Effects of developmental stage,cold acclimation and diet on the cold tolerance of three species of Cryptolestes (Coleoptera: Laemophloeidae)

Flat grain beetles (Coleoptera: Laemophloeidae) are common stored-product insect pests in Canada, infesting cereals in grain bins, equipment and end products in flour mills. We studied the cold tolerance of the three most common flat grain beetles: Cryptolestes ferrugineus, Cryptolestes turcicus and Cryptolestes pusillus, by measuring the survival at −10 °C and supercooling point (SCP) for different life stages (egg, young larva, old larva, pupa and adult) reared on flour mixed with brewer’s yeast. Probit analysis was used to estimate the lethal time for 50 and 95% mortality. This was done with non-acclimated individuals (only held at 30 °C) or cold-acclimated individuals (held at 18, 10 and 5 °C, for 1 week/temperature). In general, adults were the most cold-hardy stage for each of the species. Acclimated insects were anywhere from no increase in cold tolerance to 14-fold more cold-tolerant than the corresponding non-acclimated stage and species. Cryptolestes ferrugineus was most cold-tolerant species (58 d at −10 °C to reach 95% mortality for acclimated adult), C. turcicus was the next most cold-tolerant, (39 d) and C. pusillus was the least cold-tolerant (11 d). The cold tolerance of adults reared on three diets was measured both for acclimated and non-acclimated insects. The adults reared on grain diet (whole wheat kernels, cracked wheat kernels and wheat germ (90:5:5 mass ratio) were the most cold-tolerant, adults reared on white-wheat flour and brewer’s yeast diet (95:5 mass ratio) had the next highest cold tolerance followed by the adults reared on 100% white-wheat flour. Supercooling point (SCP) of insects ranged from −20.6 to −26.7 °C. In general, acclimated insects had slightly lower SCP than non-acclimated insects.     

Simulation of bioremediation of chlorophenols in a sandy aquifer

Bioremediation of consecutive spills of phenol, 2-chlorophenol (2-MCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlororphenol as single pollutants was investigated in eight pilot plant scale sand columns system (100 cm l, 6 cm ID), simulating the conditions, which could be created in the saturated zone of a pristine aquifer following an accidental spill. Bioremediation in this study consisted of re-circulating local groundwater through the polluted site in a controlled manner following a closed-loop configuration. Intrinsic microbial development was enhanced by adding the necessary nutrients. Consecutive accidental spills of 480-mg phenol/kg soil; 140-mg 2-MCP/kg; 14-mg 2,4,6-TCP/kg soil and 17-mg pentachlorophenol (PCP)/kg soil under saturated conditions and a continuous specific discharge of 0.56 cm min(-1) were simulated. Degradation curves demonstrated first-order kinetics. Biodegradation rates (k1) were influenced by consecutive exposures. Calculated rate constants for biodegradation for sole substrate experiments were in the range of 0.06-0.15 day(-1), 0.21-1.20 day(-1), 0.04-2.28 day(-1) and 0.01-0.03 day(-1) for phenol, 2-MCP, 2,4,6-TCP and PCP, respectively. The acclimation of the aquifer to simulated consecutive accidental spills was found to be directly proportional to the cumulative load of each single chlorophenol. A relationship between the octanol water partitioning (Kow) values and the experimental degradation rates (k1) was found.     

无介体MFC微生物催化剂的“独立驯化”与“在线驯化”结合研究

采用独立驯化和在线驯化相结合的新颖方式,以碳毡、碳布和碳纸为阳极挂膜材料,考察驯化方式和阳极材料对无介体微生物燃料电池(MFC)产电性能和有机物去除效果的影响.结果表明,独立驯化期阳极材料特性对微生物挂膜的影响较大,扫描电镜结果表明挂膜效果最好的是碳毡,碳布次之,碳纸较差;在线驯化约10 h后,微生物催化剂的电化学活性显著升高,第2个周期电压达到峰值(碳毡、碳布、碳纸的峰电压分别为0.803、0.604和0.574 V),第3个周期MFC能长时间稳定运行,其中,碳毡MFC电压平台维持在0.78 V左右长达180 h;比较MFCs的产电能力优劣顺序为:碳毡(1 339.6 mW/m3)＞碳纸(96.8 mW/m3)＞碳布(80 mW/m3);COD去除率为:碳毡(89.5%)＞碳纸(79%)＞碳布(74.7%).     

Role of Tannin-Binding Salivary Proteins and Tannase-Producing Bacteria in the Acclimation of the Japanese Wood Mouse to Acorn Tannins

We studied the defense mechanisms against the negative effects of tannins in acorns by using the Japanese wood mouse (Apodemus speciosus) and acorns of a Japanese deciduous oak Quercus crispula, which contain 9.9% tannins on a dry weight basis. For the experiment, we allocated 26 wood mice into two groups: acclimated (N = 12) and nonacclimated (N = 14). Mice in the nonacclimated group were fed only acorns for 10 d after 4 wk of receiving a tannin-free diet. In contrast, mice in the acclimated group received ca. 3 g acorns daily in addition to the tannin-free diet for the first 4 wk, then they were fed only acorns for 10 d. Body weight, food intake, and digestibility were monitored. In addition, the amount of salivary proline-rich proteins (PRPs) and abundance of tannase-producing bacteria (TPB) in the feces of mice were measured. Of the 14 mice in the nonacclimated group, 8 died, whereas only 1 of the 12 in the acclimated group died. During the first 5 d of feeding acorns only, mice in the nonacclimated group lost, on average, 17.5% of their body mass, while those in the acclimated group lost only 2.5%. Food intake, dry matter digestibility, and nitrogen digestibility were higher in the acclimated group than in the nonacclimated group. The results indicate that wood mice can mitigate the negative effects of tannins by acclimation. Path analysis revealed that increased secretion of PRPs and abundance of Lactobacillus type of TPB might explain the acclimation to tannins.     

Improving microbial electrolysis stability using flow-through brush electrodes and monitoring anode potentials relative to thermodynamic minima

Graphite fiber brush electrodes are commonly used in microbial electrolysis cells (MECs) for simultaneous wastewater treatment and electrochemical hydrogen production. Previous brush anode designs for continuous flow systems were configured to have flow over an array of brush electrodes. Here we compared the performance of two systems, one with flow through a single smaller or larger brush anode to an MEC with multiple brushes. The single brush MECs had only a single large brush that had a diameter larger than the chamber height, so that the brush fibers were compressed to nearly (4.5 cm diameter) or completely (5.5 cm diameter) fill the 1.3 cm high anode chamber. To evaluate the time needed for acclimation of the anode potentials were continuously monitored for 138 d (4.5 cm brush) or 143 d (5.5 cm brush). The best performance was obtained using the 5.5 cm brush fibers with a volumetric current density of 554 ± 26 A/m³, compared to <400 A/m³ when using the smaller 4.5 cm brush or the multiple brush reactor. Full acclimation was shown by a consistent and low anode potential, for example by ?248 ± 8 mV (vs. a standard hydrogen electrode) for the 5.5 cm brush, which was only 31 ± 8 mV above the minimum estimated for acetate oxidation under standard biological conditions. These results show that brush compression into a smaller chamber can enhance MEC performance and produce anode potentials close the thermodynamic minima.     

Effects of shock loading versus stepwise acclimation on microbial consortia during the anaerobic digestion of glycerol

Sludge from a brewery was used to produce methane by feeding glycerol (propane-1,2,3-triol) at an organic loading rate (OLR) of Chemical Oxygen Demand (COD) at 2.5 g L⁻¹ d⁻¹. Results from two different substrate-feeding approaches were compared: one was the shock loading of glycerol (Run A) and other was a gradual increase in the glycerol amount in a mixture with other carbon sources including glucose, sodium acetate, and lactate (Run B). Methane production rate was similar for both experiments (approximately 21 mmol L⁻¹ d⁻¹). Dominant bacteria in Run A were closely related to Mesotoga sp., Alkalibacter sp., and Garciella sp., while the dominant bacteria in Run B were closely related to Trichococcus sp. Dominant archaea were similar for both experiments and were closely related to Methanosaeta sp. and Methanobacterium sp. From these results, it was confirmed that the microbial consortium, especially the bacterial consortium, was strongly dependent on the feeding approach of the glycerol in the anaerobic digestion system.     

活性污泥的培养、驯化和生物膜挂膜

废水生物处理工艺经确定并设计建造投入运行时,首先要培养活性污泥,并经驯化后使之能适应不同的工业废水。对膜法处理系统须进行活性污泥挂膜。介绍了活性污泥的培养、驯化和生物膜挂膜的常用方法。     

Exposure of the marine deposit feeder Hydrobia ulvae to sediment spiked with LAS congeners

The lethal and sub-lethal toxicity of LAS congeners to the mollusc gastropod Hydrobia ulvae were assessed in spiked sediment bioassays. This complements the little knowledge available to date on mixture effects in the sediment compartment. The LAS homologues joint effect was concentration additive (∑TU_i = 0.8-1). As opposed to the 10-d LC10 based on the sediment associated LAS concentration (91-330 mg/kg) which was independent of the homologue chain length, the LC10 based on the dissolved LAS fraction (0.804-0.068 mg/L) decreased as the homologue chain length increased from 10 to 13 carbons. The quantitative structure-activity relationship (QSAR) derived from these data was log (1/LC10 (mol/L)) = 0.64 log K_ow + 4.40 (n = 5; r² = 0.76; s = 0.24). It showed an apparent higher toxicity compared to the typical QSAR for polar narcosis in water-only systems probably due to the simultaneous exposure of the snail to LAS through the dissolved and the sediment associated fractions. The egestion rate of the surviving snails recovered after few days' exposure (1-d NOEC: 40-107 mg/kg, 9-d NOEC: 65-190 mg/kg) which suggests that the organisms were able to acclimate to LAS during the exposure.     

Extreme Adaptation to Extreme Environments in Hot Dry,Hot Sub-humid and Hot Humid Climates in Mexico

The paper discusses the results of a field study carried out in four cities in Mexico： Hermosillo, Mexicali, Merida and Colima, during the warmest seasons of 2006-2007. The survey is according to the adaptive approach of thermal comfort. The cities＇ climates are hot dry, hot sub-humid and hot humid. The respondents were inhabitants of low cost housings without air conditioning. The research was performed during warm seasons and according to ISO 10551. The measurements were processed by the common method of linear regression and also by alternative methods, useful for asymmetric climates. Individuals declared comfort at very high temperatures, either high or low humidity, therefore, the resulting neutral temperatures are higher than 30 ℃, except in Colima （28.8 ℃）. The upper limits of comfort ranges achieved temperatures up to 35 ℃. The results suggest how great is the capacity of humans to adapt to conditions as extreme as those measured in the study.