Biosurfactant production and applications in oil contaminate control

Surfactants are a versatile group of chemicals. They are amphiphilic compounds that exert impacts at interfaces among air, water, oil, and solid phases. Currently, the prevalent players in the market are chemically synthesized surfactants, which have concerns of considerable toxicity and low biodegradability. Because they are mainly derived from fossil fuels, they are not sustainable in the long run and the production costs are subjected to the price variance of raw materials. In view of these limitations, biosurfactants have been proposed as promising alternatives. They are surfactant molecules produced by microorganisms during their growth. Biosurfactants exist naturally in the environment and play some roles in the ecosystem even without human interferences. In this dissertation we define this virtue as “environmental friendly”. They are also renewable and non/less toxic. They have also been found with the intriguing advantages such as enormous structural diversity, lower critical micellar concentrations (CMCs), and the feasibility to use renewable and/or waste streams as the source of production. Biosurfactants are considered as multifunctional biomolecules of the 21st century with a thriving global market share. Their applications in environmental and oil industries are among the top market sectors thanks to their environmental friendly nature. In order to harness the power of biosurfactants, the economic effectiveness of production of these molecules needs improvements. The inocula/microorganisms are the engine of a production process, which determine the maximum yield potential and the functionality of biosurfactants, yet limited inocula have been reported. The functional diversity of biosurfactants includes emulsification, dissolution, dispersion, emulsion breaking, reduction in viscosity, and surface activity, which result in a broad spectrum of potential applications in oil contaminate control including soil washing, enhanced bioremediation, oily wastewater treatment, and spilled oil dispersion. However, limited research efforts have been placed into evaluating the application potential of biosurfactants in oil contaminate control. The objectives of this thesis are to 1) identify novel and robust biosurfactant producing microorganisms and develop hyper-production mutants; 2) examine the functionality of the produced biosurfactants; and 3) investigate the potential of using these produced biosurfactants in diverse applications of oil contaminate control. The outputs of the thesis include: (1) the successful isolation, identification, characterization and functionality analysis of one-hundred-and-fourteen biosurfactant producing and oil degrading marine bacteria; (2) the discovery of a novel bacterial species, Alcanivorax atlaticus for the first time and its proposed type strain with comprehensive genotype and phenotype characterizations; (3) an in-depth characterization, functionality analysis and application demonstration of a novel bioemulsifier (exmulsins) and its bacterium (Exiguobacterium sp. N4-1P); (4) reporting of thirty-seven novel oil-in-water emulsion breaking marine bacteria for oily wastewater treatment, and a recommended screening strategy for their identification; (5) the first attempt to genetically modify Rhodococcus strains for hyper production of biosurfactant and to investigate the dispersing abilities of the the produced biosurfactants; and (6) a comprehensive investigation of 4 types of biosurfactants produced from selected isolates and mutants as marine oil spill dispersants

ENV-624: A NEW HIGH-YIELDING BIO-DISPERSANT PRODUCER MUTATED FROM RHODOCOCCUS ERYTHROPOLIS STRAIN P6-4P

Preeminent effectiveness and feasibility of dispersants have been the key reasons for their widely serving as the response agents in oil spill responses. Moreover, dispersants can also overcome the limitation factors of other countermeasures like accessibility, weather conditions, sea states, and oil thickness. However, the public concerns of the usages of the chemically synthetic dispersants are also essential due to their toxicity and persistency in the ecosystem. Bio-dispersants can be a promising alternative as the proven features of lower toxicity and persistency while with high effectiveness, but its broad application prospects are currently restricted by the high production cost that is 3-10 times more than chemical synthetic ones because of the low productivity. Thus, a hyper bio-dispersant producer will be the desired coping strategy. An isolated bio-dispersant producer from NL offshore, Rhodococcus erythropolis strain P6-4P was selected for generating high-yielding producers by mutation. After UV mutagenesis, 21 enhanced mutants were selected through oil spreading screening method. Further productivity quantify test of critical micelle dilution (CMD) with higher resolution was conducted to these mutants. An outstanding mutant showed CMD as high as 225 while 15.4 is the CMD of the wild type strain, which means the new mutant is 14.6 times increase. The 16S rDNA sequencing results revealed that the 16 S ribosomal DNA of the mutant 100% matched with the original strain indicating the mutation occurred on other parts of the genome which will be identified through next-generation sequencing and comparative analysis in the future study. This mutated high-yielding strain was capable to significantly improve the production rate and the total yield of bio-dispersants. The yield of crude bio-dispersant was 54g per liter with 6 days incubation. At 4mg/uL crude product/crude oil ratio, the dispersion effectiveness was found comparable to Corexit 9500A at 1:25 (dispersant/crude oil ratio). Future works on further mutagenesis base on this new high-producing strain by novel mutation methods were also discussed

Fish Waste Based Lipopeptide Production and the Potential Application as a Bio-Dispersant for Oil Spill Control

There is a growing acceptance worldwide for the application of dispersants as a marine oil spill response strategy. The development of more effective dispersants with less toxicity and higher biodegradability would be a step forward in improving public acceptance and regulatory approvals for their use. By applying advances in environmental biotechnology, a bio-dispersant agent with a lipopeptide biosurfactant produced by Bacillus subtilis N3-1P as the key component was formulated in this study. The economic feasibility of producing biosurfactant (a high-added-value bioproduct) from fish waste-based peptone as a nutrient substrate was evaluated. Protein hydrolyzate was prepared from cod liver and head wastes obtained from fish processing facilities. Hydrolysis conditions (i.e., time, temperature, pH and enzyme to substrate level) for preparing protein hydrolyzates were optimized by response surface methodology using a factorial design. The critical micelle dilution (CMD) value for biosurfactant produced from the fish liver and head waste generated peptones was 54.72 and 47.59 CMD, respectively. Biosurfactant product generated by fish liver peptone had a low critical micelle concentration of 0.18 g L–1 and could reduce the surface tension of distilled water to 27.9 mN/m. Structure characterization proved that the generated biosurfactant product belongs to the lipopeptide class. An alternative to the key surfactant dioctyl sulfosuccinate sodium (DOSS) used in Corexit 9500 has been proposed based on a binary mixture of lipopeptides and DOSS that exhibited synergistic effects. Using the standard baffled flask test, a high dispersion efficiency of 76.8% for Alaska North Slope oil was achieved at a biodispersant composition of 80/20 (v/v) of lipopeptides/DOSS. The results show that fish waste can be utilized to produce a more effective, environmentally acceptable and cost-efficient biodispersant that can be applied to oil spills in the marine environment

Decoding tumor heterogeneity in uveal melanoma: basement membrane genes as novel biomarkers and therapeutic targets revealed by multi-omics approaches for cancer immunotherapy

Background: Uveal melanoma (UVM) is a primary intraocular malignancy that poses a significant threat to patients’ visual function and life. The basement membrane (BM) is critical for establishing and maintaining cell polarity, adult function, embryonic and organ morphogenesis, and many other biological processes. Some basement membrane protein genes have been proven to be prognostic biomarkers for various cancers. This research aimed to develop a novel risk assessment system based on BMRGs that would serve as a theoretical foundation for tailored and accurate treatment.Methods: We used gene expression profiles and clinical data from the TCGA-UVM cohort of 80 UVM patients as a training set. 56 UVM patients from the combined cohort of GSE84976 and GSE22138 were employed as an external validation dataset. Prognostic characteristics of basement membrane protein-related genes (BMRGs) were characterized by Lasso, stepwise multifactorial Cox. Multivariate analysis revealed BMRGs to be independent predictors of UVM. The TISCH database probes the crosstalk of BMEGs in the tumor microenvironment at the single-cell level. Finally, we investigated the function of ITGA5 in UVM using multiple experimental techniques, including CCK8, transwell, wound healing assay, and colony formation assay.Results: There are three genes in the prognostic risk model (ADAMTS10, ADAMTS14, and ITGA5). After validation, we determined that the model is quite reliable and accurately forecasts the prognosis of UVM patients. Immunotherapy is more likely to be beneficial for UVM patients in the high-risk group, whereas the survival advantage may be greater for UVM patients in the low-risk group. Knockdown of ITGA5 expression was shown to inhibit the proliferation, migration, and invasive ability of UVM cells in vitro experiments.Conclusion: The 3-BMRGs feature model we constructed has excellent predictive performance which plays a key role in the prognosis, informing the individualized treatment of UVM patients. It also provides a new perspective for assessing pre-immune efficacy

Functional brain activity in patients with amnestic mild cognitive impairment: an rs-fMRI study

BackgroundAmnestic mild cognitive impairment (aMCI) is an early stage of Alzheimer’s disease (AD). Regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) are employed to explore spontaneous brain function in patients with aMCI. This study applied ALFF and ReHo indicators to analyze the neural mechanism of aMCI by resting-state functional magnetic resonance imaging (rs-fMRI).MethodsTwenty-six patients with aMCI were included and assigned to the aMCI group. The other 26 healthy subjects were included as a healthy control (HC) group. Rs-fMRI was performed for all participants in both groups. Between-group comparisons of demographic data and neuropsychological scores were analyzed using SPSS 25.0. Functional imaging data were analyzed using DPARSF and SPM12 software based on MATLAB 2017a. Gender, age, and years of education were used as covariates to obtain ALFF and ReHo indices.ResultsCompared with HC group, ALFF decreased in the left fusiform gyrus, left superior temporal gyrus, and increased in the left cerebellum 8, left inferior temporal gyrus, left superior frontal gyrus (BA11), and right inferior temporal gyrus (BA20) in the aMCI group (p < 0.05, FWE correction). In addition, ReHo decreased in the right middle temporal gyrus and right anterior cuneiform lobe, while it increased in the left middle temporal gyrus, left inferior temporal gyrus, cerebellar vermis, right parahippocampal gyrus, left caudate nucleus, right thalamus, and left superior frontal gyrus (BA6) (p < 0.05, FWE correction). In the aMCI group, the ALFF of the left superior frontal gyrus was negatively correlated with Montreal Cognitive Assessment (MoCA) score (r = −0.437, p = 0.026), and the ALFF of the left superior temporal gyrus was positively correlated with the MoCA score (r = 0.550, p = 0.004). The ReHo of the right hippocampus was negatively correlated with the Mini-Mental State Examination (MMSE) score (r = −0.434, p = 0.027), and the ReHo of the right middle temporal gyrus was positively correlated with MMSE score (r = 0.392, p = 0.048).ConclusionFunctional changes in multiple brain regions rather than in a single brain region have been observed in patients with aMCI. The abnormal activity of multiple specific brain regions may be a manifestation of impaired central function in patients with aMCI

Screening and characterization of biosurfactant producers from petroleum hydrocarbon contaminated marine sources in North Atlantic Canada for oil spill responses

As one of the oil spill responses, oil dispersion was found effective in open sea and under harsh conditions. However, currently used chemical surfactant-based dispersants may harm the environment due to the toxicity and persistency. Thus novel, environmentally friendly biosurfactant-based dispersants are desired. Biosurfactants are less toxic, biodegradable, and can be biologically produced. Their establishment is impeded by a lack of economic and versatile products. Discovery of new biosurfactant producers is the key to overcome the obstacles. This dissertation will thus fill the research gap through screening and characterization of biosurfactant producing microorganisms from petroleum hydrocarbon contaminated marine sources in the North Atlantic Canada. Fifty-five biosurfactant producers belong to 8 genera were isolated. Some of the isolated strains were found with properties such as greatly reducing surface tension, stabilizing emulsion and producing flocculant. Three strains with interesting characteristics and limited relevant publications were selected for genetype and phenotype characterization. The strains, the products and the bioprocess can be of great value to both scientific understanding and the environmental applications in offshore oil spill responses

From Challenges to Opportunities: Towards Future Strategies and a Decision Support Framework for Oil Spill Preparedness and Response in Offshore Newfoundland and Labrador

As a major energy source worldwide, oil products are increasingly produced and consumed. Despite progress in reducing spillage through a variety of technological and regulatory measures, along with improving industry practices, oil spills continue to occur. On a daily basis, hundreds to thousands of spills are likely to occur worldwide in many different types of environments such as on land, at sea, and in inland freshwater systems. Multiple sources of spillage are involved, such as tankers, offshore platforms, drilling rigs and wells, as well as through a variety of processes of transportation, refining, storage and utilization of refined petroleum products and their by-products. Spills occur for diverse reasons including structural failures, operational errors, weather-related events, earthquakes, human negligence, and even vandalism or terrorism. The biggest contributor to oil pollution in the world’s oceans (some 45%) is operational discharges from tankers. Most oil spill occurrences (72%) are on a small scale and the overall amount of these small spills accounts for less than 1% of the total spillage. The largest spills (over 30 tonnes) rarely occur (0.1% of incidents) yet involve nearly 60% of the total amount spilled. The project’s objective was to gain insight to current methodologies and technologies in oil spill response and countermeasures and to formulate a new strategic and decision making framework for supporting oil spill diagnosis, warning and emergency response in a cost-efficient and environmental friendly manner. The cold weather and harsh offshore conditions in Newfoundland and Labrador and their effects will be considered in the study. The main objectives of the research included: • Collect and analyze background information and data of historical oil spills and associated environmental, economic and societal impacts as well as relevant policies and regulations • Review current offshore oil spill response and countermeasure protocols and practices • Review the natural and social conditions, spill prevention, monitoring and analysis, assessment and modeling, and response and clean-up technologies, as well as their effectiveness and suitability in harsh environments prevailing in NL offshore areas • Identify knowledge gaps and technical challenges in offshore oil spill, monitoring, analysis, modeling, responses, and countermeasures particularly in harsh environmental conditions • Formulate a general decision making framework for integrating methods and techniques during oil spill monitoring, early warning, assessment, simulation, response and cleanup processes • Recommend oil spill management strategies and disclose the research and development needs particularly for NL offshore industry and regulatory authorities. Based on the comprehensive review, this study made general recommendations to help guide research and development efforts in oil spill response and countermeasures from the aspects of impact assessment, regulations and coordination, monitoring and analysis, modeling and prediction, preparedness and response, countermeasures, and decision making. Some special recommendations given to future investment and R&D efforts in order to address the identified knowledge gaps and technical challenges associated with the NL’s harsh offshore environment include: • Uncertainties associated with the weather and ocean conditions and the impacts on spill modeling and response decision making; • Integration of monitoring, assessment, simulation and optimization into offshore oil spill response decision making; • Capability of existing technologies in harsh environments and novel technologies customized with the specific characteristic of NL offshore oil spills; and • Adaptation of long-term contingency plans, management strategies, on-site response decision, and operational technologies to harsh environmental conditions

Engineering Rhamnolipid Biosurfactants as Agents for Microbial Enhanced Oil Recovery

This investigation considered engineered rhamnolipid biosurfactants as EOR agents that potentially could be manufactured at low cost from renewable resources, and have lower toxicity than synthetic EOR surfactants. This particular biosurfactant comes mainly from the microbe Pseudomonas aeruginosa. Disadvantages of working with this strain include that the chemical structures of the produced rhamnolipids are not easily controlled, plus there is a preference to use instead a completely non-pathogenic microbe. Towards that end, the study took the approach to clone the genetic information from a P. aeruginosa strain into E. coli to manipulate systematically the structure of the created rhamnolipids and evaluate their EOR performance by themselves (no co-surfactant or viscosity chemical added). Six E.coli strains (ETRA, ETRAB, ERAC, ETRABC, ETRhl, ETRhl-RC) that carry different combinations of the genes involoved in rhamnolipid bio-synthesis were successfully engineered and tested for their rhamnolipid production. Sand-pack core flooding tests were run to evaluate and compare the effectiveness of these products as agents for enhanced oil recovery. The brine with optimized pH and salt concentration in which a given biosurfactant product has its lowest IFT was used to saturate the core, perform a waterflood, and prepare the surfactant solution. Injection of 6 PV of only a 250 ppm rhamnolipid biosurfactant solution and 4 PV of a brine chaser could recover as much as half of the waterflood residual hydrocarbon (n-octane). The engineered E. coli strains that include more of the implanted genetic code had the better performance in these oil displacement tests. The IFT, biosurfactant concentration and pH of effluents from core flooding were monitored to address EOR mechanisms and quantify the adsorption of each product in the sand pack

Structural and functional activities of brain in patients with vascular cognitive impairment: A case-controlled magnetic resonance imaging study

This study aimed to identify abnormal brain regions and imaging indices of vascular cognitive impairment (VCI) and explore specific imaging diagnostic markers of VCI. In this study, 24 patients with VCI were allocated to the VCI group and 25 healthy subjects were assigned to the healthy control (HC) group. Demographic data and neuropsychological test scores were compared using SPSS 25.0. The structural and functional imaging data were post-processed and statistically analyzed using CAT12, DPARSF and SPM12 software, based on the MATLAB platform. The structural and functional indices of gray matter volume (GMV) and regional homogeneity (ReHo) were obtained, and inter-group data were analyzed using an independent-sample t test. Sex, age, years of education, and total brain volume were used as covariates. Compared to the HC group, the GMV of VCI in the VCI group decreased significantly in the rectus muscles of the bilateral gyrus, left superior temporal gyrus, left supplementary motor area (SMA), right insula, right superior temporal gyrus, right anterior cuneiform lobe, and right anterior central gyrus (PRECG) (P \u3c.05, FWE correction), without GMV enlargement in the brain area. ReHo decreased in the right inferior temporal gyrus (ITG), right parahippocampal gyrus, and left temporal pole (middle temporal gyrus, right lingual gyrus, left posterior central gyrus, and right middle temporal gyrus), the areas of increased ReHo were the left caudate nucleus, left rectus gyrus, right anterior cingulate gyrus and lateral cingulate gyrus (P \u3c.05, FWE correction). Correlation analysis showed that the GMV of the left superior temporal gyrus was positively correlated with the Montreal Cognitive Assessment (MoCA) score (P \u3c.05), and the GMV of the right insula was positively correlated with the MESE and long delayed memory scores (P \u3c.05). There was a significant positive correlation between the ReHo and short-term delayed memory scores in the middle temporal gyrus of the left temporal pole (P \u3c.05). The volume of GMV and ReHo decreased in VCI patients, suggesting that impairment of brain structure and function in specific regions is the central mechanism of cognitive impairment in these patients. Meanwhile, the functional indices of some brain regions were increased, which may be a compensatory mechanism for the cognitive impairment associated with VCI