Comparison of Sucrose-Hydrolyzing Enzymes Produced byRhizopus oryzaeandAmylomyces rouxii

Abstract

Rhizopus oryzae produces lactic acid from glucose but not efficiently from sucrose, while Amylomyces rouxii, a species closely related to R. oryzae, ferments these sugars equally. The properties of two sucrose-hydrolyzing enzymes purified from culture filtrates of R. oryzae NBRC 4785 and A. rouxii CBS 438.76 were compared to assess lactic acid fermentation by the two fungi. The substrate specificity of the enzymes showed that the enzymes from strains NBRC 4785 and CBS 438.76 are to be classified as glucoamylase and invertase respectively. The entity of the enzyme from strain NBRC 4785 might be a glucoamylase, because eight residues of the N-terminal amino acid sequence coincided with those of the deduced protein from the amyB gene of R. oryzae. The enzyme from NBRC 4785 was more unstable than that from strain CBS 438.76 under conditions of lower pH and higher temperature. These observations mean that the culture conditions of R. oryzae for lactic acid production from sucrose should be strictly controlled to prevent inactivation of the glucoamylase hydrolyzing sucrose.

Enzymatic Hydrolysis and Ethanol Fermentation of By-Products from Potato Processing Plants

“…The analytical conditions were as follows: column, Shodex KS-801 (8.0 mm × 30 cm, Showa Denko Co., Tokyo, Japan); column temperature 50℃; mobile phase, ultra pure water; injection volume, 20 µL, and flow rate 1.0 mL/min. Soluble sugars were analyzed by thin-layer chromatography (TLC) using TLC silica gel 60, aluminum backed (Merck) with a solvent system of 1-butanol/2-propanol/acetic acid/water (7:5:2:4, v/v) (Watanabe and Oda, 2008). Spots were visualized by spraying the plate with an anisaldehyde-sulfuric acid reagent (Sassalo et al, 2008).…”

Amylolytic fungi in starter cakes for rice beer production

“…In their study related to phylogenetic analysis, Kito et al (2009) took twenty-one strains of A. rouxii isolated from starters of Asian fermented foods and concluded that the species A. rouxii is composed of two distinct types, derived from R. oryzae or R. delemar via domestication in the starters. A. rouxii shows by the formation of rhizoids, stolons, and black pigmented sporangia, and thereby suggesting its closeness to R. oryzae (Watanabe and Oda, 2008). Also, studies have indicated the similarity of A. rouxii and R. oryzae revealed by DNA-DNA complementation.…”

“…A. rouxii have also been studied for the degradation of pentachlorophenol (PCP), which is a dangerous halogenated pollutant with persistence in the environment (Marcial et al, 2006;Montiel-González et al, 2009). The distinctive morphological characteristics of A. rouxii are the enormous number of chlamydospores produced in the aerial and substrate mycelium (Watanabe and Oda, 2008) which is seen in Fig. 1 Table 1.…”

“…It is a primary or secondary colonizer which readily invades easily accessible and digestible substrates (Battaglia et al, 2011). R. oryzae is also considered as an alternative microorganism for lactic acid fermentation as it synthesizes L-lactic acid from starchy materials by the action of external amylases in the presence of ammonium salts as the sole nitrogen source (Watanabe and Oda, 2008). In their study related to phylogenetic analysis, Kito et al (2009) took twenty-one strains of A. rouxii isolated from starters of Asian fermented foods and concluded that the species A. rouxii is composed of two distinct types, derived from R. oryzae or R. delemar via domestication in the starters.…”

“…Ghosh and Ray (2011) also reported the highest production of extra-cellular isoamylase by R. oryzae PR7 in solidstate fermentations of millet, oat, tapioca, and arum, after 72 h of growth at 28∞C and a pH of 8.0. In another study, Watanabe and Oda (2008) studied the properties of two sucrose-hydrolyzing enzymes produced by R. oryzae NBRC 4785 and A. rouxii CBS 438.76 and found that the enzymes could be classified as glucoamylase and invertase, respectively. They also found that the enzyme from the R. oryzae strain was more unstable than that from the A. rouxii strain, under conditions of lower pH and higher temperature.…”