Chroococcales

Chroococcales

Microcystis aeruginosa, a common genus in the order Chroococcales

Chroococcales is an order of cyanobacteria, which are photosynthetic prokaryotes commonly referred to as blue-green algae. This order is characterized by its unicellular or colonial forms, often surrounded by a mucilaginous sheath. Chroococcales are found in a variety of aquatic environments, including freshwater, marine, and brackish waters.

Characteristics

Chroococcales are known for their simple cellular organization. The cells are typically spherical or oval and can exist as single cells or in colonies. The colonies are often embedded in a gelatinous matrix, which provides protection and aids in buoyancy.

Cellular Structure

The cells of Chroococcales contain chlorophyll a, which is essential for photosynthesis. They also possess phycobiliproteins, which give them their characteristic blue-green color. The cell wall is composed of peptidoglycan, similar to other bacteria, but they lack the complex internal structures found in eukaryotic algae.

Reproduction

Reproduction in Chroococcales is primarily asexual, occurring through binary fission. Some species can also form akinetes, which are thick-walled dormant cells that can withstand unfavorable environmental conditions.

Ecology

Chroococcales play a significant role in aquatic ecosystems. They contribute to primary production and are involved in nitrogen fixation, a process that converts atmospheric nitrogen into a form usable by plants. This makes them important contributors to nutrient cycling in aquatic environments.

Harmful Algal Blooms

Some species within Chroococcales, such as Microcystis aeruginosa, are known to form harmful algal blooms (HABs). These blooms can produce toxins that are detrimental to aquatic life and can pose health risks to humans and animals.

Notable Genera

• Microcystis - Known for forming blooms in nutrient-rich waters and producing microcystins, potent hepatotoxins.
• Gloeocapsa - Characterized by its colonial form with cells surrounded by a thick mucilaginous sheath.
• Synechococcus - A genus of small, unicellular cyanobacteria that are important in marine and freshwater ecosystems.

Related Pages

• Cyanobacteria
• Photosynthesis
• Nitrogen fixation
• Harmful algal bloom