Microbiology and Immunology

WORLD OF MICROBIOLOGY AND IMMUNOLOGY Pyrrophyta

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biology laboratory. The heat resistance of the slide allows a

specimen to be heated directly on the slide. This is important

for stains such as the acid-fast stain for mycobacteria, in which

heating of the samples is essential for the accurate staining of

the bacteria. Also, as for the optical density measurements, the

light microscopic examination of the bacterial sample depends

upon the transparency of the support surface. Plastic is not an

appropriate support material for slides.

Another area in which Pyrex glassware is essential in a

microbiology laboratory is in the pipelines required for the

delivery of distilled water. Distillation of water is a process

that requires the boiling of the water. The pipelines must be

heat resistant. Also, because physical scrubbing of the

pipelines is not feasible, the pipes must withstand the applica-

tion of caustic chemicals to scour organic material off the inte-

rior surface of the pipes.

Other applications of borosilicate glassware in the

microbiology laboratory include nondisposable Petri plates for

the use of solid media, centrifuge tubes, titration cylinders,

and the stopcocks that control the flow rate.

Heat and chemically resistant plastics are widely used in

the typical microbiology laboratory, particularly for routine,

high-volume operations where cleaning and preparation of

glassware for re-use is time-consuming and prone to error.

However, the accuracy and advantages of Pyrex glassware

ensure its continued use in the most modern of microbiology

laboratories.

See alsoLaboratory methods in microbiology; Microscopy

PPyrrophytaYRROPHYTA

Approximately 2000 species of Pyrrophyta (from the Greek

pyrrhos, meaning flames, and phyton, meaning plant) are

known at present. Pyrrophyta have been identified in fossil

deposits around the globe, from arctic to tropical seas, as well

as in hypersaline waters, freshwater, and river deltas.

Pyrrophyta are mostly unicellular microorganic Protistsdivided

by botanists in two phyla, dinoflagellatesand criptomonads.

The taxonomic classification of Pyrrophyta is disputed

by some zoologists who consider them members of the

Protozoakingdom. Cryptomonads for instance, are considered

red-brownish algae of Cryptomonadida Order by botanists,

and protozoans of Cryptophycea Class by zoologists. This

controversy is due to the unusual characteristics of these two

phyla, sharing features with both plants and animals. For

instance, most species swim freely because of the spiraling

Pyrex labware filled with colored liquid.

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