hydrophobic compounds
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2022 ◽  
Author(s):  
Natalia A. Luchnikova ◽  
Polina Yu. Maltseva ◽  
Victoria V. Grishko ◽  
Irina B. Ivshina

The ability of actinobacteria of the genus Rhodococcus to transform oleanolic acid (OA), a plant pentacyclic triterpenoid, was shown for the first time using bioresources of the Regional Specialized Collection of AlkanotrophicMicroorganisms (IEGM; WDCM #768;www.iegmcol.ru). The most promising strains (R.opacus IEGM 488 and R.rhodochrousIEGM 285) were selected, and these catalyzed80% bioconversion of OA (0.5 g/L) in the presence of n-hexadecane (0.1% v/v) for seven days. The process of OA bioconversion was accompanied by a gradual decrease in the culture medium pH. Adaptive responses of bacterial cells to the OA effects included the formation of compact cellular aggregates, a marked change in the surface-to-volume ratio of cells, and a significant increase in the Zeta potential values. The results demonstrated that the process of OA bioconversion was catalyzed by membrane-bound enzyme complexes. Participation of cytochrome P450-dependent monooxygenases in the oxidation of the OA moleculewas confirmedusing specific inhibitors. The obtained data expand our knowledge on the catalytic activity of actinobacteria of the genus Rhodococcus and their possible use as biocatalysts for the bioconversion of complex hydrophobic compounds. The results can also be used inthe searchfor promising OA derivatives to be used in the synthesis of biologically active agents. Keywords: bioconversion, oleanolic acid, Rhodococcus, biologically active compounds


BMC Genomics ◽  
2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Silke Claus ◽  
Sylwia Jezierska ◽  
Liam D. H. Elbourne ◽  
Inge Van Bogaert

AbstractStarmerella bombicola is a non-conventional yeast mainly known for its capacity to produce high amounts of the glycolipids ‘sophorolipids’. Although its product has been used as biological detergent for a couple of decades, the genetics of S. bombicola are still largely unknown. Computational analysis of the yeast’s genome enabled us to identify 254 putative transporter genes that make up the entire transportome. For each of them, a potential substrate was predicted using homology analysis, subcellular localization prediction and RNA sequencing in different stages of growth. One transporter family is of exceptional importance to this yeast: the ATP Binding Cassette (ABC) transporter Superfamily, because it harbors the main driver behind the highly efficient sophorolipid export. Furthermore, members of this superfamily translocate a variety of compounds ranging from antibiotics to hydrophobic molecules. We conducted an analysis of this family by creating deletion mutants to understand their role in the export of hydrophobic compounds, antibiotics and sophorolipids. Doing this, we could experimentally confirm the transporters participating in the efflux of medium chain fatty alcohols, particularly decanol and undecanol, and identify a second sophorolipid transporter that is located outside the sophorolipid biosynthetic gene cluster.


2022 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiao Bu ◽  
Jing‑Yuan Lin ◽  
Chang‑Qing Duan ◽  
Mattheos A. G. Koffas ◽  
Guo‑Liang Yan

Abstract Background The limitation of storage space, product cytotoxicity and the competition for precursor are the major challenges for efficiently overproducing carotenoid in engineered non-carotenogenic microorganisms. In this work, to improve β-carotene accumulation in Saccharomyces cerevisiae, a strategy that simultaneous increases cell storage capability and strengthens metabolic flux to carotenoid pathway was developed using exogenous oleic acid (OA) combined with metabolic engineering approaches. Results The direct separation of lipid droplets (LDs), quantitative analysis and genes disruption trial indicated that LDs are major storage locations of β-carotene in S. cerevisiae. However, due to the competition for precursor between β-carotene and LDs-triacylglycerol biosynthesis, enlarging storage space by engineering LDs related genes has minor promotion on β-carotene accumulation. Adding 2 mM OA significantly improved LDs-triacylglycerol metabolism and resulted in 36.4% increase in β-carotene content. The transcriptome analysis was adopted to mine OA-repressible promoters and IZH1 promoter was used to replace native ERG9 promoter to dynamically down-regulate ERG9 expression, which diverted the metabolic flux to β-carotene pathway and achieved additional 31.7% increase in β-carotene content without adversely affecting cell growth. By inducing an extra constitutive β-carotene synthesis pathway for further conversion precursor farnesol to β-carotene, the final strain produced 11.4 mg/g DCW and 142 mg/L of β-carotene, which is 107.3% and 49.5% increase respectively over the parent strain. Conclusions This strategy can be applied in the overproduction of other heterogeneous FPP-derived hydrophobic compounds with similar synthesis and storage mechanisms in S. cerevisiae. Graphical Abstract


2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Gessesse Kebede ◽  
Tekle Tafese ◽  
Ebrahim M. Abda ◽  
M. Kamaraj ◽  
Fassil Assefa

The discharge of hydrocarbons and their derivatives to environments due to human and/or natural activities cause environmental pollution (soil, water, and air) and affect the natural functioning of an ecosystem. To minimize or eradicate environmental pollution by hydrocarbon contaminants, studies showed strategies including physical, chemical, and biological approaches. Among those strategies, the use of biological techniques (especially bacterial biodegradation) is critically important to remove hydrocarbon contaminants. The current review discusses the insights of major factors that enhance or hinder the bacterial bioremediation of hydrocarbon contaminants (aliphatic, aromatic, and polyaromatic hydrocarbons) in the soil. The key factors limiting the overall hydrocarbon biodegradation are generally categorized as biotic factors and abiotic factors. Among various environmental factors, temperature range from 30 to 40°C, pH range from 5 to 8, moisture availability range from 30 to 90%, carbon/nitrogen/phosphorous (C/N/P; 100:20:1) ratio, and 10–40% of oxygen for aerobic degradation are the key factors that show positive correlation for greatest hydrocarbon biodegradation rate by altering the activities of the microbial and degradative enzymes in soil. In addition, the formation of biofilm and production of biosurfactants in hydrocarbon-polluted soil environments increase microbial adaptation to low bioavailability of hydrophobic compounds, and genes that encode for hydrocarbon degradative enzymes are critical for the potential of microbes to bioremediate soils contaminated with hydrocarbon pollutants. Therefore, this review works on the identification of factors for effective hydrocarbon biodegradation, understanding, and optimization of those factors that are essential and critical.


2021 ◽  
Vol 11 (21) ◽  
pp. 10345
Author(s):  
Peter Walde ◽  
Sosaku Ichikawa

Lipid vesicles (liposomes) are a unique and fascinating type of polymolecular aggregates, obtained from bilayer-forming amphiphiles—or mixtures of amphiphiles—in an aqueous medium. Unilamellar vesicles consist of one single self-closed bilayer membrane, constituted by the amphiphiles and an internal volume which is trapped by this bilayer, whereby the vesicle often is spherical with a typical desired average diameter of either about 100 nm or tens of micrometers. Functionalization of the external vesicle surface, basically achievable at will, and the possibilities of entrapping hydrophilic molecules inside the vesicles or/and embedding hydrophobic compounds within the membrane, resulted in various applications in different fields. This review highlights a few of the basic studies on the phase behavior of polar lipids, on some of the concepts for the controlled formation of lipid vesicles as dispersed lamellar phase, on some of the properties of vesicles, and on the challenges of efficiently loading them with hydrophilic or hydrophobic compounds for use as delivery systems, as nutraceuticals, for bioassays, or as cell-like compartments. Many of the large number of basic studies have laid a solid ground for various applications of polymolecular aggregates of amphiphilic lipids, including, for example, cubosomes, bicelles or—recently most successfully—nucleic acids-containing lipid nanoparticles. All this highlights the continued importance of fundamental studies. The life-saving application of mRNA lipid nanoparticle COVID-19 vaccines is in part based on year-long fundamental studies on the formation and properties of lipid vesicles. It is a fascinating example, which illustrates the importance of considering (i) details of the chemical structure of the different molecules involved, as well as (ii) physical, (iii) engineering, (iv) biological, (v) pharmacological, and (vii) economic aspects. Moreover, the strong demand for interdisciplinary collaboration in the field of lipid vesicles and related aggregates is also an excellent and convincing example for teaching students in the field of complex molecular systems.


2021 ◽  
Vol 908 (1) ◽  
pp. 012034
Author(s):  
E Yu Milkheev ◽  
Yu B Tsybenov

Abstract Humic substances of soils are considered as a multicomponent system of amphiphilic (exhibiting both hydrophilic and hydrophobic properties) substances. Humic substances from soils of different genesis in the south of the Vitim Plateau (quasigley chernozem – Turbic Chernozem Molliglossic and brown soil – Stagnic Phaeozem Molliglossic) were studied. Using the hydrophobic interaction chromatography on Octyl-Sepharose® CL-4B, we separated a mixture of humic (HAs) and fulvic acids (FAs) due to their different ability to enter into hydrophobic interactions with the gel matrix. A higher percentage of hydrophobic compounds was revealed in HAs of quasigley chernozem, compared to HAs of brown soils, and FAs. The fulvic acid sample showed a lower capacity for hydrophobic interactions than the humic acid sample.


2021 ◽  
Author(s):  
Xiao Bu ◽  
Jing‑Yuan Lin ◽  
Chang‑Qing Duan ◽  
Mattheos Koffas ◽  
guoliang Yan

Abstract BackgroundThe limitation of storage space, product cytotoxicity and the competition for precursor is the major challenges for efficiently overproducing carotenoid in engineered non-carotenogenic microorganisms. In this work, to improve β-carotene accumulation in Saccharomyces cerevisiae, a strategy that simultaneous increases cell storage capability and strengthens metabolic flux to carotenoid pathway was developed using exogenous oleic acid (OA) combined with metabolic engineering approaches.ResultsThe direct separation of lipid droplets (LDs), quantitative analysis and genes disruption trial indicated that LDs are major storage locations of β-carotene in S. cerevisiae. However, due to the competition for precursor between β-carotene and LDs-triacylglycerol biosynthesis, enlarging storage space by engineering LDs related genes has minor promotion on β-carotene accumulation. Adding 2 mM OA significantly improved LDs-triacylglycerol metabolism and resulted in 36.4% increase in β-carotene content. The transcriptome analysis was adopted to mine OA-repressible promoters and IZH1 promoter was used to replace native ERG9 promoter to dynamically down-regulate ERG9 expression, which diverted the metabolic flux to β-carotene pathway and achieved additional 31.7% increase in β-carotene content without adversely affecting cell growth. By inducing an extra constitutive β-carotene synthesis pathway for further conversion precursor farnesol to β-carotene, the final strain produced 11.4 mg/DCW and 142 mg/L of β-carotene, which is 107.3% and 49.5% increase respectively over the parent strain. ConclusionsThis strategy can be applied in the overproduction of other heterogeneous FPP-derived hydrophobic compounds with similar synthesis and storage mechanisms in S. cerevisiae.


2021 ◽  
Author(s):  
Franck Marquet ◽  
Viorica Patrulea ◽  
Gerrit Borchard

AbstractDue to the lack of safe carriers for the delivery of small interfering RNA (siRNA), clinical applications of nucleotide-based therapeutics have been limited. In this study, biodegradable amphiphilic triblock copolymers with tailored molecular weights for each block composed of methoxy poly(ethylene glycol) (2000 g/mol), poly(L-lysine) (1300 g/mol) and poly(D,L-lactic acid) (1800 g/mol) (mPEG45-α-PLL10-PLA25) were synthesized and fully characterized. The peptide synthesis was carried out on a solid phase to limit the presence of cationic charges. The arrangement and availability of cationic amino groups within a micellar vector were investigated to determine the colloidal stability as well as the predisposition of these systems to vectorize siRNAs in addition to their already known ability to improve the solubility of hydrophobic compounds. For this purpose, a triblock copolymer containing an epsilon poly(L-lysine) was synthesized similarly. Accordingly, the arrangement of the cationic segment modifies the rigidity involving a complexation constraint due to limited cationic charges available on the surface, which can compromise the efficiency of delivery into cells. In addition, the two vectors were biocompatible in different human cell lines.


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