Sampling Aspergillus spores in water

ID: 15

Group:

Sampling Aspergillus spores

Prepared by:

Dr Adilia Warris MD PhD

Detail:

This sampling protocol allows the isolation and enumerate Aspergillus spp. (and other filamentous fungi) conidia in water and on water-related surfaces.

Year prepared: 2000

Date uploaded: 2010-02-26 14:36:24

Introduction

This sampling protocol allows the isolation and enumerate Aspergillus spp. (and other filamentous fungi) conidia in water and on water-related surfaces.

Materials and equipment

  • Safety cabinet (optional)
  • Vacuum filtration system (parts of system getting in contact with the water samples should be sterilised)
  • Millipore filters with pore size 0.45 µm
  • Sterile tweezers
  • Sterile glass bottles 500ml
  • Sterile cotton swabs
  • Sterile water ampoules
  • Culture plates with Sabouraud glucose agar containing penicillin 20000 IE/l and streptomycin 40 mg/l

Procedure

Sampling Procedure – water

Water samples of 500ml each were collected in sterile glass bottles just by holding the bottle under the outlet. Open the outlet (tap, shower) 5 to 10 minutes before taking the sample to get rid of accumulated dust and dirt. If outlets are normally used frequently throughout the day, the sample can be taken right away. In a safety cabinet, filter the sample through Millipore filter. Take a new filter for every 500ml water. Transfer the filters with sterile tweezers onto Sabouraud glucose agar plates containing penicillin and streptomycin.

Sampling Procedure – waterrelated surfaces

Ensure these samples are taken before taking the water samples. Lubricate sterile cotton swabs with sterile water and press the swab firmly against the water-related surface. Streak the swabs onto Sabouraud glucose agar plates containing penicillin and streptomycin.

Incubation and evaluation

The culture plates are placed in an incubator heated to 35-37oC to permit germination and colony formation. Examine the plates every 24 hours and count the number of colony forming units on the plate. Identify the colonies by macroscopic and microscopic characteristics. It is recommended to use wet needle mount using lactophenol with cotton blue staining.

Comment

The amount of water taken per sample (500ml) might need some modification depending on the geographic area the sampling is carried out. The use of a safety cabinet is recommended to prevent contamination from the surrounding air and surfaces. Other temperatures can be chosen during the incubation of the plates depending on the kind of filamentous fungi to be studied.


Laboratory Protocols


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