Introduction

The brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Most brown algae live in marine environments, where they play an important role both as food and as a potential habitat. For instance, Macrocystis, kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests. Kelp forests like these contain a high level of biodiversity.

Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Some members of the class, such as kelps, are used by humans as food.

Freshwater species are rare. Brown algae multiply by asexual and sexual reproduction; both the motile zoospores and gametes have two unequal flagella. Some seaweed species have gas-filled bladders (pneumatocysts), which keep photosynthetic parts of the algal thallus floating on or near the surface of the water.

Classification

Phaeophyceae is a class of brown algae. The other two major classes are Chlorophyceae (green algae) and Rhodophyceae (red algae).

Phaeophyceae is divided into 9 orders by Fritsch. The main orders are: Ectocarpales-e.g. Ectocarpus, etc. Laminariales-e.g. Laminaria, Macrocystis, Nerocystis (Giant Kelp), etc. Fucales-e.g. Fucus, Sargassum, etc. Dictyotales-e.g. Dictyota, etc.

Economic importance

Algae are important for their carbon fixation ability. They are an important component of the aquatic food chain as primary producers. Kelp forests support large numbers of animals.

They are widely used as edible seaweeds, e.g. Laminaria, Sargassum, etc. Alginic acid is commercially extracted and used in the food industries as a thickening agent. It is used as a stabilizer in ice cream and baking industries. Alginic acid is also used in batteries. Alginic acid is used for making pills and surgical threads. Several species are used as fertilizers. Kelp is used for producing soda ash. It is used in the production of soap and glass.

Brown algae like Laminaria are rich in iodine and have been used to treat iodine deficiency, e.g. Goitre. They have been used for medicinal purposes, e.g. sodium laminarin sulphate is an anticoagulant. They also have antibiotic and vermifuge properties.

Brown algae belong to the group Heterokontophyta, a large group of eukaryotic organisms distinguished most prominently by having chloroplasts surrounded by four membranes, suggesting an origin from a symbiotic relationship between a basal eukaryote and another eukaryotic organism. Most brown algae contain the pigment fucoxanthin, which is responsible for the distinctive greenish-brown color that gives them their name. Brown algae are unique among heterokonts in developing into multicellular forms with differentiated tissues, but they reproduce by means of flagellated spores and gametes that closely resemble cells of other heterokonts. Genetic studies show their closest relatives to be the yellow-green algae.

The journal of “Medical Microbiology & Diagnosis” is a peer reviewed medical journal that includes a wide range of topics in this fields including Bacteriology, Clinical and Medical Diagnostics, Parasitology, Bacterial Infections and creates a platform for the authors to make their contribution towards the journal. The editorial office promises a thorough peer review of the submitted manuscripts to ensure quality.

Best Regards,

Mary Wilson,

Associate Managing Editor,

Medical Microbiology & Diagnosis

E-mail: microbiology@jpeerreview.com