Kinetic Model and Numerical Simulation of Microbial Growth, Migration, and Oil Displacement in Reservoir Porous Media.

Microbial enhanced oil recovery (MEOR) is a potential tertiary oil recovery method. However, past research has failed to describe microbial growth and metabolism reasonably, especially quantification of reaction equations and operating parameters is still not clear. The present study investigated the ability of bacteria extracted from Ansai Oilfield for MEOR. Through core flooding experiments, bacteria-treated experiments produced approximately 6.28-9.81% higher oil recovery than control experiments. Then, the microbial reaction kinetic model was established based on laboratory experimental data and mass conservation. Furthermore, the proposed model was validated by matching core flooding experiment results. Lastly, the effects of different injection parameters on bacteria growth, bacteria migration, metabolite migration, residual oil distribution, and oil recovery were studied by establishing a field-scale model. The results indicate that the injected bacteria concentration and nutrient concentration have a great influence on bacteria growth in a reservoir and the low nutrient concentration seriously restricts bacteria growth. Compared with the injected bacteria concentration, nutrient concentration has a decisive effect on bacteria and metabolite migration. The injected bacteria concentration has little effect on oil recovery, while nutrient concentration and slug volume have a significant effect on oil recovery.

Alterations in Microbiota and Metabolites Related to Spontaneous Diabetes and Pre-Diabetes in Rhesus Macaques.

Spontaneous type 2 diabetes mellitus (T2DM) macaques are valuable resources for our understanding the pathological mechanism of T2DM. Based on one month's fasting blood glucose survey, we identified seven spontaneous T2DM macaques and five impaired glucose regulation (IGR) macaques from 1408 captive individuals. FPG, HbA1c, FPI and IR values were significant higher in T2DM and IGR than in controls. 16S rRNA sequencing of fecal microbes showed the significantly greater abundance of Oribacterium, bacteria inhibiting the production of secondary bile acids, and Phascolarctobacterium, bacteria producing short-chain fatty acids was significantly lower in T2DM macaques. In addition, several opportunistic pathogens, such as Mogibacterium and Kocuria were significantly more abundant in both T2DM and IGR macaques. Fecal metabolites analysis based on UHPLC-MS identified 50 differential metabolites (DMs) between T2DM and controls, and 26 DMs between IGR and controls. The DMs were significantly enriched in the bile acids metabolism, fatty acids metabolism and amino acids metabolism pathways. Combining results from physiochemical parameters, microbiota and metabolomics, we demonstrate that the imbalance of gut microbial community leading to the dysfunction of glucose, bile acids, fatty acids and amino acids metabolism may contribute to the hyperglycaemia in macaques, and suggest several microbes and metabolites are potential biomarkers for T2DM and IGR macaques.

Isolating, identifying and evaluating of oil degradation strains for the air-assisted microbial enhanced oil recovery process.

Due to the inefficient reproduction of microorganisms in oxygen-deprived environments of the reservoir, the applications of microbial enhanced oil recovery (MEOR) are restricted. To overcome this problem, a new type of air-assisted MEOR process was investigated. Three compounding oil degradation strains were screened using biochemical experiments. Their performances in bacterial suspensions with different amounts of dissolved oxygen were evaluated. Water flooding, microbial flooding and air-assisted microbial flooding core flow experiments were carried out. Carbon distribution curve of biodegraded oil with different oxygen concentration was determined by chromatographic analysis. The long-chain alkanes are degraded by microorganisms. A simulation model was established to take into account the change in oxygen concentration in the reservoir. The results showed that the optimal dissolved oxygen concentration for microbial growth was 4.5~5.5mg/L. The main oxygen consumption in the reservoir happened in the stationary and declining phases of the microbial growth systems. In order to reduce the oxygen concentration to a safe level, the minimum radius of oxygen consumption was found to be about 145m. These results demonstrate that the air-assisted MEOR process can overcome the shortcomings of traditional microbial flooding techniques. The findings of this study can help for better understanding of microbial enhanced oil recovery and improving the efficiency of microbial oil displacement.

Prebiotic Maltose Gel Can Promote the Vaginal Microbiota From BV-Related Bacteria Dominant to Lactobacillus in Rhesus Macaque.

The high incidence of bacterial vaginosis recurrence is common after treatment with an antibiotic agent and suggests the need for new treatments to prevent this. We conducted a randomized trial to evaluate the ability of maltose gel to treat bacterial vaginosis. Eighteen female rhesus macaques were randomly assigned, in a 2:1 ratio, to receive maltose gel or placebo gel by syringe to the fornix of the vagina for five consecutive days. We used 16S rRNA sequencing data from 70 swab samples of vaginal secretions in two groups in total on days 0, 3, and 5 after medication initiation and days 3 and 5 after medication withdrawal for the study of microbiome composition. We found that, in the placebo control group, there was no significant change in the composition and abundance of vaginal microbiota during the follow-up period. In the maltose gel test group, the abundance of Lactobacillus in the vagina microbiota increased gradually with the prolongation of the treatment time on Days 3 and 5 (ANOVA p = 6.99e-5 < 0.01) but began to decrease after the withdrawal of maltose gel, which was different from that of the control group. Correspondingly, the diversity and abundance of BV-related bacteria, Fusobacterium, Parvimonas, Mobiluncus, Campylobacter, Prevotella, and Sneathia, decreased on Day 0 to Day 5 of medication and increased after drug withdrawal in the maltose gel test group. The study confirms that maltose gel can facilitate the proliferation of Lactobacillus and promote the transition of the vaginal microbiota from BV-related bacteria dominant to Lactobacillus dominant in the rhesus macaque.

Age-related gene expression and DNA methylation changes in rhesus macaque.

Aging is a very complicated biological process that can change gene expressions. The Chinese rhesus macaque (Macaca mulatta lasiota; CR) is closely related to humans. We explored gene expression with increasing age and DNA methylation changes in young and old CRs. Results showed blood transcriptome and DNA methylome significantly changed from young to old CRs. The age-associated differentially expressed genes (DEGs) and differentially methylated regions (DMRs) were associated with age-related biological features, such as immunity, blood coagulation, and biosynthetic process. The measurements of coagulation indicators confirmed old CRs had shorter coagulation time than young CRs, and the activities of coagulation factor II (FII) and factor VIII (FVIII) were enhanced in old CRs. Humans and CRs exhibited the same enhanced blood coagulation with age phenotype. Our study found aging is a critical factor affecting gene expression in CRs, and also provided new insights into the blood coagulation changes in non-human primates.

Transport and Retention Behaviors of Deformable Polyacrylamide Microspheres in Convergent-Divergent Microchannels.

Knowledge of the transport and retention behaviors of soft deformable particles on the microscale is essential for the design, evaluation, and application of engineered particle materials in the fields of energy, environment, and sustainability. Emulated convergent-divergent microchannels were constructed and used to investigate the transport and retention behaviors of soft deformable polyacrylamide microspheres at various conditions. Five different types of transport and retention patterns, i.e., surface deposition, smooth passing, direct interception, deforming remigration, and rigid blockage, are observed. Flow resistance variation characteristics caused by different patterns were quantitatively analyzed. Effects of flow rate, pore-throat size, particle size, and injection concentration on transport and retention patterns have been studied, and transport and retention pattern maps are presented and discussed.

Blood transcriptome analysis reveals gene expression features of breast-feeding rhesus macaque ( Macaca mulatta) infants.

During the breast-feeding period, infants undergo remarkable changes, including rapid physiological and developmental growth. However, little is known about gene expression features and sex-specific gene expression in breast-feeding infants. In this study, we sequenced 32 blood transcriptomes from 16 breast-feeding rhesus macaque ( Macaca mulatta) infants and their lactating mothers. We identified 218 differentially expressed genes (DEGs) between infants and mothers, including 91 up-regulated and 127 down-regulated DEGs in the infant group. Functional enrichment analysis of the up-regulated DEGs and unique hub genes in infants showed primary enrichment in immunity, growth, and development. Protein-protein interaction analysis also revealed that genes at key positions in infants were mainly related to development and immunity. However, we only detected 23 DEGs between female and male infants, including three DEGs located on chromosome X and 14 DEGs located on chromosome Y. Of these DEGs, TMF1 regulated nuclear protein 1 ( Trnp1), which was highly expressed in female infants, is crucial for controlling the tangential and radial expansion of the cerebral cortex in mammals. Thus, our study provides novel insight into the gene expression features of breast-feeding infants in non-human primates (NHPs) and reveals sex-specific gene expression between these infants.

Pore-scale investigation of micron-size polyacrylamide elastic microspheres (MPEMs) transport and retention in saturated porous media.

Knowledge of micrometer-size polyacrylamide elastic microsphere (MPEM) transport and retention mechanisms in porous media is essential for the application of MPEMs as a smart sweep improvement and profile modification agent in improving oil recovery. A transparent micromodel packed with translucent quartz sand was constructed and used to investigate the pore-scale transport, surface deposition-release, and plugging deposition-remigration mechanisms of MPEMs in porous media. The results indicate that the combination of colloidal and hydrodynamic forces controls the deposition and release of MPEMs on pore-surfaces; the reduction of fluid salinity and the increase of Darcy velocity are beneficial to the MPEM release from pore-surfaces; the hydrodynamic forces also influence the remigration of MPEMs in pore-throats. MPEMs can plug pore-throats through the mechanisms of capture-plugging, superposition-plugging, and bridge-plugging, which produces resistance to water flow; the interception with MPEM particulate filters occurring in the interior of porous media can enhance the plugging effect of MPEMs; while the interception with MPEM particulate filters occurring at the surface of low-permeability layer can prevent the low-permeability layer from being damaged by MPEMs. MPEMs can remigrate in pore-throats depending on their elasticity through four steps of capture-plugging, elastic deformation, steady migration, and deformation recovery.