Biosurfactant synthesis in the oil eater rhodococcus erythropolis MK1 strain

Oil pollution is a very serious problem in the world. There were numerous oil spills in the last three decades and had great impact on the environment. They caused damages in wildlife as well as in economy by cutting down the agriculture, fishing, and tourism. Surfactants are useful weapons in the war against oil pollution. They are suitable to clean oil tanks and pipes and they are useful to solublize animal fats in food industrial wastewater. Many bacteria can produce substantial amount of biosurfactants which can emulsify hydrophobic hydrocarbons, so that the native microflora can utilize the pollutants. An additional advantage of the biosurfactants over the synthetic surface active molecules is that these compounds are easily biodegradable. A special biosurfactant group is composed of mycolic acids which are basically a-alkyl, (3-hydroxy fatty acids. Mycolic acids are the most characteristic components of the cell wall of the so called mycolata bacterial group. This group belongs to the Actinomycetales and contains the genera Mycobacterium, Corynebacterium, Nocardia, Rhodococcus and others. We aimed to map the mycolic acid biosynthesis pathway in Rhodococcus erythropolis MK1 strain isolated by us from polluted soil. In first step, we sequenced the genome of our strain by SOLID™ next generation DNA sequencer. The reads were mapped on the R. erythropolis PR4 genome in the NCBI database. We searched for rhodococcal homologs of the known mycobacterial and corynebacterial genes involved in mycolic acid biosynthesis. We found conserved regions in the genome which are likely responsible for the biosynthesis of mycolic acids. The ongoing comparative whole genome transcript analysis will reveal the genes really necessary for the anabolism of mycolic acids

Biosurfactant Synthesis In the Oil Eater Rhodococcus Erythropolis MK1 Strain

Oil pollution is a very serious problem in the world. There were numerous oil spills in the last three decades and had great impact on the environment. They caused damages in wildlife as well as in economy by cutting down the agriculture, fishing, and tourism. Surfactants are useful weapons in the war against oil pollution. They are suitable to clean oil tanks and pipes and they are useful to solubilize animal fats in food industrial wastewater. Many bacteria can produce substantial amount of biosurfactants which can emulsify hydrophobic hydrocarbons, so that the native microflora can utilize the pollutants. An additional advantage of the biosurfactants over the synthetic surface active molecules is that these compounds are easily biodegradable. A special biosurfactant group is composed of mycolic acids which are basically α-alkyl, β-hydroxy fatty acids. Mycolic acids are the most characteristic components of the cell wall of the so called mycolata bacterial group. This group belongs to the Actinomycetales and contains the genera Mycobacterium, Corynebacterium, Nocardia, Rhodococcus and others. We aimed to map the mycolic acid biosynthesis pathway in Rhodococcus erythropolis MK1 strain isolated by us from polluted soil. In first step, we sequenced the genome of our strain by SOLIDTM next generation DNA sequencer. The reads were mapped on the R. erythropolis PR4 genome in the NCBI database. We searched for rhodococcal homologs of the known mycobacterial and corynebacterial genes involved in mycolic acid biosynthesis. We found conserved regions in the genome which are likely responsible for the biosynthesis of mycolic acids. The ongoing comparative whole genome transcript analysis will reveal the genes really necessary for the anabolism of mycolic acids

Reversal of Multidrug Resistance by Symmetrical Selenoesters in Colon Adenocarcinoma Cells

Recently, selenium containing derivatives have attracted more attention in medicinal chemistry. In the present work, the anticancer activity of symmetrical selenoesters was investigated by studying the reversal of efflux pump-related and apoptosis resistance in sensitive and resistant human colon adenocarcinoma cells expressing the ABCB1 protein. The combined effect of the compounds with doxorubicin was demonstrated with a checkerboard assay. The ABCB1 inhibitory and the apoptosis-inducing effects of the derivatives were measured with flow cytometry. Whole transcriptome sequencing was carried out on Illumina platform upon the treatment of resistant cells with the most potent derivatives. One ketone and three methyl ester selenoesters showed synergistic or weak synergistic interaction with doxorubicin, respectively. Ketone selenoesters were the most potent ABCB1 inhibitors and apoptosis inducers. Nitrile selenoesters could induce moderate early and late apoptotic processes that could be explained by their ABCB1 modulating properties. The transcriptome analysis revealed that symmetrical selenoesters may influence the redox state of the cells and interfere with metastasis formation. It can be assumed that these symmetrical selenocompounds possess toxic, DNA-damaging effects due to the presence of two selenium atoms in the molecule, which may be augmented by the presence of symmetrical groups

Biodegradation of unctuous wastes of food industry

Nowadays, industrial emission of harmful materials is an extremely acute problem for humanity and Nature. Technologies with low or zero emission is of key importance to minimize the contamination of the ecosystem. However, vast amount of hazardous substances still gets out into the environment which must be made harmless. Bioremediation technologies using microorganisms to neutralize polluting materials are environmentally sound and economical tools for removal toxic compounds. It is a well-known fact that several Rhodococcus sp. can degrade a wide range of hazardous chemicals, such as aliphatic and aromatic hydrocarbons. In our laboratory, a Rhodococcus sp. was isolated from hydrocarbon polluted sites and it was successfully proven that the bacterium could efficiently degrade industrial hydrocarbons such as diesel oil and dead oil. The strain could tolerate low temperature and certain salt concentrations therefore it might be applied in oil mineralization after marine catastrophes. In this study, our aim was to test the ability of this strain to degrade food industrial and municipal waste. Lard, pig and poultry fat and cooking oil were used as sole carbon sources in minimal medium. The substrate utilization was demonstrated indirectly by measuring the respiration activity and CO2 production of the Rhodococcus sp. The strain could grow even at 10 g/1 of hydrocarbon concentration, it consumed the available oxygen and released remarkable amount of carbon dioxide within a week. These facts make this strain a promising waste cleaner both in food industrial applications and housekeeping

Biodegradation of unctuous wastes of food industry

Nowadays, industrial emission of harmful materials is an extremely acute problem for humanity and Nature. Technologies with low or zero emission is of key importance to minimize the contamination of the ecosystem. However, vast amount of hazardous substances still gets out into the environment which must be made harmless. Bioremediation technologies using microorganisms to neutralize polluting materials are environmentally sound and economical tools for removal toxic compounds. It is a well-known fact that several Rhodococcus sp. can degrade a wide range of hazardous chemicals, such as aliphatic and aromatic hydrocarbons. In our laboratory, a Rhodococcus sp. was isolated from hydrocarbon polluted sites and it was successfully proven that the bacterium could efficiently degrade industrial hydrocarbons such as diesel oil and dead oil. The strain could tolerate low temperature and certain salt concentrations therefore it might be applied in oil mineralization after marine catastrophes. In this study, our aim was to test the ability of this strain to degrade food industrial and municipal waste. Lard, pig and poultry fat and cooking oil were used as sole carbon sources in minimal medium. The substrate utilization was demonstrated indirectly by measuring the respiration activity and CO2 production of the Rhodococcus sp. The strain could grow even at 10 g/1 of hydrocarbon concentration, it consumed the available oxygen and released remarkable amount of carbon dioxide within a week. These facts make this strain a promising waste cleaner both in food industrial applications and housekeeping

Amino Acid Polymorphisms in the VHIID Conserved Motif of Nodulation Signaling Pathways 2 Distinctly Modulate Symbiotic Signaling and Nodule Morphogenesis in Medicago truncatula

Legumes establish an endosymbiotic association with nitrogen-fixing soil bacteria. Following the mutual recognition of the symbiotic partner, the infection process is controlled by the induction of the signaling pathway and subsequent activation of symbiosis-related host genes. One of the protein complexes regulating nitrogen-fixing root nodule symbiosis is formed by GRAS domain regulatory proteins Nodulation Signaling Pathways 1 and 2 (NSP1 and NSP2) that control the expression of several early nodulation genes. Here, we report on a novel point mutant allele (nsp2-6) affecting the function of the NSP2 gene and compared the mutant with the formerly identified nsp2-3 mutant. Both mutants carry a single amino acid substitution in the VHIID motif of the NSP2 protein. We found that the two mutant alleles show dissimilar root hair response to bacterial infection. Although the nsp2-3 mutant developed aberrant infection threads, rhizobia were able to colonize nodule cells in this mutant. The encoded NSP2 proteins of the nsp2-3 and the novel nsp2 mutants interact with NSP1 diversely and, as a consequence, the activation of early nodulin genes and nodule organogenesis are arrested in the new nsp2 allele. The novel mutant with amino acid substitution D244H in NSP2 shows similar defects in symbiotic responses as a formerly identified nsp2-2 mutant carrying a deletion in the NSP2 gene. Additionally, we found that rhizobial strains induce delayed nodule formation on the roots of the ns2-3 weak allele. Our study highlights the importance of a conserved Asp residue in the VHIID motif of NSP2 that is required for the formation of a functional NSP1-NSP2 signaling module. Furthermore, our results imply the involvement of NSP2 during differentiation of symbiotic nodule cells

Microbial degradation of hydrophobic compounds under various environmental conditions

Human activities related to industry, agriculture and increasing human population have a great impact on the environment and easily lead to pollution jeopardizing natural habitats and ecosystems. Oil and its derivates from inadequate disposal and accidental spills are among the most common pollutants. Microbial degradation of these hydrophobic, organic compounds is a topic currently generating a great number of studies in environmental protection. The aim of this study is the comparison of two Rhodococcus strains isolated from soil and aqueous phase regarding the biodegradation efficacy in various environmental niches: minimal media, salted water and potting soil. Being aware of the changes of enzymes activity affected by various environmental conditions, we will be able to apply the most adequate microbial strains in bioremediation processes