Rhizopus

Rhizopus is a widespread genus of multicellular fungi. These organisms function as saprophytes, which means they live by feeding on organic matter. You might find them on mature fruits and vegetables, jellies, or syrups. They also grow on leather, bread, peanuts, and tobacco. While many species are helpful or neutral, some are specialized parasites on animals. Certain species are also opportunistic human pathogens. These can cause a fatal disease known as mucormycosis.

To understand how Rhizopus grows, we must look at its physical structure. They grow as filamentous, branching hyphae. These hyphae are generally coenocytic, meaning they lack cross-walls. This structure allows the fungus to spread through its food source. The hyphae arise from distinctive, root-like structures called rhizoids. From these rhizoids, long stalks called sporangiophores emerge. These stalks support a spherical structure known as a sporangium.

Rhizopus uses two different methods to reproduce. In asexual reproduction, the fungus produces spores inside the sporangium. These spores allow the fungus to spread quickly. For sexual reproduction, the process is more complex. It occurs at the point where two compatible mycelia fuse together. This fusion results in the production of a dark zygospore. When a zygospore germinates, it grows into new colonies. These new colonies are genetically different from both parent organisms.

There are at least eight species within this genus. Each species has unique roles in nature and industry. For example, Rhizopus oligosporus is used to create tempeh. Tempeh is a fermented food made from soybeans. Another species, Rhizopus oryzae, is used to produce alcoholic beverages. This occurs in parts of both Africa and Asia. Rhizopus oryzae also practices heterothallic mating. This means it uses a plus and a minus mating type to reproduce.

Some species are known for causing decay in plants. Rhizopus stolonifer is commonly called black bread mold. It can cause fruit rot on strawberries, tomatoes, and sweet potatoes. It may also cause soft rot in Narcissus plants. Despite this, Rhizopus stolonifer is useful in commercial production. Scientists use it to produce fumaric acid and cortisone. This shows how a mold that destroys food can also create medicine.

Rhizopus also plays a vital role in environmental health. These fungi increase the nutrient content of soils. They do this by degrading certain toxins. They also inhibit the growth of Aspergillus flavus, which is a toxigenic fungus. Research has shown some specialized benefits in animals as well. A type called Rhizopus microsporus can reduce colon carcinogenesis in rats. It does this by elevating factors of mucins, organic acids, and immunoglobulin A.

In livestock, certain species provide significant protection. Rhizopus microsporus can protect piglets from Escherichia coli infections. It works by inhibiting the bacteria from adhering to intestinal membranes. This demonstrates how fungi can influence the health of entire biological systems. On a microscopic level, these fungi have large genomes. Evidence suggests they have undergone a full genome duplication. This complex genetic makeup helps them thrive in many different environments.