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Amphisphaeriales

Apiospora Sacc.; anamorph Arthrinium Kunze

Most species are saprobes, and are recorded from many vegetable sources, especially from grasses. Apiospora montagnei Sacc. (syn. Papularia arundinis (Corda) Fr.) has been isolated from flour, stored grain and molasses. See Kirk (1991a) for a description. Arthrinium phaeospermum (Corda) M.B. Ellis (no teleomorph is known) has caused the spoilage of pasteurized apple juice, and has also been found in stored flour, grain and nuts. See Pitt & Hocking (1985a) and Kirk (1991b) for references.

Khuskia oryzae H.J. Hudson; anamorph Nigrospora oryzae (Berk. & Br.) Fetch.

This fungus is known primarily as a common parasite of a range of crops (especially cereals and bananas) in the tropics, but it also causes storage rots (Pitt & Hocking, 1985a). The fungus has also been reported as producing metabolites belonging to the medically important group griseofulvins (Turner, 1975). The related species Nigrospora sphaerica (without a known teleomorph) is found in similar situations, and has been recorded from stored corn, wheat, pecans, peanuts and dried meat (Pitt & Hocking, 1985a; Kirk, 1991d).

Pestalosphaeria Barr; anamorph Pestalotiopsis Steyaert

Ascomata perithecia, immersed in host tissues, thin-walled. Paraphyses present. Asci ± cylindrical, fairly thin-walled, apparently with a single wall layer, with an inconspicuous apical ring staining blue in iodine. Ascospores pale brown, 2-septate, the middle cell more strongly pigmented, ornamented with irregular longitudinal ridges.
Conidiomata acervular, the wall composed of thin-walled angular cells. Conidiogenous cells ± cylindrical, with a single conidiogenous locus which proliferates to a small degree between the successive production of conidia. Conidia 4-septate, the septa thin, the middle cells more strongly pigmented than the end ones, with a single basal and several apical filiform, cellular, appendages.

Pestalosphaeria is dubiously distinct from Lepteutypa Petrak, and indeed was placed into synonymy with that genus by von Arx (1981b). Pestalosphaeria is more commonly encountered in an anamorphic state, commonly referable to Pestalotiopsis Steyaert. That form-genus is the most prominent member of an assemblage of segregates separated from Pestalotia de Not. by Steyaert (1949); others are Monochaetia (Sacc.) Allesch. and Truncatella Steyaert. Although some subsequent workers, notably Cuba (1961), have questioned the validity of Steyaert’s work, it is now generally accepted. See Sutton (1969, 1980) for further information.

These fungi are frequently encountered on plant debris, and a number are important plant pathogens. They are also occasionally isolated from soil, and cause damage to cotton and jute fabrics. Species of the closely related genus Broomella Sacc. are strongly cellulolytic, causing soft rots in timber, and produce antifungal compounds (Domsch et al., 1980).

The Fungi Kingdom: Ascomycotina

These were my mycology notes during my masters. Credit goes to Dr. Paul Cannon Of CABI Bioscience who taught me and provided notes on Ascomycotina.

Ascomycotina

Introduction

The Ascomycotina is the largest subdivision of the fungi, and if one includes their anamorphs it contains perhaps three quarters of all known true fungi (Hawksworth et al., 1983). As the number of all fungi has been variously estimated at anywhere between 100000 and 1600000 (Hawksworth, 1991a), it is clear that despite its image even in most informed non-specialists’ eyes as hardly meriting attention, the group is of the first importance.

As might be expected in such a monumental group, there is enormous diversity of structure and ecology. At one end of the scale are most of the unicellular organisms commonly known as the yeasts, and at the other, species with extensive mycelium and large and elaborate fruiting structures, such as the truffles and morels. The group is of enormous importance to plant pathology, and representatives may be found in almost every imaginable ecological niche. When one considers that most of the Fungi Imperfect! (hyphomycetes and coelomycetes) are either biologically linked to ascomycetes or are clearly related to them, the importance of the group becomes even more clear.

In the Ascomycotina, meiotic spores (ascospores) develop inside special cells, the asci. These either rupture or break down to release the ascospores in order that they may be dispersed. The structure of the asci are particularly important in classification. A peculiar feature of the meiotic process in ascomycetes results in the fact that in most species the number of ascospores produced within asci is strictly controlled, and in the vast majority of cases this number is eight. The asci are commonly accompanied by sterile hyphae, broadly termed paraphyses. Most members of the Ascomycotina have asci which are protected by a globose, flask-shaped or discoid conglomeration of cells, the ascoma. Where the asci are surrounded by wall material, ascospores may be released through a small opening in the ascoma wall, the ostiole, or by its general breakdown. A discoid fruit body is termed an apothecium, a flask-shaped one a perithecium and a globose, closed one a cleistothecium. These terms are losing prominence as intermediates are identified and classifications rely upon them less as basic divisions. The protective covering may be rudimentary, composed only of a web of hyphae, or may be very well-developed, with multiple and varied layers of thin-or thick-walled cells. These are often dark brown or black due to the deposition of melanin, which is probably formed primarily to protect the fungus against ultra violet radiation. The ascomata (plural of “ascoma”) may be formed into compound fruit bodies, stromata.

In many cases, ascomycetes are readily identified as such by using simple squash mounts of cultured material. In some groups of the Ascomycotina, it is not always easy to perform this basic level of identification as the asci deliquesce (the walls break down irregularly or apparently simply disappear) to release the ascospores. Particularly when examining old cultures of such fungi as Chaetomium and Microascus, asci may be hard to detect. In these cases, though, ascospores are commonly seen in clusters of eight even though the wall surrounding them is no longer present.

Mold Test Kits In Canada

Mold test kits are meant to help a homeowner or property manager to perform preliminary tests for mold. Mold test kits are not meant to replace professional advice. There are many test kits out there. While some are worth paying for a majority of the so called “Mold Test Kits” are useless. For example, settle agar plates are frequently sold to homeowners as “mold test kits”. While these may give useful information when used by a professional their results can be very misleading.

The mold test kits that we recommended are kits that utilize the same equipment that professionals use. For example, a homeowner can comfortably perform air sampling in their homes using the same equipment that is used by the professionals. This initial sampling can help the homeowner determine whether they require professional help or not. A professional is supposed to perform extensive investigation and not just air sampling.

If you would like more information on mold testing kits click Homeowner Mold Testing Kits.

Seed Pathogen Testing

Question: Hello, I represent a very important agro-industrial group in Mexico. We have several roles such as wheat mills, fruit, and vegetable processing.

Right now we have a situation in one of our facilities that we want to resolve. We have a hydroponic greenhouse where we produce lettuce, mainly 3 different varieties (Boston, Lollobionda, Lollorosa). We have had several problems in the production of lettuce. We did some analysis and we have found that the root cause of the problem is in the seed.

This seed comes from Holland, and the seed is encapsulated by some material that is supposed to protect the naked seed and improve the shelf life. In our studies we have found that the encapsulation material is contaminated with some fungal pathogens and bacteria, so this is why we are requesting your support.

In a research institute in Mexico they found in the encapsulation material the following fungal pathogens and bacteria:

– Fusarium
– Verticillium
– Acremonium
– Phythium
– Aspergillus
– Stenotrophomonas
– Acinetobacter
– Bacillus cereus

So we want to confirm with your labs if these microorganisms are present in the seed or in the encapsulation material. So we need to know if your labs are able to do this analysis, the cost of the analysis and how much time you think this will take. If by some reason MBL are not able to do this kind of analysis, could you recommend some laboratory that could help us with this request.

I’ll wait for your comments, thanks and best regards.
Answer: We can you determine the fungal and bacterial pathogens present in the seeds and the encapsulation material. However, since this material is coming from outside of Canada, an import permit from the Canadian Food Inspection Agency (CFIA) would be required. We would suggest you use a lab in Mexico for this kind of testing.

Trapping and Enumeration of Fungal Spores

The objective of trapping and enumeration of air-borne fungal spores in indoor environments may be 1) to determine the load of allergenic spores and their composition, 2) to determine whether there were hidden sources of fungal amplification, 3) to assess the effectiveness of remediation. Regardless of the objective, the methods of trapping and enumeration are the same.

Fungal spores trapping

Generally fungal spores are trapped by impacting air onto some inert media or some suitable growth agar media. Enumeration of fungal spores trapped on inert media is performed by direct microscopic examination without culturing. This is referred to as total fungal spore count or non-viable analyses. When air is impacted on growth agar media any fungal spores or hyphal fragments that can germinate on that media develops into colonies (often referred to as colony forming units) that are then enumerated and identified if necessary.

Fungal Spores Trapping for Total fungal Spore Counts (Non-viable).

The common air samplers for total fungal spores counts are slit and circular type of samplers. Slit samplers include Air-O-Cell, BioCell, VersaTrap, Allergenco, BioSis, and Burkard. Examples of circular samplers include Cyclex, Cyclex-d and Micro-5. These samplers (cassettes) are attached to a pump that can draw air at the rate recommended by the manufacturer of the cassette.

Aspergillus/Penicillium spores, Stachybotrys

Fungal spores Enumeration Using Air-O-Cell Cassettes

The Air-O-Cell cassettes are opened in the laboratory by cutting around the sealing band. The glass cover slip (containing the sample trace) is removed and slowly placed at an angle with the media collection side facing either upwards or downwards. If the glass cover slip is to be placed with the media facing down, one to two (1-2) drops of lacto phenol cotton blue is placed in the center of the microscope slide before placing the glass cover slip. The edges of the cover glass can then be secured with a drop of nail polish. If the cover glass is to be placed with the media collection side facing up, it can first be secured with nail polish and then 1-2 drops of lactophenol cotton blue is placed in the middle of the sample. A second clean cover glass is then placed to cover the sample collection media and spread out the stain. Care should be taken not to trap air bubbles as these could interfere with the analyses.

Stachybotrys, Aspergillus/Penicillium sporesThe sample deposition trace is identified at lower magnification (10X or 20X) objective and spore counting is performed at a minimum magnification of X400. There has been a lot of debate as to what magnification should be used during identification and enumeration. Some analysts have recommended use of 100X oil immersion. However, it’s important to note that use of 100X objective with oil can be very messy and in most cases may not add quality to the results. In our opinion, the most important considerations when it comes to spore enumeration and identification are a good quality microscope and a well trained analyst.

fungal sporesIn the past laboratories were using a variety of methods to analyze spore traps. This made comparison of results (and even terms used in the reports) difficult. The ASTM International has now released a new standard “Standard Test Method for Categorization and Quantification of Airborne Fungal Structures in an Inertial Impaction Sample by Optical Microscopy”. While this standard may not resolve all limitations of spore traps it will ensure that labs that use the standard analyze samples in a similar manner. The standard, however, may not improve the precision or accuracy of results, since, as it’s stated in the standard itself “…the detector in this method is the analyst, and therefore results are subjective, depending on the experience, training, qualification, and mental and optical fatigue of the analyst”.

Enumeration and Identification of Fungal Colony Forming Units.

Enumeration of colonies is performed under a stereo microscope or a suitable colony counter. Counting of colony forming units (CFU) is straight forward and easier than enumeration of total fungal spore counts. However, accuracy may be affected by:

    1. Colony density: If there are too many colonies, they tend to merge and this makes counting very difficult and inaccurate.
    2. Overgrowth: Some fungi grow faster than others thus masking the slow growing fungi

Counting is easier in some media such as dichloran 18% glycerol (DG18) agar which restricts the growth of colonies and significantly reduces the number of merging colonies. One drawback in using DG18 is that it can completely inhibit the growth of some fungi especially the hydrophilic species such as Stachybotrys and Chaetomium.

Colony forming units, CFUMalt extract agar (MEA) is commonly used in indoor air quality surveys. MEA is a nutrient rich medium and has high water activity, which favors hydrophilic and fast growing species which may mask, inhibit or entirely suppress the growth of other fungi.

Simultaneous use of MEA and DG18 is recommended since MEA supports the growth of a wide range of hydrophilic and mesophilic fungi while DG18 supports the growth of xerophilic and moderately xerophilic fungi. Therefore, use of MEA or DG18 alone may significantly reduce the number of species recovered.

For air samples collected using Andersen and other similar samplers, the colony count is adjusted (positive hole correction) before calculating the number of CFU per cubic meter of air. This adjustment is however not performed for air samples collected using the Reuter Centrifugal Sampler (RCS).

Salmonella food poisoning and symptoms

Salmonella food poisoning has been a growing concern in recent news. It has frequently lead to recalls of beef, salads and organic products and, even peanut butter products. Salmonella food poisoning occurs when one eats raw or undercooked foods such meat, poultry, eggs or egg products. Properly cooked food can get contaminated with Salmonella if […]

Legionella pneumophila – Guidelines for Laboratory Interpretation

Legionella pneumophila is a Gram negative, aerobic bacteria that is characterized as an opportunistic pathogen. It is the cause of Legionnaires’ Disease, a severe form of pneumonia and, it is the cause of Pontiac fever, a non-pneumonic form of L. pneumophila infection. Legionella spp.’s mode of transmission is through aerosols or aspiration of contaminated water. The Public Health […]

The Indoor Mold Is An Early Warning Device

The mold (or mould, in the Queen’s English) has been the victim of a bad press. Mention the word and it conjures up an image of something rotting or in the process of decomposition. And yet, were it not for the mold that inspired the discovery of penicillin millions of lives would have been lost. […]