Biological waste-treatment of hydrocarbon residues: effects of humic acids on the degradation of toluene

The biological degradation potential on toluene of the bacteria Pseudomonas fluorescens isolated from soil, as influenced by humic acids, was investigated. The major environmental factors considered of interest for this experiment were temperature, pH of the media, and agitation (rpm), which were optimized using Response Surface Methodology. A face-centered cube design was adopted for this study, and the optimal values for these factors were predicted by the resulting experimental equations. The degradation of toluene by P. fluorescens was tested by incorporating different concentrations (0.02, 0.04, 0.06, 0.08 and 0.10%) of humic acids, extracted from peat moss, in a hydrocarbon degradation medium. The results showed that the microbial degradation of toluene was inhibited by the presence of humic acids.     

新杀虫剂硫肟醚降解菌的筛选和降解动力学

硫肟醚[O-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]是国家南方农药创制中心湖南基地研制成功的具有知识产权的一种新型杀虫剂。采用富集培养法对硫肟醚降解菌的筛选、分离鉴定和降解进行了初步研究,结果从土壤中分离出了5株能降解硫肟醚的降解菌HNX1、HNX2、HNX3、HNX4和HNX5,其对硫肟醚的降解半衰期分别为1.34、2.02、1.90、2.17和1.27d。根据形态学特征和生理生化反应,初步鉴定HNX1和HNX5为假单胞菌属(Pseudomonas sp.)。     

Effect of inoculation with lactic acid bacteria on extending the shelf-life of vacuum-packed cold smoked salmon

Extending the shelf-life of vacuum-packed cold smoked salmon was tested with lactic acid bacteria. Carnobacterium spp. (10 and 39) isolated from seafood, one type strain C. piscicola NCDO 2762 and a Lactobacillus plantarum strain commonly used in meat industry, were sprayed on both sides of commercial smoked salmon slices (10⁸ CFU g⁻¹) which were vacuum packaged and stored at 4°C for up to 28 days. A control sprayed with sterile physiological saline was used. In one trial, after storage with strains 10 and 39, the smell of inoculated slices became significantly less acid, sour, amine and rancid, and more specifically salmon than the control, with maximum effect after 3 weeks. These differences were not so pronounced in laboratory-processed slices for these two strains nor for C. piscicola and L. plantarum , probably because the initial counts were much lower. The effect on H₂S-producing bacteria was variable. The yeast and mould count was always reduced on the inoculated samples. Odour differences did not correlate with chemical data, as similar concentrations of metabolites were observed in both standard and assay tests.     

Chemical characterization of medium‐chain‐length polyhydroxyalkanoates (PHAs) recovered by enzymatic treatment and ultrafiltration

BACKGROUND: Medium‐chain‐length polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated intracellularly as energy resources by bacterial species such as Pseudomonas putida. The most popular method for PHA recovery is solvent extraction using trichloromethane (chloroform) and methyl alcohol (methanol). An alternative method is enzymatic treatment, which eliminates usage of these hazardous solvents. This research focuses on the characterization of PHAs recovered by enzymatic treatments and ultrafiltration. Comparisons are made with conventional solvent extracted PHA. RESULTS: The purity of PHA in water suspension recovered by enzymatic treatments as analyzed by gas chromatography was 92.6%. Enzymatically recovered PHA was comparable to conventional solvent‐extracted PHA, which had a purity of 95.5%. PHA was further characterized for functional group analysis, structural composition analysis and molecular weight determination. It was found that the molecular weight of the PHA recovered by enzymatic treatment was less than solvent‐extracted PHA, probably due to degradation of the lipopolysaccharide layer. However, functional group and structural composition analyses showed similar results for PHA recovered by both methods. CONCLUSION: PHAs recovered through enzymatic digestion treatment have good comparability with solvent‐extracted PHAs. Thus enzymatic digestion has great potential as an alternative recovery method. Copyright © 2007 Society of Chemical Industry     

Carotenoid composition and vitamin A value of some native Brazilian green leafy vegetables

The composition of carotenoids in five native Brazilian leafy vegetables was determined. The ranges of total carotenoid contents of Amaranthus viridis, Lepidium pseudodidymum, Xanthosoma spp., Sonchus oleraceus , and Portulaca oleracea were 347–468, 237–280, 225–361, 149–334 and 71–109 μg g⁻¹, with lutein and β-carotene predominating. The mean β-carotene contents (μg⁻¹) and vitamin A values (retinol equivalents RE_g⁻¹) were 110 and 18.4, 84.6 and 14.1, 67.3 and 11.2, 62.9 and 10.5, 29.8 and 4.99, respectively. The leaves contained 54–61% of lutein plus violaxanthin, 24–34% of β-carotene, 10–14% of neoxanthin and traces of zeaxanthin and α-crypto-xanthin. The native leafy vegetables were richer sources of provitamin A than the cultivated leafy vegetables analysed previously, justifying their commercial production.     

Toxins in chrysomelid beetles Possible evolutionary sequence from de novo synthesis to derivation from food-plant chemicals

In the Chrysomelinae, it appears that de novo synthesis of chemicals for defense is the primitive state, and the sequestration of plant chemicals for defense the derived state. The derived state evolved through both the morphological and biochemical preadaptiveness of the homologous defensive glands. In the adults, we discuss one unique case of sequestration in exocrine defensive glands of host-plant pyrrolizidine alkaloids byOreina cacaliae. However, hypericin is not sequestered either in the glands or elsewhere in the body ofChrysolina spp. feeding onHypericum, which contradicts an earlier claim. In the larvae, we examine in more detail how the phenolglucoside salicin can be used as the precursor of the salicylaldehyde present in the defensive secretion ofPhratora vitellinae andChrysomela spp. with minimal changes in the biochemical mechanisms involved in the biosynthesis of iridoid monoterpenes in related species.     

Quantification of cantharidin in canthariphilous ceratopogonidae (Diptera), anthomyiidae (Diptera) and cantharidin-producing oedemeridae (Coleoptera)

Cantharidin contents were determined in several canthariphilous insects by means of quantitative gas chromatography. Usually the ceratopogonidsAtrichopogon oedemerarum andA. trifasciatus caught in the field contained low concentrations of cantharidin, with concentrations in males, in most cases, being lower than in females. When fed in the laboratory with synthetic cantharidin, these species concentrated cantharidin by as much as 100-fold (males) and 40-fold (females). Accumulation in the different body tagmata (head, thorax, abdomen) of these species is similar. Maximal concentrations of cantharidin in tissues ofAtrichopogon are comparable to those known from oedemerid and meloid beetles. InA. trifasciatus about 90% of total cantharidin content is bound in tissues. Investigations using the canthariphilous anthomyiid flyAnthomyia pluvialis and three cantharidin-producing oedemerid species revealed the same pattern of distribution in different body tagmata as inAtrichopogon.     

Bacterial-barnacle interaction: Potential of using juncellins and antibiotics to alter structure of bacterial communities

In preparation for studies using natural products to probe interactions between bacterial consortia and settlement stage barnacles, we isolated 16 strains of bacteria associated with barnacles and examined: (1) effects of films of bacterial isolates on barnacle settlement, and (2) bacteriostatic effects of juncellins and standard antibiotics. Bacteria were isolated from the biofilm associated withBalanus amphitrite. On the basis of morphological and biochemical characteristics, bacteria were classified into five major groups:Aeromonas, Alcaligenes, Flavobacterium, Pseudomonas, andVibrio. Barnacle settlement was inhibited by allVibrio films and 64% of the other isolates. No film stimulated barnacle settlement. Juncellins were approximately as potent as standard antibiotics for all bacterial species tested.Vibrio spp. were most resistant to juncellins.     

黄曲霉毒素B1降解酶的分离纯化及其酶学特性

施氏假单胞菌（Pseudomonas stutzeri）F4能产生黄曲霉毒素B1的降解酶（aflatoxin B1-degrading enzyme,ADE）,本实验通过3 步法提取纯化ADE,即包括硫酸铵分级沉淀、DEAE-Sepharose阴离子交换柱层析和SephadexG-100凝胶过滤层析。结果表明,通过以上纯化方法,ADE的回收率为56%,纯化的ADE比活力为6.4×104 U/mg,纯化了123 倍。利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测得ADE分子质量约为24 kD;ADE与AFB1反应的最适温度和pH值分别为30 ℃和6.0;Cu2+对ADE酶活性有抑制作用;利用双倒数作图法测得ADE表观Km值为5.61×10-5 mol/L。     

杏鲍菇污染菌的分离、鉴定及其特性

从夏季被细菌污染的杏鲍菇上分离纯化得到2 株病害菌（CTE722-B、CTE722-C）,结合显微结构和生理生化实验结果,以及对它们16S rDNA序列的分析确定这两株菌的系统发育地位;通过抑菌圈实验考察几种工厂常用消毒剂对病害菌的抑菌影响。结果表明：菌株CTE722-B鉴定为恶臭假单胞菌属（Pseudomonas putida）,CTE722-C为边缘假单胞菌属（Pseudomonas marginalis）。消毒剂菇保、甲酚皂、苯扎溴铵消毒液在短时间内对这两种细菌都有较好的抑菌效果;但因其具有挥发性,故防治效果不理想。从污染菇体分离得到的2 株病害菌CTE722-B和CTE722-C被鉴定为假单胞菌属,因常用消毒剂只在短时间内对其有抑菌性,防治效果较差。