Aspergillus niger : Introduction and Observation of structures on LPCB tease mount
Introduction of Aspergillus niger
Aspergillus niger is one of the most common and easily identifiable species of the genus Aspergillus, with its white to yellow mat later bearing black conidia. This species is very commonly found in aspergillomas and is the most frequently encountered agent of otomycosis. It is also a common laboratory contaminant and come under risk group (RG)-1 organism.
Aspergillosis: It is a granulomatous, narcotizing and cavity disease of the lung. often with haematogenous spread to other organs.
Otomycosis and keratis
Toxicity from ingestion of fungal contaminated foods.
Colonization of fungus in various body cavity and debilitated tissues
Invasive granulomatous disease of the lung with inflammation and necrosis
Systenic disseminated disease that is usually fatal if not treated-
increased incidence has been seen in
LPCB is a combination of fixative , staining and clearing agent. Its contents functions are as follows-Lactic acid: It helps in preserving the morphology of the fungal elements . Phenol : It acts as disinfectant. Cotton blue: It stains the fungal elements and glycerol: It is a hygroscopic agent that prevents drying.
Oservation of Aspergillus niger structures On LPCB tease mount
Put a drop of LPCB on a clean grease free glass slide.Take a small portion of the colony and the supporting agar at a point between the centre and the periphery and place it in the drop.With the help of a needle,tease the fungal culture first and spread in the LPCB. Wait for normally 30 minutes .i.e. sufficient time for the structures to take up the stain. Focus at 10 X objective and finally examine at 40 X objective under microscope. Fungi appear as dark blue stained mycelium.
Aspergillus niger on lactophenol cotton blue (LPCB) mount as shown above picture. To say Aspergillus niger, it should have following features-
Conidiophore length: 1.5-3.0 mm
Vesicle width (µm):45-75
Colour of conidia: black and
Diameter of conidia:4.5-5.0 µm.
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