Monday, December 24, 2012

Aspergillus flavus

Known for producing the carcinogen aflatoxin, Aspergillus flavus, can also produce Aspergillosis in immune compromised individuals. It is considered a plant, animal and human pathogen.

The organism is characterised by a lime green growth in culture with a rough stipe and variable head shape.  The younger heads my have only one set of supporting structures for the conidia (uniserate) where older heads will have both phialides and metulae (biserrate). 

The spores are unremarkable in appearance and would be classified as Asp/Pen like on an Air-O-Cell cassette sample.


The rough stipe of Aspergillus flavus growing in culture 400x - N. Carlson

Aspergillus flavus on a culture plate - N. Carlson
Aspergillus flavus 400x  heads can be biserrate and sometimes uniserrate- N. Carlson
 

Aspergillus nidulans

The asexual state of Emericella nidulans, Aspergillus nidulans is an easily recognizable Aspergillus spp. when grown in culture. 

The amber colored, short asymmetric foot cell combined with a bright emerald green colony make this an interesting organism.  Under certain conditions it will also produce egg like structures known as Hulle Cells.   Note: There is supposed to be a squiggle above the 'u' in Hulle cells.

The spores do not have a unique structure and would be classified as Asp/Pen like on an Air-O-Cell cassette sample.
Hulle Cells from Emericella nidulans 400x - N. Carlson
Emericella nidulans - 8 days DG-18 - 25C
Emericella nidulans 8days MEA - 25 C
Emericella nidulans 8days CYA - 25 C


Emericella nidulans - 400x - N. Carlson

Aspergillus terreus

With its tan color growing on a culture plate and the spores produced in tight columns, Aspergillus terreus is one of the easier Aspergillus spp. to identify. 

It is an infrequent cause of Aspergillosis for the strains that can grow at 37 degrees Celsius.

Aspergillus terreus 400x - Acid Fuschin stain - N. Carlson

Aspergillus terreus - dilute acid fuschin stain 400x - N. Carlson

Aspergillus terreus in culture - N. Carlson
 

Aspergillus versicolor

Another member of the Aspergillus genera often found on damp building materials is Aspergillus versicolor, It is very closely related to Aspergillus sydowii. The colony color is light green with a few other pale colors mixed in compared to Aspergillus sydowii's deep blue green.

Both Aspergillus versicolor and Aspergillus sydowii have small spathulate heads. They are shaped like like a tiny Dairy Queen malt spoon. They will also produce conidia from structures that resemble Penicillium spp.


The spores do not have distinguishing characteristics and are identified as Asp/Pen like on an Air-O-Cell cassette sample.


Aspergillus versicolor line drawing- N. Carlson
Aspergillus versicolor colonies - N. Carlson
Aspergillus versiolor - N. Carlson

 

 

Aspergillus sydowii

Another member of the Aspergillus genera often found on damp building materials is Aspergillus sydowii,  It is very closely related to Aspergillus versicolor.  The colony color is a deep blue green compared to Aspergillus versicolor's light green with a few other pale colors mixed in. According to the National Science Foundation, purple sea fan coral can be attacked by Aspergillus sydowii.

Both Aspergillus versicolor and Aspergillus sydowii have small spathulate heads.  They are shaped like like a tiny Dairy Queen malt spoon.  They will also produce conidia from structures that resemble Penicillium spp.


The spores do not have distinguishing characteristics and are identified as Asp/Pen like on an Air-O-Cell cassette sample.


Aspergillus sydowii line drawing - N. Carlson
Aspergillus sydowii in culture. - N. Carlson
Typical Aspergillus sydowii heads - N. Carlson
Aspergillus sydowii - standard head and Penicillate like structure - N. Carlson


Thursday, December 20, 2012

Aspergillus fumigatus

The thermophillic fungus, Aspergillus fumigatus, aids in decomposing compost piles and can also cause pulmonary aspergillosis in immune compromised individuals. 

It grows rapidly at 37 degrees Celsius on PDA and MEA with a flat blue green colony that can cover the plate in less than 3 days.  Growth is somewhat slower at 25 degrees on PDA and MEA.   On DG-18 the growth of the colony is restricted often less than 1 cm in 5 days. 

Unless the actual head of the Aspergillus fumigatus spore is found on an Air-O-Cell cassette sample it is not possible to identify the spore other than to put it in the category of Aspergillus/Penicillium like organism.

The spores are small, typically less than 3 microns.  The spores cover the  top 2/3rds of the vesicle.  The stipe of the conidiophore is smooth and often twisted.

Aspergillus fumigatus - line drawing - N. Carlson
 
Aspergillus fumigatus - lactophenol cotton blue stain - N. Carlson
Aspergillus fumigatus - 25C DG-18 - N. Carlson

Aspergillus fumigatus - MEA 25C in culture - N. Carlson

 
 
Aspergillus fumigatus 400x 85% lactic acid stain - N. Carlson
 
Aspergillus fumigatus 100x stereoscope lit from the side - N. Carlson
 
 
Video on Aspergillosis by the IAQ Network

Monday, December 17, 2012

Trichoderma spp.

The fungal organism, Trichoderma spp., is commonly found growing on wet building materials. 

If the spores are in clusters they can be identified on Air-O-Cell cassette air samples.  If the spores are alone it is very difficult to differentiate the conidia from Aspergillus spp. or Penicillium spp.

Trichoderma spp. grows rapidly in culture at 25 degrees C on MEA and PDA and slower on DG-18.  The colonies have a characteristic green, yellow and white color and spread rapidly across the plate.

Trichoderma spp. line drawings - N. Carlson


Trichoderma spp. growth on culture. - N. Carlson
Trichoderma spp. growth in culture -Acid Fuchsin stain - 400x N. Carlson


Positive uses of Trichoderma as a natrual method of improving plant growth.

Ulocladium spp.

A dark colored fungi that grows in places similar to Stachybotrys spp., Ulocladium spp. is often found growing in water damaged sheetrock. 

It is hard to distinguish between Alternaria spp. and Ulocladium spp. in an Air-O-Cell cassette sample if the spores are not in chains.  The colony growth on a culture plate is also similar.  The growth in culture is different. The Ulocladium spp. spores are borne singly on short conidiophores. The Alternaria spp. spores are in chains.

The organism grows well at 25 C for PDA and MEA and a bit slower on DG-18.


Ulocladium spp. line drawing - N. Carlson
 
Ulocladium spp. 400x growing in culture - N. Carlson
Ulocladium spp. growth in culture - N. Carlson

Ulocladium spp. wikipedia article video

Nigrospora spp.

A common outdoor mold, Nigrospora has a readily identifiable spore that can easily be found on an Air-O-Cell Cassette sample and identified easily in fungal culture.  The good sized oval shaped spore is perched atop a very short conidiophore. 


Nigrospora spp.  line drawings - N. Carlson
Nigrospora spp. growth in culture. - N. Carlson
Nigrospora spp. growth 400x (10 to 12.5 microns wide) - N. Carlson 
Interesting angle showing the underside of a Nigrospora spp. conidia attached.  - N. Carlson

Cunninghamella spp.

The zygomycete fungi Cunninghamella spp. is another possible cause for mucormycosis for the species that grow at 37 degrees Celsius.

The culture growth is moderate.  The spores are not readily identified on an Air-O-Cell cassette due to lack of distinctive features. 

Growth is better on PDA and MEA than on  DG-18 due to the addition of Dichloran in the media.

Cunninghamella spp. 400x with a dilute acid fuschin stain - N. Carlson
 
Cunnnghamella spp. growth on MEA 25C - N. Carlson


Zygomycosis Wiki Article video

Chaetomium spp.

The ascomycete fungi, Chaetomium spp. is commonly found growing on sheetrock and processed wood building materials.  The organism grows at a moderate rate on the culture.

The spores are readily identified in an Air-O-Cell cassette air sample with the characteristic lemon drop shaped spores.  On sheetock, Chaetomium spp. forms visible dark spots on the material.  The hard perithecia containing the spores will crack a glass cover slip. 

The organism grows best on MEA and PDA and less well on DG-18 due to the lower moisture content. 

Chaetomium spp. spores - line drawing
 
Chaetomium spp. at 100x the perithecia - line drawing
Chaetomium spp. spores - approximately 10 microns in length 400x  - N. Carlson
Chaetomium spp. perithecia 100x  N.Carlson
Chaetomium spp. growth on sheet rock no magnification -  N. Carlson
 
Chaetomium spp. growth in culture- N. Carlson

Absidia spp.

The zygomycete, Absidia spp. is another infrequent cause of mucormycosis.  The organisms produces a smaller sporangiophore than both Mucor spp. and Rhizopus spp.  The colony growth is not as rapid as Rhizopus spp.

At 25 degrees C.  Absidia spp. grows better on PDA and MEA and slower on DG-18 due to the inhibition of Dichloran.   Some species of Absidia spp. are capable of growing at body temperature 37 degrees C.  These opportunistic pathogens may cause mucormycosis.

 
Absidia spp. growth in culture at 400x lactophenol cotton blue stain - N. Carlson
 

Absidia spp. growth in culture at 400x Acid Fuchsin stain - N. Carlson
 
 
 
Absidia spp. growth in culture using 85% lactic acid stain.  Notice the off center root like structure. - N. Carlson
 
  Mucormycosis Wiki video

Mucor spp.

Another zygomycete organism similar to Rhizopus spp. is Mucor spp.  This rapidly growing organism is also an opportunistic pathogen for immune compromised individuals.  It can cause mucormycosis.  It is in the news recently (September, 2015) as a possible source for transplant patient deaths at Pittsburgh's UMPC Presbyterian - WESA FM.

The spores are round and there is no root like structure as there is for Rhizopus spp.  The spores do not have distinguishing characteristics and are not identifiable on an Air-O-Cell cassette sample.

In culture the colony grows rapidly at 25 and  for some pathogenic species at  37 degrees C.  Growth is rapid on MEA and PDA and much slower on DG-18 due to the inhibition by dichloran.  The colony growth on agar is a light brown in contrast to the white mycelium with dark pepper like spots of Rhizopus spp.

Mucor spp. line drawings showing various stages of the sporangium - N. Carlson


Mucor plumbeus 400x growth in culture -lactophenol cotton blue stain - N Carlson

Mucor racemosus growth in culture 400x lactophenol cotton blue stain - N. Carlson

Mucor spp. lactic acid stain - N. Carlson

Mucor spp. colony growth on a culture plate - N. Carlson
Mucor spp.  by the IAQ video network.