Aspergillus niger : Introduction and Observation of structures on LPCB

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 comes under risk group (RG)-1 organism.

Aspergillosis: It is a granulomatous, narcotizing, and cavity disease of the lung. often with hematogenous spread to other organs.

Manifestation

Otomycosis and keratitis
Toxicity from ingestion of fungal contaminated foods.
Allergic manifestation
Colonization of fungus in the various body cavities and debilitated tissues
The invasive granulomatous disease of the lung with inflammation and necrosis
A systemic disseminated disease that is usually fatal if not treated-
increased incidence has been seen in
Leukemia
Diabetic patient
AIDS
Renal transplantation
Cardiac transplantation

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 a disinfectant. Cotton blue: It stains the fungal elements and glycerol: Is a hygroscopic agent that prevents drying.

**Observation 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 center 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 on 10 X objective and finally examine at 40 X objective under a 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 the following features-

Conidiophore length: 1.5-3.0 mm

Vesicle width (µm):45-75

Phialides: biseriate

Colour of conidia: black and

Diameter of conidia:4.5-5.0 µm.

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