Glucoamylse Production in Submerged Co-Culture System of <i>Bacillus amyloliquefaciens</i> and <i>Rhizopus cohnii</i>

Abstract

We developed novel method for producing glucoamylase (GA) from gelatinized rice flour by co-culturing Bacillus amyloliquefaciens NBRC 14141 and Rhizopus cohnii P5. In liquid culture, the acidification of the growth medium due to the growth of R. cohnii prevented the growth of B. amyloliquefaciens; however, the B. amyloliquefaciens protease lysed R. cohnii cells, which decreased the production of GA. This antagonism was repressed by high concentrations of ammonium acetate in the growth medium. However, since low pH or high ammonium acetate concentrations inhibited the initial growth of B. amyloliquefaciens, it needed to be precultured without ammonium acetate. However, preculturing B. amyloliquefaciens for 48 h led to overproduction of protease, which inhibited the growth of R. cohnii. As a result, the maximum GA activity (740 U/ml) was obtained when B. amyloliquefaciens was precultured for 24 h followed by inoculation with R. cohnii in the presence of 3.84% (w/v) of ammonium acetate. These results indicated that GA can be produced at high levels from gelatinized rice flour by using a submerged co-culture system.

Simultaneous Increase of Glucoamylase and α-Amylase Production in Submerged Co-culture of <i>Aspergillus</i> and <i>Rhizopus</i> Strains

“…Moreover, ammonium acetate inhibits the initial growth of B. amyloliquefaciens and reduces the production of protease. Our results indicate that one organism modulates the growth and production of metabolites by the other organism in the co-culture of fungi and bacteria [12].…”

“…A-11 in submerged culture involving liquefied cassava starch, which was produced in a reaction of α-A with gelatinized cassava starch in the presence of heat and metal ions. Previously, we developed a method for increased GA production based on coculturing of Bacillus amyloliquefaciens NBRC 14141 and Rhizopus cohnii P5; we found that ammonium acetate promotes the production of GA [12]. In particular, we showed that ammonium acetate in the medium causes the mycelial weight of R. cohnii to increase and prevents the acidification of culture.…”

“…We previously reported [12] the development of a novel system for GA production in submerged co-culture of B. amyloliquefaciens and R. cohnii and found that ammonium acetate promoteds the production of GA, helping to achieve a high GA activity (740 U/mL).…”

“…The influence of sodium nitrate as a nitrogen source on (A) glucoamylase (GA) activity (U/mL), (B) α-Amylase (α-A) activity (U/mL), and (C) dry mycelial weight (DMW; grames per 100 mL) in co-cultur of Rhizopus arrhizus and Aspergillus oryzae for 96 h. Symbols: ▲, co-culture, quantities of the broth of R. arrhizus and A. oryzae were 90 mL and3.3 The co-culture system with a controlled number of sporesPreviously, we developed the following novel co-culture method: first, B. amyloliquefaciens cell suspension is added to a liquid medium and cultured for 24 h; then, coculture is initiated by inoculating the culture with R. cohnii spores. As a result, the yields of GA increases, and a maximal GA activity (740 U/mL) is obtained[12].…”