Amylolytic fungi in starter cakes for rice beer production

Area of Science:

• Microbiology
• Biotechnology
• Food Science

Background:

• Traditional starter cakes (amou, perok-kushi) are used in Assam, India for rice beer production by Bodo and Deori communities.
• These starter cakes harbor microorganisms with potential enzymatic activities.

Purpose of the Study:

• To isolate and identify amylolytic fungi from traditional starter cakes.
• To evaluate the starch-degrading and enzyme-producing capabilities of isolated fungi.
• To assess the safety of these fungi for potential industrial applications.

Main Methods:

• Isolation of fungi from starter cakes.
• Identification using internal transcribed spacer (ITS) sequencing.
• Enzyme activity assays (glucoamylase, α-amylase).
• Protein analysis using SDS-PAGE.
• Mycotoxin analysis using LC-MS/MS.

Main Results:

• Amylomyces rouxii (TU460) and Rhizopus oryzae (TU465) were identified as the primary amylolytic fungi.
• Both strains effectively degraded and saccharified starch.
• A. rouxii TU460 exhibited significantly higher glucoamylase activity (14.92 μmol/min) than R. oryzae TU465 (1.41 μmol/min).
• α-amylase activities were comparable (7.02 and 6.09 unit mL⁻¹).
• SDS-PAGE revealed distinct glucoamylase units (59 kDa, 31 kDa for A. rouxii; 72 kDa for R. oryzae).
• LC-MS/MS confirmed the absence of mycotoxin production by both strains.

Conclusions:

• The isolated Amylomyces rouxii and Rhizopus oryzae strains possess significant amylolytic properties.
• These fungi demonstrate potential for use in starch processing industries.
• The absence of mycotoxins indicates their safety for potential applications.