Conversion of Agroindustrial Wastes to Rhamnolipid by Enterobacter sp. UJS-RC and Its Role against Biofilm-Forming Foodborne Pathogens

Abstract

Rhamnolipid is the main group of biosurfactants predominantly produced by Pseudomonas aeruginosa, a ubiquitous and opportunistic pathogen, which limits its large-scale exploitation. Thus, cost-effective rhamnolipid production from a newly isolated nonpathogenic Enterobacter sp. UJS-RC was investigated. The highest rhamnolipid production (4.4 ± 0.2 g/L) was achieved in a medium constituting agroindustrial wastes (sugarcane molasses and corn steep liquor) as substrates. Rhamnolipid exhibited reduced surface tension to 72–28 mN/m with an emulsification index of 75%. The structural analyses demonstrated the presence of methoxyl, carboxyl, and hydroxyl groups in rhamnolipid. Mass spectra indicated eight rhamnolipid congeners, where dirhamnolipid (m/z 650.01) was the dominant congener. Rhamnolipid inhibited biofilm formation of Staphylococcus aureus in a dose-dependent manner, supported by scanning electron microscopy disclosing the disruption of the microcolony/exopolysaccharide matrix. Rhamnolipid’s ability to generate reactive oxygen species has thrown light on the mechanism through which the killing of test bacteria may occur.

Natural Berberine-Hybridized Benzimidazoles as Novel Unique Bactericides against Staphylococcus aureus

“…Efficient bactericidal activity is one of the most important features of an effective antibacterial agent . The bactericidal performance of active molecule 7d (6 × MIC and 8 × MIC) against S.…”

“…Efficient bactericidal activity is one of the most important features of an effective antibacterial agent. 36 The bactericidal performance of active molecule 7d (6 × MIC and 8 × MIC) against S. aureus ATCC 29213 (early and late exponential phases) was evaluated, and the results are recorded in Figure 3. Compound 7d could rapidly kill early exponential phase S. aureus ATCC 29213 (2 h, 6 × MIC; 1 h, 8 × MIC), and the late exponential phase bacteria were also killed in the presence of molecule 7d (5 h, 6 × MIC; 3 h, 8 × MIC).…”

Multifunctional, stable and low-cost lipopeptide biosurfactant produced by Enterobacter cloacae UCP 1597

“…N18, using yeast extract and sucrose as substrates (You, et al, 2015) and Enterobacter sp. UJS-RC using corn steep liquor and sugarcane molasses as alternative sources (Chandankere, et al, 2020) (Table 3). Recently, Ekprasert et al ( 2021) reported higher biosurfactant production by E. cloacae B14 using waste frying oil, compared to other agro-industrial wastes (spent coffee grounds and molasses), confirming the suitability of this alternative substrate.…”

Two New Sulfate-Modified Dibenzopyrones With Anti-foodborne Bacteria Activity From Sponge-Derived Fungus Alternaria sp. SCSIOS02F49

“…As a growing public health problem throughout the world, foodborne diseases (FBDs) have resulted in almost 1 in 10 people being ill, leading to 420,000 deaths every year (Chandankere et al, 2020 ; Li et al, 2020 ). Among them, FBDs caused by Campylobacter pylori, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Vibrio parahaemolyticus, Salmonella cholerae, Proteus mirabilis, Shigella flexneri , and other foodborne bacteria (FBB) have been widely reported and are of great concern (Tack et al, 2019 , 2020 ).…”