Anoxygenic phototroph of the Chloroflexota uses a type I reaction centre.

Scientific exploration of phototrophic bacteria over nearly 200 years has revealed large phylogenetic gaps between known phototrophic groups that limit understanding of how phototrophy evolved and diversified1,2. Here, through Boreal Shield lake water incubations, we cultivated an anoxygenic phototrophic bacterium from a previously unknown order within the Chloroflexota phylum that represents a highly novel transition form in the evolution of photosynthesis. Unlike all other known phototrophs, this bacterium uses a type I reaction centre (RCI) for light energy conversion yet belongs to the same bacterial phylum as organisms that use a type II reaction centre (RCII) for phototrophy. Using physiological, phylogenomic and environmental metatranscriptomic data, we demonstrate active RCI-utilizing metabolism by the strain alongside usage of chlorosomes3 and bacteriochlorophylls4 related to those of RCII-utilizing Chloroflexota members. Despite using different reaction centres, our phylogenomic data provide strong evidence that RCI-utilizing and RCII-utilizing Chloroflexia members inherited phototrophy from a most recent common phototrophic ancestor. The Chloroflexota phylum preserves an evolutionary record of the use of contrasting phototrophic modes among genetically related bacteria, giving new context for exploring the diversification of phototrophy on Earth.

Impact of different timing of consuming sweet snack on postprandial glucose excursions in healthy women.

AIMS: Our aim was to evaluate the acute effect of eating sweet snacks at different times of day on glycaemic parameters in young women without diabetes. METHODS: In this randomized controlled three-treatment crossover study, 17 women [(means ± SD) age: 21.2 ± 0.8 years, BMI: 20.7 ± 2.5 kg/m2, HbA1c: 36 ± 2 mmol/mol (5.1 ± 0.2%)] wore flash (continuous) glucose monitoring systems for 7 days. Each participant consumed identical test meals on days 4, 5 and 6, but consumed sweet snacks (baked cake: 498 kcal; 53.6 g of carbohydrate, 8.0 g of protein, 28.0 g of fat) at 12:30 (post-lunch), 15:30 (mid-afternoon) and 19:30 (post-dinner), respectively, on each of those days. Daily glycaemic parameters on those 3 days of snacking at different times of day were compared within-participant. RESULTS: The mean amplitude of glycaemic excursions (3.54 ± 0.32 vs. 2.73 ± 0.20 mmol/L; P < 0.05), standard deviation of glucose (1.20 ± 0.11 vs. 0.92 ± 0.07 mmol/L; P < 0.05), incremental area under the curve (IAUC) for glucose at 12:00-07:00 (986 ± 89 vs. 716 ± 88 mmol/L × min; P < 0.05) and IAUC at 07:00-10:00 the next day (141 ± 17 vs. 104 ± 12 mmol/L × min; P < 0.05) when the snack was eaten post-dinner were all significantly higher than with mid-afternoon snacking. CONCLUSION: Eating sweet snacks post-dinner should be avoided because it worsens glucose excursions as well as postprandial glucose levels after both dinner and the following day's breakfast in young healthy (non-diabetic) women.

Consuming snacks mid-afternoon compared with just after lunch improves mean amplitude of glycaemic excursions in patients with type 2 diabetes: A randomized crossover clinical trial.

AIMS: Our aim was to explore the acute effects of consuming snacks at different times on glucose excursions in patients with type 2 diabetes (T2D). METHODS: Seventeen patients with T2D [means±SD: age 67.4±9.4-years; BMI 23.5±3.1kg/m2; HbA1c 55±6mmol/mol (7.2±1.0%)] were randomly assigned in this crossover study. Each participant wore a continuous glucose monitoring device for 4 days and consumed identical test meals on the second and third days, comprising breakfast at 0700h, lunch at 1200h and dinner at 1900h. Half the participants consumed 75kcal biscuits at 1230h (just after lunch) on the second day and at 1530h (mid-afternoon) on the third day, while the other half consumed snacks at the same times, but vice versa. Each patient's glucose parameters were compared against baseline for the 2days of snacking at different times of day. RESULTS: Consuming snacks in the mid-afternoon led to significantly lower mean amplitudes of glycaemic excursions (mean±SEM: 5.19±0.48 vs. 6.90±0.69mmol/L, P<0.01; standard deviation: 1.75±0.17 vs. 2.16±0.21mmol/L, P<0.01) and incremental areas under the curve for glucose after dinner (479±76 vs. 663±104mmol/L per min, P<0.01) compared with snacking just after lunch, whereas mean glucose levels did not differ over the 2days. CONCLUSION: These results suggest that consuming snacks well separated from lunch may be an effective way to suppress postprandial glucose levels and glycaemic excursions.

Impact of respiratory function on the progression from metabolically healthy non-overweight to metabolically abnormal phenotype.

BACKGROUND AND AIMS: Recent studies identified that metabolically abnormal non-overweight phenotype is a risk factor for cardiovascular diseases. However, only little is known about risk factors for the progression from metabolically healthy non-overweight (MHNO) to metabolically abnormal phenotype. In this study, we investigated the impact of respiratory function on the progression from MHNO to metabolically abnormal phenotype. METHODS AND RESULTS: In this retrospective cohort study, 8949 (3872 men and 5077 women) individuals with MHNO, who participated in a health-checkup program from 2004 to 2015, were enrolled. Four metabolic factors (high-normal blood pressure or hypertension, impaired fasting glucose or diabetes, hypertriglyceridemia, and low HDL cholesterol concentration) were used to define metabolically healthy (less than two factors) or metabolically abnormal (two or more factors) phenotypes. Respiratory function was measured by spirometry. Over a median 4.0 years of follow-up, 927 participants progressed to metabolically abnormal phenotype. The percentage of FVC for predicted values (HR 0.98, 95% CI 0.93-1.03, p = 0.418) was not associated with the progression to metabolically abnormal phenotype after adjusting for covariates, including age, sex, alcohol consumption, exercise, smoking status, and body mass index, whereas the percentage of FEV1 for predicted values (%FEV1) (HR 0.87, 95% CI 0.84-0.91, p < 0.001) and the FEV1/FVC ratio (HR 0.86, 95% CI 0.78-0.95, p = 0.004) were associated with the progression to metabolically abnormal phenotype. CONCLUSION: Decrease in respiratory function in terms of %FEV1 and the FEV1/FVC ratio is associated with the progression to metabolically abnormal phenotype in individuals with MHNO.

Surveillance for malaria outbreak on malaria-eliminating islands in Tafea Province, Vanuatu after Tropical Cyclone Pam in 2015.

The risk of malaria outbreak surfaced in Vanuatu after Tropical Cyclone (TC) Pam in March 2015. In June and July 2015 we conducted malariometric surveys on the islands of Tanna, Aneityum, and Erromango in Tafea Province, where malaria elimination had been targeted, to determine if malaria incidence had increased after TC Pam. No Plasmodium infection was detected by microscopy and PCR in 3009 survey participants. Only 6·3% (190/3007) of participants had fever. Spleen rates in children aged ⩽12 years from Aneityum and Tanna were low, at 3·6% (14/387) and 5·3% (27/510), respectively. Overall bed net use was high at 72·8% (2175/2986); however, a significantly higher (P < 0·001) proportion of participants from Aneityum (85·9%, 796/927) reported net use than those from Tanna (67·1%, 751/1119) and Erromango (66·8%, 628/940). A recent decrease in malaria incidence in Tafea Province through comprehensive intervention measures had reduced the indigenous parasite reservoir and limited the latter's potential to spur an outbreak after TC Pam. The path towards malaria elimination in Tafea Province was not adversely affected by TC Pam.

Impact of low-carbohydrate diet on body composition: meta-analysis of randomized controlled studies.

The effect of low-carbohydrate diet (LCD) on body composition, especially fat mass, in obese individuals remains to be elucidated. We performed a meta-analysis to provide quantitative summary estimates of the mean change of body weight (kg) and fat mass (kg) in LCD comparing to those in control diet. Literature searches were performed using EMBASE, MEDLINE and Cochrane Library until Dec 2014. Fourteen randomized controlled studies were included in this meta-analysis. Eight studies including very LCD (50 g carbohydrate or 10% calorie from carbohydrate) and seven studies including mild LCD (about 40% calorie from carbohydrate). Meta-analysis carried out on data of 1416 obese individuals, showed that LCD was associated with decrease in body weight (-0.70 kg [95% CI -1.07/-0.33]) or fat mass (-0.77 kg [-1.55/-0.32]). Subgroup meta-analysis of studies in over 12 months suggested that LCD was not associated with decrease in body weight (-0.44 kg [-0.94/0.07]), but LCD was associated with decrease in fat mass (-0.57 kg [-1.05/-0.09]). In addition, very LCD was associated with decrease in fat mass (-0.97 kg [-1.50/-0.44]), but mild LCD was not associated with decrease in fat mass (-0.43 kg [-1.15/0.33]). LCD, especially very LCD, might be effective for decrease in fat mass in obese individuals. © 2016 World Obesity.

Geophysics. Migrating tremor off southern Kyushu as evidence for slow slip of a shallow subduction interface.

Detection of shallow slow earthquakes offers insight into the near-trench part of the subduction interface, an important region in the development of great earthquake ruptures and tsunami generation. Ocean-bottom monitoring of offshore seismicity off southern Kyushu, Japan, recorded a complete episode of low-frequency tremor, lasting for 1 month, that was associated with very-low-frequency earthquake (VLFE) activity in the shallow plate interface. The shallow tremor episode exhibited two migration modes reminiscent of deep tremor down-dip of the seismogenic zone in some other subduction zones: a large-scale slower propagation mode and a rapid reversal mode. These similarities in migration properties and the association with VLFEs strongly suggest that both the shallow and deep tremor and VLFE may be triggered by the migration of episodic slow slip events.

Heart rate-corrected QT interval is a novel risk marker for the progression of albuminuria in people with Type 2 diabetes.

AIMS: A close association between heart rate-corrected QT interval (QTc) and albuminuria in people with Type 2 diabetes has been reported in cross sectional studies. The aim of this study was to evaluate the relationship between QTc and change in urine albumin excretion (UAE) or progression of albuminuria in people with Type 2 diabetes. METHODS: We measured QTc in 251 consecutive people at baseline. We performed a 5-year follow-up cohort study to assess the relationship between QTc and change in UAE, defined as an increase of UAE/follow-up duration (year), or progression of albuminuria, defined as an increase in the category of diabetic nephropathy. RESULTS: During follow-up, 23 of 151 people with normoalbuminuria and 13 of 73 people with microalbuminuria at baseline had progression of albuminuria. Multiple regression analysis demonstrated that QTc was independently associated with change in UAE (ß = 0.176, P = 0.0104). Logistic regression analyses showed that QTc was a risk marker for progression of albuminuria [odds ratio per 0.01-s increase in QTc 1.35, 95% confidence interval (CI) 1.11-1.66, P = 0.0024] after adjusting for confounders. According to the receiver operator characteristic (ROC) analysis, the optimal cut-off point of QTc for progression of albuminuria was 0.418 s [area under the ROC curve 0.75 (95% CI 0.66-0.82), sensitivity = 0.86, specificity = 0.56, P < 0.0001]. CONCLUSIONS: Heart rate-corrected QT interval could be a novel risk marker for progression of albuminuria in people with Type 2 diabetes.

The influence of season and air temperature on water intake by food groups in a sample of free-living Japanese adults.

BACKGROUND/OBJECTIVES: To examine the influence of season and climate (air temperature and humidity) on water intake by the food group in a sample of free-living Japanese adults. SUBJECTS/METHODS: Four-nonconsecutive-day, semi-weighed dietary records were collected from each of the four seasons in a single 12-month period (16 days in total). The influence of season and climate on individual water intake by the food group was analyzed using a mixed linear model. Participants were 242 healthy adults (121 women aged 30-69 years and 121 men aged 30-76 years) from four areas in Japan. RESULTS: For women and men together, the mean total water intake was 2230 g/day (highest in summer: 2331 g/day; lowest in winter: 2134 g/day). Fifty-one percent of water was derived from foods and the rest from beverages. In a mixed linear model adjusted for sex, age and body mass index, intake of water from foods decreased by 3.1 g/day and that from beverages increased by 8.4 g/day, with an increase in the mean outdoor air temperature on the survey day of 1 °C (both P < 0.0001). The influence of humidity was nonsignificant. CONCLUSIONS: In contrast to previous findings in Western countries, half of water intake in Japanese adults was derived from foods. Water intake from beverages was positively associated with air temperature, whereas that from foods was inversely associated with air temperature.

Alterations in time intervals of ductus venosus and atrioventricular flow velocity waveforms in growth-restricted fetuses.

OBJECTIVE: To investigate time intervals of the ductus venosus (DV) flow velocity waveform (FVW) and those of the cardiac cycle that correspond with each DV-FVW component in fetuses with intrauterine growth restriction (IUGR) due to placental insufficiency. METHODS: Women with a pregnancy complicated by IUGR were recruited into the study, as was a normal control group. Time intervals for systolic (S) and diastolic (D) components were measured in DV-FVW as follows: S(DV), from the nadir of the a-wave during atrial contraction to the nadir between the S-wave and D-wave; D(DV), from the nadir between S-wave and D-wave to the nadir of the a-wave. Regarding cardiac cycles, the following variables were measured from ventricular inflow through the tricuspid valve (TV) and mitral valve (MV): S(TV) and S(MV), from the second peak of ventricular inflow caused by atrial contraction (A-wave) to the opening of the atrioventricular valve; D(TV) and D(MV), from the opening of the atrioventricular valve to the peak of the A-wave. In the IUGR group, only the last examination performed within 1 week of delivery was used for analysis. All variables were analyzed statistically using Z-scores. RESULTS: Data were obtained from 249 normal fetuses and 26 fetuses with IUGR. Compared to normal fetuses, S(DV) showed a significant decrease (P < 0.001), while D(DV) showed a significant increase (P < 0.001) in the IUGR group. Regarding cardiac cycles, S(TV) and S(MV) showed significant decreases (P = 0.014 and P < 0.001, respectively) and D(TV) and D(MV) showed significant increases (P = 0.008 and P = 0.002, respectively) in fetuses with IUGR. CONCLUSION: Time-interval alterations of DV-FVW in growth-restricted fetuses reflect the hemodynamic events caused by placental insufficiency.

Time-interval analysis of ductus venosus flow velocity waveforms in twin-to-twin transfusion syndrome treated with laser surgery.

OBJECTIVES: To investigate time-interval variables of ductus venosus (DV) flow velocity waveforms (FVWs) in twin-to-twin transfusion syndrome (TTTS), comparing the results with reference ranges from normal singleton fetuses. The impact of laser surgery and the effect of prognostic factors were also evaluated. METHODS: In 107 TTTS cases, DV-FVWs of both recipients and donors were recorded 1 day before and 2 days after laser therapy. Time intervals for systolic (S) and early diastolic (D) peaks were analyzed retrospectively with regard to acceleration time (acc-S and acc-D for S and D, respectively) and deceleration time (dec-S and dec-D for S and D, respectively). For each variable, Z-scores were calculated with respect to previously reported normal reference ranges. RESULTS: Z-scores for all variables showed statistically significant differences from those observed previously in normal fetuses, with the exception of dec-S of donors. The most striking differences were observed in longer dec-S of recipients (P < 0.001) and longer dec-D of donors (P < 0.001). Laser therapy showed significant impact on dec-S and acc-D in recipients and on all variables in donors. Regarding the short-term prognosis, acc-S and dec-S showed significant differences for the prediction of intrauterine fetal demise in donors (P = 0.009 and P = 0.011, respectively). CONCLUSION: This study demonstrates that time-interval variables of DV-FVWs may differentiate the characteristic hemodynamic changes caused by unbalanced blood volume between recipients and donors.

Low serum potassium concentration is a predictor of chronic kidney disease.

AIMS: The aim of this study was to examine whether low serum potassium concentration could be a predictor of chronic kidney disease (CKD) in a community-based cohort. MATERIALS AND METHODS: We enrolled 1001 subjects, median period of 5.7 years, and evaluated the risk factors for CKD, defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m(2), and assessed whether low serum potassium concentration could predict CKD. RESULTS: Compared with the subjects without development of CKD, age, body mass index, fasting plasma glucose, uric acid (UA), creatinine and serum sodium concentration were higher, and serum potassium concentration was lower in subjects with development of CKD. Univariate Cox regression analyses demonstrated that age, body mass index, fasting plasma glucose, UA, creatinine, serum sodium concentration and serum potassium concentration were associated with progression of CKD. Multiple Cox regression analysis revealed that age, gender, creatinine and serum potassium concentration were independent predictors of CKD after adjustment for covariates. When serum potassium concentration was below 4.0 mmol/l at baseline, hazard ratio (95% confidence interval) of developing CKD was 2.65 (2.04-3.44; p < 0.0001). CONCLUSIONS: Serum potassium concentration could be a clinically relevant risk factor for the progression of CKD, defined as eGFR < 60 ml/min/1.73 m(2) , in healthy subjects.

Factors affecting variability in home blood pressure in patients with type 2 diabetes: post hoc analysis of a cross-sectional multicenter study.

Recent studies have shown that variability in home blood pressure has an important role in the progression of organ damage. The objective of this study was to investigate the factors that affect variability in home blood pressure in patients with type 2 diabetes. We assessed the relationship between home blood pressure variability, defined as coefficient of variation of mean of triplicate morning and evening blood pressure for 14 consecutive days, and various factors using univariate and multivariate linear regression analyses in 1114 patients with type 2 diabetes. Age (ß=0.149, P<0.001), female sex (ß=0.125, P=0.010), duration of diabetes mellitus (ß=0.103, P=0.005), heart rate (ß=0.136, P<0.001), current smoker (ß=0.118, P=0.005), white-coat hypertension (ß=0.136, P=0.002) and treatment with calcium channel blockers (ß=-0.094, P=0.024) were independently associated with coefficient of variation of morning systolic blood pressure. Our findings implicate that factors that might be intervened such as heart rate, smoking status, use of antihypertensive medication in addition to age, sex and duration of diabetes mellitus are associated with variability in home blood pressure in patients with type 2 diabetes.

Oxidative stress and antibody levels to periodontal bacteria in adults: the Nagasaki Islands study.

OBJECTIVE: Periodontitis is a chronic inflammatory disease of the tissues supporting the teeth and is caused by subgingival plaque. Systemic increases in reactive oxygen species are involved in pathogenesis of periodontitis. This study addressed the relationship between levels of serum oxidative stress and antibodies against putative periodontopathic bacteria and their association with periodontal conditions, in a community-based study. SUBJECTS AND METHODS: Serum samples were measured for reactive oxygen metabolite (ROM) levels and anti-oxidant capacity. The serum levels of immunoglobulin G (IgG) antibodies to Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Aggregatibacter actinomycetemcomitans (Aa), and Eikenella corrodens (Ec) were determined by ELISA. RESULTS: The participants with greater clinical attachment loss had higher serum ROM levels and IgG antibody titers to Pg. Serum ROM levels were positively correlated with antibody titers to Pg, Pi, and Ec. When the participants with greater probing pocket depth and clinical attachment loss were used as the dependent variables, high ROM levels showed a statistically significant associations in multivariate logistic analyses; the adjusted odds ratios were 2.9 (95% confidence interval = 1.0-8.5) and 6.0 (95% confidence interval = 2.0-17.6), respectively. CONCLUSIONS: It was concluded that an increased oxidative stress may be detrimental to periodontitis in Japanese community-dwelling adults.

Chemical composition and in vitro schistosomicidal activity of the essential oil from the flowers of Bidens sulphurea (Asteraceae).

In this study, the chemical composition and the in vitro schistosomicidal properties of the essential oil obtained from Bidens sulphurea flowers (Bs-EO) were investigated. Its major constituents were identified as being 2,6-di-tert-butyl-4-methylphenol (44.98%), germacrene D (33.70%) and ß-caryophyllene (10.23%). Bs-EO at 100 µg mL(-1) caused death of all the adult worms and promoted separation of the couple pairs into individual male and female within 48 h, besides leading to a significant decrease in the motility of the parasites. This oil was also responsible for a remarkable reduction in the number of eggs and the percentage of developed eggs produced by adult worms. These results suggest that the Bs-EO can be considered a promising source for the development of new schistosomicidal agents.

Andropausal symptoms in men with Type 2 diabetes.

AIMS: Serum androgen concentration is reported to be low in patients with Type 2 diabetes. There have been no studies comparing andropausal symptoms such as sleep disturbance, depression, erectile dysfunction and lower urinary tract symptoms simultaneously between men with Type 2 diabetes and subjects without diabetes. METHODS: We compared andropausal symptom scores such as the Pittsburgh Sleep Quality Index, the Self-Rating Depression Scale, the International Index of Erectile Function and the International Prostate Symptom Score in 296 men with Type 2 diabetes and in 267 subjects without diabetes. Furthermore, we evaluated relationships of andropausal symptom scores to various anthropometric factors and compared andropausal symptom scores according to diabetic complications in men with Type 2 diabetes. RESULTS: Andropausal symptom scores such as the Pittsburgh Sleep Quality Index, the Self-Rating Depression Scale, the International Index of Erectile Function and the International Prostate Symptom Score were 4.2 ± 2.6 vs. 5.0 ± 3.3, P<0.01 by unpaired Student's t-test, 34.8 ± 8.2 vs. 38.4 ± 9.3, P<0.0001, 11.5 ± 6.4 vs. 9.9 ± 6.9, P<0.01 and 7.3 ± 6.7 vs. 9.0 ± 7.1, P<0.01 in subjects without diabetes and in patients with diabetes, respectively. The Pittsburgh Sleep Quality Index was higher in patients with neuropathy than without. The Self-Rating Depression Scale was higher in patients with advanced retinopathy. The International Index of Erectile Function was lower in patients with advanced retinopathy and nephropathy. The International Index of Erectile Function was lower and the International Prostate Symptom Score was higher in patients with cardiovascular disease than without. CONCLUSIONS: Our data demonstrated that men with Type 2 diabetes have higher prevalence of andropausal symptoms, especially those with diabetic complications.

Low serum bilirubin concentration in haemodialysis patients with Type 2 diabetes.

AIMS: Previous studies have implicated reduced serum bilirubin concentrations in the development of cardiovascular disease. The aim of this study was to examine whether bilirubin may explain the high incidence of vascular complications in haemodialysis patients with Type 2 diabetes. METHODS: We compared serum bilirubin concentrations, as well as other known aetiological risk factors for cardiovascular disease, in 206 Type 2 diabetes patients on haemodialysis with those in 741 Type 2 diabetes patients not receiving haemodialysis, and evaluated the association between serum bilirubin concentration and cardiovascular disease incidence. RESULTS: Incidences of cardiovascular disease and systolic blood pressure were higher; however, BMI and serum total cholesterol were lower in haemodialysis patients compared with those in patients without haemodialysis. Serum total (0.30 ± 0.10 vs. 0.74 ± 0.26 mg/dl, 0.005 ± 0.002 vs. 0.013 ± 0.004 mmol/l, P < 0.0001) and indirect (0.17 ± 0.08 vs. 0.70 ± 0.23 mg/dl, 0.003 ± 0.001 vs. 0.012 ± 0.004 mmol/l, P < 0.0001) bilirubin were lower in haemodialysis patients compared with those in patients without haemodialysis. Stepwise regression analysis demonstrated that age (ß = 0.109, F = 5.959, P < 0.05), duration of diabetes (ß = -0.112, F = 6.048, P < 0.05), sex (ß = -0.123, F = 8.623, P < 0.05), cardiovascular disease events (ß = -0.099, F = 5.131, P < 0.05) and presence of haemodialysis (ß = -0.626, F = 201.727, P < 0.01) were independent factors for serum total bilirubin. Logistic regression demonstrated that age (OR 1.089, 95% CI 1.044-1.136; P < 0.0001), duration of diabetes (OR 1.029, 95% CI 1.001-1.059; P = 0.0423), body mass index (OR 1.115, 95% CI 1.001-1.242; P = 0.0487), habit of smoking (OR 2.445, 95% CI 1.046-5.716; P = 0.0391) and serum total bilirubin (OR 0.192, 95% CI 0.037-0.989; P = 0.0484) were independent factors for cardiovascular disease events. CONCLUSIONS: Low serum bilirubin concentration could be one of the important factors for the high incidence of cardiovascular disease in Type 2 diabetes patients receiving haemodialysis.

Temperature-dependent differences in community structure of bacteria involved in degradation of petroleum hydrocarbons under sulfate-reducing conditions.

AIM: The aim of this study was to characterize the microbial community involved in anaerobic degradation of petroleum hydrocarbon under low- and moderate-temperature conditions. METHODS AND RESULTS: Sulfate-reducing enrichment cultures growing on crude oil and p-xylene were established at low and moderate temperatures. Bacterial community structures of the cultures were characterized by 16S rRNA gene-based analysis and organisms responsible for degradation of p-xylene were investigated by analysis of the bamA gene, involved in anaerobic degradation of aromatic compounds. The PCR-denaturing gradient gel electrophoresis analysis indicated significant differences in microbial community structures among the cultures, depending on the temperatures of incubation. Difference depending on the temperatures was also observed in the cloning analysis of the bamA gene performed on the p-xylene-degrading enrichment cultures. Majority of clones detected in the culture of moderate temperature were related to Desulfosarcina ovata, whereas more diverse bamA gene sequences were obtained from the culture incubated at low temperature. CONCLUSIONS: Temperature-dependent differences in microbial community were demonstrated by the analyses of two genes. It was suggested that sulfate-reducing bacteria of phylogenetically different groups might be involved in the degradation of petroleum hydrocarbons in different temperature environments. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report of p-xylene-degrading sulfate-reducing enrichment culture at low temperature. The results of the experiments at low temperature were distinctly different from those reported in previous studies performed at moderate temperatures.