Production and characterization of rhamnolipids from Pseudomonas aeruginosa san-ai

Abstract

The production and characteristics of rhamnolipid biosurfactant obtained by the strain Pseudomonas aeruginosa san-ai were investigated. With regard to the carbon and nitrogen sources, several media were tested to enhance the production of rhamnolipids. Phosphate-limited proteose peptone-ammonium salt (PPAS) medium supplemented with sunflower oil as a source of carbon and mineral ammonium chloride and peptone as nitrogen sources greatly improved the production of rhamnolipid, from 0.15 on basic PPAS (C/N ratio 4.0) to 3 g L-1 on optimized PPAS medium (C/N ratio 7.7). Response surface methodology analysis was used for testing the effect of three factors, i.e., temperature, concentration of carbon and nitrogen source (mass %), in the optimized PPAS medium on the production of rhamnolipid. The isolated rhamnolipids were characterized by infrared (IR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The IR spectra confirmed that the isolated compound corresponded to the rhamnolipid structure, whereas MS indicated that the isolated preparation was a mixture of mono-rhamno-mono-lipidic, mono-rhamno-di-lipidic and di-rhamno-di-lipidic congeners.

U ovom radu je opisana produkcija i karakterizacija ramnolipidnog biosurfaktanta soja Pseudomonas aeruginosa san-ai. Ispitan je uticaj različitih izvora ugljenika i azota na produkciju ramnolipida. Podloga proteoze pepton-amonijum soli sa ograničenom količinom fosfata (PPAS) sa suncokretovim uljem kao izvorom ugljenika i amonijum-hloridom i peptonom kao izvorom azota, znatno povećava produkciju ramnolipida, od 0,15, na PPAS sa standardnim sastavom (odnos C/N 4,0), do 3 g L-1 na optimizovanoj PPAS podlozi (odnos C/N 7,7). Metodom planiranog eksperimenta (response surface methodology) ispitan je efekat tri parametra: temperature, koncentracije izvora ugljenika i azota na optimizovanoj podlozi. Karakterizacija izolovanog preparata ramnolipida urađena je pomoću IR i ESI-MS analiza. IR analiza je potvrdila prisustvo strukturnih elemenata karakterističnih za ramnolipide. MS analiza pokazala je da reč o smeši u kojoj su prisutne mono-ramno-monolipidne, di-ramno-mono-lipidne i di-ramno-di-lipidne komponente.