ABSTRACT
Production of trehalolipid biosurfactants by Rhodococcus erythropolis S67 depending on the growth temperature was studied. R. erythropolis S67 produced glycolipid biosurfactants such as 2,3,4-succinoyl-octanoyl-decanoyl-2'-decanoyl trehalose and 2,3,4-succinoyl-dioctanoyl-2'-decanoyl trehalose during the growth in n-hexadecane medium at 26 and 10 °C, despite the different aggregate state of the hydrophobic substrate at low temperature. The surface tension of culture medium was found being reduced from 72 to 27 and 45 mN m-1, respectively. Production of trehalolipid biosurfactants by R. erythropolis S67 at low temperature could be useful for the biodegradation of petroleum hydrocarbons at low temperatures by enhancing the bioremediation performance in cold regions.
Subject(s)
Biodegradation, Environmental , Cold Temperature , Rhodococcus/growth & development , Rhodococcus/metabolism , Surface-Active Agents/chemistry , Surface-Active Agents/metabolism , Alkanes/metabolism , Culture Media/chemistry , DNA Gyrase/genetics , Fatty Acids/analysis , Glycolipids/chemistry , Glycolipids/metabolism , Hydrocarbons/metabolism , Petroleum/metabolism , Phylogeny , Rhodococcus/classification , Rhodococcus/genetics , Surface Tension , Surface-Active Agents/isolation & purification , Trehalose/metabolismABSTRACT
The process of naphthalene degradation by indigenous, introduced, and transconjugant strains was studied in laboratory soil microcosms. Conjugation transfer of catabolic plasmids was demonstrated in naphthalene-contaminated soil. Both indigenous microorganisms and an introduced laboratory strain BS394 (pNF142::TnMod-OTc) served as donors of these plasmids. The indigenous bacterial degraders of naphthalene isolated from soil were identified as Pseudomonas putida and Pseudomonas fluorescens. The frequency of plasmid transfer in soil was 10(-5)-10(-4) per donor cell. The activity of the key enzymes of naphthalene biodegradation in indigenous and transconjugant strains was studied. Transconjugant strains harboring indigenous catabolic plasmids possessed high salicylate hydroxylase and low catechol-2,3-dioxygenase activities, in contrast to indigenous degraders, which had a high level of catechol-2,3-dioxygenase activity and a low level of salicylate hydroxylase. Naphthalene degradation in batch culture in liquid mineral medium was shown to accelerate due to cooperation of the indigenous naphthalene degrader P. fluorescens AP1 and the transconjugant strain P. putida KT2442 harboring the indigenous catabolic plasmid pAP35. The role of conjugative transfer of naphthalene biodegradation plasmids in acceleration of naphthalene degradation was demonstrated in laboratory soil microcosms.
Subject(s)
Naphthalenes/metabolism , Plasmids/genetics , Pseudomonas fluorescens/genetics , Pseudomonas putida/genetics , Biodegradation, Environmental , Gene Transfer, Horizontal , Plasmids/metabolism , Pseudomonas fluorescens/metabolism , Pseudomonas putida/metabolismABSTRACT
The ability of microbial degraders of polycyclic aromatic hydrocarbons to grow at 24 degrees C in liquid mineral medium supplemented with oil as the sole source of carbon and energy was studied. Growth characteristics (CFU) and the level of oil destruction by plasmid-bearing and plasmid-free strains were determined after seven days of cultivation. The presence of catabolic plasmids in the degrader strains, including rhizosphere pseudomonads, was shown to increase cell growth and enhance the level of oil degradation. Strain Pseudomonas chlororaphis BS 1391 bearing plasmid pBS216 was found to be the most effective oil degrader.