ABSTRACT
The petroleum-derived degrading Dietzia cinnamea strain P4 recently had its genome sequenced and annotated. This allowed employing the data on genes that are involved in the degradation of n-alkanes. To examine the physiological behavior of strain P4 in the presence of n-alkanes, the strain was grown under varying conditions of pH and temperature. D. cinnamea P4 was able to grow at pH 7.0-9.0 and at temperatures ranging from 35 ºC to 45 ºC. Experiments of gene expression by real-time quantitative RT-PCR throughout the complete growth cycle clearly indicated the induction of the regulatory gene alkU (TetR family) during early growth. During the logarithmic phase, a large increase in transcriptional levels of a lipid transporter gene was noted. Also, the expression of a gene that encodes the protein fused rubredoxin-alkane monooxygenase was enhanced. Both genes are probably under the influence of the AlkU regulator.
Subject(s)
Actinomycetales/genetics , Actinomycetales/metabolism , Alkanes/metabolism , Gene Expression Profiling , Genes, Bacterial , Hydrocarbons/metabolism , Metabolic Networks and Pathways/genetics , Actinomycetales/growth & development , Biotransformation , Hydrogen-Ion Concentration , Real-Time Polymerase Chain Reaction , TemperatureABSTRACT
The response of a genetically modified Pseudomonas flurescens to nutrient starvation and starvation-induced stress cross-protection were investigated. Strain BR12 was starved for carbon, nitrogen, phosphorus and sulphur individually and for all nutrients in defined mineral media and exposed for 6 h to chemical (ethanol 20 percentage), oxidative (H2O220µM), osmotic (NaCl3M), cold shock (0 degree) and heat shock (47 degree C) stresses at different incubationtimes. Response to starvation and stress cross-protection development were evaluated by viable bacteria counts. There was a significant increase in resistance of late phase cultures grown in rich medium to stress, except for ethanol, in all starvation situations. Multiple nutrient starved cultures were more resistant to stress than individual nutrient starved ones. This strain inoculated in oligotrophic stream water microcosms also showed the starvation-induced stress protection mechanism but it presented a higher resistance to ethanol than cultures starved in mineral media. the acquisition of nonspecific resistance to stress can favour the persistance of Genetically Modified Microorganisms (GMMos) in apparently unfavourable.
Subject(s)
Stress, Physiological/etiology , Pseudomonas fluorescens/physiology , Genetic Engineering , Food Deprivation , Sulfur , Carbon , Phosphorus , NitrogenABSTRACT
Nossos conhecimentos sobre ecologia de microorganismos em ambientes naturais têm sido limitados por se basearem em técnicas clássicas de Microbiologia. Entretanto, os recentes avanços em técnicas de biologia molecular, juntamente com os constantes desenvolvimentos em tecnologias de informaçäo e computadores, têm transformado os estudos de Ecologia Microbiana e abriram uma nova área da Microbiologia denominada Ecologia Molecular Microbiana. Atualmente, estudos sobre comunidades microbianas naturais säo possíveis mesmo sem a necessidade de técnicas baseadas em cultivo, e novas estratégias moleculares têm sido desenvolvidas permitindo a realizaçäo de estudos sobre expressäo gênica, assim como um melhor entendimento sobre as interaçöes entre comunidades microbianas no ecossistema. Algumas das principais e/ou mais recentes técnicas foram revisadas.