What are Spore Structures in Gram +ve cells Few species of bacteria have the ability to produce highly resistant structures known as endospores

* Bacterial spores are NOT a reproductive structure, like plant or fungal spores

* Occurrence

* Produced by very few genera of bacteria

* Major examples: Bacillus and Clostridium

* Significance in Medicine & Industry

* Spores are resistant to killing

* Cannot be killed by 100°C (boiling)

* Requires heating to 120°C for 15-20 min (autoclaving or pressure cooking)

* Sporulation

* The process of spore formation

* Governed by genetic mechanism

* A copy of the bacterial chromosome is surrounded by a thick, durable spore coat

* This forms an endospore within a vegetative cell

* When the vegetative cell dies and ruptures, the free spore is released

* Spore Germination

* When a spore encounters favourable growth conditions

* The spore coat ruptures and a new vegetative cell is formed

SPORES

Bacterial SPORES (or ENDOSPORES) are the toughest forms of life known. They are so resistant to destruction that some scientists have proposed that life arrived on earth when bacterial spores drifting through space fell to earth. Only G+ cells form spores, specifically members of the genera Bacillus and Clostridium. Spores are formed by bacteria to survive during PERIODS OF DEPRIVATION, such as the loss of a food or water supply. When a spore-forming-bacterium (SFB) senses that tough times are coming a series of COMPLEX EVENTS are triggered that lead to the formation of a spore. Basically a spore is a structure that contains the ABSOLUTE MINIMUM of genetic information and associated materials required to produce the vegetative form once times become good again. The genetic material (DNA) and other indispensable substances are packaged into a dry, heavily shielded spore that is able to resist high temperature, drying, UV light, deleterious chemicals and other harmful conditions. All metabolic activity ceases and spores appear "DEAD" or in deep HIBERNATION (stasis). We do not know how long this resting state can last, but viable spores have been found in sealed tombs that are 1,000s of years old. Recently, Jurassic spores that are approximately 65 million years old were reported to have been germinated after recovery from insects in amber. When spores sense that the environment is suitable for growth the spore is triggered to GERMINATE. Germination is the process whereby spores change (DIFFERENTIATE) into VEGETATIVE CELLS that grow, reproduce and metabolise. One spore turns into ONE vegetative cell. The vegetative cell has NONE of the resistant properties of the spore; that is, it is easily killed by heat, UV light and drying.

Because the spore is protected by a thick, tough covering, it is difficult to stain. To force the stain into the spore body we use the thermal energy present in stream. We then counter-stain any vegetative cell components that are attached to the spore with a dye of a contrasting colour. Therefore a spore stain contains spores alone, spores inside vegetative cells and vegetative cells without spores formed in them.