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81.
Mutants for 9 of the 10 steps in histidine biosynthesis have been isolated and identified by enzyme assay. Each locus has been mapped in relation to the aro cluster and to other histidine loci by deoxyribonucleic acid-mediated transformation. The genes which code for enzymes 3, 6, and 8 of the pathway are linked to the aro cluster. A major histidine linkage group is composed of the genes which specify enzymes 1, 2, 5, 7, and 10. The locus which codes for step 9 of the pathway is unlinked to any other identified his loci. The major histidine cluster is loosely linked to cysB and is unlinked to any of the loci concerned with aromatic amino acid biosynthesis. 相似文献
82.
1. Measurements of the rates of oxidation of various compounds by a fluorescent Pseudomonas indicated that metabolism of 2,4-xylenol was initiated by oxidation of the methyl group para to the hydroxyl group. 2. 4-Hydroxy-3-methylbenzoic acid was isolated as the product of oxidation of 2,4-xylenol by cells inhibited with alphaalpha'-bipyridyl. 3. 4-Hydroxyisophthalic acid accumulated at low oxygen concentrations when either 2,4-xylenol or 4-hydroxy-3-methylbenzoic acid was oxidized by cells grown with 2,4-xylenol. 4. When supplemented with NADH, but not with NADPH, cell extracts oxidized 4-hydroxy-3-methylbenzoic acid readily. 2-Hydroxy-5-methylbenzoic acid was not oxidized. 5. Both 4-hydroxyisophthalic acid and p-hydroxybenzoic acid were oxidized to beta-oxoadipic acid by cell extracts supplemented with either NADH or NADPH. 4,5-Dihydroxyisophthalic acid was not oxidized. 6. From measurements of oxygen consumed and carbon dioxide evolved it was concluded that protocatechuic acid is an intermediate in the conversion of 4-hydroxyisophthalic acid into beta-oxoadipic acid. 相似文献
83.
The bacterial degradation of catechol, 3-methylcatechol, 2,3-dihydroxy-β-phenylpropionic acid, and protocatechuic acid has been studied in detail. From the results obtained a general sequence has been proposed for the microbial oxidation of dihydroxy aromatic compounds. 相似文献
84.
The pigments of Sarcina flava: a new series of C50 carotenoids 总被引:2,自引:0,他引:2
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Bacteria pathogenic to crucifers were isolated from 92% of the eggs from flies of the cabbage maggot, Hylemyia brassicae (Bouché) of a population from rutabaga (Swede; Brassica napus napobrassica) and from 90% of those from a population from Chinese cabbage (Brassica pekinensis). The larvae transmitted the decay-causing bacteria to healthy tissues and aided in the development and spread of the rot. Of bacterial isolates from the interior of surface-sterile puparia, decay was caused by 100% of those from the rutabaga population and 35% of those from Chinese cabbage. Pathogenic cultures were also obtained from 44% of the prepupal linings of the Chinese cabbage population. The light internal contamination of adults at eclosion showed that the flies became contaminated externally from the interior of the puparia.The two populations of H. brassicae studied were contaminated with distinctly different types of bacteria. Erwinia sp., the predominant isolate from the rutabaga population, grew best on rutabaga. It caused a slow necrotic collapse and a dark pigmentation of the tissues, but not a soft-rot. Many different types of bacterial contaminants were associated with the stages of the cabbage maggot from Chinese cabbage. Green pigmenting, non-pathogenic forms were very prevalent. All pathogenic cultures caused some type of soft-rot. Some of these cultures were identified as Pseudomonas sp. and Aerobacter sp.
Approved for publication by the Director of the Wisconsin Agricultural Experiment Station. 相似文献
Zusammenfassung Es wurde die Beziehung zweier Kohlfliegen-Populationen (Hylemyia brassicae Bouché) zu fäulniserregenden Bakterien an Kreuzblütlern in Verbindung mit dem von den Larven verursachten Schaden untersucht. 92 bez. 90% der Eier und 100 bez. 35% der Puparien, die sich an Kohlrüben und Chinakohl entwickelten, trugen pathogene Bakterien. Pathogene Kulturen wurden von 44% der Präpuppen-Häute aus Puparien der Chinakohl-Populationen erhalten. Die Larven vermochten fäulniserregende Bakterien wirksam auf gesunde Gewebe zu übertragen und förderten die Entwicklung und Ausbreitung der Fäule. Beim Schlüpfen waren die Imagines innerlich nicht stark kontaminiert, beschmierten sich aber offenbar äußerlich durch Kontakt mit dem Inneren der Puppengehäuse und der Präpuppen-Häute.Ein als Erwinia spec. identifizierter Bakterientyp konnte durchgängig von allen Stadien der Kohlfliege isoliert werden, die sich an Kohlrüben entwickelten. Er verursacht bei Kohlrüben eine langsame nekrotische Fäulnis und dunkle Verfärbung der befallenen Gewebe. Dieses Bakterium scheint antagonistisch zu anderen Bakterien zu sein, da nur sehr wenige andere Keime mit Stadien der Insekten dieser Population vergesellschaftet gefunden wurden. Umgekehrt fanden sich viele verschiedene Bakterientypen auf Stadien der auf dem Chinakohl lebenden Kohlfliegen. Die Virulenz der pathogenen Kulturen variierte beträchtlich, jedoch verursachten alle irgendeine Art der Weichfäule. Einige dieser aus dem Inneren oberflächlich sterilisierter Puparien isolierten Kulturen wurden als Pseudomonas spec. and Aerobacter spec. bestimmt.Die Art der bakteriellen Kontamination der Kohlfliege scheint hauptsächlich von der Empfänglichkeit ihrer kreuzblütigen Wirtspflanzen gegenüber verschiedenen Typen der Fäulnis nach Verletzung durch die Kohlfliegenmaden abhängig zu sein.Die allgemeinen Zusammenhänge zwischen dem Insekt und den fäulniserregenden Bakterien werden beschrieben.
Approved for publication by the Director of the Wisconsin Agricultural Experiment Station. 相似文献
88.
Relationship between Protein Synthesis in Tuber Discs and the Protein Synthetic Activity of a Cell-Free Preparation 总被引:2,自引:1,他引:1 下载免费PDF全文
A cell-free system which synthesizes protein was isolated from `aged' discs of Jerusalem artichoke tubers. The synthetic activity was largely associated with the fraction containing mitochondria. Preparations from freshly cut tissue were virtually inactive but increasingly active preparations were obtained from discs `aged' for progressively longer periods; those from 24 hour discs showing maximum activity. The characteristics of this change are reminiscent of the rate of development of invertase, a marker for protein synthesis in the intact disc. Extensive investigations showed that bacterial contamination was not a significant factor in the synthetic activity. 相似文献
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