L-乳酸生产菌分批发酵动力学模型

对L-乳酸生产菌的分批发酵动力学进行了研究.通过对Logistic方程、Luedeking-Piret方程和LuedekingPiret-Like方程进行最优参数估计和非线性拟舍,得到了菌体生长、产物生成和底物消耗的动力学模型和模型参数.对动力学模型的拟合曲线进行分析,发现发酵实验值与拟合值能较好地拟合.结果表明,所建立的分批发酵动力学模型能较好地反映L-乳酸分批发酵过程.     

酿酒酵母生产谷胱甘肽分批发酵动力学研究

以麦芽汁为发酵培养基,对7.5L 自动发酵罐中酿酒酵母Y518 分批发酵生产谷胱甘肽的实验数据进行分析,建立谷胱甘肽分批发酵动力学模型。通过对符合菌体生长的Logistic 方程、产物生成的Luedeking-Piret 方程和基质消耗的物料衡算方程进行最优参数估计和非线性拟合,分别得到了相应的动力学模型和最佳模型参数值。对动力学模型的拟合曲线进行分析,发现模型的计算值与实验值能较好地拟合,表明本实验建立的分批发酵动力学模型能较好地反映谷胱甘肽分批发酵过程。     

短梗霉多糖分批发酵动力学模型

对短梗霉多糖分批发酵动力学进行了研究.基于Logistic方程和Luedeking-Piret方程分别建立了短梗霉多糖发酵过程菌体生长、产物合成及底物消耗随时间变化的数学模型,同时对实验值与模型进行了验证比较.结果表明,模型模拟计算结果与实验值能较好地吻合,该模型能较好地反映短梗霉多糖分批发酵的过程.     

纳豆菌发酵动力学研究初探

研究纳豆菌菌体生产的发酵动力学。以70L发酵罐进行分批发酵,并基于Logistic方程和Luedeking-Piret方程,得到了描述分批发酵过程的菌体生长和底物消耗动力学模型及模型参数,同时对实验数据和模型进行了验证比较,模型计算值与实验数据拟合较好。结论:模型基本反映了纳豆菌分批发酵过程的动力学特征,可用于预测发酵过程。     

酿酒酵母工程菌分批发酵产UMP动力学模型

对酿酒酵母工程菌产UMP的分批发酵动力学进行了研究。通过对Logistic方程、Leudeking-Piret方程和类Luedeking-Piret方程进行参数估计和非线性数据拟合,分别得到发酵过程中菌体干重、UMP产量、残糖含量动力学模型及模型参数。对拟合曲线进行分析,结果表明模型值与实验值拟合性良好,线性拟合度大于98%,所建立模型能较好的反映UMP的分批发酵过程。     

γ-氨基丁酸分批发酵动力学的研究

对短乳杆菌产γ-氨基丁酸(GABA)的分批发酵动力学进行了研究.基于Logistic方程和Luedeking-Piret方程分别建立了菌体生长、产物合成及底物(葡萄糖、L-谷氨酸钠)消耗的动力学模型,并利用1 stopt软件对模型参数进行非线性曲线拟合.对实验值与模型值进行了验证比较,结果该组模型能较好的拟合发酵过程.进一步用该模型对发酵过程进行分析.     

黑曲霉浅盘生料发酵产单宁酶动力学研究

对黑曲霉浅盘生料发酵产单宁酶动力学进行研究。基于Logistic方程和Leudeking-Piret方程,提出了菌体生长动力学、单宁酶生成动力学、基质消耗动力学模型,同时对分批发酵实验数据应用软件Origin8.0进行了非线性拟合得出参数值。动力学分析结果表明:所建立的分批发酵动力学模型能较好地反映黑曲霉产单宁酶分批发酵的过程,相关性良好。     

黑曲霉生产葡萄糖酸钠的分批发酵动力学模型

对黑曲霉发酵生产葡萄糖酸钠的分批发酵动力学特性进行了研究,通过对Logistic方程,Luedeking-Piret方程和Luedeking-Piret/Like方程进行最优参数估计和非线性拟合,得到了描述发酵过程中菌体生长、葡萄糖酸钠合成、葡萄糖消耗的动力学模型.对实验数据与模型预测值进行比较,发现模型预测值与实验数据能较好地拟合,基本上反映了黑曲霉分批发酵过程的动力学特征,结果还表明葡萄糖酸钠的发酵合成是部分生长偶联型的.     

尿苷产生菌枯草芽孢杆菌Tc142分批发酵动力学研究

通过建立菌体生长、产物形成和基质消耗的动力学模型,并应用MATLAB软件进行模型拟合分析,对枯草芽孢杆菌Tc142(6-Aur 2-Tur Upase-)5L罐尿苷分批发酵实验教据讲行分析,建立尿苷分批发酵动力学模型.结果是拟合模型能较好地反映尿苷产生菌Tc142的分批发酵过程.结论是以发酵动力学为指导,应用Matlab分析方法对尿苷发酵动力学模型进行拟合,其结果与实验结果相符.     

枯草芽孢杆菌发酵生产γ-聚谷氨酸的动力学研究

对枯草芽孢杆菌合成γ-聚谷氨酸的发酵动力学特性进行了研究,通过Logistic方程,提出了发酵过程中菌体生长、γ-聚谷氨酸合成、基质消耗的动力学模型.应用MATLAB数值应用软件对实验数据进行处理,得到了枯草芽孢杆菌分批发酵合成γ-聚谷氨酸的动力学模型参数.对实验数据与模型进行比较,结果表明模型与实验数据能较好地拟合,基本上反映了枯草芽孢杆菌分批发酵过程的动力学特征.     

Variation in susceptibility to insecticides and synergistic effect of enzyme inhibitors in Pakistani strains of Trogoderma granarium

Trogoderma granarium is an important quarantine insect pest of economic importance worldwide. Insecticides are heavily used against this pest that can reduce its susceptibility levels, and if left unchecked, this could lead to misuse of insecticides. Here, the susceptibility of five field strains of T. granarium in comparison to a reference strain (Lab-TG) was determined against pirimiphos-methyl, permethrin and spinosad using dose-mortality bioassays. Based on lethal dose (LD₅₀ and LD₉₉) values, the Lab-TG strain was the most susceptible to all the insecticides in comparison to the field strains. In the case of field strains, LD₅₀ values varied from: 17.68–31.97 mg/kg for pirimiphos-methyl, 20.50–42.47 mg/kg for permethrin, and 1.34–5.00 mg/kg for spinosad. Whereas LD₉₉ values for pirimiphos-methyl, permethrin and spinosad of field strains varied from 409.07 to 730.24 mg/kg, 374.24–949.48 mg/kg, and 11.41–72.25 mg/kg, respectively. The resistance ratios (RR) at LD₅₀ and LD₉₉ levels were in the range of 13.71–24.78 and 39.33–70.21 fold for pirimiphos-methyl; 13.49–27.94 and 37.31–94.66 fold for permethrin; 2.35–8.77 and 3.37–21.31 fold for spinosad, respectively. Considering the overall results, spinosad proved to be the most toxic insecticide to the laboratory and field strains of T. granarium when compared with toxicity of pirimiphos-methyl or permethrin. Insecticidal bioassays implementing enzyme inhibitors revealed no effect on synergizing the toxicity of all the insecticides in the Lab-TG strain; however, enzyme inhibitors significantly synergized toxicity of pirimiphos-methyl in all the field strain suggesting the major involvement of metabolic mechanism associated with pirimiphos-methyl resistance. The study demonstrates variation in susceptibility to insecticides in T. granarium strains. The results might be helpful for monitoring future variation in susceptibility to insecticides in T. granarium and for setting field rates.     

Insecticidal effect of spinosad dust, in combination with diatomaceous earth, against two stored-grain beetle species

Laboratory bioassays were carried out to determine the efficacy of spinosad applied alone or combined with the diatomaceous earth (DE) SilicoSec against adult rice weevils, Sitophilus oryzae and confused flour beetles, Tribolium confusum. Efficacy was assessed on wheat and maize at three dosages of spinosad dust formulation (corresponding to 0.0625, 0.1875 and 0.625 ppm of active ingredient [AI] for S. oryzae and to 0.1875, 0.625 and 1.25 ppm of AI for T. confusum), alone or combined with SilicoSec at 150 ppm for S. oryzae and 250 ppm for T. confusum. The mortality of S. oryzae exposed for 14 d on wheat treated with spinosad ranged between 83% and 100%. Conversely, the mortality of S. oryzae on maize treated with DE or on maize treated with lower doses of spinosad dust did not exceed 19% and was only 59% on maize with the highest spinosad dust treatment. Generally, the presence of SilicoSec combined with spinosad did not significantly increase S. oryzae mortality compared with spinosad alone. For T. confusum, mortality on both commodities was lower than for S. oryzae. After 14 d of exposure on wheat, mortality was 14% at the highest dose of spinosad, but increased to 33% in the presence of DE. Similar results were also obtained for T. confusum exposed on treated maize, which indicated a joint action between spinosad and DE. In the case of S. oryzae, the inclusion of DE reduced progeny production in comparison with spinosad alone. Progeny production of T. confusum was relatively low in all treatments, compared to progeny production of S. oryzae. The results of the study show the potential of combination treatments of spinosad dust and DE, but efficacy varies with the target insect species and commodity.     

Base-line susceptibility of field populations of Rhyzopertha dominica (F.) to spinosad in Australia

Spinosad has recently been registered in several countries for long-term protection against a range of stored grain insects including the lesser grain borer, Rhyzopertha dominica (F.). The potential for development of resistance to spinosad is demonstrated by the existence of resistance in many insect pests of agriculture. The aim of this study was to determine the base-line susceptibility of R. dominica to spinosad, to provide a basis for future resistance monitoring. Eighteen insect populations of R. dominica were collected from field storage sites across four States within Australia, and exposed to a range of spinosad rates, including its current registered rate of 1 mg kg⁻¹ (1 ppm). Base-line susceptibility was assessed based on adult mortality and production of F₁ adults. Comparison of LC₅₀ and LC_99.9 indicated the existence of low level of variation among the tested R. dominica populations, in their susceptibility to spinosad. For adults, there was a narrow range of LC₅₀ values with the highest (0.027 ppm) being 2.5 × the lowest (0.011 mg kg⁻¹). Similarly, LC_99.9 values showed a narrow range with the highest (0.36 mg kg⁻¹) being 3.6 × the lowest (0.10 mg kg⁻¹). For adult progeny produced in spinosad treated grain, there was a narrow range of LC₅₀ values with the highest (0.025 mg kg⁻¹) being 5 × the lowest (0.004 mg kg⁻¹) and the highest LC_99.9 values (0.67 mg kg⁻¹) being 5 × the lowest LC_99.9 (0.13 mg kg⁻¹). Based on the data generated from this study, we recommend a dose of 1 mg kg⁻¹(1 ppm) to be used to discriminate between susceptible and resistant populations for future resistance monitoring programs.     

2.5%菜喜悬浮剂(spinosad)对三种储粮害虫的毒力测定

用药膜法室内测定了新型生物杀虫剂2.5%菜喜悬浮剂(主要成分为多杀菌素,spinosad)对储粮害虫嗜虫书虱、米象、锯谷盗的作用效果。结果表明菜喜对嗜虫书虱、锯谷盗和米象触杀毒力LC50分别为0.0022、0.0046、0.0059mg/m2。对书虱的防治效果明显高于对其他两种储粮害虫的防治效果。本试验结果对多杀菌素在储粮害虫防治方面的合理应用提供了基本依据。     

Deltamethrin- and spinosad-mediated survival,activity and avoidance of the grain weevils Sitophilus granarius and S. zeamais

The granary and maize weevils are serious worldwide threats to stored products and their control has heavily relied on synthetic insecticides, which are largely recommended based on studies with acute lethal doses neglecting the importance of potential sublethal effects of insecticides. Deltamethrin has been widely used for managing grain weevils and other stored grain pest species, but reported control failures with this insecticide sparked the search for alternative insecticidal compounds. The bioinsecticide spinosad is one of such alternatives whose use against stored grain insect pests is relatively recent, but encompasses the control of grain weevils. Nonetheless, little is known about the sublethal effects of spinosad on these insect pest species. Here we assessed the insecticidal effects of commercial formulations of spinosad and deltamethrin against the weevil species Sitophilus granarius and S. zeamais. Both spinosad and deltamethrin were able to effectively control the insects, although the latter caused a faster mortality than the former. Behavioral pattern changes were caused by both insecticides, especially deltamethrin, triggering irritability (i.e., avoidance after contact). Different feeding and drinking responses were also detected for both weevil species, which exhibited significant avoidance to deltamethrin and to spinosad, but with a milder response to the latter. Apparently spinosad is not as easily recognizable as deltamethrin by S. zeamais and S. granarius, remaining effective against both species without minimizing as much the potential exposure as deltamethrin.     

Effectiveness of spinosad as a grain protectant against resistant beetle and psocid pests of stored grain in Australia

Effectiveness of the bacterium-derived insecticide, spinosad, was determined against eight storage pests of Australia. Laboratory experiments were carried out on relevant resistant strains of four beetle and four psocid species, with the aim of determining the potential of spinosad as a new grain protectant. To explore the possibility that spinosad could have delayed effects, we exposed all insects for 14 d initially and then a further 14 and 28 d for psocids and beetles, respectively. Adult insects of each strain were exposed to untreated wheat (control) and wheat treated with spinosad at 0.1, 0.5 and 1 mg [a.i.]/kg of grain, and adult mortality and reduction of progeny were determined. Among beetles, spinosad was most effective against Rhyzopertha dominica (F.), with 100% adult mortality and progeny reduction after 14 d exposure at 1 mg [a.i.]/kg. Efficacy of spinosad was less with Sitophilus oryzae (L.), and least with Tribolium castaneum (Herbst) and Oryzaephilus surinamensis (L.). Against the psocids, spinosad was most effective against Liposcelis entomophila (Enderlein), with 100% adult mortality after 28 d exposure at 1 mg [a.i.]/kg and 92% progeny reduction after 14 d exposure and 100% subsequently. Spinosad was only moderately effective against Liposcelis bostrychophila Badonnel, L. decolor (Pearman) and L. paeta Pearman. Our findings suggest spinosad to be a potential protectant against R. dominica and L. entomophila in stored grain in Australia. This potential use would be in combination with another protectant capable of controlling other members of the pest complex.     

Effects of spinosad and spinetoram on larval mortality,adult emergence,progeny production and mating in Cadra cautella (Walk.) (Lepidoptera: Pyralidae)

The bacterial formulations, spinosad and spinetoram, were evaluated for their efficacy in suppressing development and mating success in Cadra cautella (Walk.) (Lepidoptera: Pyralidae), the almond moth. A dilution series of spinosad and spinetoram was sprayed on rice flour. Rice flour samples sprayed with water served as the control. Late instar C. cautella larvae were introduced onto spinosad-, spinetoram-, or water-treated rice flour. The first experiment tested the effects of spinosad and spinetoram on larval mortality, as well as emergence of adults and progeny at different insecticide concentrations. In the second experiment, the mating success of C. cautella adults that had emerged from larvae exposed to spinosad was tested inside a cubicle. Both spinosad and spinetoram increased larval mortality, whereas both compounds reduced adult emergence and progeny production. Natural mating was reduced in the presence of the synthetic sex pheromone (Z,E)-9,12-tetradecadienyl acetate. However, exposure of C. cautella larvae to spinosad did not alter mating in adult progeny. Spinosad was more effective than spinetoram at suppressing C. cautella development. The study concludes that both spinosad and spinetoram suppress the development of immatures of C. cautella to the adult stage as well as mating. Thus, the both compounds can be used to protect stored grains from infestation by C. cautella.     

多杀菌素在储粮害虫防治中的研究及应用进展

多杀菌素是一种安全、高效的新型生物杀虫剂。对多杀菌素的来源、结构、作用机理、在储粮害虫防治中的研究及应用、残留检测等进行综述,以期为多杀菌素的深入研究和推广应用提供参考,并促进多杀菌素在我国储粮害虫防治领域的研究和应用。     

Effects of spinosad on the heat tolerance and cold tolerance of Sitophilus oryzae L. (Coleoptera: Curculionidae) and Rhyzopertha dominica F. (Coleoptera: Bostrichidae)

Sitophilus oryzae and Rhyzopertha dominica are serious insect pests of stored products in Sri Lanka. Currently pirimiphos methyl and phosphine fumigation are used as control measures but grain handlers seek for alternatives. Exposure to high or low temperature is popular in stored-product insect pest management but is expensive. Spinosad is effective against certain stored-product insects but has not yet been tested for its synergy with heat or cold. This experiment was conducted to evaluate the effect of spinosad on the heat tolerance and cold tolerance of S. oryzae and R. dominica adults. The experiment was a two-factor factorial, complete randomized design with four replicates. The spinosad concentration and exposure period were changed. Adults of S. oryzae and R. dominica were first exposed to a series of spinosad concentrations. Later they were held at higher (40 °C) or lower (6–11 °C) temperatures than room temperature for different durations.Pre exposure of S. oryzae adults to Spinosad at 18 ppm or above synergized the adult mortality at high or low temperature showing a dose response. Pre-exposure of R. dominica adults to spinosad concentrations 12.5 ppm or higher synergized the mortality at high temperature whereas the spinosad synergized the mortality of R. dominica at low temperature when exposed to 6.25 ppm or higher concentrations; the effects followed a dose response. This study shows that heat and cold tolerance of S. oryzae and R. dominica adults are reduced by pre-exposure to spinosad. Therefore, spinosad is a potential grain protectant at high or low temperatures against these two insect species.     

Response of different population sizes to traps and effect of spinosad on the trap catch and progeny adult emergence in Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Tribolium castaneum is a major pest in stored products throughout the world. Male T. castaneum adults produce aggregation pheromone 4,8-dimethyldecanal (4,8 DMD) which is synthetically developed and available for monitoring T. castaneum populations but low trapping by 4,8 DMD is reported. Effects of biorational insecticides on orienting to pheromone and progeny production is shown but such tests using spinosad has areas for further discovery. Therefore the objective of this research was to determine the effect of population size and spinosad exposure on the trap catch and progeny production in T. castaneum adults. In the first experiment, T. castaneum adults were released at different population sizes and the attraction to the pheromone traps was determined. The second experiment tested attraction of T. castaneum adults pre-exposed to spinosad to the pheromone traps. In the third experiment, progeny production of T. castaneum adults exposed to spinosad was assessed. The trapping of T. castaneum is increased at high population sizes and pre-exposure to spinosad while progeny was reduced on exposure to spinosad showing sex-based effects. This study concludes with management opportunities for different population levels of T. castaneum through effects of spinosad on pheromone perception and progeny production.