangbanna City. This disease was destructive in these trees and plant wilt death rate reached 5%. The diseased wood pieces (0.5cm long) from trunk of rubber was surface disinfected with 75% ethanol for 30s and 0.1% mercuric chloride (HgCl2) for 2min, rinsed three times with sterile distilled water, plated onto malt extract agar medium (MEA), and incubated at 28℃. After 7 days, fungal-like filaments were growing from the diseased trunk. Six cultures from 6 rubber trunk were obtained and incubated on MEA at 28℃, after 7 days to observe the cultural features. The mycelium of each culture was white initially on MEA, and then became dark green. Cylindrical endoconidia apices rounded, non-septate, smooth, single or borne in chains (8.9 to 23.6 × 3.81 to 6.3μm) (Fig. 1 C). Chlamydospores (Fig. 1 D) were abundant, thick walled, smooth, forming singly or in chains (11.1 to 19.2 × 9.4 to 12.0μm). The mould fungus was identifed as Chalaropsis based on morphology (Paulin-Mahady et al. 2002). PCR amplification was carried out for 3 isolates, using rDNA internal transcribed spacer (ITS) primer pairs ITS1F and ITS4 (Thorpe et al. 2005). The nucleotide sequences were deposited in the GenBank data base and used in a Blast search of GenBank. Blast analysis of sequenced isolates XJm8-2-6, XJm8-2 and XJm10-2-6 (accessions KJ511486, KJ511487, KJ511489 respectively) had 99% identity to Ch. thielavioides strains hy (KF356186) and C1630 (AF275491). Thus the pathogen was identified as Ch. thielavioides based on morphological characteristics and rDNA-ITS sequence analysis. Pathogenicity test of the isolate (XJm8-2) was conducted on five 1-year-old rubber seedlings. The soil of 5 rubber seedlings was inoculated by drenching with 40 ml spore suspension (106 spores / ml). Five control seedlings were inoculated with 40 ml of sterile distilled water. All the seedlings were maintained in a controlled greenhouse at 25°C and watered weekly. After inoculated 6 weeks, all the seedlings with spore suspension produced wilt symptoms, as disease progressed, inoculated leaves withered (Fig. 1 E) and vascular stains (Fig. 1 F) by 4 months. While control seedlings inoculated with sterile distilled water remained healthy. The pathogen re-isolated from all inoculated symptomatic trunk was identical to the isolates by morphology and ITS analysis. But no pathogen was isolated from the control seedlings. The pathogenicity assay showed that Ch. thielavioides was pathogenic to rubber trees. Blight caused on rubber tree by Ceratocystis fimbriata previously in Brazil (Valdetaro et al. 2015), and wilt by Ch. thielavioides was not reported. The asexual states of most species in Ceratocystis are “chalara” or “thielaviopsis” (de Beer et al. 2014). To our knowledge, this is the first report of this fungus causing wilt of rubber in China. The spread of this disease may pose a threat to rubber production in China.

Improvement of New PCR Assay Targeting Mutations for Fast Recognition of Azole Resistant Mould Fungus, Aspergillus fumigatus

Allergenic mould fungus, Aspergillus fumigatus well known for its invasive aspergillosis disease is intrinsically resistant to most of the fluconazole group of medicines. It was studied that the mutations encoding 14a-sterol demethylase has the capacity to make triazole-resistant to this clinical fungal isolates. The present study is a multiplex allele-specific PCR assay targeting mutations for rapid detection of azole-resistant A. fumigatus for suitable patient management. During the present work clinical and wild isolates of A. fumigatus were employed to evaluate MAS-PCR, which was confirmed by direct DNA sequencing of cyp5 IA98 region from selected isolates of A. fumigatus. MAS-PCR assay was successfully developed to simplify the rapid detection of L98H mutation in cyp51A gene that confers the resistance to triazoles in A. fumigatus strains. The assay would help in primary acknowledgement of triazole-resistant A. fumigatus strains for proper management of patients with invasive aspergillosis.

The influence of mould fungus on pigments used in wall and ceiling décor on the example of the wooden church of Saint George in Ostropa

The influence of mould fungus on pigments used in wall and ceiling décor on the example of the wooden church of Saint George in Ostropa. This research aimed to establish the change in colour of selected pigments used in polychrome due to the effects of Aspergillus niger. The research was conducted on the following pigments: cremnitz white, zinc white, vermilion, colcothar, chrome green, artificial ultramarine, burnt umber, carbon black, smalt, minium, azurite, Prussian blue and chalk. Measurements were taken using a colorimeter in the CIELAB colour space. The biggest change in colour was exhibited by artificial ultramarine, while the most stable in colour turned out to be minium. The smallest change in colour of dried samples was shown by burnt umber, while the biggest change was noted again for artificial ultramarine.

Fungal LysM effectors that comprise two LysM domains bind chitin through intermolecular dimerization

SUMMARYChitin is a polymer of β-(1,4)-linked N-acetyl-D-glucosamine (GlcNAc) and a major structural component of fungal cell walls that acts as a microbe-associated molecular pattern (MAMP) that can be recognized by plant cell surface-localized pattern recognition receptors (PRRs) to activate a wide range of immune responses. In order to deregulate chitin-induced plant immunity and successfully establish their infection, many fungal pathogens secrete effector proteins with LysM domains. We previously determined that two of the three LysM domains of the LysM effector Ecp6 from the tomato leaf mould fungus Cladosporium fulvum cooperate to form a chitin-binding groove that binds chitin with ultra-high affinity, allowing to outcompete host PRRs for chitin binding. In this study, we describe functional and structural analyses aimed to investigate whether LysM effectors that contain two LysM domains bind chitin through intramolecular or intermolecular LysM dimerization. To this end, we focus on MoSlp1 from the rice blast fungus Magnaporthe oryzae, Vd2LysM from the broad host range vascular wilt fungus Verticillium dahliae, and ChElp1 and ChElp2 from the Brassicaceae anthracnose fungus Colletotrichum higginsianum. We show that these LysM effectors bind chitin through intermolecular LysM dimerization, allowing the formation of polymeric complexes that may precipitate in order to eliminate the presence of chitin oligomers at infection sites to suppress activation of chitin-induced plant immunity. In this manner, many fungal pathogens are able to subvert chitin-triggered immunity in their plant hosts.

Incidence of spiraling whiteflies Aleurodicus dspersus Russell (Hemiptera: Aleyrodidae) and its natural enemies on guava orchards

Population dynamics of spiraling whitefly and its natural enemies on guava orchards are essential for improvement of existing pest control methods. To find out the seasonal abundance of guava whitefly and its natural enemies and levels of infestations were studied on guava orchards severely infested by A. dispersus. Five guava plants were selected randomly. To determine each stage of the insect density, six leaves comprising upper, middle and lower part of each plant were randomly sampled. Sooty mould infested leaves and presence of natural enemies of A. dispersus were also recorded. The highest number of egg mass (5.0) and nymphs (10.0) per leave were found in the month of September. The highest (0.20%) ladybird beetle, Scymnus sp. (Coccinellidae: Coleoptera) and Encarsia sp. (0.15%) were found in the months of October and January, respectively. The number of leaves infested with sooty mould fungus was estimated highest (93%) during October to January. A. dispersus population was peak in the months of August to January and the associated natural enemies may successfully contribute to the existing pest control methods.J. bio-sci. 24: 67-74, 2016