Search Results (7)

The development of multidrug resistance by pathogenic bacteria and yeast is a significant medical problem that needs to be addressed. One possible answer could be the combined use of antibiotics and silver nanoparticles, which have different mechanisms of antimicrobial action. In the same way, these nanoparticles can be combined with antifungal agents. Biogenic silver nanoparticles synthesized using environmentally friendly biosynthesis technology using extracts of biologically active plants are an effective nanomaterial that needs to be comprehensively investigated for implementation into medical practice. In this study, the synergistic effects arising from their combined use with antibiotics and fungicides against various bacteria and yeasts were studied. The following methods were used: disco-diffusion analysis and construction of plankton culture growth curves. The synergistic effect of silver nanoparticles and antibiotics (fungicides) has been determined. Effective concentrations of substances were established, recommendations for the studied pathogenic species were presented, and the effect of destruction of the bacterial membrane was illustrated. The most significant synergistic effect was manifested in pathogenic candida and brewer’s yeast. Full article

Biosurfactants are much-discussed alternatives to petro- and oleochemical surfactants. Alcanivorax borkumensis, a marine, Gram-negative γ-proteobacterium, produces a glycine-glucolipid biosurfactant from hydrocarbons, pyruvate, and acetate as carbon sources. Sustainable acetate production from lignocellulose or syngas adds to its relevance for the bioeconomy. This study investigated nitrogen sources and carbon-to-nitrogen ratios (C/N) to optimize fed-batch fermentation for biosurfactant production using A. borkumensis with acetate as the carbon source. Urea enabled high biosurfactant production, which was confirmed in DO-based fed-batch fermentation. Varying C/N ratios led to increased glycine-glucolipid production and decreased biomass production, with improvement plateauing at a C/N ratio of 26.7 Cmol Nmol⁻¹. pH-stat fed-batch fermentation using glacial acetic acid as the carbon source and a pH-adjusting agent doubled the biosurfactant production. Finally, bubble-free membrane aeration was used to prevent extensive foam formation observed during conventional bubble aeration. The efficient production made it possible to investigate the bioactivity of glycine-glucolipid in combination with antibiotics against various microorganisms. Our findings allow for the leverage of glycine-glucolipid biosurfactant production using acetate as a carbon source. Full article

Five psychrotolerant Alcanivorax spp. strains were isolated from Antarctic coastal waters. Strains were screened for molecular and physiological properties and analyzed regarding their growth capacity. Partial 16S rDNA, alk-B1, and P450 gene sequencing was performed. Biolog EcoPlates and the API 20E test were used to evaluate metabolic and biochemical profiles. Bacterial growth in sodium acetate was determined at 4, 15, 20, and 25 °C to evaluate the optimal temperature. Furthermore, the ability of each strain to grow in a hydrocarbon mixture at 4 and 25 °C was assayed. Biosurfactant production tests (drop-collapse and oil spreading) and emulsification activity tests (E₂₄) were also performed. Concerning results of partial gene sequencing (16S rDNA, alk-B1, and P450), a high similarity of the isolates with the same genes isolated from other Alcanivorax spp. strains was observed. The metabolic profiles obtained by Biolog assays showed no significant differences in the isolates compared to the Alcanivorax borkumensis wild type. The results of biodegradative tests showed their capability to grow at different temperatures. All strains showed biosurfactant production and emulsification activity. Our findings underline the importance to proceed in the isolation and characterization of Antarctic hydrocarbon-degrading bacterial strains since their biotechnological and environmental applications could be useful even for pollution remediation in polar areas. Full article

Typically, oil pollution cleanup procedures following first response actions include dispersion. Crude oil is biodegradable, and its bioavailability can be increased when dispersed into very fine droplets by means of chemical surfactants. Although their use is widely spread in many applications, the latter may prove toxic, depending on the extent of use. The use of biological means, such as bioremediation and biosurfactants, has emerged over the past years as a very promising ‘green’ alternative technology. Biosurfactants (BSs) are amphiphilic molecules produced by microorganisms during biodegradation, thus increasing the bioavailability of the organic pollutants. It is their biodegradability and low toxicity that render BSs as a very promising alternative to the synthetic ones. Alcanivorax borkumensis SK2 strain ability to produce BSs, without any impurities from the substrate, was investigated. The biosurfactant production was scaled up by means of a sequencing batch reactor (SBR) and a heavy oil residue substrate as the carbon source. The product is free from substrate impurities, and its efficiency is tested on oil bioremediation in the marine environment. The product’s dispersion efficiency was determined by the baffled flask test. The production method proposed can have a significant impact to the market, given the ever-increasing demand for ecologically friendly, reliable, commercially viable and economically competitive environmental cleanup techniques. Full article

The environmental accumulation of plastics worldwide is a consequence of the durability of the material. Alternative polymers, marketed as biodegradable, present a potential solution to mitigate their ecological damage. However, understanding of biodegradability has been hindered by a lack of reproducible testing methods. We developed a novel method to evaluate the biodegradability of plastic samples based on the monitoring of bacterial respiration in aqueous media via the quantification of CO₂ produced, where the only carbon source available is from the polymer. Rhodococcus rhodochrous and Alcanivorax borkumensis were used as model organisms for soil and marine systems, respectively. Our results demonstrate that this approach is reproducible and can be used with a variety of plastics, allowing comparison of the relative biodegradability of the different materials. In the case of low-density polyethylene, the study demonstrated a clear correlation between the molecular weight of the sample and CO₂ released, taken as a measure of biodegradability. Full article

ω-Aminododecanoic acid is considered as one of the potential monomers of Nylon 12, a high-performance member of the bioplastic family. The biosynthesis of ω-aminododecanoic acid from renewable sources is an attractive process in the polymer industry. Here, we constructed three artificial self-sufficient P450s (ArtssP450s) using CYP153A13 from Alcanivorax borkumensis and cytochrome P450 reductase (CPR) domains of natural self-sufficient P450s (CYP102A1, CYP102A5, and 102D1). Among them, artificial self-sufficient P450 (CYP_153A13BM3_CPR) with CYP102A1 CPR showed the highest catalytically activity for dodecanoic acid (DDA) substrate. This form of ArtssP450 was further co-expressed with ω-TA from Silicobacter pomeroyi and AlkJ from Pseudomonas putida GPo1. This single-cell system was used for the biotransformation of dodecanoic acid (DDA) to ω-aminododecanoic acid (ω-AmDDA), wherein we could successfully biosynthesize 1.48 mM ω-AmDDA from 10 mM DDA substrate in a one-pot reaction. The productivity achieved in the present study was five times higher than that achieved in our previously reported multistep biosynthesis method (0.3 mM). Full article

The marine hydrocarbonoclastic bacterium Alcanivorax borkumensis is well known for its ability to successfully degrade various mixtures of n-alkanes occurring in marine oil spills. For effective growth on these compounds, the bacteria possess the unique capability not only to incorporate but also to modify fatty intermediates derived from the alkane degradation pathway. High efficiency of both these processes provides better competitiveness for a single bacteria species among hydrocarbon degraders. To examine the efficiency of A. borkumensis to cope with different sources of fatty acid intermediates, we studied the growth rates and membrane fatty acid patterns of this bacterium cultivated on diesel, biodiesel and rapeseed oil as carbon and energy source. Obtained results revealed significant differences in both parameters depending on growth substrate. Highest growth rates were observed with biodiesel, while growth rates on rapeseed oil and diesel were lower than on the standard reference compound (hexadecane). The most remarkable observation is that cells grown on rapeseed oil, biodiesel, and diesel showed significant amounts of the two polyunsaturated fatty acids linoleic acid and linolenic acid in their membrane. By direct incorporation of these external fatty acids, the bacteria save energy allowing them to degrade those pollutants in a more efficient way. Such fast adaptation may increase resilience of A. borkumensis and allow them to strive and maintain populations in more complex hydrocarbon degrading microbial communities. Full article