Total Bacterial Concentration Research Articles

일부 어린이집의 실내공기 중 메치실린내성 포도알균의 오염 실태 및 특성

Objectives: This study aims to understand the concentration, diversity, and antibiotic characteristics of staphylococci present in the indoor air of child-care facilities. Methods: Air sampling was performed from October 2012 to January 2013 in 120 child-care facilities in Seoul, Korea. Methicillin-resistant bacteria were selected from the total obtained airborne bacteria and subjected to 16S rRNA analysis for methicillin-resistant staphylococcal species determination. Identified staphylococcal strains were tested for resistance to a range of antibiotics. Results: Average total airborne bacterial concentration was 508.9 ± 246.3 CFU/m 3 . Indoor concentration of total airborne bacteria had a significant positive correlation with the CO2 concentration in the child-care facilities. Methicillin-resistant staphylococci were present in 13.3% of the child-care facilities studied. A total of four species (S. epidermidis, S. cohnii, S. saprophyticus, S. sp.) and 55 strains were identified from the indoor air of the child-care facilities. Staphylococcus cohnii was the most common species (54.5%), followed by S. epidermidis (38.2%). All of the isolated staphylococcal strains exhibited high resistance to oxacillin, erythromycin, mupirocin, and ceftizoxime. Especially, S. saprophyticus strains showed more multidrug resistance to oxacillin, vancomycin, clindamycin, erythromycin, lincomycin, ceftizoxime, mupirocin, and tetracycline than did other species. Conclusion: The results of this study showed that a monitoring system for multidrug-resistant bacteria is needed in facilities for children, as the community-associated infections of these bacteria are increasing.

Spatial variation of physicochemical and bacteriological parameters elucidation with GIS in Rangat Bay, Middle Andaman, India

The purpose of this study was to determine the concentration, distribution of bacteria and physicochemical property of surface seawater in Rangat Bay, Middle Andaman, Andaman Islands (India). The bay experiences tidal variations. Perhaps physicochemical properties of seawater in Rangat Bay were found not to vary significantly. The concentration of faecal streptococci was high (2.2×103CFU/100mL) at creek and harbour area, whereas total coliforms were high (7.0×102CFU/100mL) at mangrove area. Similarly, total heterotrophic bacterial concentration was high (5.92×104CFU/100mL) in mangrove and harbour area. The Vibrio cholerae and Vibrio parahaemolyticus concentration was high (4.2×104CFU/100mL and 9×103CFU/100mL) at open sea. Cluster analysis showed grouping of stations in different tidal periods. The spatial maps clearly depicted the bacterial concentration pattern in the bay. The combined approach of multivariate analysis and spatial mapping techniques was proved to be useful in the current study.

Biogas production by encased bacteria in synthetic membranes: protective effects in toxic media and high loading rates

A bioreactor including encased digesting bacteria for biogas production was developed, and its performance in toxic media and under high organic loading rates (OLRs) was examined and compared with traditional digestion reactors. The bacteria (3 g) were encased and sealed in 3×6 cm2 PVDF (polyvinylidene fluoride) membranes with a pore size of 0.1 μm, and then several sachets were placed in the reactors. They were then examined in toxic medium containing up to 3% limonene as a model inhibitor in batch reactors, and OLRs of up to 20 g COD/L.day in semi-continuous digestions. The free and encased cells with an identical total bacterial concentration of 9 g in a medium containing 2% limonene produced at most 6.56 and 23.06 mL biogas per day, respectively. In addition, the digestion with free cells completely failed at an OLR of 7.5 g COD/L.day, while the encased cells were still fully active with a loading of 15 g COD/L.day.

Hindgut fermentation in pigs induced by diets with different sources of starch

A proportion of dietary starch reaches the hindgut, being fermented there. The characteristics of in vitro caecal fermentation and microbial community in pigs given different sources of starch were studied. Twenty-four Duroc × (Landrace × Large White) gilts given diets based on barley (B), broken rice (R), maize (M) or peas (P) (n=6) for five weeks were slaughtered with 93.6 ± 6.41 kg. No differences (p>0.10) were recorded in caecal pH, total short chain fatty acid (SCFA) and total bacterial concentration, nor in in vitro gas production from caecal contents, indicating the lack of a quantitative dietary effect on caecal environment. This could be partly due to the length of fasting time before slaughter (around 10 h). Molar SCFA proportions did not differ among diets; however, relative proportion of Lactobacillus sobrius/amylovorus as the species-type in starch digestion in hindgut of pigs, was highest with P diet (p = 0.010), and gas production from potato starch as substrate with P diet was highest at 2 h incubation (p = 0.012), and higher than B and R diets at 4 (p = 0.055) and 6 (p = 0.10) h incubation. Caecal bacterial biodiversity was higher for M and R diets than for P and B diets (Shannon index, p = 0.003). Sources of resistant or slowly digestible starch such as peas promote a microbial community with a different profile and higher capacity to ferment the starch arriving to the organ than other sources which are mostly digested in the small gut.

Characterisation of caecal microbial diversity of lactating does and their offspring given diets with different neutral detergent soluble to insoluble fibre ratios

The effect of neutral detergent soluble fibre (NDSF) to neutral detergent fibre (NDF) dietary ratio (0.29, LR and 0.43, HR) on the caecal ecosystem of lactating does and their offspring was studied. From the 17th day of lactation, each diet was given to four does, allowing for free access to their litters. Does were sampled at 17 and 28 days of lactation, and also two pups per litter at 17 (milk-fed only), 28 (milk and solid fed) and 49 days of age. DGGE was used to study bacterial caecal biodiversity, and total bacterial concentration and relative proportions of Ruminococcus albus and Butyrivibrio fibrisolvens were quantified by real time PCR. In does, diet did not affect (P > 0.10) diversity indexes, total bacterial concentration or relative abundance of B. fibrisolvens, but at 28 days of lactation the proportion of R. albus was higher with LR (interaction Diet × Time, P = 0.037). Caecal communities of pups of 17 days were grouped by litter, but the influence of the mother was reduced at 28 days with solid feed intake, and at 49 days rabbits clustered by diet. Caecal biodiversity increased from 17 to 28 days, and was reduced at 49 days (Shannon index of 3.60, 3.71 and 3.57, respectively; P = 0.049). Total bacterial concentration and relative abundance of R. albus and B. fibrisolvens increased with solid feed intake from 17 to 28 days (P < 0.01), remaining unaffected thereafter. Access of pups to solid feed from 17 days of age modulates the development and composition of the caecal microbiota at weaning.

Bacterial profile from caecal contents and soft faeces in growing rabbits given diets differing in soluble and insoluble fibre levels

To verify if non-invasive collection of soft faeces (SF) from rabbits can be used as an index of bacterial biodiversity in caecal contents (CC), 24 weaned rabbits were given diets with low (LI) and high (HI) levels of insoluble fibre (neutral detergent fibre, NDF) and low (LS) and high (HS) levels of soluble fibre (neutral detergent soluble fibre, NDSF). After 21 days, animals were fitted with neck collars for SF collection. Two days later, animals were slaughtered and CC sampled. Total bacterial concentration quantified by real time PCR (log10 ng DNA/mg DM) was higher in SF than CC (2.615 vs. 2.383). Among diets, in CC it was (P = 0.059) lowest in LILS diet, whereas in SF it decreased (P = 0.025) with the NDF level. DGGE profiles showed that structure of bacterial communities of SF was close to that of CC; however, similarity was higher in LI than HI diets (0.82 vs. 0.74). Diversity indexes in CC decreased with NDSF (P < 0.05), whereas the effect of NDF (P < 0.05) was also appreciated in SF. Soft faeces can be an alternative to surgery or slaughter techniques to monitor changes in caecal bacterial community; however, high dietary NDF may decrease similarity between both communities.

Interaction of Operational and Physicochemical Factors Leading to Gordonia amarae-Like Foaming in an Incompletely Nitrifying Activated Sludge Plant

The overgrowth of Gordonia amarae-like bacteria in the mixed liquor of an incompletely nitrifying water reclamation plant was inversely correlated with temperature (r = -0.78; P < 0.005) and positively correlated with the solids retention time (SRT) obtained a week prior to sampling (r = 0.67; P < 0.005). Drops followed by spikes in the food-to-mass ratio (0.18 to 0.52) and biochemical oxygen demand concentrations in primary effluent (94 to 298 mg liter(-1)) occurred at the initiation of G. amarae-like bacterial growth. The total bacterial concentration did not increase as concentrations of G. amarae-like cells increased, but total bacterial cell concentrations fluctuated in a manner similar to that of G. amarae-like bacteria in the pseudo-steady state. The ammonium ion removal rate (percent) was inversely related to G. amarae-like cell concentrations during accelerated growth and washout phases. The dissolved oxygen concentration decreased as the G. amarae-like cell concentration decreased. The concentrations of G. amarae-like cells peaked (2.47 × 10(9) cells liter(-1)) approximately 1.5 months prior to foaming. Foaming occurred during the late pseudo-steady-state phase, when temperature declines reversed. These findings suggested that temperature changes triggered operational and physicochemical changes favorable to the growth of G. amarae-like bacteria. Fine-scale quantitative PCR (qPCR) monitoring at weekly intervals allowed a better understanding of the factors affecting this organism and indicated that frequent sampling was required to obtain statistical significance with factors changing as the concentrations of this organism increased. Furthermore, the early identification of G. amarae-like cells when they are confined to mixed liquor (10(7) cells liter(-1)) allows management strategies to prevent foaming.

Total bacterial number concentration in free tropospheric air above the Alps

Over a period from June to October 2010, we carried out four short campaigns on the northern alpine ridge (High Altitude Research Station Jungfraujoch, 3,450 m above sea level) to determine bacterial number concentrations by collecting aerosol with liquid impingers, followed by filtration, fluorescent staining and counting with a microscope. Impinger liquid was also subjected to drop freeze tests to determine the number of ice nucleators. Parallel measurements of 222Rn enabled us to distinguish air masses with no, or little, recent land surface contact (free troposphere, 222Rn ≤ 0.50 Bq m−3) from air masses influenced by recent contact with land surface (222Rn > 0.50 Bq m−3). In free tropospheric air, concentration of total bacteria was on average 3.4 × 104 cells m−3 (SD = 0.8 × 104 cells m−3). When wind conditions preceding sampling were calm, or when the station was in clouds during sampling, there was no detectable difference in bacterial number concentrations between free tropospheric air and air influenced by recent land surface contact. One campaign was preceded by a storm. Here, recent land surface contact had enriched the air in bacterial cells (up to 7.5 × 104 cells m−3). Very few of these bacteria may act as ice nucleators in clouds. The median ratio of ice nucleators to the number of bacterial cells in our study was 1.0 × 10−5. We conclude that injection of bacterial cells into the free troposphere is an intermittent process. Conditions controlling the release of bacteria into near surface air are probably more of a limiting factor than vertical transport and mixing of near surface air into the free troposphere.

Human occupancy as a source of indoor airborne bacteria.

Exposure to specific airborne bacteria indoors is linked to infectious and noninfectious adverse health outcomes. However, the sources and origins of bacteria suspended in indoor air are not well understood. This study presents evidence for elevated concentrations of indoor airborne bacteria due to human occupancy, and investigates the sources of these bacteria. Samples were collected in a university classroom while occupied and when vacant. The total particle mass concentration, bacterial genome concentration, and bacterial phylogenetic populations were characterized in indoor, outdoor, and ventilation duct supply air, as well as in the dust of ventilation system filters and in floor dust. Occupancy increased the total aerosol mass and bacterial genome concentration in indoor air PM10 and PM2.5 size fractions, with an increase of nearly two orders of magnitude in airborne bacterial genome concentration in PM10. On a per mass basis, floor dust was enriched in bacterial genomes compared to airborne particles. Quantitative comparisons between bacterial populations in indoor air and potential sources suggest that resuspended floor dust is an important contributor to bacterial aerosol populations during occupancy. Experiments that controlled for resuspension from the floor implies that direct human shedding may also significantly impact the concentration of indoor airborne particles. The high content of bacteria specific to the skin, nostrils, and hair of humans found in indoor air and in floor dust indicates that floors are an important reservoir of human-associated bacteria, and that the direct particle shedding of desquamated skin cells and their subsequent resuspension strongly influenced the airborne bacteria population structure in this human-occupied environment. Inhalation exposure to microbes shed by other current or previous human occupants may occur in communal indoor environments.

Pengaruh Level Formalin dan Frekuensi Penambahan Litter terhadap Karakteristik Litter Ayam Broiler (The Effect of Formalin Level and Litter Addition Frequency on the Characteristics Broiler Litter)

&lt;p&gt;The research was conducted to evaluate the effect of formalin level and litter addition frequency on the broiler litter characteristics. One hundred and fifty broiler chickens were divided into 10 litter treatment with three replication&lt;br /&gt;and five chickens each. The treatments were combination level of formalin sprayed (0, 4, 8, and 12%) and frequencies of spraying (every 1, 2, and 3 weeks) on to litter (D0F0, D4F1, D4F2, D4F3, D8F1, D8F2, D8F3, D12F1, D12F2 dan D12F3). The data collected were pH, temperature, total bacterial, and ammonia concentration in the litter of broiler chicken. The results showed that level of formalin sprayed (0, 4, 8 and 12%) and frequencies of sprayed (every 1, 2, and 3 weeks)on to litter had not significantly affected litter pH (8.3; 8.7; 8.8; 9.0; 9.0; 9.2; 9.0; 9.0; 9.8 and 9.0) litter ammonia contents (317.1; 475.2; 454.5; 425.3; 218.4; 300.1; 384.0; 375.3 and 417.2 ppm) for (D0F0, D4F1, D4F2, D4F3, D8F1, D8F2, D8F3, D12F1, D12F2 dan D12F3) respectively. Litter temperature had significant differences (33.89; 32.31; 32.83; 32.58; 32.81; 32.81; 32.42; 32.28; 33.28 and 32.72 0C) and total litter of bacteria (1.7X108;&lt;br /&gt;1.1X108; 9.9X107; 1.2X108; 7.1X107; 8.5X107; 1.1X108; 4.8X107; 4.8X107; 4.9X107 and 8.2X107 CFU). It is concluded that the formalin sprayed as much as 12% to litter every 1 week (D12F1), produced the best result to reduced litter&lt;br /&gt;total bacteria, but had not decreated the ammonia litter.&lt;/p&gt;&lt;p&gt;(Key words: Broiler chicken, Formalin, Litter, Total bacteria, Ammonia)&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;

Molecular comparison of the sampling efficiency of four types of airborne bacterial samplers

In the present study, indoor and outdoor air samples were collected using four types of air samplers often used for airborne bacterial sampling. These air samplers included two solid impactors (BioStage and RCS), one liquid impinger (BioSampler), and one filter sampler with two kinds of filters (a gelatin and a cellulose acetate filter). The collected air samples were further processed to analyze the diversity and abundance of culturable bacteria and total bacteria through standard culture techniques, denaturing gradient gel electrophoresis (DGGE) fingerprinting and quantitative polymerase chain reaction (qPCR) analysis.The DGGE analysis indicated that the air samples collected using the BioStage and RCS samplers have higher culturable bacterial diversity, whereas the samples collected using the BioSampler and the cellulose acetate filter sampler have higher total bacterial diversity. To obtain more information on the sampled bacteria, some gel bands were excised and sequenced. In terms of sampling efficiency, results from the qPCR tests indicated that the collected total bacterial concentration was higher in samples collected using the BioSampler and the cellulose acetate filter sampler.In conclusion, the sampling bias and efficiency of four kinds of air sampling systems were compared in the present study and the two solid impactors were concluded to be comparatively efficient for culturable bacterial sampling, whereas the liquid impactor and the cellulose acetate filter sampler were efficient for total bacterial sampling.

Cooperative antimicrobial activity of CdTe quantum dots with rocephin and fluorescence monitoring for Escherichia coli

In this study, the cooperative antibacterial efficiency of CdTe quantum dots (QDs) and rocephin against Escherichia coli (E. coli) was investigated. Colony-forming capability assay and diameter of inhibition zone (DIZ) measurement showed the antibiotic action of CdTe QDs-rocephin complex was better than the superposition of pure CdTe QDs and rocephin. The fractional inhibitory concentration index (FICI) indicated that CdTe QDs-rocephin complex could achieve great cooperative antimicrobial effects. The infrared ray (IR) spectrum, photoluminescence (PL) spectrophotometry, and detection of reactive oxygen species (ROS) indicated that CdTe QDs and rocephin formed a stable antimicrobial group through electrostatic attraction and hydrogen bonds and then killed the E. coli together. Meanwhile, the fluorescence intensity of CdTe QDs and the optical density (OD) value of E. coli showed a good linear relationship. Thus, dynamic monitoring to total bacterial concentration in the antibacterial process was realized by the CdTe QDs.

Seasonal Difference of Airborne Bacteria and Fungi in Commuter Buses

Size distributions of aerobiological concentrations in commuter buses in northern Taiwan were examined from December 2006 until May 2007. Two six-stage (>7, 4.7–7, 3.3–4.7, 2.1–3.3, 1.1–2.1, and 0.65–1.1 μm) cascade impactors were used to collect viable bacteria and fungi. Results showed that bacterial concentrations ranged from 113 to 601 colony forming units (CFU)/m3 and averaged 282 CFU/m3. Fungal concentrations ranged from 42 to 2,193 CFU/m3 and averaged 674 CFU/m3. Additionally, the highest fractions occurred in the fourth stage (2.1–3.3 μm) for both bacteria and fungi. Respirable fractions (particles smaller than 4.7 μm in aerodynamic diameter) for bacteria and fungi were 68% and 78%, respectively, which are higher than those in other studies. The number median diameters of the total bacterial and fungal concentration were 1.67 and 2.67 μm in winter and 3.02 and 2.30 μm in spring, respectively. Airborne microorganisms are often associated with asthma, rhinitis, sick building syndrome, and hypersensitivity pneumonitis. Although total bacterial or fungal concentrations did not exceed the recommended standard (1,000 CFU/m3) in Taiwan, we found a relatively high respirable fraction in commuter buses. The relationship between bioaerosol aerodynamic diameter and a greater health risk for sensitive commuters, such as those with asthma, warrants further investigation in the future. The small sample size is a limitation in this study and the results indicated that there were no statistical significances found among bacterial/fungal concentrations, fungal respirable fraction, and seasons (p > 0.05). However, statistical significance was found between bacterial respirable fraction, the fourth fraction, and seasons (p < 0.05). Bioaerosol concentration measurements in commuter buses performed by this study provide basic information for further research on exposure assessment.

Size and seasonal distributions of airborne bioaerosols in commuting trains

Aerobiological studies in commuting trains in northern Taiwan were carried out from August, 2007 until July, 2008. Two six-stage (>7 μm, 4.7∼7 μm, 3.3∼4.7 μm, 2.1∼3.3 μm, 1.1∼2.1 μm, 0.65∼1.1 μm) cascade impactors of 400 orifices were used to collect viable bacteria and fungi, respectively. The levels of carbon monoxide (CO), carbon dioxide (CO 2), formaldehyde (HCHO), temperature, and relative humidity in the commuting trains were also recorded during the sampling period. Results show that bacterial concentrations ranged from 25 to 1530 CFU m −3, and averaged 417 CFU m −3. The fungal concentrations ranged from 45 to 1906 CFU m −3, and averaged 413 CFU m −3. Additionally, the highest fractions occurred in the fifth stage (1.1∼2.1 μm) for both bacteria and fungi. The respirable fractions, R b and R f, for bacteria and fungi were 62.8% and 81.4%, respectively, which are higher than those in other studies. Furthermore, the bacterial concentration reached its highest level in autumn, and its lowest level in winter. However, the fungal concentration was highest in spring and lowest in winter. Though the total bacterial or fungal concentration did not exceed the recommendation standard in Taiwan, the relatively high respirable fraction in commuting trains probably implies a higher adverse health risk for sensitive commuters. This study further conducted multiple regression analysis to determine the relationship of various stage fractions of airborne bacteria and fungi with indoor air pollutants (CO and HCHO) and environmental parameters (CO 2, temperature, and relative humidity). The correlation coefficients of multiple regression analysis for total bacteria and fungi concentrations with indoor air pollutants and environmental parameters were 0.707 ( p < 0.00376) and 0.612 ( p < 0.00471), respectively. There are currently no formally regulated laws for indoor air quality (IAQ) in Taiwan, and this preliminary study can provide references to the Taiwan government on IAQ management.

Trends in Antibiotic Resistance Genes Occurrence in the Haihe River, China

The occurrence of antibiotics and antibiotic resistance genes (ARGs) was quantified in water and sediment samples collected from a 72 km stretch of the Haihe River, China. Tetracycline resistance genes (tetW, tetQ, tetO, tetT, tetM, tetB, and tetS) were not detected by quantitative PCR in many samples. In contrast, sul1 and sul2 (coding for sulfonamide resistance) were present at relatively high concentrations in all (38) samples. The highest ARG concentrations detected were (7.8 ± 1.0) × 10(9) copies/g for sul1 and (1.7 ± 0.2) × 10(11) copies/g for sul2, in sediment samples collected during the summer. The corresponding total bacterial concentration (quantified with a universal 16S-rDNA probe) was (3.3 ± 0.4) × 10(12) cells/g. Sul1 and sul2 concentrations in sediments were 120-2000 times higher than that in water, indicating that sediments are an important ARG reservoir in the Haihe River. Statistical analysis indicated a positive correlation between the relative abundance of these ARGs (i.e., sul1/16S-rDNA and sul2/16S-rDNA) and the total concentration of sulfamethoxazole, sulfadiazine, plus sulfachlororyridazine, suggesting that sulfonamides exerted selective pressure for these ARGs. A class 1 integron was implicated in the propagation of sul1. Overall, the widespread distribution of sulfonamide ARGs underscores the need to better understand and mitigate their propagation in the environment and the associated risks to public health.

Assessment of Bacterial and Fungal Aerosol in Different Residential Settings

The concentration and size distribution of bacterial and fungal aerosol was studied in 15 houses. The houses were categorized into three types, based on occupant density and number of rooms: single room in shared accommodation (type I), single bedroom flat in three storey buildings (type II) and two or three bedroomed houses (type III). Sampling was undertaken with an Anderson six-stage impactor during the summer of 2007 in the living rooms of all the residential settings. The maximum mean geometric concentration of bacterial (5,036 CFU/m3, ± 2.5, n = 5) and fungal (2,124 CFU/m3, ± 1.38, n = 5) aerosol were in housing type III. The minimum levels of indoor culturable bacteria (1,557 CFU/m3, ±1.5, n = 5) and fungal (925 CFU/m3, ±2.9, n = 5) spores were observed in housing type I. The differences in terms of total bacterial and fungal concentration were less obvious between housing types I and II as compared to type III. With reference to size distribution, the dominant stages for culturable bacteria in housing types I, II and III were stage 3 (3.3–4.7 μm), stage 1 (7 μm and above) and stage 5 (1.1–2.1 μm), respectively. Whereas the maximum numbers of culturable fungal spores were recovered from stage 2 (4.7–7 µm), in housing type I, and from stage 4 (2.1–3.3 μm) in both type II and III houses. The average geometric mean diameter of bacterial aerosol was largest in type I (4.7 μm), followed by type II (3.89 μm) and III (1.96 μm). Similarly, for fungal spores, type I houses had the highest average mean geometric diameter (4.5 μm), while in types II and III the mean geometric diameter was 3.57 and 3.92 μm, respectively. The results indicate a wide variation in total concentration and size of bioaerosols among different residential settings. The observed differences in the size distributions and concentrations reflect their variable airborne behaviour and, as a result, different risks of respiratory exposure of the occupants to bioaerosols in various residential settings.

Set up of a newin vitromodel to study dietary fructans fermentation in formula-fed babies

A new in vitro fermentation model with immobilised infant faecal microbiota simulating the proximal colon of a formula-fed baby was developed and used to test the effects of known prebiotic fructans. Intestinal fermentation, based on a previously developed colonic fermentation model, using a new feeding medium simulating a formula-fed infant ileal chyme, was carried out for seventy-one consecutive days divided into four stabilisation periods intercalated with four prebiotic treatment periods. At the end of the first stabilisation period, total bacterial concentration in colonised beads and in faecal sample was similar, metabolite concentrations returned to stabilisation values after each treatment period. As expected, the four prebiotic treatments significantly increased the bifidobacterial populations, whereas they decreased bacteroides and clostridia. No difference was observed in the prebiotic effect of these substrates selected. The treatments significantly increased total production of SCFA and decreased ammonia compared to stabilisation periods. Long-term stability of the system together with the reproducibility of the known prebiotic effects highlights the potential of the present model to quantify and compare the effects of different substrates in a formula-fed infant microbiota within the same fermentation experiment.

Bioaerosols as contributors to poor air quality in Taichung City, Taiwan

Bioaerosols are a type of suspended sediments that contribute to poor air quality in Taiwan. Bioaerosols include allergens such as: fungi, bacteria, actinomycetes, arthropods and protozoa, as well as microbial products such as mycotoxins, endotoxins and glucans. When allergens and microbial products are suspended in the air, local air quality will be influenced adversely. In addition, when the particle size is small enough to pass through the respiratory tract entering the human body, the health of the local population is also threatened. Therefore, the purpose of this study is to attempt to understand the concentration and types of bacteria and the bacteria numbers for various particle size ranges during a study period of June 2005 to February 2006 in Taichung City, Central Taiwan. The results indicate that the total average bacterial concentration by using NA medium incubated for 48 h were 8.0 x 10(2), 1.4 x 10(3), 2.4 x 10(3) and 1.3 x 10(3), 1.9 x 10(3), 3.5 x 10(3) cfu/m(3) for CMES, TRIPS and RFS sampling sites during the daytime and nighttime period of June 2005 to February 2006. Moreover, the total average bacterial concentration by using R(2)A medium incubated for 48 h were 8.5 x 10(2), 1.5 x 10(3), 2.2 x 10(3) and 1.2 x 10(3), 1.7 x 10(3), 2.5 x 10(3) cfu/m(3) for CMES, TRIPS and RFS sampling sites the daytime and nighttime during the same sampling period. The total average bacteria concentration was the same in either NA or R(2)A medium for the same sampling times or sites. The total average bacterial concentration was higher in daytime period than that of nighttime period for CMES, TRIPS and RFS sampling sites. The high average bacterial concentration was found in the particle size range of 0.53-0.71 mm (average bioaerosol size was in the range of 2.1-4.7 microm) for each sampling site. Also, 20 kinds of bacteria exceeded levels for each sampling site and were classified as according to shape: rod, coccus and filamentous.

Exposure to culturable airborne bioaerosols during noodle manufacturing in central Taiwan

Biological hazards associated with the manufacturing of noodles have not been well characterized in Taiwan. This is an issue that flour workers can be exposed to bioaerosols (airborne fungi and bacteria) resulting flour-induced occupational asthma or allergic diseases. This study is to survey the species and concentrations of bioaerosols at different sites within a noodle factory for one year, and to investigate the effects of environmental factors on concentrations of bioaerosols. Air samples were taken twice a day, one day each month using a MAS-100 bioaerosol sampler. Nine species of culturable fungi were identified, with the main airborne fungi being Cladosporium, Penicillium, Aspergillus spp., non-sporing isolates and yeasts. Cladosporium, Penicillium and Aspergillus were the dominant fungal isolates in the indoor and outdoor air samples. Micrococcus spp. and Staphylococcus xylosus were the dominant bacterial isolates. Peak fungal and bacterial concentrations occurred at the crushing site, with mean values of 3082 and 12,616 CFU/m 3. Meanwhile, the most prevalent fungi and bacteria at the crushing site were in ranges of 2.1–1.1 μm and 1.1–0.65 μm, respectively. Significant seasonal differences in total bacterial concentration were observed at all sampling sites (⁎ P < 0.05). Moreover, significant seasonal differences were observed for most of the fungal genera except Fusarium. Levels of Aspergillus and Rhizopus differed significantly during the two sampling times, as did levels of Micrococcus spp. and Staphylococcus arlettae. Regarding the same operation procedures, relative humidity affected fungi levels more than temperature did. However, crushing generated the highest concentration of bioaerosols among all operation procedures. Furthermore, levels of bacteria at sites fitted with ventilation systems were lower than at sites without ventilation systems, especially at the crushing site. Therefore, we recommend these workers at the crushing site wear breathing protection and improve the local ventilation systems to minimize the biological hazards.

Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor

Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index ( H) and Species evenness ( E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the β-Proteobacteria group, then γ-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with γ-Proteobacteria, then β-Proteobacteria and CFB. Shannon's index ( H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness ( E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 × 10 5 μg/μl, twice that in ASR of 4.67 × 10 5 μg/μl under normal operation of two reactors. But the MLSS in GCOR was only 4.5 mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa both in GCOR (15 no. per 20 ml) and in ASR (15 no. per 20 ml); the next abundant group was attachment plants 10 no. per 20 ml in GCOR and 4 no. per 20 ml in ASR, respectively. Rotifers and copepoda belonging to metazoan were only present in GCOR (8 no. per 20 ml for both rotifers and copepoda). The microbial diversity and population difference both in the GCOR carriers and ASR sludge indicated that the diverse microbes, a large amount of biomass forming longer microbial food chains attached on the carriers may be the main functions for the excess sludge reduction in GCOR.