Growth Of Sulfate-reducing Bacteria Research Articles

Corrosion behavior of X65 steel in seawater containing sulfate reducing bacteria under aerobic conditions

The corrosion behavior of X65 steel was investigated in the seawater inoculated with sulfate reducing bacteria (SRB) under the aerobic environment by electrochemical impedance techniques and immersion tests. The corroded morphologies and the composition of the corrosion products were investigated. The variation of the solution parameters including the bacterium number, the pH value and the soluble iron concentration were also investigated. The results indicated that in the SRB-containing system, the impedance responses presented a depressed semi-circle in the initial period, which then turned into the blocked electrode characteristic during the later immersion. The biofilm, mainly composed of extracellular polymeric substances, Fe(OH)3, γ-FeOOH and α-Fe2O3, formed and degraded with the SRB growth. The soluble iron concentration initially increased, then rapidly decreased and later slowly increased. In the SRB-containing seawater under the aerobic environment, the X65 steel was corroded in the initial immersion. The corrosion became inhibited with the forming of the biofilm during the subsequent immersion. The inhibition efficiency rapidly increased in the logarithmic phase, remained stable in the stationary phase and then decreased in the declination phase. In the corrosion process, the biofilm metabolized by SRB played a key role in the corrosion inhibition of X65 steel.

Effect of sulfate-reducing bacteria and cathodic potential on stress corrosion cracking of X70 steel in sea-mud simulated solution

The submarine oil and gas pipelines steel buried in sea mud are always influenced by microorganisms and cathodic protection potential. In this paper, the single and combined effect of sulfate-reducing bacteria (SRB) and cathodic potential on stress corrosion cracking (SCC) behavior of X70 pipeline steel in sea-mud simulated solution was investigated by slow strain rate tests and fractographic observation. Whether in sterile or SRB-inoculated solution, the SCC susceptibility at − 850 mVSCE showed a decline compared with that at open circuit potential. The reason is that the lower number of corrosion pits and the slighter hydrogen evolution at − 850 mVSCE inhibited both of the cracks nucleation and propagation. The SCC susceptibility of X70 steel increased drastically as the cathodic potential shifted from − 850 mVSCE to − 1200 mVSCE in sterile or SRB-inoculated solution. SRB assisted pitting corrosion and the promotion effect on hydrogen permeation make SRB plays a positive role in promoting SCC susceptibility. The SCC susceptibility can be elevated in the co-existence of SRB and cathodic potential but the combined action between them became limited as the potential shifted negatively, which was attributed to the fact that alkalization of solution caused by cathodic potential restricts the growth of SRB.

The presence of nitrate- and sulfate-reducing bacteria contributes to ineffectiveness souring control by nitrate injection

Nitrate injection has been widely used to minimize the production of biological hydrogen sulfide in oil and gas field industry, by controlling the growth of sulfate-reducing bacteria (SRB) chemically and biologically. This study aimed to investigate the changes in the bacterial community in response to nitrate addition used to control biological souring. Specifically, we examined the effect of nitrate addition in an artificial souring experiment, using diluted crude oil as substrate and electron donor. Desulfotignum sp. was the predominant SRB under all conditions tested. Addition of nitrate at the beginning (N0) repressed the growth of SRB, as revealed by chemical and bacterial community analysis, concomitant with significant growth of the nitrate-reducing bacteria (NRB) Thalassospira sp. Nitrate addition after SRB growth (at day 28, N28) successfully remediated the sulfide produced by SRB, but no significant reduction in sulfate was observed subsequently; moreover, the bacterial communities before and after nitrate addition remained identical. Isolation of Desulfotignum YB01 (D. YB01) proved the resistance of this predominant SRB in high nitrate environment. Simultaneous reduction of sulfate and nitrate by D. YB01 was also observed in this study. Therefore, the phenomenon in the N28 experiment might be the result of the role of Arcobacter sp. which are nitrate-reducing sulfide-oxidizing bacteria, and/or the ability of Desulfotignum sp. to reduce nitrate and/or nitrite as a stress response. Thus, SRB might persist after nitrate addition, potentially causing subsequent SRB outbreaks.

Mechanistic aspects of microbially influenced corrosion of X52 pipeline steel in a thin layer of soil solution containing sulphate-reducing bacteria under various gassing conditions

Corrosion of X52 pipeline steel under a thin layer of soil solution containing sulphate-reducing bacteria (SRB) was investigated under various gassing conditions (i.e., air, nitrogen and 5% CO2). In the sterile solution, the steel suffers from the highest corrosion rate upon air-purging. In the presence of SRB, the steel corrosion is affected by the aeration of the solution layer. While the oxygen inhibits the bacterial growth, the SRB growth and biofilm formation are enhanced in the presence of CO2, accelerating the steel corrosion. There is a synergism of SRB and CO2 on the steel corrosion.

Short Communication: The potential of Sulfate Reducing Bacteria of ex-coal mine sediment pond as sulfate reducing agents of acid land in Samarinda, Indonesia

Kusumawati E, Sudrajat, Purnamasari I, Panggabean BC, Apriyanti M. 2017. Short Communication: The potential of Sulfate Reducing Bacteria of ex-coal mine sediment pond as sulfate reducing agents of acid land in Samarinda, Indonesia. Bonorowo Wetlands 1: 79-82. The study aims to determine the effect of pH medium on the growth of sulfate reducing bacteria taken from the e-coal mine sediment pond and to determine its potential as a reducing sulphate agent of acid ex-coal mine land in Samarinda, East Kalimantan, Indonesia. Six SRB isolated from ex-coal mine sediment pond in Samarinda were used in this study. The SRB potency test in reducing sulfate was conducted by growing the SRB on Postgate liquid medium at different pH of 2, 4 and 6 by the addition of acid soils on each treatment. The results showed that sulfate reducing bacteria isolated from ex-coal mine sediment pond in Samarinda,, i.e., sp.1 (Desulfococcus sp.), sp.2 (Desulfotomaculum sp.), sp.3 (Desulfobacter sp.), sp.4 (Desulfobulbus sp. ), sp.5 (Desulfobacterium sp.) and sp.6 (Desulfotomaculum sp.) had potential as sulfate reducing agent of acid land. The efficiency of sulfate reduction was 89%, 91% and 91% in the pH of 2, 4 and 6, respectively. This indicated that the highest number of sulfate reduction is in the medium with pH 4 and pH 6. In addition, sp.5 (Desulfobacterium sp.) growing on medium at pH 4 had the best sulfate reduction efficiency (93%) compared with other SRB isolates.

Initial stage of the biofilm formation on the NiTi and Ti6Al4V surface by the sulphur-oxidizing bacteria and sulphate-reducing bacteria

The susceptibility to the fouling of the NiTi and Ti6Al4V alloys due to the adhesion of microorganisms and the biofilm formation is very significant, especially in the context of an inflammatory state induced by implants contaminated by bacteria, and the implants corrosion stimulated by bacteria. The aim of this work was to examine the differences between the sulphur-oxidizing bacteria (SOB) and sulphate-reducing bacteria (SRB) strains in their affinity for NiTi and Ti6Al4V alloys. The biofilms formed on alloy surfaces by the cells of five bacterial strains (aerobic SOB Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans, and anaerobic SRB Desulfovibrio desulfuricans—3 strains) were studied using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The protein concentrations in liquid media have also been analyzed. The results indicate that both alloys tested may be colonized by SOB and SRB strains. In the initial stage of the biofilm formation, the higher affinity of SRB to both the alloys has been documented. However, the SOB strains have indicated the higher (although differentiated) adaptability to changing environment as compared with SRB. Stimulation of the SRB growth on the alloys surface was observed during incubation in the liquid culture media supplemented with artificial saliva, especially of lower pH (imitated conditions under the inflammatory state, for example in the periodontitis course). The results point to the possible threat to the human health resulting from the contamination of the titanium implant alloys surface by the SOB (A. thiooxidans and A. ferrooxidans) and SRB (D. desulfuricans).Graphical abstract

Mechanism of microbiologically influenced corrosion of X52 pipeline steel in a wet soil containing sulfate-reduced bacteria

In this work, corrosion of an X52 pipeline steel was investigated in a field-collected soil containing sulfate-reducing bacteria (SRB) by weight-loss testing, bio-testing, electrochemical measurements and surface analysis techniques. The SRB can grow well in the soil and attach to the steel surface, leading to microbiologically influenced corrosion (MIC) of the steel. The SRB are able to accelerate corrosion of the steel remarkably. Compared to the corrosion rate of 0.0473mm/y in SRB-absent soil, the corrosion rate of the steel is up to 0.282mm/y when SRB are contained in the soil. An increase of the water content in the soil favors the growth of SRB, increasing the thickness of the biofilm formed on the steel surface and accelerating the steel MIC. At individual water contents, the presence of CO2 in the soil accelerates the steel MIC induced by SRB, which is associated with the increasing amount of SRB cells in CO2-containing soil. The SRB also result in localized corrosion of the steel. This is associated with the unique soil corrosion environment, where the sessile SRB cells and corrosion products do not move freely. The porous structure of the surface film contributes to the initiation of localized corrosion.

Control of Microbiologically Influenced Corrosion using Ultraviolet Radiation

Baram Delta Operation had been producing oil and gas since 1960’s and serious pipelines failure was reported in the year of 2005. The final investigation has concluded that one of the species of bacteria that has been identified to cause microbiologically influenced corrosion, specifically known as sulfate reducing bacteria (SRB) was found to be one of the potential contributing factors to the incidents. This work investigates the potential use of ultraviolet (UV) radiation to inhibit the SRB consortium that was cultivated from the crude oil in one of the main trunk lines at Baram Delta Operation, Sarawak, Malaysia. The impact of UV exposure to bio-corrosion conditions on carbon steel coupon in certain samples for 28 days was discussed in this study. The samples were exposed to UV radiation based on variations of parameters, namely: time of UV exposure; and power of UV lamp. The significant changes on the amount of turbidity reading and metal loss of the steel coupon were recorded before and after experiment. The results showed that SRB growth has reduced rapidly for almost 90% after the UV exposure for both parameters as compared to the abiotic samples. Metal loss values were also decreased in certain exposure condition. Additionally, field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS) was performed to observe the biofilm layer formed on the metal surface after its exposure to SRB. The evidence suggested that the efficiency of UV treatment against SRB growth could be influenced by the particular factors studied.

Controlled extracellular biosynthesis of ZnS quantum dots by sulphate reduction bacteria in the presence of hydroxypropyl starch as a mediator

Metal sulphide quantum dots (QDs) have broad applications. Sulphate-reducing bacteria (SRB) have been recognized as synthesizers of metal sulphides, with the characteristics of a high-production efficiency and easy product harvest. However, SRB are incapable of synthesizing metal sulphide QDs. In the present study, cheap hydroxypropyl starch (HPS) was used to assist SRB in manufacturing the ZnS QDs. The results exhibited that the HPS accelerated the growth of SRB and reduction of SO4 2+ into S2−, while it blocked the precipitation between S2− and Zn2+ to control the nucleation and growth of ZnS, resulting in the formation of ZnS QDs. When the HPS concentration increased from 0.2 to 1.6 g/L, the average crystal size (ACS) of ZnS QDs dropped from 5.95 to 3.34 nm, demonstrating the controlled biosynthesis of ZnS QDs. The ZnS QDs were coated or adhered to by both HPS and proteins, which played an important role in the controlled biosynthesis of ZnS QDs. The remarkable blue shift of the narrow UV absorption peak was due to the quantum confinement effect. The sequential variation in the colour of the photoluminescence spectrum (PL) from red to yellow suggested a tunable PL of the ZnS QDs. The current work demonstrated that SRB can fabricate the formation of ZnS QDs with a controlled size and tunable PL at a high-production rate of approximately 8.7 g/(L × week) through the simple mediation of HPS, with the yield being 7.46 times the highest yield in previously reported studies. The current work is of great importance to the commercialization of the biosynthesis of ZnS QDs.

Characterization of sulfate reducing bacteria isolated from urban soil

Sulfate reducing bacteria (SRB) was isolated from urban soil and applied for the remediation of heavy metals pollution from acid mine drainage. The morphology and physiological characteristics (e.g. pH and heavy metals tolerance) of SRB was investigated. The SRB was gram-negative bacteria, long rod with slight curve, cell size 0.5× (1.5-2.0) μm. The pH of medium had significant effect on SRB growth and the efficiency of sulfate reduction, and it showed that the suitable pH range was 5-9 and SRB could not survive at pH less than 4. The maximum tolerance of Fe (II), Zn (II), Cd (II), and Cu (II) under acidic condition (pH 5.0) was about 600 mg/L, 150 mg/L, 25 mg/L and 25 mg/L, respectively. The result indicated that SRB isolated in this study could be used for the bioremediation of acid mine drainage (pH>4) within the heavy metals concentrations tolerance.

Growth Inhibition of Sulfate-Reducing Bacteria in Produced Water from the Petroleum Industry Using Essential Oils.

Strategies for the control of sulfate-reducing bacteria (SRB) in the oil industry involve the use of high concentrations of biocides, but these may induce bacterial resistance and/or be harmful to public health and the environment. Essential oils (EO) produced by plants inhibit the growth of different microorganisms and are a possible alternative for controlling SRB. We aimed to characterize the bacterial community of produced water obtained from a Brazilian petroleum facility using molecular methods, as well as to evaluate the antimicrobial activity of EO from different plants and their major components against Desulfovibrio alaskensis NCIMB 13491 and against SRB growth directly in the produced water. Denaturing gradient gel electrophoresis revealed the presence of the genera Pelobacter and Marinobacterium, Geotoga petraea, and the SRB Desulfoplanes formicivorans in our produced water samples. Sequencing of dsrA insert-containing clones confirmed the presence of sequences related to D. formicivorans. EO obtained from Citrus aurantifolia, Lippia alba LA44 and Cymbopogon citratus, as well as citral, linalool, eugenol and geraniol, greatly inhibited (minimum inhibitory concentration (MIC) = 78 µg/mL) the growth of D. alaskensis in a liquid medium. The same MIC was obtained directly in the produced water with EO from L. alba LA44 (containing 82% citral) and with pure citral. These findings may help to control detrimental bacteria in the oil industry.

Stress Corrosion Cracking Behavior of X80 Pipeline Steel in Acid Soil Environment with SRB

Self-designed experimental device was adopted to ensure the normal growth of sulphate-reducing bacteria (SRB) in sterile simulated Yingtan soil solution. Stress corrosion cracking (SCC) behavior of X80 pipeline steel in simulated acid soil environment was investigated by electrochemical impedance spectroscopy, slow strain rate test, and scanning electron microscope. Results show that the presence of SRB could promote stress corrosion cracking susceptibility. In a growth cycle, polarization resistance first presents a decrease and subsequently an increase, which is inversely proportional to the quantities of SRB. At 8 days of growth, SRB reach their largest quantity of 1.42 × 103 cells/g. The corrosion behavior is most serious at this time point, and the SCC mechanism is hydrogen embrittlement. In other SRB growth stages, the SCC mechanism of X80 steel is anodic dissolution. With the increasing SRB quantities, X80 steel is largely prone to SCC behavior, and the effect of hydrogen is considerably obvious.

Potential of Palm Oill Mill Effluent (POME) as Growth Medium for Sulfate-Reducing Bacterium in Microbial Fuel Cell

This study is conducted to determine the potential of palm oil mill effluent (POME) as medium for growing sulfate-reducing bacterium (SRB) in anaerobic condition for microbial fuel cell application. In this study, effect of different percentage (20-70%) of POME was investigated on the growing cell of SRB. The bacterium was propagated in 400 ml Schott bottle at 35°C, pH 7.8 purged with nitrogen gas. The optical density during the growth of SRB was measured using UV-Vis Spectrophotometer at 600nm wavelength and the weight of dry cell was calculated to determine the specific growth rate. The highest specific growth rate (0.0636/hr) of SRB was achieved using 20% of POME compared to the media without POME (0.0464/hr). The increment is around 37%. The output voltage with 20% of POME is 0.23V which is 55.5% improvement compared to the medium without POME, thus proved that POME has the potential as growth medium for SRB in anaerobic condition for microbial fuel cell application. Booster circuit is possible to be used to boost the output voltage of the MFC until 3V which is more useful for electronic applications.

Effects of sulfate on heavy metal release from iron corrosion scales in drinking water distribution system

Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R2 > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe3O4) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe3O4. The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe6(OH)12CO3 content under higher sulfate concentrations.

Perchlorate, nitrate, and sulfate reduction in hydrogen-based membrane biofilm reactor: Model-based evaluation

A biofilm model was developed to evaluate the key mechanisms including microbially-mediated ClO4−, NO3−, and SO42− reduction in the H2-based membrane biofilm reactor (MBfR). Sensitivity analysis indicated that the maximum growth rate of H2-based denitrification (μ1) and maximum growth rate of H2-based SO42− reduction (μ3) could be reliably estimated by fitting the model predictions to the experimental measurements. The model was first calibrated using the experimental data of a single-stage H2-based MBfR fed with different combinations of ClO4−, NO3−, and/or SO42− together with a constant dissolved oxygen (DO) concentration at three operating stages. μ1 and μ3 were determined at 0.133h−1 and 0.0062h−1, respectively, with a good level of identifiability. The model and the parameter values were further validated based on the experimental data of a two-stage H2-based MBfR system fed with ClO4−, NO3−, SO42−, and DO simultaneously but at different feeding rates during two running phases. The validated model was then applied to evaluate the quantitative and systematic effects of key operating conditions on the reduction of ClO4−, NO3−, and SO42− as well as the steady-state microbial structure in the biofilm of a single-stage H2-based MBfR. The results showed that i) a higher influent ClO4− concentration led to a higher ClO4− removal efficiency, compensated by a slightly decreasing SO42− removal; ii) the H2 loading should be properly managed at certain critical level to maximize the ClO4− and NO3− removal while limiting the growth of sulfate reducing bacteria which would occur in the case of excessive H2 supply; and iii) a moderate hydraulic retention time and a relatively thin biofilm were required to maintain high-level removal of ClO4− and NO3− but restrict the SO42− reduction.

REGULATION OF NUMBER OF SULFATE-REDUCING BACTERIA IN ACTIVATED SLUDGE UNDER THE OZONATION IN LOW DOSES

Aim. Excessive growth of sulfate reducing bacteria in aeration tanks indicates the prevalence of anaerobic conditions in activated sludge, as a result of which the processes of aerobic oxidation of organic matter of wastewater deteriorate and the quality of treated water in general decreases. Until recently, ozone was used in water treatment as the active oxidizer, only to disinfect sewage. However, the hot interest is ozonation in low doses, which does not lead to total extinction in microbiological cenosis, but only corrects the number of bacteria and microbiological processes in sludge. Methods. In this research were applied classical microbiological cultural methods and enumeration of sulfate-reducing bacteria under most probable number method. Dehydrogenase activity ware measured by Gunter technique. Results. This paper discusses about impact of ozonation in low doses to quantity of sulfure reducing bacteria in activated sludge. Describes possible corrective actions aimed at regulating the processes of sulfate reduction in activated sludge. Conclusions. The effect of ozonation in low doses on sulfate-reducing bacteria in active sludge has been established. The increase of dehydrogenase activity with the use of ozonation has been demonstrated.

Experimental Study on the Influence of Sulfate Reducing Bacteria on the Metallic Corrosion Behavior under Disbonded Coating

A rectangle disbonded coating simulation device was used to research the effect of sulfate reducing bacteria (SRB) on the metallic corrosion behavior under disbonded coating by the electrochemical method. The results showed that the metal self-corrosion potential at the same test point had little change in the initial experiment stage, whether the solution was without or with SRB. The potential amplitude in the solution with SRB was larger than that without SRB in the later corrosion period. The corrosion current density of the metal at the same test point increased gradually over time in the solution with or without SRB, and SRB could accelerate the corrosion of the metal in the disbonded crevice. The metal self-corrosion potential in the crevice had little change in the SRB solution environment after adding the fungicide, but the corrosion current density decreased significantly. That meant the growth and reproduction of SRB were inhibited after adding the fungicide, so the metal corrosion rate slowed down. Among the three kinds of solution environment, increasing the coating disbonded thickness could accelerate the corrosion of the metal in the crevice, and it was the largest in the solution with SRB.

Growth of magnetotactic sulfate-reducing bacteria in oxygen concentration gradient medium.

Although dissimilatory sulfate-reducing bacteria (SRB) are generally described as strictly anaerobic organisms with regard to growth, several reports have shown that some SRB, particularly Desulfovibrio species, are quite resistant to O2 . For example, SRB remain viable in many aerobic environments while some even reduce O2 to H2 O. However, reproducible aerobic growth of SRB has not been unequivocally documented. Desulfovibrio magneticus is a SRB that is also a magnetotactic bacterium (MTB). MTB biomineralize magnetosomes which are intracellular, membrane-bounded, magnetic iron mineral crystals. The ability of D. magneticus to grow aerobically in several different media under air where an O2 concentration gradient formed, or under O2 -free N2 gas was tested. Under air, cells grew as a microaerophilic band of cells at the oxic-anoxic interface in media lacking sulfate. These results show that D. magneticus is capable of aerobic growth with O2 as a terminal electron acceptor. This is the first report of consistent, reproducible aerobic growth of SRB. This finding is critical in determining important ecological roles SRB play in the environment. Interestingly, the crystal structure of the magnetite crystals of D. magneticus grown under microaerobic conditions showed significant differences compared with those produced anaerobically providing more evidence that environmental parameters influence magnetosome formation.

Estimating the Abundance of Endospores of Sulfate-Reducing Bacteria in Environmental Samples by Inducing Germination and Exponential Growth

ABSTRACTIt is a challenge to quantitatively distinguish active from dormant microbial populations in environmental samples. Here we present an approach for estimating the abundance of dormant sulfate-reducing bacteria (SRB), present as viable endospores in environmental samples. This is achieved by inducing endospores to germinate and grow exponentially. We demonstrate this approach for thermophilic SRB in temperate sediment from Aarhus Bay, Denmark. The approach is based on measuring bulk sulfate reduction rates (SRRs) in pasteurized sediment and calculating associated cell-specific SRRs based on average values for SRB growth yield and cell size known from exponentially growing pure cultures. The method presented is a faster bioassay than most probable number enumerations and has the potential to distinguish between slow- and fast-growing SRB populations in the same sample. This bioassay is attractive given the challenges posed by endospores with respect to cell permeabilization and lysis, which are prerequisite in quantitative microscopy- and nucleic acid extraction-based strategies. These molecular approaches additionally rely on designing target-appropriate oligonucleotide probes, whereas the method presented here considers the trait of interest more broadly. This strategy thus presents a useful complement to other methods in ecological investigations of microbial biogeography and for specific industrial applications such as reservoir souring and corrosion risk assessments in the oil and gas sector.

Efficacy and role of inulin in mitigation of enteric sulfur‐containing odor in pigs

The efficacy and role of inulin in the mitigation of enteric sulfur-containing odor gases hydrogen sulfide (H2 S) and methyl mercaptan (CH3 SH) in pigs were examined in this study. Twelve Duroc × Landrace × Yorkshire male finisher pigs (60.7 ± 1.9 kg), housed individually in open-circuit respiration chambers, were randomly assigned to two dietary groups, namely basal diet (control) and basal diet supplemented with 1% (w/w) inulin. At the end of the 45 day experiment, pigs were slaughtered and volatile fatty acid (VFA) concentration, sulfate radical (SO42- ) concentration, population of sulfate-reducing bacteria (SRB) and expression of methionine gamma-lyase (MGL) gene were determined in contents from the caecum, colon (two segments) and rectum. Metabonomic analysis was used to compare differences in biochemical composition, and the Illumina MiSeq procedure to investigate differences in bacterial components, in the different parts of the large intestine between inulin-supplemented and inulin-free (control) groups. Inulin decreased (P < 0.05) the average daily enteric H2 S and CH3 SH production by 12.4 and 12.1% respectively. The concentrations of acetate, propionate and butyrate in the large intestinal content were significantly increased (P < 0.05) with inulin treatment, whereas valerate concentration and MGL mRNA expression decreased (P < 0.05). The growth of Lactobacillus, Butyrivibrio, Pseudobutyrivibrio, Bifidobacterium and Clostridium butyricum was stimulated, while that of Desulfovibrio, the dominant SRB, was inhibited, and there was an accumulation of SO42- in the large intestinal content of the inulin-supplemented pigs, suggesting that inulin mitigates H2 S generation from the SO42- reduction pathway by reducing the growth of SRB. The results showed that inulin mitigates CH3 SH generation via three methionine degradation metabolic pathways and H2 S generation from two cysteine degradation metabolic pathways, thus resulting in increased synthesis of these two sulfur-containing amino acids in the pig large intestine. © 2016 Society of Chemical Industry.