A two‐phase partitioning airlift bioreactor for the treatment of BTEX contaminated gases

This investigation characterizes a novel 11 L airlift two‐phase partitioning bioreactor (TPPB) for the treatment of gases contaminated with a mixture of benzene, toluene, ethylbenzene, and o‐xylene (BTEX). The application of the TPPB technology in an airlift bioreactor configuration provides a novel technology that reduces energy intensity relative to traditional stirred tank TPPB configurations. The addition of a solid second phase of silicone rubber beads (10%, v/v) or of a liquid second phase of silicone oil (10%, v/v) resulted in enhanced performance of the airlift bioreactor relative to the single phase case, with 20% more BTEX being removed from the gas phase during an imposed transient loading. During a 4 h loading step change of three times the nominal loading (60 g m^?3 h^?1), overall removal efficiencies for the airlift TPPBs containing a liquid or solid phase remained above 75%, whereas the single phase airlift had an overall removal efficiency of 47.1%. The airlift TPPB containing a silicone rubber second phase was further characterized by testing performance during steady‐state operation over a range of loadings and inlet gas flow rates in the form of a 3² factorial experimental design. Optimal operating conditions that avoid oxygen limitations and that still have a slow enough gas flow rate for sufficient BTEX transfer from the gas phase to the working volume are identified. The novel solid–liquid airlift TPPB reduces energy inputs relative to stirred tank designs while being able to eliminate large amounts of BTEX during both steady‐state and fluctuating loading conditions. Biotechnol. Bioeng. 2009;103: 1077–1086. © 2009 Wiley Periodicals, Inc.     

Addressing biofilter limitations: A two-phase partitioning bioreactor process for the treatment of benzene and toluene contaminated gas streams

A two-phase partitioning bioreactor (TPPB) achievedsimultaneous and continuous removal and degradation of benzene and toluene froman air stream. The aqueous-organic system utilized n-hexadecane as the organicphase, and the organism Alcaligenes xylosoxidans Y234 in the aqueous phaseto achieve the degradation of benzene and toluene. The system, which operates asa well-mixed dispersion and is therefore resistant to substrate surges, was firstshown to be capable of utilizing toluene while operating at a loading capacity of 235 g m^-3 h^-1with an elimination capacity of 233 g m^-3 h^-1. It was also determined that to characterize TPPB performance in terms of elimination capacity thedefinition of elimination capacity must be extended to include the cell mass present, a readilycontrollable variable given the nature of the system. Based on this criterion, it wasestimated that for a cell concentration of 1 g l^-1 present in the TPPB, thepotential maximum toluene elimination capacity is 1290 g m^-3 h^-1 whichis substantially higher than any toluene elimination capacity achieved by biofiltersat a high removal efficiency. If no other factor were to limit the system, eliminationcapacities could be many times higher still, and are dependent on maintaining desiredcell concentrations above 1 g l^-1. The TPPB was then operated at nominalloading capacities of 63 g m^-3h^-1 (benzene) and 51 g m^-3 h^-1 (toluene) at a removal efficiency greater than 99% to demonstratedthe applicability of this system in dealing with two chemical species simultaneously. TPPBsystems therefore have been shown to be effective at removing gaseous organiccontaminants at high removal efficiencies while also possessing desirable operatingfeatures, such as providing and maintaining high cell concentrations throughout thereactor, and a capacity to effectively deal with high contaminant loadings.     

A strategic approach for the design and operation of two‐phase partitioning bioscrubbers for the treatment of volatile organic compounds

A strategic approach for the design of two‐phase partitioning bioscrubbers (TPPBs) has been formulated using, as a basis, a re‐evaluation of extensive literature data available for the degradation of benzene by Achromobacter xylosoxidans Y234 in TPPBs with n‐hexadecane as the partitioning phase. Using a previously determined maintenance coefficient for benzene, we determined that an inlet benzene loading rate of 100 mg/h requires 5,928 mg cell mass at biological steady state and 243.0 mg O₂/h. The total oxygen‐transfer rates (TOTRs) into the TPPB increased by 83.5% with 33.3% of organic phase compared with a single aqueous phase and were significantly influenced by gas flow rate, whereas agitation has a minor affect. The fraction of organic phase used was suggested to be the primary parameter with which the TOTR into the TPPB may be altered. Although the presence of an organic solvent in the TPPB remarkably increased the TOTR, the total benzene transfer rate into the TPPB remained largely insensitive due to the intrinsic low Henry's law constant (or relatively high solubility) of benzene in water. Finally, we have integrated the elements of this analysis into a set of heuristic criteria that can serve as a guideline for the design of TPPB systems for future volatile organic compound treatment applications. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Estimating the cellular maintenance coefficient and its use in the design of two-phase partitioning bioscrubbers

One of the key roles of an organic solvent has emerged to be the enhancement of oxygen transfer in two-phase partitioning bioscrubbers (TPPBs). In order to determine an optimum organic fraction for a given VOCs loading, the oxygen demand of the total cell mass must be estimated, which depends upon the magnitude of the cellular maintenance coefficient. We have estimated the dynamics of the maintenance coefficient for benzene degradation by Achromobacter xylosoxidans Y234 in a TPPB and found that the maintenance coefficient generally decreased as cells accumulated in the TPPB but converged to a specific value of 1.750 × 10⁻² h⁻¹ at biological steady state. Due to its important influence on all of the essential design parameters of the TPPB system, including optimum organic fraction, aeration rate and agitation speed, the maintenance coefficient should be considered as a key biological determinant for microorganism selection, as well as in overall TPPB design.     

Enhanced Degradation of a Mixture of Polycyclic Aromatic Hydrocarbons by a Defined Microbial Consortium in a Two-Phase Partitioning Bioreactor

Biological treatment methods are effective at destroying polycyclic aromatic hydrocarbons (PAHs), and some of the highest rates of PAH degradation have been achieved using two-phase-partitioning bioreactors (TPPBs). TPPBs consist of a cell-containing aqueous phase and a biocompatible and immiscible organic phase that partitions toxic and/or recalcitrant substrates to the cells based on their metabolic demand and on maintaining the thermodynamic equilibrium of the system. In this study, the degradation of a 5-component mixture of high and low molecular weight PAHs by a defined microbial consortium of Sphingomonas aromaticivorans B0695 and Sphingomonas paucimobilis EPA505 in a TPPB was examined. The extremely low aqueous solubilities of the high molecular weight (HMW) PAHs significantly reduce their bioavailability to cells, not only in the environment, but in TPPBs as well. That is, in the two-phase system, the originally selected solvent, dodecane, was found to sequester the HMW PAHs from the cells in the aqueous phase due to the inherent high solubility of the hydrophobic compounds in this solvent. To circumvent this limitation, the initial PAH concentrations in dodecane were increased to sufficient levels in the aqueous phase to support degradation: LMW PAHs (naphthalene, phenanthrene) and fluoranthene were degraded completely in 8 h, while the HMW PAHs, pyrene and benzo[a]pyrene, were degraded by 64% and 11%, at rates of 42.9 mg l⁻¹ d⁻¹ and 7.5 mg l⁻¹ d⁻¹, respectively. Silicone oil has superior PAH partitioning abilities compared to dodecane for the HMW PAHs, and was used to improve the extent of degradation for the PAH mixture. Although silicone oil increased the bioavailability of the HMW PAHs and greater extents of biodegradation were observed, the rates of degradation were lower than that obtained in the TPPB employing dodecane.     

Enhanced biodegradation of phenol by a microbial consortium in a solid–liquid two phase partitioning bioreactor

Two phase partitioning bioreactors (TPPBs) operate by partitioning toxic substrates to or from an aqueous, cell-containing phase by means of second immiscible phase. Uptake of toxic substrates by the second phase effectively reduces their concentration within the aqueous phase to sub-inhibitory levels, and transfer of molecules between the phases to maintain equilibrium results in the continual feeding of substrate based on the metabolic demand of the microorganisms. Conventionally, a single pure species of microorganism, and a pure organic solvent, have been used in TPPBs. The present work has demonstrated the benefits of using a mixed microbial population for the degradation of phenol in a TPPB that uses solid polymer beads (comprised of ethylene vinyl acetate, or EVA) as the second phase. Polymer modification via an increase in vinyl acetate concentration was also shown to increase phenol uptake. Microbial consortia were isolated from three biological sources and, based on an evaluation of their kinetic performance, a superior consortium was chosen that offered improved degradation when compared to a pure strain of Pseudomonas putida ATCC 11172. The new microbial consortium used within a TPPB was capable of degrading high concentrations of phenol (2000mgl^–1), with decreased lag time (10h) and increased specific rate of phenol degradation (0.71g phenolg^–1cellh). Investigation of the four-member consortium showed that it consisted of two Pseudomonas sp., and two Acinetobacter sp., and tests conducted upon the individual isolates, as well as paired organisms, confirmed the synergistic benefit of their existence within the consortium. The enhanced effects of the use of a microbial consortium now offer improved degradation of phenol, and open the possibility of the degradation of multiple toxic substrates via a polymer-mediated TPPB system.     

Modeling of crude oil biodegradation using two phase partitioning bioreactor

In this work, crude oil biodegradation has been optimized in a solid‐liquid two phase partitioning bioreactor (TPPB) by applying a response surface methodology based d ‐optimal design. Three key factors including phase ratio, substrate concentration in solid organic phase, and sodium chloride concentration in aqueous phase were taken as independent variables, while the efficiency of the biodegradation of absorbed crude oil on polymer beads was considered to be the dependent variable. Commercial thermoplastic polyurethane (Desmopan®) was used as the solid phase in the TPPB. The designed experiments were carried out batch wise using a mixed acclimatized bacterial consortium. Optimum combinations of key factors with a statistically significant cubic model were used to maximize biodegradation in the TPPB. The validity of the model was successfully verified by the good agreement between the model‐predicted and experimental results. When applying the optimum parameters, gas chromatography‐mass spectrometry showed a significant reduction in n‐alkanes and low molecular weight polycyclic aromatic hydrocarbons. This consequently highlights the practical applicability of TPPB in crude oil biodegradation. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:797–805, 2014     

Phosphonium ionic liquids for degradation of phenol in a two-phase partitioning bioreactor

Six ionic liquids (ILs), which are organic salts that are liquid at room temperature, were tested for their biocompatibility with three xenobiotic-degrading bacteria, Pseudomonas putida, Achromobacter xylosoxidans, and Sphingomonas aromaticivorans. Of the 18 pairings, seven were found to demonstrate biocompatibility, with one IL (trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl) amide) being biocompatible with all three organisms. This IL was then used in a two-phase partitioning bioreactor (TPPB), consisting of 1 l aqueous phase loaded with 1,580 mg phenol and 0.25 l IL, inoculated with the phenol degrader P. putida. This initially toxic aqueous level of phenol was substantially reduced by phenol partitioning into the IL phase, allowing the cells to utilize the reduced phenol concentration. The partitioning of phenol from the IL to the aqueous phase was driven by cellular demand and thermodynamic equilibrium. All of the phenol was consumed at a rate comparable to that of previously used organic-aqueous TPPB systems, demonstrating the first successful use of an IL with a cell-based system. A quantitative ³¹P NMR spectroscopic assay for estimating the log P values of ILs is under development.     

Dynamic simulation of benzene vapor treatment by a two-phase partitioning bioscrubber: Part II: Model calibration,validation, and predictions

The two-phase partitioning bioscrubber (TPPB) model presented in Part I has been validated using experimental data under constant and transient operating conditions for the treatment of benzene waste gases by Achromobacter xylosoxidans Y234 with n-hexadecane as an immiscible, organic phase. Model calibration was performed to account for observed enhancements of benzene biodegradation rates in biphasic media, postulating that direct benzene uptake from dispersed organic droplets increased substrate bioavailability. This led to the use of an ‘effective dissolved substrate concentration’ to model cell specific growth rates. Model predictions were greatly improved using this empirical modification. The characteristics of the organic phase, both in terms of the volume fraction selected and its high equilibrium solubility, are found to be of critical importance for minimizing effluent gas VOC concentrations and stabilizing performance during transient operation. The biokinetic parameters μ_max and K_S are also particularly important, greatly influencing the response of the TPPB both during and while recovering from transient periods. K_S was found to be important for influencing steady-state benzene removal efficiencies under even invariant operation, leading to the conclusion that microorganisms which can maintain high rates of biological activity under very dilute substrate concentrations will make ideal biocatalysts in the TPPB.     

Biodegradation of a phenolic mixture in a solid–liquid two-phase partitioning bioreactor

A solid–liquid two-phase partitioning bioreactor (TPPB) in which the non-aqueous phase consisted of polymer (HYTREL) beads was used to degrade a model mixture of phenols [phenol, o-cresol, and 4-chlorophenol (4CP)] by a microbial consortium. In one set of experiments, high concentrations (850 mg l⁻¹ of each of the three substrates) were reduced to sub-inhibitory levels within 45 min by the addition of the polymer beads, followed by inoculation and rapid (8 h) consumption of the total phenolics loading. In a second set of experiments, the beneficial effect of using polymer beads to launch a fermentation inhibited by high substrate concentrations was demonstrated by adding 1,300 and 2,000 mg l⁻¹ total substrates (equal concentrations of each phenolic) to a pre-inoculated bioreactor. At these levels, no cell growth and no degradation were observed; however, after adding polymer beads to the systems, the ensuing reduced substrate concentrations permitted complete destruction of the target molecules, demonstrating the essential role played by the polymer sequestering phase when applied to systems facing inhibitory substrate concentrations. In addition to establishing alternative modes of TPPB operation, the present work has demonstrated the differential partitioning of phenols in a mixture between the aqueous and polymeric phases. The polymeric phase was also observed to absorb a degradation intermediate (arising from the incomplete biodegradation of 4CP), which opens the possibility of using solid–liquid TPPBs during biosynthetic transformation to sequester metabolic byproducts.     

Transformation of ferulic acid to vanillin using a fed‐batch solid–liquid two‐phase partitioning bioreactor

Amycolatopsis sp. ATCC 39116 (formerly Streptomyces setonii) has shown promising results in converting ferulic acid (trans‐4‐hydroxy‐3‐methoxycinnamic acid; substrate), which can be derived from natural plant wastes, to vanillin (4‐hydroxy‐3‐methoxybenzaldehyde). After exploring the influence of adding vanillin at different times during the growth cycle on cell growth and transformation performance of this strain and demonstrating the inhibitory effect of vanillin, a solid–liquid two‐phase partitioning bioreactor (TPPB) system was used as an in situ product removal technique to enhance transformation productivity by this strain. The thermoplastic polymer Hytrel^® G4078W was found to have superior partitioning capacity for vanillin with a partition coefficient of 12 and a low affinity for the substrate. A 3‐L working volume solid–liquid fed‐batch TPPB mode, using 300 g Hytrel G4078W as the sequestering phase, produced a final vanillin concentration of 19.5 g/L. The overall productivity of this reactor system was 450 mg/L. h, among the highest reported in literature. Vanillin was easily and quantitatively recovered from the polymers mostly by single stage extraction into methanol or other organic solvents used in food industry, simultaneously regenerating polymer beads for reuse. A polymer–liquid two phase bioreactor was again confirmed to easily outperform single phase systems that feature inhibitory or easily further degraded substrates/products. This enhancement strategy might reasonably be expected in the production of other flavor and fragrance compounds obtained by biotransformations. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:207–214, 2014     

Degradation of polycyclic aromatic hydrocarbons in soil by a two-step sequential treatment

The objectives of this work were to isolate the microorganisms responsible for a previously observed degradation of polycyclic aromatic hydrocarbons (PAH) in soil and to test a method for cleaning a PAH-contaminated soil. An efficient PAH degrader was isolated from an agricultural soil and designated as Mycobacterium LP1. In liquid culture, it degraded phenanthrene (58%), pyrene (24%), anthracene (21%) and benzo(a)pyrene (10%) present in mixture (initial concentration 50 μg ml⁻¹ each) and phenanthrene (92%) and pyrene (94%) as sole carbon sources after 14 days of incubation at 30°C. In soil, Mycobacterium LP1 mineralised ¹⁴C-phenanthrene (45%) and ¹⁴C-pyrene (65%) after 10 days. The good ability of this Mycobacterium was combined with the benzo(a)pyrene oxidation effect obtained by 1% w/w rapeseed oil in a sequential treatment of a PAH-spiked soil (total PAH concentration 200 mg kg⁻¹). The first step was incubation with the bacterium for 12 days and the second step was the addition of the rapeseed oil after this time and a further incubation of 22 days. Phenanthrene (99%), pyrene (95%) and anthracene (99%) were mainly degraded in the first 12 days and a total of 85% of benzo(a)pyrene was transformed during the whole process. The feasibility of the method is discussed.     

Life history parameters for Nesidiocoris tenuis (Reuter) (Het., Miridae) under different temperature regimes

The development time for eggs and nymphs and female fertility were determined for Nesidiocoris tenuis Reuter (Het., Miridae: Dicyphini) at 15, 20, 25, 30, 35 and 40 ± 1°C, using tomato, Solanum esculentum (Miller), as substrate and eggs of Ephestia kuehniella Zeller as substitute prey. At 40°C, N. tenuis was unable to develop and barely reproduced. Egg development ranged from 30.8 days at 15°C to 6.3 days at 35°C. The cumulative thermal requirements for the eggs were 148.6 degree days (°d) and the lower thermal threshold, 10.3°C. The duration of the nymphal instar decreased from 55.9 days at 15°C to 8.6 days at 35°C. The thermal constant for the nymphs was 182.3 °d and the lower thermal threshold 11.7°C. No nymphs survived at 40°C, and the highest mortalities were at extreme temperatures (15 and 35°C). Female and male weights were influenced significantly by temperature. The fertility of N. tenuis females was reduced greatly at 15 and 40°C. The highest fertility during an observation period of 18 days following female emergence (79.5–60.0 nymphs per female) was within the temperature range of 20 to 35°C. Fertility was related directly to female weight and temperature (r² = 0.932). Based on development, reproduction data and thermal requirements, the optimum temperature range for N. tenuis was established as being between 20 and 30°C. Overall, N. tenuis is the most thermophilous of all dicyphines from vegetable crops in the Mediterranean area studied so far.     

Ecophysiological adaptations of two Mediterranean red algae in relation to distribution

Effects of irradiance and temperature on the Mediterranean red algae Eupogodon spinellus and Eupogodon planus were tested. Growth of both species was saturated at an irradiance of 10–20?μmol?m^?2?s^?1, which is in accordance with their sublittoral habitat. Eupogodon spinellus and E. planus survived permanently at temperatures between 8 and 30?°C. The temperature optimum for growth was 25?°C with suboptimal growth occurring at (10?)15 and 30?°C in both species. At their collection locality (Corsica), potential monthly growth yields would be highest in summer and in winter would be only about 20% of the maximum. Reproductive requirements could be determined only in E. planus. Gametophytes reproduced both in long and in short days but only at 20?°C. Tetrasporophytes reproduced at 15–20?°C but only in short days. Geographic distribution boundaries are not set by growth or survival limits. However, the reproductive requirements of E. planus did account for its restricted distribution in the Mediterranean and on the Canary Islands.     

Digestibility of timothy hay by African elephants

Two juvenile, female African elephants (Loxodonta africana) were used in summer and winter trials to determine the apparent digestibility of timothy (Phleum pratense) hay. After 12–14 days of dietary adjustment, dry matter intake and fecal excretion were quantitatively measured for 7 days. Dry matter of timothy hay contained 8.6 and 7.7% crude protein, 57.3 and 44.0% acid detergent fiber, and 6.5 and 6.4% ash during the summer and winter trials, respectively. Estimates of apparent digestibility during summer and winter, respectively, were 39 and 35% for dry matter, 43 and 32% for gross energy (GE), 45 and 30% for crude protein (CP), and 36 and 24% for acid detergent fiber (ADF). While GE and CP digestibility estimates tended (P < .09) to be greater in the summer trial, only the digestibility of ADF was different (P < .05) between summer and winter. Dry matter intake was 1.4–1.6% of body weight (BW), providing an average of 144 kcal of digestible energy per kg BW^0.75. This value is similar to that (155 kcal per kg BW^0.75) used for estimating digestible energy requirements for maintenance of light-breed horses.     

Post-harvest age-induced seed dormancy of Acer ginnala and its alleviation by growth regulator and low temperature treatments

One-month-old fruits of Acer ginnala with winged pericarp attached gave 44% germination and this was not increased by cold treatment at 4°C for 0, 10, 20, or 30 days, gibberellic acid treatment at 0, 1, 10, 100 or 1000 mg litre^-1, or ethephon treatment at 0, 2, 20, 200 or 2000 mg litre^-1. After 6 months of storage at 20–25 °C, germination of untreated fruits fell to 5% but could be restored to that of 1-month-old fruits by incubation at 4 °C for 30 days. After 9 months storage, no germination occurred in untreated fruits. Cold treatment (30 days at 4 °C partially restored germination (26%). Treatment with either gibberellic acid (1000 mg litre^-1) and 30 days at 4 °C (40%) or ethephon (100 mg litre^-] and 30 days at 4 °C improved germination (69%). The combination of all three treatments, i.e. 100 mg litre^-1 gibberellic acid, 100 mg litre^-1 ethephon and 30 days at 4 °C, optimised germination (86%). Thus, dormancy of A. ginnala developed during storage but could be reversed by a combination of treatment with low temperature and growth regulators. The highest germination (86%) was achieved after low temperature and growth regulator treatment of stored fruit.     

Trypanosoma evansi: Ca(2+) ATPase activity and lipid peroxidation in skeletal muscle from rats experimentally infected

The aim of this study was to evaluate Ca²⁺ ATPase activity and the lipid peroxidation in muscles from rats experimentally infected by Trypanosoma evansi and its roles in the muscle pathogenesis in trypanosomosis. Thirty-six rats were divided in two groups. Group A was infected with an isolate from T. evansi and group B was used as a negative control. Group A was divided into three subgroups (A1, A2 and A3), three animals each group, as well as group B (B1, B2 and B3). The collection of samples were performed at days 5 (A1 and B1), 15 (A2 and B2) and 30 (A3 and B3) post-infection (PI) with the purpose of comparison between healthy and infected rats in the course of the disease. The Ca²⁺ ATPase enzyme activity was determined in skeletal muscle samples. Muscle tissue lipid peroxidation was determined by TBARS levels, and histopathologically it was investigated a possible damage to the muscle tissue of rats infected with T. evansi. It was observed a significant decrease of Ca²⁺ ATPase activity in infected rats compared to not-infected. This enzymatic inhibition was observed at days 5, 15 and 30 PI. A significant increase was observed for TBARS levels in the muscles of infected rats at days 5, 15 and 30 PI. It was not identified any histological alterations for gastrocnemius in rats infected by T. evansi at days 5 and 15 PI. Nevertheless, at day 30 PI it was verified inflammatory infiltrate with mononuclear cells between muscle fibers in three infected rats (50%). T. evansi infections in rats showed a negative correlation between Ca²⁺ ATPase and TBARS levels. Based on these results we suggest that the leg weakness and muscle injuries common in infected animals with T. evansi may be related to a reduced activity of Ca²⁺ ATPase and oxidative stress.     

Enhancement of mass transfer characteristics and phenanthrene degradation in a two-phase partitioning bioreactor equipped with internal static mixers

Oxygen and substrate supply have always been considered physical constraints for the performance and operation of two-phase partitioning bioreactors (TPPB), widely used for the degradation of hydrophobic substrates. In this regard, the potential advantages of static mixers in upgrading the oxygen transfer and liquid-liquid dispersions in TPPB have been highlighted. In the present paper, the concomitant influence of static mixers on the gas-liquid mass transfer coefficient k _L a and on substrate bioavailability was examined in TPPB. The static method based on conventional forms was developed to estimate the oxygen volumetric mass transfer coefficient. Over a broad range of liquid and air flow rates, the presence of static mixers was found to significantly enhance k _L a relative to a mixer-free mode of operation. For identical conditions, static mixers improved the k _L a threefold. In the presence of external aeration supply, the boost in the k _L a was associated with an increase of 16% in the phenanthrene biodegradation rate due to bubble break up accomplished by the static mixers. On the other hand, static mixers were efficient in enhancing substrate bioavailability by improving the liquid-liquid interfacial area. This effect was reflected by a threefold increase in the degradation rate in the bioreactors with no external supply of air when equipped with static mixers.     

Assessment of the range of attraction of pheromone traps to Agriotes lineatus and Agriotes obscurus

• 1 The range of attraction of YATLOR pheromone traps was studied to gain information on the number of traps needed for mass trapping of males of two Agriotes species.
• 2 Male click beetles of the species Agriotes lineatus (L.) and Agriotes obscurus (L.) (25–30 individuals per release point) were marked and released at a distance of 2, 5, 10, 15, 20 and 60 m from a pheromone trap both along and opposite to the known prevailing wind direction. Traps were regularly inspected over approximately 1 month. The percentage of recaptured beetles was calculated and analyzed using analysis of variance. Maximum sampling ranges and effective sampling areas were calculated.
• 3 Averaged over all five trials and distances, approximately 40% of the released beetles (A. lineatus and A. obscurus) were recaptured. The percentage recapture of male adults was significantly affected by release distance, whereas no differences were found for species and release direction.
• 4 Males were recaptured from all release points and the percentage recapture decreased (in part significantly) with increasing distance from 76% (2 m) to 35% (15 m) and 9% (60 m), respectively. Most of the beetles were recaptured within the first 3 days after release, independent of the distance, except 60 m. The effective sampling area for A. lineatus was 1089 m² after 12 days and increased to 1735 m² after 30 days. Corresponding values for A. obscurus were considerably higher: 1518 m² for 12 days and 2633 m² for 30 days.
• 5 We conclude that the range of attraction of the pheromone traps for A. lineatus and A. obscurus is comparatively low, providing high percentage recapture only for release distances up to 10 m. Accordingly, any approach targeted on preventing mating by male mass trapping would require a dense network of pheromone traps.

     

Metabolism of pyridoxine in the liver of vitamin B-6-deficient rats

The metabolism of [6-³H]pyridoxine · HCl was investigated in the liver of vitamin B-6-deficient rats. Rats were made vitamin B-6 deficient by feeding adlititum for 42 days a diet lacking pyridoxine but otherwise optimal. Animals were each injected intraperitoneally with 33 μCi of [6-³H]pyridoxine · HCl and killed at different time intervals afterwards up to 7 days. Radioactively labeled hepatic B-6 compounds were extracted with acid and chromatographically separated on Dowex-X8 (H⁺) columns and the percent radioactivity for each vitamin compound was then calculated. Maximal uptake in control and deficient animals was observed 30 and 60 min, respectively, after administration of label. Radioactivity was not retained by the control animals but decreased steadily in a linear fashion after 30 min, reaching a low level after 3 h. On the other hand, vitamin deficient animals accumulated almost twice as much radioactivity in their liver as the controls and retained it through 7 days.In vitamin B-6-deficient animals 93% of the injected radioactivity was metabolized within 2 min at which time pyridoxine 5′-P and pyridoxal 5′-P reached 36 and 44% levels, respectively. Pyridoxine 5′-P dropped to minimal values (3%) within 15 min and remained unchanged for 7 days while pyridoxal 5′-P reached a peak (79%) level at 15 min and then began to drop linearly reaching a plateau (29%) at 5 days. Further, as the level of pyridoxal 5′-P was falling, pyridoxamine 5′-P was linearly synthesized reaching a plateau level (62%) in 5 days which also remained unchaged through 7 days. Some pyridoxal was also formed (7% at 1 h) which by 12 h had dropped to a plateau low level (3%). The specific activity level of pyridoxal kinase decreased 3.2 times and that of pyridoxine 5′-phosphate oxidase increased 1.5 times in the state of deficiency. The results presented show that metabolism of [³H]pyridoxine in deficiency is characterized by (a) a delayed, two-fold increase in label uptake as well as an extended label retention period, (b) a rapid pyridoxal 5′-P synthesis, and (c) a continuouus synthesis (and accumulation) of pyridoxamine 5′-P which is not utilized or further metabolized.