Screening and selection of surfactant‐producing bacteria from waste lubricating oil

Abstract

A. MANRESA. 1996. Forty-four strains with the ability to grow o n waste lubricating oil as sole carbon source were isolated from soil-contaminated samples and identified.O f these, four Rhodococcus and one Bacillus strain were selected for their capacity to lower the surface tension of culture medium from 55 mN m-l to less than or equal to 40 m N m -' and the interfacial tension between the culture medium and kerosene from 21 m N m -' to less than 5 mN m-I, respectively. T h e surface-active compounds, identified by means of TLC and specific reagents, from cultures of Rhodococcus strains and Bacillus were glycolipids and lipopeptide, respectively. T h e percentage loss of waste lubricating oil after 120 h of incubation ranged from 7.87% to 45.8% depending o n the strain selected compared with uninoculated control. Decreases in paraffinic compounds and accumulation of new products, mainly with amide groups, were observed by direct and differential infrared spectrometry when selected strains grew on waste lubricating oil.

Production of biosurfactant by hydrocarbon degrading Rhodococcus ruber and Rhodococcus erythropolis

“…Although cultures growing as clumps produced biosurfactants, as acceptable. Maximum values obtained for surface tension reduction were around 20 dynes/cm, comparable to findings by other authors (4, 15), but not economically competitive when compared to recommended values of at least 40 dynes/cm (13). Virtually all emulsifying activity of cultures was associated to cell fraction (Fig.…”

Isolation of Surfactant-Resistant Pseudomonads from the Estuarine Surface Microlayer

“…The excretion of biosurfactants is considered an adaptation to interfacial life, increasing cell hydrophobicity and improving floatation and dispersion [26,79]. Attempts to isolate surfactantresistant bacteria from surfactant-rich environments [7,48,72], and biosurfactant-producing strains from environments enriched in hydrophobic substrates [54], are documented in the literature. However, the SML remains a rather unexplored compartment in both the perspectives.…”

“…However, hydrophobic substrates are not a prerequisite for biosurfactant production [74], and biosurfactant-producing microorganisms have been isolated with other carbon sources, namely, Zobell medium [21], nutrient agar [1], minimal medium with glucose [13,25], and PY medium amended with synthetic surfactants [54]. Some of the attempts to use hydrophobic carbon sources in selective or enrichment media have also achieved modest percentages of positive results, despite intense screening efforts: less than 10% of the isolates from oil-contaminated soils [48,72,77], 4% from oil-spilled seawater [46], and 9.2% from terrestrial and marine samples [7]. A high percentage of surfactantproducing isolates (73.8%) was retrieved from the guts of sea polychaetes [54], but the concentrations produced were very low, and since the method used for the detection was the oil-spreading assay [81], the results can hardly be compared.…”

Isolation and characterization of a novel native Bacillus strain capable of degrading diesel fuel

“…(Mercade et al, 1996). Commercial diesel fuel was added as the sole carbon source to the autoclaved medium.…”