E. Cervantes-Gonzalez

Bio: E. Cervantes-Gonzalez is an academic researcher from Instituto Politécnico Nacional. The author has contributed to research in topics: Serratia liquefaciens. The author has an hindex of 1, co-authored 1 publications receiving 14 citations.

Isolation and characterization of novel strains of Pseudomonas aeruginosa and Serratia marcescens possessing high efficiency to degrade gasoline, kerosene, diesel oil, and lubricating oil.

Abstract: Bacteria possessing high capacity to degrade gasoline, kerosene, diesel oil, and lubricating oil were screened from several areas of Hokkaido, Japan. Among isolates, two strains, WatG and HokM, which were identified as new strains of Pseudomonas aeruginosa and Serratia marcescens species, respectively, showed relatively high capacity and wide spectrum to degrade the hydrocarbons in gasoline, kerosene, diesel, and lubricating oil. About 90–95% of excess amount of total diesel oil and kerosene added to mineral salts media as a sole carbon source could be degraded by WatG within 2 and 3 weeks, respectively. The same amount of lubricating oil was 60% degraded within 2 weeks. Strain HokM was more capable than WatG in degrading aromatic compounds in gasoline. This strain could also degrade kerosene, diesel, and lubricating oil with a capacity of 50–60%. Thus, these two isolates have potential to be useful for bioremediation of sites highly contaminated with petroleum hydrocarbons.

Biological upgrading of heavy crude oil

Abstract: Heavy crudes (bitumen) are extremely viscous and contain high concentrations of asphaltene, resins, nitrogen and sulfur containing heteroaromatics and several metals, particularly nickel and vanadium. These properties of heavy crude oil present serious operational problems in heavy oil production and downstream processing. There are vast deposits of heavy crude oils in many parts of the world. In fact, these reserves are estimated at more than seven times the known remaining reserves of conventional crude oils. It has been proven that reserves of conventional crude oil are being depleted, thus there is a growing interest in the utilization of these vast resources of unconventional oils to produce refined fuels and petrochemicals by upgrading. Presently, the methods used for reducing viscosity and upgradation is cost intensive, less selective and environmentally reactive. Biological processing of heavy crudes may provide an ecofriendly alternative or complementary process with less severe process conditions and higher selectivity to specific reactions to upgrade heavy crude oil. This review describes the prospects and strengths of biological processes for upgrading of heavy crude oil.

Molecular and Microbiological Insights on the Enrichment Procedures for the Isolation of Petroleum Degrading Bacteria and Fungi.

Abstract: Autochthonous bioaugmentation, by exploiting the indigenous microorganisms of the contaminated environment to be treated, can represent a successful bioremediation strategy. In this perspective, we have assessed by molecular methods the evolution of bacterial and fungal communities during the selective enrichment on different pollutants of a soil strongly polluted by mixtures of aliphatic and polycyclic hydrocarbons. Three consecutive enrichments were carried out on soil samples from different soil depths (0-1 m, 1-2 m, 2-3 m), and analysed at each step by means of high-throughput sequencing (HTS) of bacterial and fungal amplicons biomarkers. At the end of the enrichments, bacterial and fungal contaminants degrading strains were isolated and identified in order to i) compare the composition of enriched communities by culture-dependent and culture-independent molecular methods and to ii) obtain a collection of hydrocarbon degrading microorganisms potentially exploitable for soil bioremediation. The molecular results highlighted that for both bacteria and fungi the pollutant type had a partial shaping effect on the enriched communities, whereas on the contrary neither the soil depth or the enrichment step had significant effects on the composition of the final microbial communities. Molecular analyses were quite well in agreement with culture-dependent analyses in terms of most abundant microbial genera. A total of 95 bacterial and 94 fungal strains were isolated after selective enrichment procedure on different pollutants. On the whole, isolated bacteria where ascribed to manly Pseudomonas genus followed by Sphingobacterium, Bacillus, Stenothrophomonas, Achromobacter and Serratia. For the fungal isolates, Fusarium was the most abundant genus followed by Trichoderma and Aspergillus. The microbial species comprising more isolates, such as P. putida, A. xylosoxidans and O. anthropi for bacteria, F. oxysporum and F. solani for fungi, were also the dominant OTUs assessed in Illumina.

Degradation of asphaltenes by two Pseudomonas aeruginosa strains and their effects on physicochemical properties of crude oil

Abstract: Microbes can enhance oil recovery through the degradation of some heavy fractions of crude oil. Two Pseudomonas aeruginosa strains (Gx and Fx) using crude oil as the carbon source were isolated from oil-contaminated soils. The potential of Gx and Fx for oil displacement was assessed by testing their ability to degrade pure asphalt and crude oil asphaltenes. Approximately ∼10% of pure asphalt and 59–72% of crude oil asphaltenes were degraded using cell-containing fermentation broths. The content of lighter fractions (saturates and aromatics, maximum 11%) increased and the content of heavier fractions (resins and others, maximum 75%) decreased in the degraded oil compared with the controls. The relative quantity of vaporizable fractions (230 °C) increased after treatment, 10% by Gx and 19% by Fx. The oil viscosity (35 °C) was reduced by nearly half from 76.5 m Pa∙s, and ∼90% of oil adsorbed on filter paper was removed after treatment. Gx and Fx produced surfactants with crude oil as the sole carbon source, and the oil-spreading diameter ranged from 15 to 17 cm. In conclusion, biosurfactant-producing P. aeruginosa strains Gx and Fx could efficiently degrade recalcitrant asphaltenes in crude oil and are therefore candidate strains for microbial enhanced oil recovery.

The Gut Microbiota Composition of the Moth Brithys crini Reflects Insect Metamorphosis

Abstract: Lepidoptera is a highly diverse insect order with major importance in agriculture as many species are considered pests. The role of the gut microbiota in insect physiology is still poorly understood, despite the research undertaken in recent years. Furthermore, Lepidoptera are holometabolous insects and few studies have addressed the influence of the changes taking place on the gut microbiome composition and diversity during metamorphosis, especially in monophagous species. The V3-V4 region of the 16S rRNA gene was sequenced to investigate the microbiota composition and diversity of the monophagous moth Brithys crini during three different life stages: egg, larvae (midgut and hindgut), and adult (gut). Our results showed that the microbiota composition of B. crini was stage specific, indicating that the developmental stage is a main factor affecting the gut microbiome in composition and potential functions. Moreover, the diversity of the gut microbiome reflected the developmental process, since a drop in diversity occurred between the larval and the adult phase, when the intestine is completely renewed. In spite of the changes in the gut microbiota during metamorphosis, 29 genera were conserved throughout the three developmental stages, mainly belonging to the Proteobacteria phylum, which define the core microbiome of B. crini. These genera seem to contribute to host physiology by participating in food digestion, nutrition, and detoxification mechanisms.