光电子和光生空穴对粪产碱杆菌代谢产物的影响

【目的】探讨光催化下纳米TiN对粪产碱杆菌代谢情况的影响。【方法】我们通过分别添加空穴捕获剂及电子捕获剂,使用三维荧光光谱分析比较光生空穴和光电子对粪产碱杆菌(Alcaligenes faecalis)生长代谢的不同作用。【结果】光照条件下,空穴捕获剂组明显生成了较多的类腐殖质类物质,且比其他实验组有更强的NADH的荧光峰出现,峰强度是其他实验组的4到5倍。黑暗条件下,各实验组之间的代谢产物无明显变化。光照条件下的电子捕获剂组比黑暗条件下有更强的类蛋白质类荧光峰。【结论】本文首次报道光电子会促进粪产碱杆菌产生腐殖质类物质,且会产生更多的能量。光生空穴会促进粪产碱杆菌产生蛋白质类物质。     

The fermentation of cell wall substances in grass silage and in potato pulp

Summary The amount of acid formed in grass silage was greater than could have been formed from the soluble sugars present, even when only a lactic fermentation took place. This seemed to point to fermentation of cell wall substances by lactic acid bacteria. Lactic acid fermentation in potato pulp always takes place with cell wall substances as substrates, as sugars are absent. It was found that galactose, probably occurring as galactan, and also some pectic acid were fermented in potato pulp. Some lactobacilli were isolated from potato pulp; streptobacteria which could ferment galactan but no pectic or galacturonic acid, and betabacteria which could ferment galacturonic acid but no galactan or pectic acid. A number of homofermentative lactobacilli were all found to belong to the speciesStreptobacterium casei. It was shown that a strain of this species could ferment galactan in potato pulp sterilised previously with ethylene oxide. Part of this work was carried out at the Netherlands Institute for Dairy Research, Ede, Netherlands.     

Mutagenicity of and Formation of Oxygen Radicals by Trioses and Glyoxal Derivatives

Dihydroxyacetone, glyceraldehyde, glyoxal, methyl glyoxal, and glyoxylic acid were found to show mutagenicity on Salmonella typhimurium TA 100. The mutagenicities of these substances were inhibited by the addition of S-9 or some free radical scavengers. The alkaline buffered solutions of these mutagenic substances were found to reduce Nitro Blue tetrazolium chloride. DNA was degraded by the addition of these mutagenic substances. It has also been confirmed that free radicals derived from autoxidation of these substances are responsible for their mutagenicity.     

Biologically active oxylipins from seaweeds

Our previous research has shown that many red algae metabolize polyunsaturated fatty acids to oxidized products resembling the eicosanoid hormones from mammals. We have extended these studies to members of the Phaeophyceae and Chlorophyta and find they also possess similar biosynthetic pathways. From several we have identified novel prostaglandin-like substances. Studies of the molecular mechanisms by which some of these marine oxylipins are formed have revealed that novel oxidative reactions are utilized. Understanding of these biosynthetic pathways in detail has allowed their utilization to produce research biochemicals of high value, such as 12S-hydroperoxyeicosatetraenoic acid (12S-HPETE). Because of their biological properties, seaweed-derived oxylipins have potential utility as pharmaceuticals and research biochemicals.     

Effects of Abscisic Acid, Salicylic Acid and Trans-cinnamic Acid on Phosphate Uptake, ATP-level and Oxygen Evolution in Scenedesmus

The effects of abscisic acid, salicylic acid and trans-cinnamic acid were tested on the light-induced phosphorylating reactions and oxygen evolution of the unicellular green alga Scenedesmus. It was found that abscisic acid and cinnamic acid had practically no influence on the total inorganic phosphate uptake, while salicylic acid in the concentration range of 10^-6 to 10^-3M gave a small decrease in the total inorganic phosphate uptake. The ATP level in the cells is in most cases increased when these three acids are given to the algae. The oxygen output is not significantly changed by abscisic acid or salicylic acid. Trans- cinnamic acid inhibits the oxygen evolution at concentrations of 10^-4–10^-3M None of the substances investigated caused such effects on photophosphorylation and oxygen evolution in Scenedesmus as those caused by the inhibitor β-complex from potatoes according to earlier reports. It is suggested that these effects are due to other components in the inhibitor β-complex.     

On the Mechanism of Metabolism of (−)-Epicatechin

(?)-Epicatechin was administered orally to rabbits and vanillic acid, 3-hydroxybenzoic acid, protocatechuic acid, and three kinds of neutral substances were found to be excreted in the urine. The three kinds of neutral substances were identified as 1-δ-(3-methoxy-4-hydroxyphenyl)-, 1-δ-(3-hydroxyphenyl)-, and 1-δ-(3,4-dihydroxyphenyl)-γ-valerolactones, which are optical isomers of the three kinds of neutral substances excreted after administration of (+)-catechin. From the presence of these intermediate metabolites, it was verified that (?)-epicatechin is metabolized by the same mechanism as (+)-catechin described earlier.     

Metabolism of Aromatic Compounds by Microbes

The metabolic products of m-hydroxybenzoic acid formed by certain Pseudomonas, Micrococcus, and Bacterium strains which possess oxidizing ability of this acid were detected by paperchromatography. It was recognized that protocatechuic acid or gentisic acid are intermediary metabolites of m-hydroxybenzoic acid by these bacteria and the both acids are not detected in one cultural broth.     

GROWTH-INHIBITORS AND GROWTH-PROMOTERS IN ENTEROMORPHA COMPRESS A (CHLOROPHYTA)1

Methanol extracts from the alga Enteromorpha compressa (L.) Grev. contain substances which inhibit the elongation of Lepidium roots. Chromatographic separation of the inhibiting substances revealed that one of the inhibitory zones of the chromatograms had properties of the so-called inhibitor β. Neither abscisic acid (ABA) nor lunularic acid proved to be responsible for the growth-inhibiting property of this zone. Moreover, the extracts contain substances which promote the elongation of Avena coleoptile segments. One of these substances could be tentatively identified as indole-3-acetic acid by thin-layer and gas-liquid chromatography. (In addition to indole-3-acetic acid a second growth-promoting factor with the properties of the so-called accelerator α could be detected.)     

CHEMICAL CONTROL OF ADVENTITIOUS ORGAN FORMATION IN LACTUCA SATIVA EXPLANTS

Both kinetin and adenine promote bud initiation in excised cotyledons of Lactuca sativa. Controls lacking these substances form abundant roots but have never formed buds. Indoleacetic acid and certain mineral salts are also necessary for regeneration of shoots. Although bud growth from cotyledons is extensive on a medium containing both indoleacetic acid and kinetin, excised roots display a low propensity toward bud formation and typically develop callus tissue with roots. Growth of hypocotyl sections is intermediate with respect to bud formation. Shoot initiation in lettuce thus varies with the region of the seedling as well as with the culture medium.     

Demethylation of aromatic compounds by strain B10 and complete degradation of 3-methoxybenzoate in co-culture with Desulfosarcina strains

Summary A pure culture presumably of an Acetobacterium sp. from a waste water pond, strain B10, was able to grow with several methoxylated aromatic compounds by demethylation (or demethoxylation) to the corresponding hydroxilated substances. Acetate was formed from the eliminated methyl or methoxy groups and from CO₂. Demethylation of 3-methoxybenzoate occurred simultaneously with glucose or lactate fermentation if induced, methanol-grown cells of strain B10 were used as an inoculum. If 2-vanillin or 2,3-dimethoxybenzaldehyde were supplied as the only carbon sources, these substances were first oxidized to the corresponding benzoic acid derivatives and subsequently demethylated. In mixed cultures of strain B10 and Desulfosarcina variabilis or Desulfosarcina strain DSU3 the 3-hydroxybenzoate formed by strain B10 from 3-methoxybenzoate was completely degraded to acetate and presumably CO₂ by the sulphate reducers. Acetate could be oxidized to CO₂ upon extended incubation. The complete degradation of 3-methoxybenzoate to CO₂ by co-cultures of strain B10 and Desulfosarcina strains seemed to proceed via a commensalistic, rather than via a syntrophic interaction of the participating organisms. Offprint requests to: J. Winter     

Responses of the African Armyworm and three species of borers to carbohydrates and phenolic substances: an electro- and behavioural physiological study

Electrophysiological recordings were made from the maxillary sensilla styloconica of fifth instars of the African Armyworm, Spodoptera exempta (Wlk.) (Lep.: Noctuidae), and the borers (Lep.: Pyralidae) Eldana saccharina Wlk. and Maruca testulalis (Geyer), and fifth and sixth instars of the borer Chilo partellus (Swinhoe). Stimuli were different concentrations of 13 carbohydrates and 11 phenolic substances. It appeared that a sucrose sensitive cell is present in the lateral styloconic sensilla of Spodoptera, Maruca and Chilo, and in both the lateral and medial sensilla of Eldana. The sucrose cell of fifth-instar Chilo is more sensitive than that of sixth instars. The additional responses of the medial cells to the phagostimulant sucrose are supposed to have contributed to the widespread infestation of sugarcane by Eldana. The medial sensilla of the Armyworm contain a cell type responding to both meso-inositol and D-ribose. Chilo appeared to be the only one of the three borer species able to perceive phenolic substances. It has a cell responsive to chlorogenic acid in its medial sensilla, which is a bit more sensitive in fifth- than in sixth-instar larvae. The presence of this cell may account for the positive correlation between total phenols content and resistance of sorghum cultivars to this borer. Spodoptera can perceive four phenolic acids. Its lateral sensilla contain a cell responsive to chlorogenic acid and its medial sensilla a cell responsive to 4-hydroxybenzoic acid, gallic acid as well as vanillic acid. Feeding experiments showed that the latter substances inhibit feeding in the Armyworm.So far, in the borers adequate stimuli could be determined for only tow or three of the four taste cells present in each sensillum styloconicum. This indicates that we are still unaware of chemicals that may be important to these caterpillars. On the other hand, for the sensilla styloconica of Spodoptera, electrophysiology suggests the presence of five or six taste cell types, whereas only four taste cells are known from morphological studies.     

Lumi-ergometrine – structural identification and occurrence in sclerotia

The fungus Claviceps purpurea grows on grasses and cereal grains and produces six predominant ergot alkaloids. These toxic substances undergo different transformation reactions during storage and cereal processing. One of these reactions is the addition of water to a double bond in the ergoline skeleton. Since light is required for this process, the substances formed were named lumi-ergot alkaloids. From these, a new asymmetric carbon and consequently two epimers with different polarities are formed. For investigations of lumi-ergot alkaloids, ergometrine was used exemplarily as it represents one of the six ergot alkaloids predominantly formed by Claviceps purpurea. The main reaction product, the less polar compound of the two lumi-ergometrine epimers, was separated by HPLC and unambiguously identified as 10-(S)-lumi-ergometrine using X-ray structural analysis. A HPLC-MS/MS method was developed for the detection of this substance in sclerotia extracts. Using this method, the existence of both epimeric forms of lumi-ergometrine could be proved in the sclerotia. This is the first time that the existence of a lumi-transformation product of ergot alkaloids was proved in naturally grown samples.     

The Role of Auxin Metabolism in Root Meristem Regeneration by Pinus lambertiana Embryo Cuttings

Since the existence of root promoting substances that consist of a complex between auxin and another molecule has been suggested, we have examined the role of auxin conversion products in root regeneration by Pinus lambertiana embryo cuttings. Auxin conversion products were detected using radioactive forms of the auxins IAA (indoIe-3-acetic acid), NAA (a-napthaleneacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid). 10^?7M NAA was more effective than 10^?6M IAA at promoting rooting, yet it formed conversion products much less rapidly. Also continuous exposure to IAA was necessary for optimum root formation. Based on these and other findings, we conclude that free auxin, and not the conversion products we detected, is essential to root meristem formation.     

Odour sensitivity of antennal olfactory cells underlying grooved pegs of Anopheles gambiae s.s. and An. quadriannulatus

In female mosquitoes of the anthropophilic species Anopheles gambiae Giles s.s. and the zoophilic An. quadriannulatus Theobald single sensillum recordings from grooved pegs were made. In both species, the majority of these sensilla responded to ammonium hydroxide, butylamine and propanoic acid, whereas a smaller part responded to acetone. Lactic acid, butanone, 3-methyl phenol and 1-octen-3-ol evoked responses in a minority of grooved pegs only. In An. gambiae these four substances evoked either excitatory or inhibitory responses. In An. quadriannulatus excitatory and inhibitory responses were only found on stimulation with lactic acid; butanone, 3-methyl phenol and 1-octen-3-ol only evoked inhibition in the pegs of this species. More than half of the grooved pegs responded to water vapour with an increase in spike frequency. As opposed to this, in some pegs inhibitory responses were found upon stimulation with vapour of low humidity. This suggests that grooved pegs may play a role in humidity perception in Anopheles. Dose-response relations were investigated for cells excited by ammonium hydroxide, butylamine and propanoic acid. Excitatory responses to these three substances were dose-dependent. No significant differences were found between the dose-response curves of the two species. It is concluded that in both species the host odours tested are not perceived by specialist cells. Combined information from generalist cells may provide a detailed `odour profile' of the host.     

Stem Internode Elongation in the Japanese Morning Glory (Pharbitis nil Choisy) in Relation to an Inhibitor System of Auxin Destruction

Further investigations on a wild-type strain of the Japanese morning glory (Pharbitis nil Choisy) to ascertain the relationship between stem internode maturation, decreasing rate of internode elongation, and increasing auxin destruction, have established the following: There exists in young, elongating, internode tissue, substances which prevent the destruction of indoleacetic acid by enzymes normally found in stem tissue. Almost all of the protecting activity can be attributed to two substances, one of them possessing an apparent molecular weight in the 5000 to 10,000 g/mol range, the other, in the 1500–5000 g/mol range. Both are water soluble, and heat labile, at least in vitro. It is further suggested that associated with Japanese morning glory stem maturation, is the loss of these auxin-protecting substances, and as a consequence of this loss, the loss of further endogenous auxin-induced elongation.     

Biochemical changes in infection droplets containing spores of Botrytis spp. Incubated in the seed cavities of pods of bean (Vicia faba L.)

Infection droplets containing spores of Botrytis cinerea become inhibitory to the growth of germ tubes of the fungus within 18 hr. of their incubation in bean pods. The inhibition is caused by an ether-soluble substance, which has been partially purified, and which counteracts the stimulatory effect of sucrose, glucose, fructose, galacturonic acid and several amino acids, which are also present in the infection droplets. Changes in concentration of these substances have been described in the first 24 hr. after placing infection droplets in pods. The only major difference between droplets containing B. fabae and B. cinerea concerns the nature of the ether-soluble substances produced. Following B. fabae infection a biologically inactive u.v. absorbing substance appears in high yield in place of the antifungal substance formed following B. cinerea infections.     

Seasonal Rhythm of Rooting of Salix atrocinerea cuttings

The response of rooting and the content of growth substances in Salix atrocinerea cuttings were studied every month throughout the whole year. To study the rooting response 100 cuttings were put into a rooting mist-propagator frame and the results were observed 30 days later. The hormone content was studied with the same type of cuttings by means of methanol extraction, fractionating into acid, basic and neutral substances and chromatographic analysis on paper and bioassays. Salix atrocinerea cuttings have three rooting phases: one very active in January, February, March and April with plentiful roots, not ramified, originating at the base of the cutting; a second lesser phase from May to August with numerous small and very ramified roots formed at a more ample area on the stalk. Both peaks are separated by a sharp fall in June. From September to December the third phase of rooting takes place. Response is practically nil and the few small roots formed are originated at the base of the stalk, again, as in the first phase. In the histograms a remarkable activity in the acid fraction at Rf = 0.30–0.50 was found and IAA was identified. The rooting capacity of these cuttings and the IAA content show some correlation but not exact enough to assert that the root response is governed by an optimum hormonal content. In Salix atrocinerea cuttings inhibitors are absent during the whole year which support the hypothesis that root formation might in some cases be influenced also by the presence or absence of inhibitory growth substances.     

Combined effects of an oxidative enzyme and dissolved humic substances on 13C-labelled 2,4-D herbicide as revealed by high-resolution 13C NMR spectroscopy

Phenoxyalkanoic acids are a widely used class of herbicides. This work employed high-resolution ¹³C NMR to study the structural changes induced by humic substances and horseradish perodixase on 2,4-dichorophenoxyacetic acid (2,4-D) ¹³C-labelled in the side chain. NMR spectra showed that humic substances chemically catalyze abiotic splitting of [¹³C]2,4-D into 2,4-dichlorophenol and [¹³C]acetic acid at pH 7 but not at pH 4.7. Peroxidase did not catalyze the oxidative degradation of [¹³C]2,4-D at any pH tested and inhibited the effect of humic substances. Catalytic degradation by humic substances was attributed to free-radical reactions enhanced by the stereochemical contribution of large conformational structures formed by heterogeneous humic molecules at neutral pHs. Inhibition of 2,4-D degradation when humic substances were combined with peroxidase was explained by modification of both chemical and conformational humic structure due to peroxidase-promoted oxidative cross-coupling among humic molecules. Our findings show for the first time that the abiotic degradation of 2,4-D is catalyzed by dissolved humic substances at neutral pH. Journal of Industrial Microbiology & Biotechnology (2001) 26, 70–76. Received 09 February 2000/ Accepted in revised form 22 May 2000     

Protective Effects of a Culture Supernatant of Lactobacillus acidophilus and Antioxidants on Ileal Ulcer Formation in Rats Treated with a Nonsteroidal Antiinflammatory Drug

Ileal ulcers and thiobarbituric acid (TBA)-reactive substances in the ileal mucosa were induced in rats treated with a nonsteroidal antiinflammatory drug, 5-bromo-2-(4-fluorophenyl)-3-(4-methylsulfonylphenyl)thiophene (BFMeT), at a dose of 1,000 mg/kg administered with tap water as drinking water. However, the formation of ileal ulcers and TBA-reactive substances in the ileal mucosa was repressed by giving the animals a culture supernatant of Lactobacillus acidophilus as drinking water. We measured the antioxidative activity of the culture supernatant and found that the supernatant inhibited the formation of t-butyl hydroperoxide-induced TBA-reactive substances in erythrocyte membrane ghosts. Therefore, the effects of various known antioxidative compounds on the ileal ulcer formation induced by BFMeT were investigated. While α-tocopherol, t-butyl-1,4-hydroxyanisole and allopurinol did not repress ulcer formation after BFMeT treatment, ascorbic acid, dimethyl sulfoxide, glutathione and β-carotene significantly inhibited formation. Among these compounds, ascorbic acid was the most effective. Accumulation of TBA-reactive substances in the ileal mucosa after BFMeT treatment also decreased significantly in rats treated with ascorbic acid. In addition, the percentage of Gram-negative rods in the ileal contents of rats treated with BFMeT and tap water was dramatically increased, but it was not increased in rats treated with BFMeT and these antioxidants. A positive correlation between the percentage of Gram-negative rods and the number of ileal ulcers was also observed. These results suggest that lipid peroxidation mediated by oxygen radicals plays an important role in the induction of ileal ulcers by BFMeT in rats, and that lipopolysaccharide-activated neutrophils probably produce highly reactive hypochlorous acid and hydrogen peroxide, which are inactivated by ascorbic acid and glutathione, respectively.     

Metabolism of Phenylalanine in Aspergillus sojae

It was found that a new compound of phenylalanine metabolites (2-hydroxy-3-phenylpropenoic acid) and phenylacetic acid were formed in the cultured Czapek medium containing phenylalanine by Aspergillus sojae. 2-Hydroxy-3-phenylpropenoic acid (HPPA) was formed from phenylalanine (d- and l-form) via phenyllactic acid (d- and l-form), and degraded to benzoic acid, p-hydroxybenzoic acid, protocatechuic acid, and catechol in this order.

On the other hand, phenylacetic acid was formed from phenylpyruvic acid, and converted to homogentisic acid via o-hydroxyphenylacetic acid. From these results, a metabolic pathway of phenylalanine in Asp. sojae was proposed.