PAHs contamination and PAH-degrading bacteria in Xiamen Western Sea

Abstract

Six stations were established in Xiamen Western Sea (24°29’ N, 118°04’ E) on summer and autumn cruises in July and October 2001 to investigate the level of polyaromatic hydrocarbons (PAHs) and PAHs-degrading bacteria in surface water and sediments. PAHs in the surface water were mainly dominated by low molecular weight PAH compounds (2–3 rings PAH) in July and by high molecular weight PAH compounds (4–6 rings PAH) in October. PAHs in sediments were mainly dominated by high molecular weight PAH compounds (4–6). The percentage of 4–6 rings PAH to total PAHs ranged from 80.4 to 94.9% in July and 78.3 to 88.7% in October. No correlation was found between Fluoranthene-degrading bacteria numbers and Fluoranthene concentration among different stations in the surface water on the two cruises, and the same situation occurred between Pyrene-degrading bacteria numbers and pyrene concentration. But the numbers of fluorene- and phenanthrenedegrading bacteria were positively related to the fluorene and phenanthrene concentrations respectively. In the sediments, a significant positive relationship was found between PAH-degrading bacteria and PAHs concentration, except at station 6 on the two cruises.     

Pollution,sources, and ecological-health risks of polycyclic aromatic hydrocarbons in coastal waters along coastline of China

Abstract

This study investigated the distribution, sources, and potential risks of polycyclic aromatic hydrocarbons (PAHs) in coastal waters along over 18,000?km of coastline in China. Concentrations of PAHs in coastal waters ranged from 141.99 to 717.72?ng/L. Approximately 84.38% of sampling sites were determined at moderate PAH pollution level. PAHs in coastal waters at most of sampling sites mainly originated from combustion based on characteristic ratios of PAHs. Ecological risks posed by PAHs in coastal waters were evaluated as high level at 59.38% of sampling sites and moderate level at 40.63% of sampling sites although toxic equivalent quotients of PAHs only ranged from 2.86 to 126.52?ng/L benzo[a]pyrene that was not detected at all sampling sites. Maximal cancer risk/hazard quotient of total PAHs in coastal waters for adults and children reached 6.34?×?10^?4/5.85?×?10^?2 and 2.25?×?10^?3/7.72?×?10^?2, respectively. PAHs exerted high cancer risks for children at 31.25% of sampling sites. Health risks posed by PAHs in coastal waters of this study were higher than those of Japan, Belgium, Greece, Italy, Spain, USA, and Australia, but much lower than those of Singapore, Iran, Brazil, and Egypt. These findings indicate that PAH pollution has become a crucial stress affecting the sustainable development of coastal regions.     

Polycyclic aromatic hydrocarbons in traffic soil and Pinus needles of Beijing,China

Abstract

This study was conducted to examine the impact of vehicular traffic on the contamination status of urban traffic sites in Beijing with respect to polycyclic aromatic hydrocarbons (PAHs). The soil and Pinus pinea needle samples were collected at 12 sites on Three Ring Road in Beijing, China, from July 2009 to March 2010. Total PAH concentrations at traffic sites ranged from 113.86 to 2226.24 ng g^?1 with an average value of 658.71 ± 742.41 ng g^?1 in soil samples and 112.03 to 2016.80ng g^?1 with an average value of 680.29 ± 485.61 ng g^?1 in needle samples. The PAH pattern was dominated by two- and three-ring PAHs (contributing >80% to the total PAHs) at all the 12 traffic sites. Seasonal variations of PAHs compounds indicated the PAHs concentrations in autumn and winter were higher than those in spring and summer due to temperature effects. This work indicates that the low ring PAHs were the major profile at the roadside of a busy street with heavy traffic in Beijing.     

Polycyclic Aromatic Hydrocarbons in Surface Soils of Kunming,China: Concentrations,Distribution, Sources,and Potential Risk

The concentrations, distribution, possible sources, and potential risk of polycyclic aromatic hydrocarbons (PAHs) in surface soils were studied in Kunming, which is situated in a lake basin of the Yunnan-Guizhou plateau. 15 PAHs were analyzed in 40 surface soil samples (0–5 cm layer) collected from six types of land uses in the Kunming urban area. Meanwhile, the potential sources of PAHs in surface soils of Kunming were investigated by PAH composition ratios, isomer ratios, and principal component analysis (PCA). The total concentrations of 15 PAHs ranged from 101.64 to 6,208.25 ng/g (dry weight basis). The concentrations in different land uses increased in an order as: green space (541.43 ng/g) < education area (756.49 ng/g) < business area (810.17 ng/g) < residential area (1,034.36 ng/g) < industrial area (1,166.79 ng/g) < roadside greens (2,146.76 ng/g). The results of sources identification suggested that PAHs in surface soils of the Kunming urban area were greatly affected by combustion activities which came mainly from coal combustion and vehicular traffic. In addition, the toxic equivalency factors (TEFs) were used to estimate benzo[a]pyrene-equivalent concentration in surface soils of Kunming, and the risk level of PAHs in Kunming's urban surface soils was low as a whole.     

Prevalence of esophageal squamous dysplasia in relatives of patients with esophageal cancer in Southwestern Kenya

BackgroundEsophageal squamous cell carcinoma (ESCC) and its asymptomatic precursor lesion, esophageal squamous dysplasia (ESD), are common in East Africa. It is unknown whether family history of esophageal cancer is a risk factor for both ESD and ESCC in Africa, and whether family members of affected persons should be screened.MethodsWe recruited 296 asymptomatic adult first-degree relatives of ESCC patients residing in southwestern Kenya. Participants completed questionnaires and underwent endoscopy with Lugol’s iodine staining and biopsy to determine the prevalence of ESD. Prevalence comparisons were made with a prior population-based cohort from the same catchment area who also underwent Lugol’s chromoendoscopy.ResultsMean age was 40.7 years, compared to 62.7 years in the prior population study. The overall prevalence of ESD/ESCC among first-degree relatives was 14.7%, comparable to the background population prevalence of 14.4%, and this comparability remained even after adjusting for the different age distributions of the studies. Post-primary education was the only measured variable that was associated with a decreased risk of ESD/ESCC (adjusted OR=0.31, 95% CI: 0.11, 0.83). There was heterogeneity in the ESD prevalence across families, even after adjustments for varying age and other measured factors.ConclusionsThe prevalence of esophageal squamous dysplasia among first-degree relatives of persons with ESCC was similar to that of the background population of southwestern Kenya; however, there was heterogeneity in ESD prevalence between families, suggesting other genetic or environmental factors may influence family prevalence. Further study of families with a high prevalence of ESD or ESCC is justified.     

Neither altered incubation temperature during fetal development nor preferred rearing temperature improves leg bone characteristics of broilers

The present study evaluated whether broiler femoral and tibiotarsal characteristics (as assessed at slaughter age) could be improved if birds were reared under their preferred temperature and whether continuous high or low incubation temperature during the fetal period improves bone characteristics of broilers reared under heat stress or thermal preference. Broiler breeder eggs were incubated from day 13 until hatching under cold (36 °C), control (37.5 °C), or hot (39 °C) temperatures. Under these conditions, the eggshell temperatures were 37.4 ± 0.1°C, 37.8 ± 0.15°C, and 38.8 ± 0.3°C, respectively. Then, broiler chicks were reared under control, preferred (determined previously in thermal preference test), or high temperatures. At day 42 of age, the broilers were weighed and euthanized, and femora and tibiotarsi collected to measure weight, length, diaphysis perimeter, breaking strength, maximum flexion, rigidity, ash, phosphorus, and calcium. Rearing under the preferred temperature did not affect broiler body weight or femoral and tibiotarsal characteristics (P > 0.05). In contrast, high rearing temperature, decreased the body weight, mineral contents of both bones, femoral breaking strength, and tibiotarsal rigidity (P < 0.05). Regarding incubation temperature effects, egg exposure to cold and hot temperatures during the fetal period minimized or avoided a few effects of high rearing temperature, such as those on femoral and tibiotarsal morphological characteristics, mineral composition, and mechanical properties at slaughter age (P < 0.05), but not all. In conclusion, rearing under the preferred broiler temperature did not improve the bone characteristics, and the negative effects of high rearing temperature on bone development were minimized but not completely prevented by high or low temperature incubation during the fetal period.     

Association of p53 and MDM2 polymorphisms with risk of human papillomavirus (HPV)-related esophageal squamous cell carcinoma (ESCC)

PurposeThough polymorphisms of the tumor suppressor gene p53 have been extensively investigated in numerous tumors, particularly tumors associated with human papillomavirus (HPV) infection. However, the results remain controversial. Our previous study showed that HPV serostatus is not an independent risk factor for esophageal squamous cell carcinoma (ESCC) in nonsmokers and nondrinkers. Given the roles of p53 and HPV E6 as well as MDM2 oncoproteins in p53 degradation, we validated the association of p53 and MDM2 polymorphisms with ESCC risk stratified by HPV16 sero-status.MethodsSingle nucleotide polymorphisms of p53 Arg72Pro (rs1042522) and MDM2 (rs937283) in 307 ESCC patients and 311 healthy controls were genotyped. The presence or absence of HPV16 in serum was measured by enzyme-linked immunosorbent assay. Multivariable logistic regression analysis was used to evaluate the possible associations of p53 and MDM2 polymorphisms with ESCC risk stratified by HPV16 sero-status.ResultsPatients carrying p53 Arg/Arg or Arg/Pro had a higher risk of esophageal SCC (P < 0.001, Odds ratio [OR] 4.98, 95% confidential interval [CI] 3.46–7.17), however, not found in MDM2 rs937283. The risk of esophageal SCC increased significantly among patients carrying p53 Arg/Arg, or Arg/Pro and HPV16-seropositivity (P < 0.001, OR 9.33, 95% CI 5.44–16.0), but not for MDM2 rs937283. The risk of esophageal SCC was further elevated among patients carrying Arg/Arg or Arg/Pro and HPV16-seropositivity who were smokers (P < 0.001, OR 27.05, 95% CI 11.06–66.16) or drinkers (P < 0.001, OR 13.20, 95% CI 5.74–30.38).ConclusionHPV16 seropositivity synergized with p53 Arg/Arg or Arg/Pro and increased ESCC risk, especially in smokers or drinkers.     

Distribution characteristics,sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Haizhou Bay,China

Sixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography–mass spectrometry. Twenty samples were collected from the surface sediments of Haizhou Bay in this survey. This research aimed to identify the PAHs' contamination level, composition pattern, pollution sources, and assess the ecological risk of PAHs. The results showed that the sum of PAH concentrations ranged from 116.6 ng g^?1 to 2414.9 ng g^?1 (mean: 662.42 ng g^?1), which is higher than the reported values for different wetlands worldwide. Three- and four-ring PAHs (accounts for more than 70% of the total PAH content) were predominant in the wetland sediment. The PAHs source distribution in the surface sediments were determined using diagnostic ratio and PCA/MLR. Consequently, multiple PAHs sources were found. Of the total PAH, 79.25% was derived from vehicular emission, 20.75% from coal combustion. The effect range low/effect range median (ERL/ERM) values indicated a low toxicity risk level. However, the fluoranthene concentrations exceeded the ERL level, and even the ERM level, in some stations. The mean effects range–median quotient (M-ERM-Q) suggests a low ecological risk for the PAHs in the sediments.     

Effects of Parturition and Feeding on Thermal Preference of Atlantic Stingray, Dasyatis sabina (Lesueur)

Synopsis Temperature is the most important and least well documented environmental entity affecting reproduction and feeding of elasmobranch fishes, but it is unclear to what extent these fish may exploit behavioral thermoregulation to optimize physiological processes. Laboratory thermal preference determinations are important to understanding behavioral processes because they provide the vital quantitative link between environment, physiology, and adaptive behavior. Temperature preference data were collected on Atlantic stingrays, Dasyatis sabina (Lesueur) to assess the fishs’ ability to behaviorally optimize feeding and reproduction. Groups of male and pregnant female Atlantic stingrays exhibited statistically higher preferred median temperatures (26.2 and 26.1°C, respectively) than non-pregnant females (25.3°C; One-Way ANOVA on ranked data, F _[2,26] = 3.72, p=0.038). Median preferred temperatures in unfed stingrays of both genders ranged from 24.5 to 31.0°C, whereas, fed fish preferred temperatures between 23.5 and 27.5°C. Unfed stingrays preferred a median temperature of 24.5°C; however, after feeding fish preferred significantly warmer water temperatures of 25.7°C (Wilcoxon one-tail, matched-pairs, signed rank analysis; p<0.088). While overall differences were subtle, small preference adjustments can have important physiological consequences. For example, the 1°C increase seen in pregnant females over non-pregnant fish would reduce gestation time by as much as two weeks. Likewise, by moving to cooler water after feeding, stingrays may increase nutrient uptake efficiency by reducing evacuation rates. Our data indicate that movement and distribution of Atlantic stingrays are dictated, in part, by temperature effects on physiology.     

Influence of a high-temperature programme on serum,urinary and sweat levels of selenium and zinc

IntroductionThe effect of hyperthermia on the antioxidant system in the human organism is well known.AimThe objective of this study was to observe the effects of heat on the concentration of Se and Zn, elements related to antioxidant systems.MethodsTwenty-nine subjects voluntarily participated in this study. They were divided into a control group (CG; n = 14) and an experimental group (EG; n = 15). All of them underwent two incremental tests until exhaustion in normothermia (22 °C, 20–40%RH) and hyperthermia (42 °C, 20–40%RH). EG experienced nine sessions of repeated heat exposure at high temperatures (100 °C, 20%RH) for three weeks (HEHT). After the intervention, the initial measurements were repeated. Urine and blood samples were collected before and after each test. Additionally, sweat samples were collected after tests in hyperthermia.ResultsThere were no significant changes in serum. An increase in the elimination of Zn and Se in EG was observed in urine after HEHT (p < .05). The elimination of Zn by sweating decreased after HEHT in EG (p < .05).ConclusionsExposure to heat at high temperatures increases the urinary excretion of Se and Zn.     

HLA-DRB1*1501 and HLA-DQB1*0301 alleles are positively associated with HPV16 infection–related Kazakh esophageal squamous cell carcinoma in Xinjiang China

Multiple determinant factors are involved in the occurrence and progression of esophageal squamous cell carcinoma (ESCC). Human papillomavirus (HPV) and human leukocyte antigen (HLA) polymorphism were identified as important factors. This study examined the associations between the development of Kazakh ESCC and the determinant factors including HLA-DRB1*0901, 1501; DQB1*0301, 0602; high-risk HPV infection in the area of Xinjiang, China. 200 Kazakh patients with ESCC and 150 controls were recruited, and polymerase chain reaction (PCR) was performed to detect HLA-DRB1*0901, 1501 and DQB1*0301,0602 using sequence-specific primers (SSPs). HPV16 was detected in esophageal specimens using PCR. HPV16 infection rate in Kazakh ESCC case group was 41 %, significantly higher than that of control group 14 % (OR = 3.62; 95 % CI, 2.15–6.09; P < 0.001). A positive association between ESCC and HLA-DRB1*1501 (OR = 2.46, P < 0.0125) or HLA-DQB1*0301 (OR = 3.34, P < 0.0125) alleles was observed. Similar tendencies were observed for HLA-DRB1*1501 (OR = 3.095, P < 0.0125) and HLA-DQB1*0301 (OR = 2.410, P < 0.0125) alleles with HPV16-positive ESCC. HLA-DRB1*1501, HLA-DQB1*0301 and DQB1*0602 were significantly associated with ESCC when the age was ≥55 years (P < 0.0125 for all), whereas only HLA-DQB1*0301 was significantly associated with ESCC when the age was <55 years (P < 0.0125). HLA-DRB1*1501 and HLA-DQB1*0301 were significantly associated with an increase in ESCC occurrence in females (P < 0.0125), whereas only HLA-DQB1*0301 was significantly associated with ESCC in males. Moreover, the occurrence of HLA-DQB1*0602 gene in poorly differentiated ESCC group (68.8 %) was slightly higher than that of well-differentiated squamous cell carcinoma group (31.2 %). The difference was not statistically significant (P > 0.0125). The study suggests that HLA-DRB1*1501 and HLA-DQB1*0301 may influence the immune response to specific tumor and HPV-encoded epitopes and affect the risk of Kazakh ESCC in XinJiang, China.     

Shading by Napier Grass Reduces Malaria Vector Larvae in Natural Habitats in Western Kenya Highlands

Increased human population in the Western Kenya highlands has led to reclamation of natural swamps resulting in the creation of habitats suitable for the breeding of Anopheles gambiae, the major malaria vector in the region. Here we report on a study to restore the reclaimed swamp and reverse its suitability as a habitat for malaria vectors. Napier grass-shaded and non-shaded water channels in reclaimed sites in Western Kenya highlands were studied for the presence and density of mosquito larvae, mosquito species composition, and daily variation in water temperature. Shading was associated with 75.5% and 88.4% (P < 0.0001) reduction in anopheline larvae densities and 78.1% and 88% (P < 0.0001) reduction in Anopheles gambiae sensu lato (s.l.) densities in two sites, respectively. Shading was associated with a 5.7°C, 5.0°C, and 4.7°C, and 1.6°C, 3.9°C, and 2.8°C (for maximum, minimum, and average temperatures, respectively) reduction (P < 0.0001) in water temperatures in the two locations, respectively. An. gambiae s.l. was the dominant species, constituting 83.2% and 73.1%, and 44.5% and 42.3%, of anophelines in non-shaded and shaded channels, respectively, in the two sites, respectively. An. gambiae sensu stricto (s.s.) constituted the majority (97.4%) of An. gambiae s.l., while the rest (2.6%) comprised of Anopheles arabiensis. Minimum water temperature decreased with increasing grass height (P = 0.0039 and P = 0.0415 for Lunyerere and Emutete sites, respectively). The results demonstrate how simple environmental strategies can have a strong impact on vector densities.     

Tea consumption reduces ovarian cancer risk

Objective: To ascertain the relationship between tea drinking and the risk of ovarian cancer among southern Chinese women, a case–control study was conducted in southern China during 2006–2008. Methods: Five hundred incident patients with histologically confirmed epithelial carcinoma of the ovary and 500 controls (mean age 59 years) were recruited from four public hospitals in Guangzhou. Information on frequency, quantity and duration of tea drinking, amount of dried tea leaves brewed, together with habitual diet and lifestyle characteristics, was obtained face-to-face from participants using a validated and reliable questionnaire. Logistic regression analyses were performed to assess the association between tea consumption variables and the ovarian cancer risk. Results: The control subjects reported higher tea consumption levels and prevalence (78.8%) than the ovarian cancer patients (51.4%). Regular drinking of green tea, black tea and/or oolong tea was associated with a lower risk of ovarian cancer, the adjusted odds ratio being 0.29 (95% confidence interval 0.22–0.39) after accounting for confounding factors. When compared with non-drinkers, apparent inverse dose–response relationships were observed for years of drinking, number of cups and quantity of tea consumed, as well as amount of dried tea leaves brewed (p < 0.01). Conclusion: Regular tea consumption is associated with a reduced risk of ovarian cancer for southern Chinese women.     

Effect of ammonia and urea treatments on digestibility and nitrogen content of dehydrated lucerne

Dehydrated lucerne of low (L: 0.53), normal (N: 0.55) and high (H: 0.73) in vivo dry matter (DM) digestibility were treated with ammonia or urea to study the effects on in situ and pepsin-cellulase DM digestibilities, water solubility and nitrogen content (Experiments 1, 2, 4) and on cell wall composition and degradability (Experiment 3). (1) N lucerne was treated with 30 g NH₃ kg⁻¹ DM for 1 to 12 weeks at 30°C and 2 to 6 days at 80°C; (2) L, N and H lucerne were treated with increasing ammonia levels: 15 to 100 g kg⁻¹ DM for 3 weeks at 30°C and 4 days at 80°C; (3) L, N and H lucerne were treated with 60 g NH₃ kg⁻¹ DM for 3 weeks at 30°C and 4 days at 80°C; (4) L, N and H lucerne were treated with 60 g urea kg⁻¹ DM without addition of urease for 3 and 6 weeks at 30°C. All treatments were carried out at 40% humidity.In situ and pepsin-cellulase DM digestibilities increased significantly (P < 0.05) with the duration of treatment (up to 3 weeks at 30°C and 4 days at 80°C) and with the level of ammonia (P < 0.01) (up to 30 g kg⁻¹ DM). The greatest improvements (similar at both temperatures) were for L, N and H of 7.3, 7.2 and 3.9 points for in situ and of 10.6, 11.3 and 6.3 points for cellulase digestibilities, respectively. Water solubility also increased with duration of treatment and level of ammonia (P < 0.01) and was greater at 80°C than at 30°C. Urea treatment significantly improved (P < 0.01) digestibilities and water solubility but the doubling of treatment duration had no influence. The degree of ureolysis was only 50 to 60%. Ammonia and urea treatments considerably increased (P < 0.01) nitrogen content.Treatment with 60 g NH₃ kg⁻¹ DM induced a decrease in ethanol insoluble residue content, which was significant (P < 0.01 for L and N, P < 0.05 for H) at 80°C but not at 30°C, and was greater for L and N than for H (about 12 and 5 points, respectively). This decrease was essentially due to solubilisation of hemicelluloses (− 15%) and uronic acids (− 26%). Thus, at 30°C, the chemical solubility of the cell wall was lower than at 80°C for the same total increase in microbial degradation. This result indicates that other phenomena are involved, such as an increase in cell wall porosity and consequently improved accessibility of cell wall polysaccharides to glycolytic enzymes.     

Effect of the critical thermal maximum on the preferred temperatures of Ictalurus punctatus exposed to constant and fluctuating temperatures

No significant differences were found in the temperature of the onset of behavioural response spasms and equilibrium loss in Ictalurus punctatus maintained in constant and fluctuating temperatures. The preferred temperature was determined in an aquatic gradient to be 29.0°C and the temperatures avoided were 21.7–34.1°C. The temperature that causes the loss of equilibrium of acclimation at constant or fluctuating temperatures changes the organisms final preferendum and the avoided temperatures were significantly different (p<0.05) if compared with the control group. The behavioural response that should be considered as the critical thermal maximum (CTMax) of I. punctatus is the equilibrium loss that reflects a major deep core reaction.     

Effect of exposure to high temperatures in the excretion of cadmium and lead

ObjectiveThis study aims to observe the effect on urine and sweat excretion levels of cadmium (Cd) and lead (Pb) in healthy men in a maximum incremental test until exhaustion and repeated exposure to heat.Methodstwenty-nine adult men divided into control group (CG; n = 14) and experimental group (EG; n = 15) performing two maximum tests until exhaustion in normothermia (22 °C) and hyperthermia (42 °C). EG experienced 9 sessions of heat exposure at high temperatures (100 °C) (HEHT). After the nine sessions, the initial tests were repeated in both groups. Urine samples were collected before and after each test. After the hyperthermia tests, sweat samples were gathered.ResultsUrinary Cd increased after initial tests in GC and in hyperthermia in EG (p < 0.05). Urinary excretion of Pb rose after HEHT (p < 0.05). Pb in sweat was higher in EG than in CG after HEHT (p < 0.05).ConclusionHeat exercise and constant exposure to heat can be a valid method to increase the excretion of toxic metals.     

Definition and risk factors of early recurrence based on affecting prognosis of esophageal squamous cell carcinoma patients after radical resection

Early recurrence after surgery could affect cancerous patients’ prognosis, but the definition of early recurrence and its risk factors for esophageal squamous cell carcinoma (ESCC) patients are still unclear. This study analyzed the clinical data of 468 post-surgery recurrent ESCC patients retrospectively. A minimum p-value approach was used to evaluate the optimal cut-off value of recurrence free survival (RFS) to define early recurrence. Risk factors of early recurrence were developed based on a Cox model. The optimal cut-off value of RFS to distinguish early recurrence was 21 months (p <0.001). Independent risk factors for early recurrence included tumor locations (HR=0.562, p <0.001), pathological T stage (HR=1.829, p <0.001), tumor diameter (HR=1.344, p = 0.039), positive lymph nodes (HR=1.361, p <0.001), and total resected lymph nodes (HR=1.271, p = 044). For the late recurrent patients, there was a much more significant survival advantage for recurrence after concurrent chemoradiotherapy than that after sequential chemoradiotherapy and radiotherapy alone (p = 0.0066). In conclusion, this study defined 21 months of RFS as early recurrence and also identified its risk factors. Concurrent chemoradiotherapy was suggested as preferred post-relapse treatment for late recurrent ESCC patients.     

Effect of constant and fluctuating temperature on the circadian foraging rhythm of the red imported fire ant,Solenopsis invicta Buren (Hymenoptera: Formicidae)

Understanding circadian foraging rhythms activity of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae) foragers at different temperatures is an important step towards developing control measures in Integrated Pest Management (IPM) programs. In this study, the circadian foraging rhythm activities of S. invicta foragersat different temperature were investigated under laboratory and field conditions. Results indicated that the foraging activity increased after sunrise, and maximum foraging occurred at 14:00 (foraging rate was 69.22 ± 0.57 and 72.58 ± 1.15 foragers/min in the first and second year, respectively) in the tea fields of Guangzhou during autumn. Furthermore, foragers demonstrated circadian rhythms and exhibited a unimodal after 24 h. A significant correlation was found between foraging activity and temperature. S. invicta colonies were active at moderate soil temperatures (approximately 26.65 °C to 29.24 °C). The preferred temperature of the colonies was 26 °C, followed by 22 °C and 18 °C in the laboratory. The individual S. invicta activity was maximum at 17:00 (18.67 ± 1.66 times /10 min) and minimum at 5:00 (8.33 ± 2.51 times/10 min) at 26 °C. The fluctuating temperature had a significant impact on individual locomotor activity (r = 0.8979, P < 0.01) but did not alter the rhythm activity. Our results demonstrated that temperature might play an important role in circadian foraging rhythms activity of S. invicta. These results may have implications for the development of more effective fire ant management strategies.     

Biosurfactant production and hydrocarbon-degradation by halotolerant and thermotolerant Pseudomonas sp.

A hydrocarbon degrading and biosurfactant producing, strain DHT2, was isolated from oil-contaminated soil. The organism grew and produced biosurfactant when cultured in variety of substrates at salinities up to 6 g l⁻¹ and temperatures up to 45°C. It was capable of utilizing crude oil, fuels, alkanes and PAHs as carbon source across the wide range of temperature (30–45°C) and salinity (0–6%). Over the range evaluated, the salinity and temperature did not influence the degradation of hydrocarbon and biosurfactant productions. Isolate DHT2 was identified as Pseudomonas aeruginosa by analysis of 16S rRNA sequences (100% homology) and biochemical analysis. PCR and DNA hybridization studies revealed that enzymes involved in PAH metabolism were related to the naphthalene dioxygenase pathway. Observation of both tensio-active and emulsifying activities indicated that biosurfactants were produced by DHT2 during growth on both, water miscible and immiscible substrates, including PAH. The biosurfactants lowered the surface tension of medium from 54.9 to 30.2 dN/cm and formed a stable emulsion. The biosurfactant produced by the organism emulsified a range of hydrocarbons with hexadecane as best substrate and toluene was the poorest. These findings further indicate that the isolate could be useful for bioremediation and bio-refining application in petroleum industry.     

Isolation of a psychrotolerant Debaryomyces hansenii strain from fermented tea plant (Camellia sinensis) leaves

Abstract

A psychrotolerant, halotolerant and alkalophilic yeast was isolated from fermented leaves of Camellia sinensis Kuntze, the tea plant. The yeast strain, named Tea-Y1, was both phenotypically and genotypically identified as belonging to the species Debaryomyces hansenii. This assignment was confirmed by scanning and transmission electron microscopy. The analysis of growth curves demonstrated the ability this yeast strain to grow in a temperature range between 4°C and 28°C, with an optimum of 23°C. The ecology of this yeast in the C. sinensis phyllosphere, as well as its possible role in tea fermentation and storage, with particular reference to iced tea, are discussed.