Fate of antibiotic resistance genes in cultivation substrate and its association with bacterial communities throughout commercial production of Agaricus bisporus.

Animal manure is an important raw material for Agaricus bisporus production; however, it is also a reservoir for antibiotic residues, antibiotic resistance genes (ARGs), and antibiotic-resistant bacteria. Little is known about the influence of the commercial cultivation of A. bisporus on the dynamics of ARGs and the underlying mechanisms that cause their variations. In this study, we investigated the fate of 285 ARGs, 10 mobile genetic elements, and seven major categories of antibiotic residues in substrate and mushroom samples at different production phases. The results showed that commercial substrate preparation, particularly the pasteurization phase, was highly efficient in removing ARGs from the substrate. We further found that mycelium proliferation of A. bisporus contributed significantly to the removal of ARGs from the substrate and casing soil. The bacterial community is the key driver of changes in ARGs during the commercial cultivation of A. bisporus, which explained 46.67% of the variation in ARGs. Our results indicate that, despite the addition of animal manure, the risk of ARG dissemination to fruiting bodies and the environment is low. We propose that bioremediation by specific edible fungi might be a novel and promising method for scavenging antimicrobial resistance contamination from soil environment.

Bacillus fungorum sp. nov., a bacterium isolated from spent mushroom substrate.

A facultatively anaerobic, Gram-stain-positive, spore-forming Bacillus strain, 17-SMS-01T, isolated from spent mushroom substrate in the Fangshan District, Beijing, PR China, was initially identified as a Bacillus cereus group species based on 16S rRNA gene sequences. Strain 17-SMS-01T had the highest sequence similarities to Bacillus wiedmannii FSL W8-0169T (99.9 %), Bacillus albus N35-10-2T (99.9 %), Bacillus luti TD41T (99.9 %) and Bacillus proteolyticus TD42T (99.9 %). However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (DDH) values between strain 17-SMS-01T and the most closely related species were less than the previously proposed cut-off values of 96 % (ANI) and 70 % (DDH) for differentiating species within the genus, suggesting that this strain represents a novel Bacillus group species. The fatty acid profile of strain 17-SMS-01T, which showed a predominance of iso-C15 : 0 and anteiso-C15 : 0, supported the allocation of the strain to the genus Bacillus. The predominant menaquinone was MK-7 (100%). The major polar lipids were diphosphatidylglycerol, phosphatidyl ethanolamine, phosphatidyl glycerol, an unidentified aminophospholiped and unidentified lipids. The DNA G+C content of the novel strain was 35.0 mol%. The results of physiological and biochemical tests also allowed the phenotypic differentiation of strain 17-SMS-01T from the most closely related recognized species. On the basis of the phylogenetic and phenotypic evidence, strain 17-SMS-01T represents a novel Bacillus species, for which the name Bacillus fungorum sp. nov. is proposed. Type strain of the novel species is 17-SMS-01T (=MCCC 1K03483T=KCTC 33949T).

Early clinical predictors for the prognosis of invasive pneumococcal disease.

BACKGROUND: Risk factors related to mortality due to invasive pneumococcal disease (IPD) have been unveiled previously, but early clinical manifestations of IPD based on prognosis remain uncovered. METHODS: The demographic characteristics, clinical features, serotype, antibiotic susceptibility, and outcomes of 97 hospitalized children with laboratory-confirmed IPD from Suzhou, China, were collected and analyzed retrospectively. RESULTS: The median age was 0.69 (0.49-1.55) years in the non-survivor group compared with 2.39 (0.90-3.81) years in the survivor group. The mortality of 97 children with laboratory-confirmed IPD was 17.5% (17/97), and 53.6% of them were aged less than 2 years. Pathogens were mainly from the blood and cerebrospinal fluid, and sepsis was the most frequent type. Statistically significant differences were found in hyperpyrexia, vomiting, anorexia, lethargy, poor perfusion of extremities, Hb level, and Plt count between the nonsurvival and survival groups. Further, the multivariate regression analysis showed that early signs, including hyperpyrexia, vomiting, anorexia, lethargy, and poor perfusion of extremities, were independent risk factors for the in-hospital mortality of children with laboratory-confirmed IPD. The mortality was also associated with antimicrobial sensitivity in pneumococcal isolates. The microbes in 1/17 (5.9%) children who were prescribed an antibiotic showed antimicrobial sensitivity in the nonsurvival group, compared with 21/80 (26.3%) children who survived. The most common serotypes identified were 6B (35.3%, 6/17), 14 (23.5%, 4/17), 19F (23.5%, 4/17), 19A (5.9%, 1/17), 23F (5.9%, 1/17), and 20 (5.9%, 1/17) in the nonsurvival group. The coverage of IPD serotypes of the 7-valent pneumococcal conjugate vaccine (PCV7) was 88.2% (15/17), while that of the 13-valent S. pneumoniae vaccine (PCV13) was 94.1% (16/17) of the coverage in the nonsurvival group. CONCLUSIONS: Recurrent hyperpyrexia, vomiting, anorexia, lethargy, and poor perfusion of extremities in the early stage were independent predictors for the in-hospital mortality of children with laboratory-confirmed IPD. Appropriate use of antibiotics and PCV immunization were the keys to improve the outcome of IPD.

Diaphorobacter polyhydroxybutyrativorans sp. nov., a novel poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-degrading bacterium isolated from biofilms.

A novel Gram-stain-negative, facultatively aerobic and rod-shaped strain, designated SL-205(T), was isolated from the biofilms of a denitrifying reactor using poly(3-hydoxybutyrate-co-3-hydroxyvalerate) as the sole carbon source in Beijing, PR China. A polyphasic taxonomic characterization was performed on the novel isolate. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that strain SL-205(T) is a member of the genus Diaphorobacter. High levels of 16S rRNA gene sequence similarity were found between strain SL-205(T) and Diaphorobacter nitroreducens NA10B(T) (99.4%) and Diaphorobacter oryzae RF3(T) (98.5%), respectively. However, the DNA-DNA relatedness values between strain SL-205(T) and D. nitroreducens NA10B(T) and D. oryzae RF3(T) were 57 ± 1% and 45 ± 1.5%, respectively. The G+C content of the genomic DNA of strain SL-205(T) was 66.8 mol%. The major fatty acids consisted of summed feature 3 (including C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and C18 : 1ω7c. Ubiquinone Q-8 was the only respiratory quinone; the polar lipid profile comprised phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and one uncharacterized phospholipid. We conclude that strain SL-205(T) represents a novel species of the genus Diaphorobacter for which the name Diaphorobacter polyhydroxybutyrativorans is proposed; the type strain is SL-205(T) ( = ACCC 19739(T) = DSM 29460(T)).

[Nitrate removal from recirculating aquaculture system using polyhydroxybutyrate-co-hydroxyvalerate as carbon source ].

[ OBJECTIVE] Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) was used as solid carbon source and biofilm carrier to remove nitrate from recirculating aquaculture system (RAS). Dynamics of microbial community structure in biofilm coating on carbon source packed into denitrification reactor were investigated. [METHODS] Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community in biofilm from denitrifiation reactor. Bacteria degrading PHBV were isolated from the reactor using pure culture method. [RESULTS] Nitrate decreased remarkably in the RAS connected with dentrification reactor. In contrast, Nitrate increased continuously in the conventional RAS without dentrification reactor. According to the phylogenetic analysis, the microbes in the biofilm samples from denitrification reactor were divided into Proteobacteria ( p-proteobacteria, γ-proteobacteria and δ- proteobacteria) , Firmicutes and Bacteroidetes. The major advantageous populations were Acidovorax and Bacillus in the 40-day reactor. The advantageous populations in the 150-day reactor were in order of Clostridium, Desulfitobacterium, Dechloromonas, Pseudoxanthomonas and Flavobacterium. Pure cultures of bacteria degrading PHBV isolated from denitrification reactor were classified into Acidovorax, Methylibium, Pseudoxanthomonas and Dechloromonas. [CONCLUSION] Nitrate could be removed effectively from RAS using PHBV as carbon source. Advantageous bacteria and their dynamic changes were ascertained in biofilm from denitrification reactor packed with PHBV.

Analysis of sleep quality, disease uncertainty, and psychological tolerance in patients undergoing chemotherapy for digestive tract malignancies.

BACKGROUND: Colorectal cancer is the second leading cause of cancer-related deaths among digestive tract malignancies, following gastric cancer. Sleep is of great significance for maintaining human health. The incidence of sleep disorders in patients with cancer is approximately twice that observed in the general population. Lack of sleep can prolong hospital stays, increase the likelihood of infection, and increase mortality rates. Therefore, studying the factors related to sleep quality is significant for improving the quality of life of patients with malignant tumors of the digestive tract. AIM: To investigate the relationships among sleep quality, disease uncertainty, and psychological resilience in patients undergoing chemotherapy for digestive tract malignancies. METHODS: A total of 131 patients with malignant digestive tract tumors who were treated at Hefei BOE Hospital between April 2021 and September 2022 were selected as research participants. Based on their Pittsburgh Sleep Quality Index (PSQI) scores, participants were divided into either the sleep disorder group (PSQI score > 7) or the normal sleep group (PSQI score ≤ 7). The clinical data-together with the Mishel Uncertainty in Illness Scale for Adults (MUIS-A) and Connor-Davidson Resilience Scale (CD-RISC) scores-were compared. RESULTS: In this study, 78 (59.54%) patients with digestive tract malignancies developed sleep disorders after chemotherapy. Sleep disorder incidence was higher in patients with colorectal cancer than in those with gastric and esophageal cancers (P < 0.05). The total MUIS-A score and those for each item in the sleep disorder group were higher than those in the normal sleep group. The total CD-RISC score and those for each item in the sleep disorder group were lower than those in the normal sleep group (P < 0.05). The PSQI scores of patients with malignant digestive tract tumors were positively correlated with the scores for lack of disease information, disease uncertainty, and unpredictability in the MUIS-A and negatively correlated with the scores for tenacity, self-improvement, and optimism in the CD-RISC (P < 0.05). CONCLUSION: Patients undergoing chemotherapy for digestive tract malignancies are prone to sleep problems related to disease uncertainty and psychological resilience. Therefore, interventions can be implemented to improve their sleep quality.

The evaluation of cytokines in predicting the organ injury of critically pediatric patients: a retrospective study.

Background: The current early warning model for organ damage in critically ill patients has certain limitations. Based on the pathological mechanism, the establishment of an early warning system for organ damage in critically ill children using cytokines profile has not been explored. The aim of this study is to explore the predicting value of cytokines in critically ill patients. Methods: There were 200 critically pediatric patients and 49 general patients between August 22, 2018 and April 28, 2023 from Children's Hospital of Soochow University enrolled in this study. The clinical information was retrospectively collected and analyzed. The cytokine profiles of these patients were detected by flow cytometry. Receiver operating characteristic (ROC) curves were plotted to determine the association between the cytokines and organ injury. Results: There were no statistically significant differences in gender, age and underlying disease between critically ill patients and general patients. The interleukin (IL)-6 (P<0.001), IL-10 (P<0.001), IL-17A (P=0.001), tumor necrosis factor-α (TNF-α) (P=0.02) and interferon-γ (IFN-γ) (P=0.02) level in the critically patients were significantly higher than those in the general patients. The results showed that the incidence of acute gastrointestinal injury (AGI) and acute kidney injury (AKI) in critically ill patients was 39% and 23.5%, respectively. Moreover, there were 4% and 3.5% patients with the occurrence of cardiac arrest and acute live injury. The IFN-γ level was increased in these patients with acute liver injury compared to those without these organ injuries, but reduced in the patients with AGI compared to those without. The patients with AKI showed a significant increase in IL-10 in contrast to those without. The IL-2, IL-4, IL-6, IL-10 and IL-17A were higher in patients with acute liver failure (ALF), but TNF-α was reduced, compared to those without. The IL-2, IL-4, IL-6 and IL-10 were significantly increased in the patients with cardiac arrest compared to those without. When IL-10 was higher than 279.45 pg/mL, the sensitivity and specificity for predicting cardiac arrest were 0.875 and 0.927, respectively. While the sensitivity and specificity of IL-6 (more than 1,425.6 pg/mL) were 0.625 and 0.844, respectively. However, no synergistic effect of IL-6 and IL-10 was observed for predicting cardiac arrest. Additionally, the IL-17A (more than 21.6 pg/mL) was a good predictor for the incidence of ALF (sensitivity =0.714, specificity =0.876). Conclusions: The cytokines profile was different between critically ill patients with organ injury and those without organ injury. The IL-6 and IL-10 levels were good predictors for cardiac arrest in critically ill patients. Additionally, higher IL-17A predicted the incidence of ALF of the critically ill patients.

Treatment of First-Time Perianal Abscess in Childhood, Balance Recurrence and Fistula Formation Rate with Medical Intervention.

PURPOSE: Because of differences in therapy for first-time perianal abscess, a wide range of recurrences and/or development of fistula-in-ano (RF) rates have been reported. The indication for determining when surgical intervention is needed remains obscure and controversial. This retrospective study sought to compare outcomes of conservative treatment with those after incision and drainage (ID) to determine the optimal time for surgical intervention. METHODS: A total of 697 patients with first-time perianal abscess were included in this study. The median patient age at the time of onset was 129 days (range: 5-5,110 days). The median follow-up period was 395 days (range: 120-760 days). RESULTS: Of the 697 patients with first-time perianal abscess, 355 (50.9%) patients who received conservative treatment had 12.7% (45/355) RF rate, which is less than that of abscesses treated with ID (24.6%, 72/297; p < 0.001). The median course was 23 (2,466) days, which did not differ significantly from that of abscesses with ID (18 [3,510] days) (p = 0.609). Forty-six (6.6%) patients with abscesses that perforated spontaneously had 10.9% (5/46) RF rate, which was less than that of abscesses with ID (p = 0.019), and the median course was 9 (3,316) days, which was shorter than that of abscesses with ID (p = 0.04). CONCLUSION: Conservative treatment is a safe and effective technique for most first-time perianal abscesses with less recurrence and a lower fistula formation rate. Incision must be performed when an abscess is likely to spread or shows no sign of spontaneous perforation.

Caulobacter zeae sp. nov. and Caulobacter radicis sp. nov., novel endophytic bacteria isolated from maize root (Zea mays L.).

Four bacterial strains designated 410T, 441, 695T and 736 were isolated from maize root in Beijing, P. R. China. Based on 16S rRNA gene phylogeny, the four strains formed two clusters in the genus Caulobacter. Since strain 441 was a clonal variety of strain 410T, only three strains were selected for further taxonomic studies. The whole genome average nucleotide identity (ANI) value between strains 410T and 695T was 94.65%, and both strains shared less than 92.10% ANI values with their close phylogenetic neighbors Caulobacter vibrioides DSM 9893T, Caulobacter segnis ATCC 21756T and Caulobacter flavus CGMCC 1.15093T. Strains 410T and 695T contained Q-10 as the sole ubiquinone and their major fatty acids were C16:0, 11-methyl C18:1ω 0, 11-methyl C18: 1ω7c, summed feature 3 (C16:1ω7c and/or C16:1ω 1ω7c and/or C16: 1ω6c) and summed feature 8 (C18:1ω7c and/or C18:1ω 1ω7c and/or C18: 1ω6c). Their major polar lipids consisted of glycolipids and phosphatidylglycerol, and phenotypic tests differentiated them from their closest phylogenetic neighbors. Based on the results obtained, it is proposed that the three strains represent two novel species, for which the names Caulobacter zeae sp. nov. (type strain 410T=CGMCC 1.15991=DSM 104304) and Caulobacter radicis sp. nov. (type strain 695T=CGMCC 1.16556=DSM 106792) are proposed.

Size-related bacterial diversity and tetracycline resistance gene abundance in the air of concentrated poultry feeding operations.

Concentrated animal-feeding operations (CAFOs) are considered a source of airborne human pathogens and antibiotic resistance genes. Although bacterial abundance and diversity have been well studied, limited information on the size distribution of bioaerosols has prevented a clear understanding of the health effects of exposure to bioaerosols from CAFOs. Here, different sizes of particles were sampled from the inside and outside of atmospheric environments of layer and broiler feeding operations using 8-stage Andersen samplers. The quantitative real-time polymerase chain reaction (qPCR) and 16S rDNA-based sequencing were used to analyze the characteristics of biological abundance and diversity, respectively, according to size. The results indicated that size-related differences occurred in terms of airborne bacterial richness, diversity, and concentration at poultry-feeding operations. The richness of biological genera in the urban atmospheric environment was lower than in concentrated poultry-feeding operations. The biological diversity of airborne bacterial genera, including genera associated with potential pathogens, varied according to size. The bacterial lineages of bioaerosols present in the 7 size stages for layers clustered apart from those for broilers, suggesting that the type of poultry house is a more important factor than the particle size in shaping the microbial communities. In most cases, the concentrations of the 16S rDNA, Escherichia coli, tetW, and tetL genes increased as the particle size increased, with the geometric mean diameters varying from 4.7 to 5.8 µm. These results regarding the size-related differences in the diversity and abundance of bioaerosols will facilitate a better understanding of the potential health impact on both poultry and humans working in such environments.

Bacterial community dynamics in a biodenitrification reactor packed with polylactic acid/poly (3-hydroxybutyrate-co-3-hydroxyvalerate) blend as the carbon source and biofilm carrier.

While heterotrophic denitrification has been widely used for treating such nitrogen-rich wastewater, it requires the use of additional carbon sources. With fluctuations in the nitrate concentration in the influent, controlling the C/N ratio to avoid carbon breakthrough becomes difficult. To overcome this obstacle, solid-phase denitrification (SPD) using biodegradable polymers has been used, where denitrification and carbon source biodegradation depend on microorganisms growing within the reactor. However, the microbial community dynamics in continuous-flow SPD reactors have not been fully elucidated yet. Here, we aimed to study bacterial community dynamics in a biodenitrification reactor packed with a polylactic acid/poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PLA/PHBV) blend as the carbon source and biofilm carrier. A lab-scale denitrifying reactor filled with a PLA/PHBV blend was used. With 85 mg/L of influent NO3-N concentration and a hydraulic retention time (HRT) of 2.5 h, more than 92% of the nitrate was removed. The bacterial community of inoculated activated sludge had the highest species richness in all samples. Bacterial species diversity in the reactor first decreased and then increased to a stable level. Diaphorobacter species were predominant in the reactor after day 24. In total, 178 clones were retrieved from the 16S rRNA gene clone library constructed from the biofilm samples in the reactor at 62 days of operation, and 80.9% of the clones were affiliated with Betaproteobacteria. Of these, 97.2% were classified into phylotypes corresponding to Diaphorobacter nitroreducens strain NA10B with 99% sequence similarity. Diaphorobacter, Rhizobium, Acidovorax, Rubrivivax, Azospira, Thermomonas, and Acidaminobacter constituted the biofilm microflora in the stably running reactor.

[Ammonia Removal Rate and Microbial Community Structures in Different Biofilters for Treating Aquaculture Wastewater].

Three MBBRs and three curtain type trickling filters (CTFs) with different carriers were operated in lab-scale simulated RASs. The characteristics of biofilms, ammonia removal rates and microbial communities in six reactors were compared with each other. Compared with the biofilms of MBBRs, the biofilms of CTFs were heavier and grew faster. The weight of biofilms on CTFs with carbon fiber carriers was the maximum (45.97 g·m-2), and the ammonia nitrogen removal efficiency (86.76%) of this CTFs was higher than the other filters or reactors (61.96%~78.76%). In addition, the concentration of the accumulated nitrite in the carbon fiber CTFs was the lowest in all the six reactors. The microbial communities of biofilms in the six biofilters were evaluated by the high-throughput Illumina-MiSeq sequencing technology. The results showed that the microbial (bacteria and eukaryote) community in biofilms of CTFs was different from that in biofilms of MBBRs. At both bacteria and micro-eukaryote level, the species richness and biological diversity of biofilms in the trickling filters were higher than those in the MBBRs. On the contrary, the Simpson index of bacterial community in biofilms of MBBRs was higher than that in the trickling filters. In all the six biofilters, Nitrospira and Nakamurella were the dominated bacterial genera. Saprospiraceae was more abundant in CTFs than in MBBRs, but Comamonadaceae was enriched in the MBBRs. At the micro-eukaryote genus level, Rhabditida norank genus was more abundant in CTFs, while Chlorophyceae norank genus was more abundant in the MBBRs. The results provide useful information about microbial ecology that can be used for the application of CTFs in RAS.

Cathepsin L is involved in X-ray-induced invasion and migration of human glioma U251 cells.

An important therapeutic method of glioblastoma, the most common primary brain tumor, is radiotherapy. However, several studies reported recently that radiation could also promote the invasion and migration of malignant tumor. Herein, we have identified that a significant increase of migration and invasiveness of human glioma U251 cells undergoing X-ray was observed compared to controls, accompanied by the increase of cathepsin L (CTSL), which is a lysosomal cysteine protease overexpressed and secreted by tumor cells. To verify if there was a relationship between CTSL and the X-ray-induced glioma invasion, a CTSL specific inhibitor Z-FY-CHO or a short hairpin RNA interference was used to pretreat U251 cells. As a result, the cell invasion and migration was impaired via down-regulation of CTSL. Additionally, a marked reduction of the cell-signaling molecules Rho kinase was also detected compared with controls. We also found that CTSL is involved in EMT progress: both in vitro and in clinical specimens. Overall, our findings show that CTSL is an important protein which mediates cell invasion and migration of human glioma U251 cells induced by X-ray, and the inhibition of CTSL expression might diminish the invasion of U251 cells by reducing the activity of RhoA and CDC42 as well as EMT positive markers.

Cathepsin L knockdown enhances curcumin-mediated inhibition of growth, migration, and invasion of glioma cells.

Curcumin can be used to prevent and treat cancer. However, its exact underlying molecular mechanisms remain poorly understood. Cathepsin L, a lysosomal cysteine protease, is overexpressed in several cancer types. This study aimed to determine the role of cathepsin L in curcumin-mediated inhibition of growth, migration, and invasion of glioma cells. Results revealed that the activity of cathepsin L was enhanced in curcumin-treated glioma cells. Cathepsin L knockdown induced by RNA interference significantly promoted curcumin-induced cytotoxicity, apoptosis, and cell cycle arrest. The knockdown also inhibited the migration and invasion of glioma cells. Our results suggested that the inhibition of cathepsin L can enhance the sensitivity of glioma cells to curcumin. Therefore, cathepsin L may be a new target to enhance the efficacy of curcumin against cancers.

Concentration and size distribution of viable bioaerosols during non-haze and haze days in Beijing.

Accumulation of airborne particulate matter (PM) has profoundly affected the atmospheric environment of Beijing, China. Although studies on health risks have increased, characterization of specific factors that contribute to increased health risks remains an area of needed exploration. Chemical composition studies on PM can readily be found in the literature but researches on biological composition are still limited. In this study, the concentration and size distribution of viable airborne bacteria and fungi were determined in the atmosphere from May to July 2013 in Beijing, China. Samples were collected during non-haze days and haze days based on the value of air quality index (AQI) PM2.5. Multiple linear regression results indicated that concentrations of viable bioaerosol exhibited a negative correlation with PM2.5 (AQI) ranging from 14 to 452. There was a little difference in size distribution of bioaerosol between non-haze and haze days that all airborne bacteria showed skewed trends toward larger sizes and airborne fungi followed a Gaussian distribution. Spearman's correlation analysis showed that a fraction of bioaerosol with fine and coarse particles had negative and positive relations with PM2.5 (AQI), respectively. Moreover, the temporal variation of d g (aerodynamic diameter) of bioaerosol with PM2.5 (AQI) fluctuated from 9:00 to 21:00, which suggested that their deposition pattern would vary during a day. The primary research in this study implied that aerodynamic size variation should be considered in assessing the bioaerosol exposure during haze weather.

[Concentration and size distribution of bioaerosols at non-haze and haze days in Beijing].

In recent years, haze has been observed frequently in Beijing. Haze was one of the atmospheric phenomena caused by the accumulation of particulate matter. As an important fraction of particular matter, bioaerosol could potentially cause significantly negative health effects. In this study, we detected the concentration and size distribution of viable bioaerosol during non-haze and haze days, analyzed correlation of viable bioaerosol with the ambient temperature and relative humidity using Spearman's correlation coefficient and finally detected the changing of size distribution of viable bioaerosol in summer and winter. Results indicated that concentrations of viable bioaerosol exhibited a negative correlation with Air Quality Index (AQI) of PM2.5 and positive correlation with temperature. Relative humidity had a negative correlation with airborne bacteria while positive correlation with airborne fungi. The highest concentration of airborne bacteria and fungi were detected at size arrange of 4.5-7.0 µm and 2. 1-3.3 µm in the winter, respectively. In the summer, both the highest concentration of airborne bacteria and fungi were observed at size arrange of 3.3-4.5 µm. The results of this study will provide the basis data for hazard evaluation of bioaerosol on human health at non-haze and haze days.

Simultaneous removal of nitrate and pentachlorophenol from simulated groundwater using a biodenitrification reactor packed with corncob.

Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98% and 40-45% when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91% of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.

[Analysis on microbial community in biofilm coating onto solid carbon source using the PCR-DGGE technique].

Polylactic acid/Poly (3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PLA/PHBV) granules were used as both carbon source and biofilm carrier for nitrate removal from the contaminated water. The polymerase chain reaction-denature gradient gel electrophoresis (PCR-DGGE) was used to investigate the dynamic change of microbial community in the biofilm coating onto PLA/PHBV granules. The results showed that a decrease in microbial diversity was observed at the initial stage of reactor operation. Shannon-Wiener and Simpson diversity indexes of microbial community in the biofilm slightly changed during the stable period of the reactor running. The major microorganisms in the biofilm were Gram-negative rod bacteria including the genera of Diaphorobacter, Acidovorax, Rubrivivax, Azospira, Thermomonas and Devosia, and all of them belonged to alpha-, beta- and gamma- Proteobacteria, according to the SEM photo of biofilm and 16S rDNA sequences of the DGGE profile. Moreover, the abundance of Diaphorobacter-like genera was the highest in the solid-phase-denitrification biofilm.