What are the little "buggers"?

 Before 18th century, people believed that there was a mystic power in the world which

made wine from fruit juice, and turned healthy people sick and dead in a matter of days. Not until 1676, when Antony van Leeuwenhoek, who was the owner of a dry goods store, the janitor for the city hall, and the official wine taster for the city of Delft in Holland, first reported the observation of some "little" animal in rain water through the usage of his home-made microscope. Since then a lot of people have developed a profound interest in these little "buggers" which is now called microorganisms.Through the intensive efforts of various researchers, it is generally accepted that microorganisms can be divided into five groups, namely bacteria, fungi, viruses, algae and protozoa. A brief description of these agents and their roles in our daily life will be given below.

Bacteria, the most numerous component of the microbial world, are procaryote which lacking the nuclear membrane and other organized intracellular structures. Some of the bacteria, like Vibrio cholerae, Salmonella typhi, Staphylococcus aureus, etc., once get into our body will be able to make our life miserable, while other intestinal residing bacteria, such as Bifidobacterium, lactic acid bacteria, play important roles in keeping us healthy. Antibiotic, the magical compound that help to extend the life span beyond the imagination of the people living before 19th century can also produced by some of the Streptomyces. Besides medical aspect, bacteria also act as decomposer helping to recycle the fixed nutrient elements through the biosphere. In doing so, they help to remediate the environment that was polluted by toxic compounds, however, sometimes undesirable side-effect, such as the production of greenhouse gas, was detected. Furthermore, bacteria are also involved in the production of various dairy products, such as cheese, yogurt, and stink bean curd. Ya Mi or Yak !!

Fungi are eucaryotic organisms which may be either unicellular or multicellular. When talking about fungi, the first impression that comes into our mind is those delicious mushroom we see in the gourmet shop and the disgusting moldy specks on our bread and shower curtain. These organisms also play an important role in the recycle of various elements in the biosphere, especially they help to decompose those recalcitrant compoungs, such as cellulose and lignin. The first antibiotic discovered was produced by Penicillium, but fungi are also known to be able to produce toxins. Although some of the infections are only minor and irritating, such as athlete's foot, while others can be detrimental to our health. Besides health related aspect, fungi are also responsible for the production of various cooking ingredients, like soy sauce.

Protozoa are single-celled eucaryote. They are the little "buggers" that Leeuwenhoek had observed in his primitive microscope, and lead to the discovery of microorganisms. In the food chain, they serve as primary consumer helping to sustain the upper trophic level. In the environment, they can moving freely by means of cilia, flagella or pseudopod. Prorozoa are responsible for diminishing the total bacterial numbers in the sewage treatment plant and helping food digestion in the ruminant. However, some protozoa, like Giardia lamblia, will give you the diarrhea so bad that you will wish that you were never born.

Algae have rigid cell wall and are considered plantlike because they contain chlorophyll. In the food chain, they serve as primary producer, and without them, we will face a serious problem in food shortage. They are the agent responsible for the earthy-odor in our drinking water and eutrophication. Furthermore, some algae, like dinoflagellates, can produce highly toxic compounds, if ingested will cause serious consequence.

Viruses are the smallest microbes discussed thus far and they live within other organisms. Although they are small, once they get inside the host cell, they can cause great harm. Unfortunately, both animal and plant are their potential host. Common cold, genital herpes, poliomyelitis, and hepatitis are but few of the diseases that are caused by viruses. During the past twenty years, the most well known disease AIDs is caused by human immunodeficiency virus (HIV). Despite they can cause great havoc in our daily life, due to their abilities to insert themselves into the genetic material of host cells, some viruses are widely used in the operation of genetic engineering.

Together with the rapid development in various sciences, microbiology had also become a major scientific discipline within the biological sciences. It is foreseen that it will play a most important role in improving the welfare of mankind in the 21th century. If you want to learn more about this fascinating "microbes' world", please come and join us at Department of Microbiology, Soochow University.