A novel enrichment combined with a rapid screening method was employed to isolate bioemulsifying strains of Bacillus subtilis. Among a total of twenty isolates from railway soil at six geographically distant sites, ten produced bioemulsifiers for soybean oil and crude oil. Qualitative drop-collapse assays indicated the bioemulsifiers were surfactants.

Yarrowia lipolytica is a widely used microorganism in biotechnology since it is capable of producing a wide range of products. A less studied related strain is Y. divulgata, which is also capable of erythritol production in even higher concenctration then most Y. lipolytica wild strains. Thus the aim of this work was to investigate Y. divulgata’s complex utilisation based on erythritol fermentation to establish a Yarrowia based biorefinery in which both the fermentation broth and separated cells are utilised in high-value products. An important parameter of erythritol fermentation is the adequate oxygen level, so the effect of it was investigated in baffled flasks and fermentor as well. Furthermore, we measured the cosmetic applicability of cell lysates and the efficiency of biodetergent produced during erythritol fermentation. The results were showed that Yarrowia divulagata NCAIM 1485 strain could produce relative high amount of erythritol (44.14±1 g/l) under adequate oxygen supply while its cell lysate could exert good skin moisturizing effect. In all cases, the collected samples had emulsification index above 50% of which stability was also high, above 50% even after 24 hours.Therefore, it can be considered as an effective bioemulsifier. In conclusion, the erythritol fermentation of Y. divulgata is suitable for complex utilisation in a biorefinery, since the fermentation broth can be used for isolation of sweetener and bioemulsifier, meanwhile the cells can be processed for cosmetic application as skin moisturizer.

In this work was investigated the potential of Bacillus subtilis UCP 0146 in the bioconversion of the medium containing 100% of cassava flour wastewater to obtain bioemulsifier. The evaluation of the production was carried out by the emulsification index (IE24) and surface tension (TS). The ionic charge, stability (temperature, salinity and pH measured by IE24 and viscosity), ability to remove and disperse oil and textile dye were investigated. B.subtilis produced an anionic bioemulsifier in the medium containing 100% of cassava wastewater in condition 4 of the factorial design (9% of the inoculum, at 35 °C and agitation of 100 rpm) with surface tension of 39mN/m, IE24 of 95.2 % and yield 2.69 g.L-1. Stability at different pH (2-8), temperatures (0-120ºC) and NaCl, dispersed (55.83 cm2-ODA) and reduced the viscosity of the burned engine oil (90.5 cP) , removed 94.4% petroleum and demonstrated efficiency in methylene blue removal (62.2%). The bioemulsifier and its synthesis from bacteria and also emphases on the role of surfactants in oil remediation.