Isolation and characterization of a newly naphthalene-degrading Halomonas pacifica, strain Cnaph3: biodegradation and biosurfactant production studies

A newly marine Halomonas pacifica strain Cnaph3 was isolated, as a naphthalene degrader and biosurfactant producer, from contaminated seawater collected in Ataya’s fishing harbor, located in Kerkennah Islands, Tunisia. Chromatography flame ionization detector analysis revealed that 98.8% of naphthalene (200 mg/L) was degraded after 7 days of incubation, at 30 g/L NaCl and 37 °C. Strain Cnaph3 showed also a noticeable capacity to grow on a wide range of aliphatic, aromatic, and complex hydrocarbons. Interestingly, strain Cnaph3 showed a significant potential to produce biosurfactants in the presence of all tested substrates, particularly on glycerol (1%, v/v). Electrospray ionization analysis of the biosurfactant, designated Bios-Cnaph3, suggested a lipopeptide composition. The critical micelle concentration of Bios-Cnaph3 was about 500 mg/L. At this concentration, the surface tension of the water was reduced to 27.6 mN/m. Furthermore, Bios-Cnaph3 displayed interesting stabilities over a wide range of temperatures (4–105 °C), salinities (0–100 g/L NaCl), and pH (2.2–12.5). In addition, it showed promising capacities to remove used motor oil from contaminated soils. The biodegradation and biosurfactant-production potential of the Halomonas sp. strain Cnaph3 would present this strain as a favorite agent for bioremediation of hydrocarbon-contaminated sites under saline conditions

Promising abilities of mercapto-degrading Staphylococcus capitis strain SH6 in both crude oil and waste motor oil as sole carbon and energy sources: its biosurfactant production and preliminary characterization

BACKGROUND: It was shown previously that a Staphylococcus capitis strain SH6 was able to degrade several malodorous mercaptans and simultaneously reduce the surface tension. RESULTS: This present work revealed the capacity of strain SH6 to grow on various hydrocarbons, used as the only carbon and energy sources. Based on GC–MS analyses, the substantial ability to degrade up to 45% and 64% of aliphatic hydrocarbons (n-alkanes) of crude oil and waste motor oil, respectively, after 30 days of incubation at 37 °C and 180 rpm, was shown. The properties of biosurfactant produced by strain SH6 grown on different oil substrates (diesel oil and waste motor oil) were studied. Biosurfactants exhibited enhanced emulsification capacities and significant stabilities over a wide range of salinity (20–150 g L-1), temperature (–20–100 °C), and pH, and also the ability to remove crude oil from contaminated soils. Their critical micelle concentrations (CMC) were of 800 mg L-1. FTIR analyses suggested the lipopetide nature of biosurfactants. CONCLUSION: The stabilities of biosurfactants over a wide pH range, high temperatures and variable concentrations of salt, as well as emulsifying properties, suggest potential applications in bioremediation processes. © 2017 Society of Chemical Industry

Biodegradation of hydrocarbons and biosurfactants production by a newly halotolerant Pseudomonas sp. strain isolated from contaminated seawater

A strain NAPH6 of Pseudomonas aeruginosa, isolated from contaminated seawater taken from the fishing harbor of Sfax, Tunisia, was able to degrade almost completly the naphthalene (200 mg/l) and the aliphatic hydrocarbons of crude oil (1%, v/v), after 7 and 20 days of culture, respectively, at 30 g/l NaCl. Moreover, the isolated NAPH6 exhibited a notable potentiality to synthesize biological surfactants (BS-NAPH6) on inexpensive carbon sources. The Fourier Transform Infrared (FTIR) analysis suggested that BS-NAPH6 belonged to the glycolipid family. Besides, BS-NAPH6 displayed a high steadiness against a wide spectrum of pHs, temperatures and salinities. The treatment of human HEK293 cells by different concentrations of BS-NAPH6 displayed that this latter exhibited no cytotoxic effect at concentrations below 200 μg/mL. Furthermore, the application of BS-NAPH6 in hydrocarbons removal from polluted soil, demonstrated that it was more efficient than tested chemical surfactants. Interestingly, BS-NAPH6 highlighted a significant healing activity on the wound site in a rat model compared to a commercial cream. Due to their attractive biological properties, strain NAPH6 as well as its biosurfactant BS-NAPH6 are considered as promising candidates for various applications including environmental and biomedical ones

Study of microbial communities and environmental parameters of seawater collected from three Tunisian fishing harbors in Kerkennah Islands: Statistical analysis of the temporal and spatial dynamics

Surface seawater, collected from three fishing harbors during different seasons of the years 2015, 2016 and 2017, were assessed for physico-chemical analyses. Results showed that seawater was mainly polluted by hydrocarbons and some heavy metals. Microbial communities' composition and abundance in the studied harbors were performed using molecular approaches. SSCP analysis indicated the presence of Bacteria, Archaea and Eucarya, with dominance of the bacterial domain. Illumina Miseq analysis revealed that the majority of the sequences were affiliated with Bacteria whereas Archaea were detected at low relative abundance. The bacterial community, dominated by Proteobacteria, Bacteroidetes, Planctomycetes, Cyanobacteria, Firmicutes, Actinobacteria and Chloroflexi phyla, are known to be involved in a variety of biodegradation/biotransformation processes including hydrocarbons degradation and heavy metals resistance. The main objectives of this study are to assess, for the first time, the organic/inorganic pollution in surface seawater of Kerkennah Islands harbors, and to explore the potential of next generation marine microbiome monitoring to achieve the planning coastal managing strategies worldwide. 2022 Elsevier LtdThe present work was supported by the Tunisian Ministry of Higher Education and Scientific Research and the Hubert Curien Program ( CMCU 15G0808 ) supported by the French Ministry of Foreign Affairs .Scopu

Detection of Cerebral Electroencephalographic Patterns After Median Nerve Stimulation During Propofol-Induced General Anesthesia : a Prospective Interventional Cohort Study

International audienceBackground: Devices used to assess depth of anesthesia and clinical parameters may not be sufficient to prevent intraoperative accidental awareness 1. An alternative would be to detect the patient's intention to move in order to alert the medical staff 2. We believe that the data obtained after multiple median nerve stimulation (MNS) during general anesthesia will help us to prevent intraoperative awareness 2. Methods: In this prospective, interventional trial, 30 volunteers aged from 18 to 81 years with informed consent will be enrolled for scheduled surgery from 15th January 2023 to 31st December 2026. Are excluded patients who are allergic to propofol or have a history of anaphylactic reaction, pregnant women and patients with a psychiatric disease. This study is approved by the CHU Brugmann ethical committee (CE 2021/225) and is registered at EUDRACT (2021-006457-56) and ClinicalTrials.gov (NCT05272202). EEG data based on MNS is first recorded with the patient awake, then a second recording is made under general anesthesia during the surgery. MNS is obtained by electrodes placed on the wrist. EEG signal is acquired by using a TMSi 64-channel system covering the scalp. An EEG amplifier records the changes in ERD (event-related desynchronization) and ERS (event-related synchronization) patterns at various concentrations of propofol delivered by a target-controlled infusion pump. The primary endpoint is the comparison of the average maximal values of amplitude of the ERD/ERS at rest and at various concentrations of propofol. The average ERDs max and ERSs max are compared with a Student t-test (P<0.05). Results: Our intermediate results (n=4 curarized patients) shows the ERS in the mu/beta frequency band after MNS before general anesthesia (Fig. 1A). After propofol induction, the post-stimulation ERS disappears significantly (Fig. 1B; P<0.01 with FDR correction). Conclusions: The preliminary data extracted from the ERD/ERS consecutive to MNS seems to disappear with high concentration of propofol contrary to previous studies at lower levels2. Therefore, this study is not conclusive in terms of the ERD/ERS patterns used but other EEG features (i.e., brain connectivity, somatosensory evoked potential) could be investigated and will be the subject of future research