Microbial contamination of diesel-biodiesel blends in storage tank; an analysis of colony morphology

Influence of consortium culture and mixed culture on carbon steel corrosion in B30 storage system

B30, which consisted of 30 %-v biodiesel and 70 %-v petrodiesel, is a renewable fuel that is being developed in Indonesia. In the B30 storage system, microbes utilize B30 and cause corrosion of carbon steel. This research aims to compare the interaction effect of consortium culture (S. marcescens - B. megaterium and S. marcescens - B. licheniformis) and mixed culture on the corrosion of carbon steel in the B30 storage system. The experiment was carried out by immersing carbon steel ST-37 specimens in B30 test medium for 21 days. Sample testing and analysis includes the number of microbial colonies, chemical bonds of biofilm composition, morphology of biofilms and metal surfaces, corrosion rate and corrosion products. The results shows that antagonistic interactions occurred in the consortium culture, resulting in the decrease of corrosion rate. Meanwhile, synergistic interaction occurred between the microbes in the mixed culture, resulting in higher corrosion rate. The corrosion mechanism that occurs in consortium culture and mixed culture involves the same electrochemical reactions.

Combating Fuel Biocontamination: Tailored Antimicrobial Peptides and an Innovative Delivery Strategy

Microbial invasion and subsequent fuel biocontamination have long posed significant challenges, leading to a significant infrastructural damage. The lack of systematic data on the correlation between environmental parameters and microbial growth has hampered the development of targeted solutions to date. To address this challenge, this study reports a targeted strategy to inactivate and control the proliferation of commonly identified fuel-contaminating microbial clusters through the development of synthetic peptides that can be delivered directly to fuel samples. From a library of short peptides which was designed based on the indolicidin template peptides, three unique sequences were found to have good broad-spectrum activity toward a range of microbes such as Bacillus, Sphingomonas, and Hormoconis, with P17, showing the highest killing potential. The structural analyses of the peptides based on circular dichroism spectroscopy revealed the helical propensity of the peptides in SDS micelles and a random flexible structure in solution. The peptides showed stability under biological conditions and minimal cytotoxicity against mammalian cells. This study presents an innovative method to effectively address fuel biocontamination using short peptides coupled with a potentially scalable protocol to administer the peptides to fuel samples.

Comparative analysis of microbial contamination in diesel fuels using MALDI-TOF MS

Microbiological contamination in fuels poses a significant threat to fuel quality, operational safety, and the efficiency of fuel systems. Effective management of microbial risks can extend fuel systems' lifespan and minimize the environmental footprint of fuel usage. Therefore, we aimed to identify the microbiological contaminants using two MALDI-TOF MS systems (Bruker Daltonik GmbH and Zybio Inc.). Detection and characterization of microbiological contamination in fuels were performed with further validation by 16 S rRNA gene sequencing. Microorganisms collected from three types of diesel fuel were cultured, and fuel samples were analyzed. Significant differences in microbiological contamination were observed between the fuel types, with 272 isolates of bacteria and fungi identified across all fuel samples. Ekodiesel Ultra B0 had the highest number of identified microorganisms. The Zybio system identified 48% of all microorganisms at the species level, whereas the Bruker system identified only 33%. The 16 S rDNA sequencing confirmed proteomic identifications by the MALDI systems with high accuracy. Our study indicates that MALDI-TOF MS technology can effectively assess microbiological contamination in fuels. Integrating MALDI-TOF MS with other molecular techniques could provide a comprehensive view of fuel's microbial communities.

Laser-Induced Graphene for Electrochemical Sensing of Antioxidants in Biodiesel

Synthetic antioxidants are often introduced to biodiesel to increase its oxidative stability, and tert-butyl hydroquinone (TBHQ) has been selected due to its high efficiency for this purpose. The monitoring of antioxidants in biodiesel therefore provides information on the oxidative stability of biodiesels. Herein, a laser-induced graphene (LIG) electrode is introduced as a new sensor for detecting tert-butyl hydroquinone (TBHQ) in biodiesel samples. An infrared CO2 laser was applied for LIG formation from the pyrolysis of polyimide (Kapton). Based on the voltammetric profile of a reversible redox probe, the fabrication of LIG electrodes was set using 1.0 W power and 40 mm s-1 speed, which presented an electroactive area of 0.26 cm2 (higher than the geometric area of 0.196 cm2). Importantly, lower engraving speed resulted in higher electroactive area, probably due to a more efficient graphene formation. Scanning-electron microscopy and Raman spectroscopy confirmed the creation of porous graphene induced by laser. The sensing platform enabled the differential-pulse voltammetric determination of TBHQ from 5 and 450 μmol L-1. The values of detection limit (LOD) of 2 μmol L-1 and RSD (relative standard deviation) of 2.5% (n = 10, 10 μmol L-1 of TBHQ) were obtained. The analysis of spiked biodiesel samples revealed recoveries from 88 to 106%. Also, the method provides a satisfactory selectivity, as it is free of interference from metallic ions (Fe3+, Mn2+, Cr2+, Zn2+, Pb2+, and Cu2+) commonly presented in the biofuel. These results show that LIG electrodes can be a new electroanalytical tool for detecting and quantifying TBHQ in biodiesel.

Automotive Diesel Fuel Internal Stability Testing with the Use of UV and Temperature as Degradation Factors

Diesel fuel stability can be considered from many points of view, of which the two considered most important are stability in contact with the environment and internal stability. Fuel stability in touch with the environment is often defined as oxidation stability, of which measurement procedures are well developed. The presented paper shows that fuel's internal stability can also be important. The internal stability of diesel fuel with the local use of thermal and ultraviolet radiation (UV) as degradation factors and fluorescence signals as a probe is presented in this paper. We show that the internal degradation of fuel with temperature use differs from that with UV and simultaneous both factors use. Our study shows that using temperature as a degradation factor introduces significant fluorescence fading. Moreover, the fluorescence signal restores significantly later than the sample stabilizes at room temperature. The novelty proposed based on examination is hybrid degradation and an examination cycle that enables the simultaneous use of degradation factors and fluorescence reading. For this purpose, a dedicated measurement setup of signal control and processing was constructed and programmed. The measurement procedure of the data series for specific wavelength enables calculation of signal shifts that allow the internal stability classification of diesel fuel samples in less than 30 min with the cost of a single disposable capillary probe and one polymer plug. Premium and regular fuel examination results show that internal fuel stability can be related to polycyclic aromatic hydrocarbons (PAH) concentrations and can be modified with dedicated additives.

Enhanced laccase production by mutagenized Myrothecium verrucaria using corn stover as a carbon source and its potential in the degradation of 2-chlorophen

Chlorophenols are widely used in industry and are known environmental pollutants. The degradation of chlorophenols is important for environmental remediation. In this study, we evaluated the biodegradation of 2-chlorophenol using crude laccase produced by Myrothecium verrucaria. Atmospheric and room temperature plasma technology was used to increase laccase production. The culture conditions of the M-6 mutant were optimized. Our results showed that corn stover could replace glucose as a carbon source and promote laccase production. The maximum laccase activity of 30.08 U/mL was achieved after optimization, which was a 19.04-fold increase. The biodegradation rate of 2-chlorophenol using crude laccase was 97.13%, a positive correlation was determined between laccase activity and degradation rate. The toxicity of 2-CP was substantially reduced after degradation by laccase solution. Our findings show the feasibility of the use of corn stover in laccase production by M. verrucaria mutant and the subsequent biodegradation of 2-chlorophenol using crude laccase.