Variants of lipopeptides and glycolipids produced by Bacillus amyloliquefaciens and Pseudomonas aeruginosa cultured in different carbon substrates

Abstract

The quantitative and qualitative effect of water immiscible and miscible carbon-rich substrates on the production of biosurfactants, surfactin and rhamnolipids, by Bacillus amyloliquefaciens ST34 and Pseudomonas aeruginosa ST5, respectively, was analysed. A small-scale high throughput 96 deep-well micro-culture method was utilised to cultivate the two strains in mineral salt medium (MSM) supplemented with the water miscible (glucose, glycerol, fructose and sucrose) and water immiscible carbon sources (diesel, kerosene and sunflower oil) under the same growth conditions. The biosurfactants produced by the two strains were isolated by acid precipitation followed by an organic solvent extraction. Ultra-performance liquid chromatography coupled to electrospray ionisation mass spectrometry was utilised to analyse yields and characterise the biosurfactant variants. For B. amyloliquefaciens ST34, maximum surfactin production was observed in the MSM supplemented with fructose (28 mg L−1). In addition, four surfactin analogues were produced by ST34 using the different substrates, however, the C13–C15 surfactins were dominant in all extracts. For P. aeruginosa ST5, maximum rhamnolipid production was observed in the MSM supplemented with glucose (307 mg L−1). In addition, six rhamnolipid congeners were produced by ST5 using different substrates, however, Rha–Rha–C10–C10 and Rha–C10–C10 were the most abundant in all extracts. This study highlights that the carbon sources utilised influences the yield and analogues/congeners of surfactin and rhamnolipids produced by B. amyloliquefaciens and P. aeruginosa, respectively. Additionally, glucose and fructose were suitable substrates for rhamnolipid and surfactin, produced by P. aeruginosa ST5 and B. amyloliquefaciens ST34, which can be exploited for bioremediation or as antimicrobial agents.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-017-0367-4) contains supplementary material, which is available to authorized users.

Rhamnolipid exhibits anti-biofilm activity against the dermatophytic fungi Trichophyton rubrum and Trichophyton mentagrophytes

“…Screening of the in vitro antifungal activity can be useful to detect resistance trends and the capacity of a prospective antimicrobial to eradicate a specific fungal species [ 36 ]. The antifungal activities of RL-SS14 samples produced using different carbon sources were different, which can be explained by the variation in the RL congeners influenced by the type of substrates used for production, as reported previously by others [ 37 , 38 ]. In our study, RL-SS14 produced using glucose and glycerol exhibited the highest antifungal potentials against T. rubrum and T. mentagrophytes , respectively.…”

Identification and ultra‐high‐performance liquid chromatography coupled with high‐resolution mass spectrometry characterization of biosurfactants, including a new surfactin, isolated from oil‐contaminated environments

“…Similar behaviour was also observed by other authors (Belgacem et al ., ). It is known from the literature (Christova et al ., ; Ndlovu et al ., ; Nicolò et al ., ) that several growing factors such as the carbon source, specific culture conditions, age of culture and the Pseudomonas strain influence the composition of the rhamnolipid biosurfactant produced by Pseudomonas, influencing the emulsification activity.…”

Microbial production of rhamnolipids using sugars as carbon sources

“…The yield of rhamnolipids reached 36.7 g/L when P. aeruginosa was grown in a medium containing sunflower oil [ 115 ]. It has been noted that altering the components of the medium can improve rhamnolipids yields when glucose was used as a carbon source [ 116 ].…”