Enhanced low-cost optimization strategies for antimicrobial rhamnolipid production by Pseudomonas aeruginosa PAO1

Abstract

The use of advanced biotechnological methods with agro-industrial waste is an outstanding approach for low-cost production. This study aimed to enhance rhamnolipid production by Pseudomonas aeruginosa PAO1 using agro-industrial waste and statistical modeling. The Box-Behnken model significantly increased rhamnolipid yield by 7.6-fold (661.7 ± 2.57 mg/L) at 40 g/L glycerol, 20 g/L glucose, 30 g/L peptone, pH 9, and 40 °C for 5 days. The replacement of glycerol and glucose with prickly pear peel (Opuntia ficus-indica) resulted in an increase of rhamnolipids to 847.3 ± 4.5 mg/L. The rhamnolipid concentration increased to 1521 mg/L after optimizing the air flow rate and agitation speed in the pilot-scale bioreactor. The rhamnolipids showed antimicrobial activity against Candida albicans, Escherichia coli, and Staphylococcus aureus strains. A concentration of 115 mg/L resulted in a 42.3 % reduction of the surface tension from 65 to 37.5 mN/m. The optimization processes using agricultural waste are promising approaches for future low-cost industrial production.