Effects of different probiotics on the gut microbiome and metabolites in the serum and caecum of weaning piglets

The objective of the study was to determine the effects of antibiotics, yeast culture (YC), and Lactobacillus culture (LC) on the gut microbiome and metabolites in the serum and caecum of weaning piglets. Twenty-four weaning piglets were divided into four treatment groups: control, antibiotic (1% chlortetracycline), 1.8% yeast culture (YC), and 1.6% Lactobacillus culture groups (LC). Each group had six replicated pens with one pig per pen. Feed and water were available ad libitum. Dietary supplementation with antibiotics, YC and LC increased the abundance of phylum, Firmicutes, and decreased the abundance of phylum, Proteobacteria. Beneficial bacteria such as Lactobacillus and Megasphaera in YC and LC groups increased, whereas the proportion of Shigella was decreased. Genera Alloprevotella and Lachnospira were biomarkers in the control and antibiotic groups, respectively. Phylum, Bacteroidetes, and genus, Collinsella, were biomarkers in the YC group, and Mitsuokella, Anaerotruncus, Syntrophococcus and Sharpea were biomarkers in the LC group. Dietary supplementation with different probiotics changed the serum and caecum metabolite profiles too. Antibiotic supplementation increased the levels of D-mannose, D-glucose, and hexadecanoic acid in the serum, and the levels of myo-inositol, D-mannose and benzenepropanoic acid in the caecum. LC increased the concentrations of D-mannose, cis-9-hexadecenoic acid and heptadecanoic acid in caecum compared with the control group. YC and LC supplementation in the weaning diet could improve the abundance of beneficial bacteria by changing the concentrations of some metabolites in the serum and caecum. Therefore, dietary supplementation with YC or LC could be used as additives instead of antibiotics in weaning piglets.Keywords: antibiotic; lactobacillus culture; yeast culture; high-throughput sequencing; gas chromatography mass spectrometr

Numerical simulation of coalbed methane generation, dissipation and retention in SE edge of Ordos Basin, China

This paper presents a numerical study on the formation history of coalbed methane (CBM) reservoir in the southeast edge of Ordos Basin, China. The coal seams studied belong to the Late Palaeozoic coal-bearing series. These coal seams have a burial history and experienced the process of subsidence, rapid subsidence alternated with uplift and then uplift, sequentially, and underwent the geothermal actions at normal, extremely high, and then normal temperatures, respectively. Coal organic matter of the coal seams matured in the Triassic Period and in the Late Jurassic to Early Cretaceous Period. The results from numerical simulation reveal that CBM reservoir evolution history can be classified into five stages, namely primary, initial, stagnant, active and dissipative stages. In the first (primary) stage, coal rank was very low and there was little methane generated and stored in the coal seams. In the second (initial) stage, the coal was converted to middle-high volatile bituminous coal. As a result, a certain amount of methane was generated and began to accumulate in coal seams except part of it escaped from coal seams by diffusion and cap outburst. In the third (stagnant) stage, generation of methane was almost stagnant due to the temperature of the coal seam that dropped slightly and the maturation of coal organic matter stopped. Meanwhile CBM would keep dissipating through diffusion. In the fourth (active) stage, coal rank varied from high volatile bituminous coal A to semianthracite which accelerated pyrolysis gas formation and resulted in a large amount of methane generated at a high speed. During this period, CBM was increasingly accumulated in coal seams although there would be considerable amounts of gas dissipated from the coal seams. In the last (dissipative) stage, due to coal seams uplifted at various rates and no more methane generated, CBM was continuously dissipated by diffusion throughout the whole coal seams and by permeation at some local areas. The simulation provides insights for further interpretation of how many factors that control or affect the CBM reservoir formation history and CBM accumulation. These factors include features of coal-bearing series, characteristics of coal seams, physical properties of coal reservoir, tectonic evolution history, burial history and geothermal conditions, etc. In particular, tectonic evolution history and gas generation are critical. Under given conditions, CBM reservoirs in the study area were developed in different ways and the CBM was accumulated in the reservoirs at different levels. For example, the west part of study area is favourable for CBM accumulation. As a result, the gas content of the main coal seams in this region has a maximum of about 28 m/t at depths of 900-1100 m, and generally increases with the increasing of burial depth from the east to the west. The coal reservoir is under-saturated in the east part where the burial depth is shallower than about 500 m while the west part is saturated. There is a close correlation of the lateral distribution of both gas content and saturation to the gas generation in the geological history

Simulation study on evolution of coalbed methane reservoir in Qinshui basin, China

A dynamic equilibrium model has been proposed to describe the coalbed methane concentration-dissipation evolution process in coal. including its generation, storage and migration. The model, developed with a computational program, has been applied to the Qinshui basin, China, which allows to evaluate features of coal seam of the basin including coal quality and burial, palaeo-geothermal field, and coal organic material maturation evolution history. The simulation study was focused on coalbed methane concentration-dissipation evolution history of the upper and lower main coal seams in the basin. The results indicate that the whole evolution process can be divided into three stages. At the first stage, i.e. the primary concentration stage, gas generation quantity and gas content were lower and only weak diffusion took place. The second stage can be called the active concentration-dissipation stage. During this period, coal organic material was matured at a higher rate, generating a large amount of gas because of abnormal high palaeo-geothermal field in the Middle and Late Yanshan Epoch. As a result, gas content in coal reservoir was higher and gas could be lost in different ways including diffusion, cap outburst and permeation. The third stage can be defined as the absolute dissipation stage at which coal organic material no longer generates gas. Meanwhile much gas was lost mainly by diffusion and partly by permeation. Simulation results further show that, although the high gas generation led to active dissipation in the coal reservoir, there still remains comparatively high gas content on the south and north ends of the Qinshui basin due to the preserving geological conditions. This suggests that these regions are favorable for coalbed methane exploitation which has been confirmed by recent geological exploitations in Qinshui basin. (c) 2007 Published by Elsevier B.V