Rhamnolipid production by a gamma ray-induced Pseudomonas aeruginosa mutant under solid state fermentation

Abstract

Solid-state fermentation has a special advantage of preventing the foaming problem that obstructs submerged fermentation processes for rhamnolipid production. In the present work, a 50:50 mixture of sugarcane bagasse and sunflower seed meal was selected as the optimum substrate for rhamnolipid production using a Pseudomonas aeruginosa mutant 15GR and an impregnating solution including 5% v/v glycerol. Using Box–Behnken design, the optimum fermentation conditions were found to be an inoculum size 1% v/v, temperature 30 °C and unlike other studies, pH 8. These optimized conditions yielded a 67% enhancement of rhamnolipid levels reaching 46.85 g rhamnolipids per liter of impregnating solution, after 10 days, which was about 5.5 folds higher than that obtained by submerged liquid fermentation. Although maximum rhamnolipids concentration was obtained after 10 days of incubation, rhamnolipids concentration already reached high levels (41.87 g/l) after only 6 days. This rhamnolipid level was obtained in a shorter time and using lower carbon source concentrations than most studies reported so far. The findings obtained indicate an enormous potential for employing solid-state fermentation for rhamnolipid production by the studied isolate.

Use of waste canola oil as a low-cost substrate for rhamnolipid production using Pseudomonas aeruginosa

“…Partial sequencing of the 16S rRNA gene in combination with the biochemical tests results enabled the confirmation of the identity of the strain as P. aeruginosa. This species is considered a metabolically versatile bacterium that is able to use a variety of simple and complex carbon sources and can survive under normal and harsh environmental conditions (Rojo 2010 ; El-Housseiny et al 2019 ). These characteristics make P. aeruginosa an excellent candidate for rhamnolipid production using unusual carbon sources.…”

“…For instance, compared to water-soluble carbon sources (e.g., glucose), the use of water-insoluble carbon such as vegetable oil generally produces rhamnolipids in higher titers (Chong and Li 2017 ). The use of factorial design to optimize culture conditions has been proven to be a successful approach to significantly increase the rhamnolipid yield obtained using several P. aeruginosa strains (Camilios-Neto et al 2008 ; Kumar et al 2015 ; Ozdal et al 2017 ; El-Housseiny et al 2019 ). Various studies (see Table 1 ) have explored economical production methods using low-cost and readily available nutrients.…”

Innovative Production of Bioproducts From Organic Waste Through Solid-State Fermentation

“…These authors reached yield and productivity of 0.21 g g −1 and 0.58 g L −1 h −1 , which, however, are low when compared to traditional production systems. Other biosurfactants produced by SSF are rhamnolipids (El-Housseiny et al, 2019). Productivities of 0.19 g L −1 h −1 were obtained using agroindustrial residues as substrates and Pseudomonas aeruginosa as inoculum.…”

“…As with the sophorolipids, the productivities are lower than those observed in traditional production systems. However, it is expected that by devoting more effort to SSF optimization, both reactor design and control parameters, further improvements can be reached (Wang et al, 2018;El-Housseiny et al, 2019). Jimenez-Peñalver et al 2018also reported that there is a high influence of the substrates on the type and yield of sophorolipid produced.…”

Optimized Biosurfactant Production by <i>Pseudomonas aeruginosa</i> Strain CGA1 Using Agro-Industrial Waste as Sole Carbon Source

“…Several bacterial genera have been reported as biosurfactant producers, for example, Acinetobacter, Arthrobacter, Pseudomonas, Halomonas, Bacillus, Rhodococcus, Enterobacter, Serratia [5] [6] [7] [8], and fungal species such as Saccharomyces cerevisiae [9], Fusarium fujikuroi [10], Candida tropicalis [11], Pseudozyma [12], Xylaria regalis [13]. Pseudomonas aeruginosa strains are among the effective producers of biosurfactant [14] [15].…”