Environ Exp Biol (2025) 23: 103–110

Isolation and selection of bioflocculant-producing and starch-degrading Bacillus spp. from bread production wastewater

Abstract

In many developing countries, limited wastewater treatment infrastructure can lead to environmental pollution from the food processing industry. Therefore, selecting bacterial strains capable of wastewater treatment and well-adapted to local conditions is essential. The aim of the present study was to isolate and characterize Bacillus spp. strains capable of producing amylase and bioflocculants for the treatment of starch-rich wastewater from traditional bread production facilities in Can Tho, Vietnam. From bread production wastewater, 13 Bacillus spp. strains were isolated with starch-degrading capability, of which seven strains exhibited the strongest substrate degradation after two days. The CT14 bacterial strain showed the highest starch degradation capability. After 24 h of wastewater treatment application of cultivated CT14 at a 4% concentration, the reduced sugar content reached a high level of 1.36 mg mL⁻¹. Additionally, the strain CD11 exhibited effective bioflocculant production in the form of polysaccharides, achieving 81.4% flocculation efficiency after 5 min of settling. Using 16S rRNA gene sequencing combined with several biochemical tests, two bacterial strains, CT14 and CD11, were identified as Bacillus amyloliquefaciens, with a similarity of over 99.7%.