Microbiology and Immunology

WORLD OF MICROBIOLOGY AND IMMUNOLOGY Wong-Staal, Flossie

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The many varieties of wine, including champagne, are

the results of centuries of trial and error involving the myriad

varieties of grape and yeast.

See alsoEconomic uses and benefits of microorganisms;

Fermentation

WWinogradsky columnINOGRADSKY COLUMN

In a Winogradsky column the conditions change from oxygen-

rich (aerobic) at the top of the column to oxygen-deficient

(anaerobic) at the bottom. Different microorganismsdevelop

in the various environmental niches throughout the column.

The products of one microbe’s metabolic activities support the

growth of another microbe. The result is that the column

becomes a self-supporting ecosystem, which is driven only by

the energy received from the incoming sunlight. Winogradsky

columns are easily constructed, and are often used in class-

room experiments and demonstrations.

The Winogradsky column is named after Sergius

Winogradsky, a Russian microbiologist who was one of the

pioneers of the study of the diversity of the metabolic activi-

ties of microorganisms.

To set up a Winogradsky column, a glass or clear plastic

tube is filled one-third full with a mixture of mud obtained from

a river bottom, cellulose, sodium sulphate, and calcium carbon-

ate. The remaining two-thirds of the tube is filled with lake or

river water. The capped tube is placed near a sunlit window.

Over a period of two to three months, the length of the

tube becomes occupied by a series of microbial communities.

Initially, the cellulose provides nutrition for a rapid increase in

bacterial numbers. The growth uses up the available oxygen in

the sealed tube. Only the top water layer continues to contain

oxygen. The sediment at the bottom of the tube, which has

become completely oxygen-free, supports the growth only of

those bacteria that can grow in the absence of oxygen.

Desulfovibrio and Clostridium will predominate in the sediment.

Diffusion of hydrogen sulfide produced by the anaero-

bic bacteria, from the sediment into the water column above

supports the growth of anaerobic photosynthetic bacteria such

as green sulfur bacteria and purple sulfur bacteria. These bac-

teria are able to utilize sunlight to generate energy and can use

carbon dioxide in a oxygen-free reaction to produce com-

pounds needed for growth.

The diminished hydrogen sulfide conditions a bit fur-

ther up the tube then support the development of purple sulfur

bacteria such as Rhodopseudomonas, Rhodospirillum, and

Rhodomicrobium.

Towards the top of the tube, oxygen is still present in the

water. Photosynthetic cyanobacteria will grow in this region,

with the surface of the water presenting an atmosphere con-

ducive to the growth of sheathed bacteria.

The Winogradsky column has proved to be an excellent

learning tool for generations of microbiology students, and a

classic demonstration of how carbon and energy specifics

result in various niches for different microbes, and of the recy-

cling of sulfur, nitrogen, and carbon.

See alsoChemoautotrophic and chemolithotrophic bacteria;

Methane oxidizing and producing bacteria

WWong-Staal, Flossie ONG-STAAL, FLOSSIE (1947- )

Chinese American virologist

Although Flossie Wong-Staal is considered one of the world’s

top experts in virusesand a codiscoverer of the human immun-

odeficiency virus(HIV) that causes AIDS, her interest in sci-

ence did not come naturally.

Born as Yee Ching Wong in communist mainland

China, she fled with her family in 1952 to Hong Kong, where

she entered an all-girls Catholic school. When students there

achieved high grades, they were steered into scientific studies.

The young Wong had excellent marks, but initially had no

plans of becoming a scientist. Against her expectations, she

gradually became enamored with science. Another significant

result of attending the private school was the changing of her

name. The school encouraged Wong to adopt an English

name. Her father, who did not speak English, chose the name

Flossie from newspaper accounts of Typhoon Flossie, which

had struck Hong Kong the previous week.

Even though none of Wong’s female relatives had ever

gone to college or university, her family enthusiastically sup-

ported her education and in 1965, she went to the United States

to study at the University of California at Los Angeles. In 1968,

Wong graduated magna cum laude with a B.S. in bacteriology,

also obtaining a doctorate in molecular biologyin 1972.

During postgraduate work at the university’s San Diego

campus in 1971–72, Wong married and added Staal to her

name. The marriage eventually ended in divorce. In 1973,

Flossie Wong-Staal, a pioneer in AIDS research.

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