INTRODUCTION

Most people in the field of science know that microorganisms such as bacteria are found almost everywhere.  Bacteria can grow in many different habitats, yet some conditions can limit bacterial growth (3).  These conditions might include high or low temperatures, high or low pH values, or even high salt concentrations.   However, some bacteria can survive and grow in these harsh conditions.

The types of bacteria that are able to grow in high salt conditions are known as halobacteria.  Some of these halobacteria are considered to be halotolerant in that they can grow in environments without salt along with environments that contain salt.  Others are halophilic in that they require salt to function properly (13).   Bacteria in these habitats also have special extracellular enzymes that allow them to grow and reproduce in different nutritional environments (4).  One such extracellular enzyme is amylase, which degrades starch.  Starch is a plant polysaccharide consisting of many monosaccharide (glucose) molecules attached together by glycosidic covalent bonds.  Starch consists of a soluble form, amylose, and an insoluble form, amylopectin.  The glycosidic bonds of starch are broken by amylase, which forms glucose and maltose, a monosaccharide and disaccharide respectively, that can be taken in by the organism for subsequent catabolism to produce energy and intermediates for anabolic pathways (3).  Enzyme performance and production in halophiles can also be affected by varying salt concentration as well as temperature and pH.  Testing the enzyme performance at different conditions can produce an interesting view of how the enzymes function in their natural habitat (8,9).

Amylase can be produced at all times by the organism or produced only when induced by factors in the environment.  Conditions surrounding the halobacterium can also control the amount of extracellular amylase that is produced by the organism (7).   Since growth can be directly related to enzyme production, growth of bacteria can be inhibited by various components found in the environment.  However, simple energy sources, such as glucose, can enhance growth since it is the main energy source for most organisms (5).  Still, amylase production is often decreased when glucose is put into a bacterium’s growth medium because there is no need for the enzyme (6).

The original purpose for this research was to study the production and characteristics of an amylase produced by a halophilic bacterium isolated from an inland salt spring located near Jackson, Alabama.  These springs produce water of high salinity and variable salinity and provide a unique ecological area for studying the organisms adapted to this area (1).  Although the research on the amylase proved unsuccessful, an unusual phenomenon was observed which proved to yield more interesting results.  The research reported in this thesis demonstrated that a halophilic bacterium isolated from this salt spring has some very unusual and interesting growth properties.