The aim of this work was to study chemical structures and biological activities of rhamnolipids produced by Pseudomonas aeruginosa B189 isolated from milk factory waste. The culture produced two biosurfactants, a and b, which showed strong activity and were identified as L-rhamnopyranosyl-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate or Rha-Rha C10-C10 and L-rhamnopyranosyl-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydodecanoate or Rha-Rha C(10)-C(12), respectively. Both compounds exhibited higher surfactant activities tested by the drop collapse test than several artificial surfactants such as SDS and Tween 80. Rhamnolipid a showed significant antiproliferative activity against human breast cancer cell line (MCF-7) at minimum inhibitory concentration (MIC) at 6.25 microg/mL while rhamnolipid b showed MIC against insect cell line C6/36 at 50 microg/mL.

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Aims: To isolate polystyrene-degrading bacteria from the gut of superworms and investigate their ability to degrade polystyrene (PS). Methods and Results:Three PS-degrading bacteria identified as Pseudomonas sp.EDB1, Bacillus sp. EDA4 and Brevibacterium sp. EDX were successfully isolated from the gut of superworms (Zophobas atratus Larvae) that ingest PS. Incubating PS with each strain for 30-day led to the formation of biofilm on the PS film. Scanning electron microscopy (SEM) revealed considerable damage (in terms of pits formation) on the surface of the PS films. FTIR analysis suggested the incorporation of carbonyl group into the carbon backbone of PS. Decreasing of WCA of microbial-treated PS film confirmed a chemical change from hydrophobicity to hydrophilicity on the PS surface. Based on these results, we conclude that all isolates had the ability to degrade PS.Conclusions: Brevibacterium sp. EDX (GenBank MZ32399) was isolated as the most efficient PS-degrading strain based on the most changing in both PS surface morphology (SEM and WCA analyses) and chemical modification (FTIR analysis) in its PS degradation process. Significance and Impact of the Study:This was the first study to describe the PS degradation by Brevibacterium sp. EDX, and thus provided for its development in the plastic remediation process.