spirillák

Spirilla are a group of Gram-negative bacteria characterized by their spiral or helical shape. They are motile, typically using flagella to propel themselves through aqueous environments. This distinct morphology sets them apart from other bacterial shapes like cocci (spherical) and bacilli (rod-shaped).

Spirilla are found in a variety of habitats, including freshwater, saltwater, and soil. They are generally aerobic, meaning they require oxygen for respiration. Some species can also be facultative anaerobes, capable of surviving in the absence of oxygen under certain conditions. Their ecological roles vary; some are free-living decomposers, while others can be parasitic or pathogenic, causing diseases in humans and animals.

A notable example is Spirillum minus, a bacterium that can cause rat-bite fever, a zoonotic disease transmitted through the bite of infected rodents. However, many other spirilla species are harmless and play important roles in nutrient cycling within their ecosystems.

The classification of spirilla has evolved with advancements in molecular biology. Historically, the genus Spirillum was used for many spiral-shaped bacteria. However, modern taxonomy has reclassified many of these organisms into different genera based on genetic and biochemical analysis, reflecting a more nuanced understanding of their evolutionary relationships. Despite these reclassifications, the term "spirilla" remains in common use to describe bacteria with this general helical form.