[4] In the past, strains were identified through isolating active components of the species that were commonly found in food and alcoholic drinks in Indonesia, China, and Japan.
[4] Rhizopus oryzae grows quickly in optimal temperatures, at 1.6 mm per hour (nearly 0.5 μm per second - enough to be able to directly visualize hyphal elongation in real-time under the microscope).
The sporangia in R. oryzae are globose or subglobose, wall spinous and black when mature, 60-180 μm in diameter.
Dormant and germinated sporangiospores show deep furrows and prominent ridges with a pattern that makes it distinguishable from that of R. stolonifer.
[3] Zygospores are produced by diploid cells when sexual reproduction occurs under nutrient poor conditions.
[8] The stolons found in R. oryzae are smooth or slightly rough, almost colorless or pale brown, 5-18 μm in diameter.
For example, it has been found in India, Pakistan, New Guinea, Taiwan, Central America, Peru, Argentina, Namibia, South Africa, Iraq, Somalia, Egypt, Libya, Tunisia, Israel, Turkey, Spain, Italy, Hungary, Czech Republic, Slovakia, Germany, Ukraine, British Isles, and the USA.
[1] It is present in maize, beans, sorghum, and cowpeas, pecans, hazelnuts, pistachios, wheat, barley, potatoes, sapodillas, and various other tropical foods.
[1] Maize meal on which isolates of R. oryzae had been grown was found to be toxic to ducklings and rats, causing growth depression.
[4] Rhizopus oryzae is one of the most common causes of a disease known as mucormycosis, characterized by growing hyphae within and surrounding blood vessels.
The causal agents of mucormycosis may also produce toxins like agroclavine which is toxic to humans, sheep and cattle.
[9][10] Common risk factors associated with primary cutaneous mucormycosis is ketoacidosis, neutropenia, acute lymphobloastic leukemia, lymphomas, systemic steroids, chemotherapy, and dialysis.
[12] Rhizopus oryzae is considered GRAS by the FDA and thus recognized as safe to use industrially as it can consume a range of carbon sources.
R. oryzae produce amylase, lipase, and protease activity to increase nutrient's ability to use many compounds as an energy and carbon source.
Overall, fruits, grains, nuts, and legumes mold-fermentation with R. oryzae produces sensory changes in foods such as creating acidity, sweetness and bitterness.
[17] Among finding cellulases and hemicellulases, other enzymes such as protease, urease, ribonuclease, pectate lyase, and polygalacturonase are found in cultural media of R. oryzae.
Cellulases in R. oryzae can be applied to biotechnology, in food, brewery and wine, animal feed, textiles and laundry, pulp and paper industries, and agriculture.
R. oryzae can convert both glucose and xylose under aerobic conditions into pure L (+)-lactic acids with by-products such as xylitol, glycerol, ethanol, carbon dioxide and fungal biomass.
Isoamylase was found to saccharify potato starch, arrow root, tamarind kernel, tapioca, and oat.
One strain of R. oryzae was found to secrete alkaline serine protease which shows high pH stability within 3 to 6 and poor thermos-stability.
Lipases hydrolyze fats and oils with subsequent release of free fatty acids such as diacylglycerols, monoacylglycerols and glycerol.
Lipases have been involved in biotechnology applications because of its ability to catalyze synthetic reactions in non-aqueous solutions.
R. oryzae strain ENHE isolated from contaminated soil was found to be capable of tolerating and removing pentachlorophenol.
Dry mycelium of four R. oryzae strains proved effective for catalysing the synthesis of different flavor esters.
Olive oil or oleic acid was found to be effective for enhancing methanolysis activity which is a promising results within the biodiesel industry.