Raoultella planticola, a new strain degrading 2,4,5-trichlorophenoxyacetic acid

A new strain that degrades the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was isolated from soil, which was exposed to factors related to the petrochemical industry. According to its physiological, biochemical, cultural, and morphological traits, together with the sequence of the 16S rRNA gene, the strain was identified as Raoultella planticola 33-4ch. The strain could consume 2,4,5-T as a sole source of carbon and energy. The amount of 2,4,5-T in the culture medium decreased by 51% after five days of incubation. Raoultella planticola 33-4ch consumes 2,4,5-T to produce 4-chlorophenoxyacetic, phenoxyacetic, and 3-methyl-2,6-dioxo-4-hexenoic acids.     

Klebsiella pneumoniae Produces No Histamine: Raoultella planticola and Raoultella ornithinolytica Strains Are Histamine Producers

Histamine fish poisoning is caused by histamine-producing bacteria (HPB). Klebsiella pneumoniae and Klebsiella oxytoca are the best-known HPB in fish. However, 22 strains of HPB from fish first identified as K. pneumoniae or K. oxytoca by commercialized systems were later correctly identified as Raoultella planticola (formerly Klebsiella planticola) by additional tests. Similarly, five strains of Raoultella ornithinolytica (formerly Klebsiella ornithinolytica) were isolated from fish as new HPB. R. planticola and R. ornithinolytica strains were equal in their histamine-producing capabilities and were determined to possess the hdc genes, encoding histidine decarboxylase. On the other hand, a collection of 61 strains of K. pneumoniae and 18 strains of K. oxytoca produced no histamine.     

Isolation and lipid degradation profile of Raoultella planticola strain 232-2 capable of efficiently catabolizing edible oils under acidic conditions

The lipids (fats and oils) degradation capabilities of soil microorganisms were investigated for possible application in treatment of lipids-contaminated wastewater. We isolated a strain of the bacterium Raoultella planticola strain 232-2 that is capable of efficiently catabolizing lipids under acidic conditions such as in grease traps in restaurants and food processing plants. The strain 232-2 efficiently catabolized a mixture (mixed lipids) of commercial vegetable oil, lard, and beef tallow (1:1:1, w/w/w) at 20–35 °C, pH 3–9, and 1,000–5,000 ppm lipid content. Highly effective degradation rate was observed at 35 °C and pH 4.0, and the 24-h degradation rate was 62.5?±?10.5 % for 3,000 ppm mixed lipids. The 24-h degradation rate for 3,000 ppm commercial vegetable oil, lard, beef tallow, mixed lipids, and oleic acid was 71.8 %, 58.7 %, 56.1 %, 55.3?±?8.5 %, and 91.9 % at pH 4 and 30 °C, respectively. R. planticola NBRC14939 (type strain) was also able to efficiently catabolize the lipids after repeated subculturing. The composition of the culture medium strongly influenced the degradation efficiency, with yeast extract supporting more complete dissimilation than BactoPeptone or beef extract. The acid tolerance of strain 232-2 is proposed to result from neutralization of the culture medium by urease-mediated decomposition of urea to NH₃. The rate of lipids degradation increased with the rates of neutralization and cell growth. Efficient lipids degradation using strain 232-2 has been achieved in the batch treatment of a restaurant wastewater.     

Physiological and Cellular Responses of the 2,4-D Degrading Bacterium, Burkholderia cepacia YK-2, to the Phenoxyherbicides 2,4-D and 2,4,5-T

Our previous research has demonstrated that novel 43-kDa DnaK and 41-kDa GroEL proteins are synthesized in Burkholderia sp. YK-2 in response to sublethal concentrations of 2,4-D stress [Cho et al. (2000) Curr Microbiol 41:33–38]. In this study, we have extended this work to examine the cellular responses of strain YK-2 to stresses induced in response to the phenoxyherbicides 2,4-D or 2,4,5-T. Strain YK-2 exhibited a more sensitive response to 2,4,5-T stress than to 2,4-D stress, as shown in physiological and morphological changes, suggesting a greater cytotoxic effect of 2,4,5-T. SEM analyses revealed the presence of perforations and irregular rod forms with wrinkled surfaces for cells treated with either herbicide. These irregularities were found more frequently for 2,4,5-T-treated cells than for 2,4-D-treated cells. Analysis of cellular fatty acids showed similar effects in the shifts of total cellular fatty acid composition in response to 2,4-D and 2,4,5-T. Strain YK-2 could degrade 2.25 mM 2,4-D completely during 28 h of incubation with transient production of 2,4-dichlorophenol as a metabolite; however, 2,4,5-T was not catabolized at any of the concentrations tested. BIOLOG and 16S rDNA analyses revealed that strain YK-2 was 98% similar to the Burkholderia cepacia species cluster; therefore, we have designated this strain as B. cepacia YK-2. Received: 7 February 2002 / Accepted: 7 March 2002     

Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil

Agent Orange contaminated soils were utilized in direct enrichment culture studies to isolate 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) mineralizing bacteria. Two bacterial cultures able to grow at the expense of 2,4,5-T and/or 2,4-D were isolated. The 2,4,5-T degrading culture was a mixed culture containing two bacteria, Burkholderia species strain JR7B2 and Burkholderia species strain JR7B3. JR7B3 was able to metabolize 2,4,5-T as the sole source of carbon and energy, and demonstrated the ability to affect metabolism of 2,4-D to a lesser degree. Strain JR7B3 was able to mineralize 2,4,5-T in pure culture and utilized 2,4,5-T in the presence of 0.01 yeast extract. Subsequent characterization of the 2,4-D degrading culture showed that one bacterium, Burkholderiaspecies strain JRB1, was able to utilize 2,4-D as a sole carbon and energy source in pure culture. Polymerase chain reaction (PCR) experiments utilizing known genetic sequences from other 2,4-D and 2,4,5-T degrading bacteria demonstrated that these organisms contain gene sequences similar to tfdA, B, C, E, and R (Strain JRB1) and the tftA, C, and E genes (Strain JR7B3). Expression analysis confirmed that tftA, C, and E and tfdA, B, and C were transcribed during 2,4,5-T and 2,4-D dependent growth, respectively. The results indicate a strong selective pressure for 2,4,5-T utilizing strains under field condition.     

Biodegradation of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid by dichlorophenol-adapted microorganisms from freshwater,anaerobic sediments

Reductive dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was investigated in anaerobic sediments by non-adapted microorganisms and by microorganisms adapted to either 2,4- or 3,4-dichlorophenol (DCP). The rate of dechlorination of 2,4-D was increased by adaptation of sediment microorganisms to 2,4-DCP while dechlorination by sediment microorganisms adapted to 3,4-DCP displayed a lag phase similar to non-adapted sediment slurries. Both 2,4- and 3,4-DCP-adapted microorganisms produced 4-chlorophenoxyacetic acid by ortho-chlorine removal. Lag phases prior to dechlorination of the initial addition of 2,4,5-T by DCP-adapted sediment microorganisms were comparable to those from non-adapted sediment slurries. However, the rates of dechlorination increased upon subsequent additions of 2,4,5-T. Biodegradation of 2,4,5-T by sediment microorganisms adapted to 2,4- and/ or 3,4-DCP produced 2,5-D as the initial intermediate followed by 3-chlorophenol and phenol indicating a para > ortho > meta order of dechlorination. Dechlorination of 2,4,5-T, by either adapted or non-adapted sediment microorganisms, progressed without detection of 2,4,5-trichlorophenol as an intermediate.     

A comparative study on phosphotransferase activity of acid phosphatases from Raoultella planticola and Enterobacter aerogenes on nucleosides,sugars, and related compounds

Natural and modified nucleoside-5′-monophosphates and their precursors are valuable compounds widely used in biochemical studies. Bacterial nonspecific acid phosphatases (NSAPs) are a group of enzymes involved in the hydrolysis of phosphoester bonds, and some of them exhibit phosphotransferase activity. NSAP containing Enterobacter aerogenes and Raoultella planticola whole cells were evaluated in the phosphorylation of a wide range of nucleosides and nucleoside precursors using pyrophosphate as phosphate donor. To increase the productivity of the process, we developed two genetically modified strains of Escherichia coli which overexpressed NSAPs of E. aerogenes and R. planticola. These new recombinant microorganisms (E. coli BL21 pET22b-phoEa and E. coli BL21 pET22b-phoRp) showed higher activity than the corresponding wild-type strains. Reductions in the reaction times from 21 h to 60 min, from 4 h to 15 min, and from 24 h to 40 min in cases of dihydroxyacetone, inosine, and fludarabine, respectively, were obtained.     

Degradation of 2,4,5-Trichlorophenoxyacetic acid by a Nocardioides simplex culture

A Nocardioides simplex strain 3E was isolated which totally dechlorinated 2,4,5-trichlorophenoxyacetic acid and was capable of its utilization as the sole source of carbon. The mechanism of 2,4,5-trichlorophenoxyacetic acid degradation by this strain was investigated. Chloroaromatic metabolites that occur in the lag, exponential and stationary growth phases of the strain Nocardioides simplex 3E were isolated and identified bases on a combination of TLC, GC-MS and HPLC data. Decomposition of 2,4,5-trichlorophenoxyacetic acid at the initial stage was shown to proceed by two pathways: via the splitting of the two-carbon fragment to yield 2,4,5-trichlorophenol and the reductive dechlorination to produce 2,4-dichlorophenoxyacetic acid. Hydrolytic dechlorination of 2,4,5-trichlorophenoxyacetic acid was found to yield dichlorohydroxyphenoxyacetic acid, thus pointing to the possible existence of a third branch at the initial stage of degradation of the xenobiotic. 2,4,5-Trichlorophenol and 2,4-dichlorophenoxyacetic acid produced during the metabolism of 2,4,5-trichlorophenoxyacetic acid and in experiments with resting cells are utilized by the strain Nocardioides simplex 3E as growth substrates.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - 2,4,5-T 2,4,5-trichlorophenoxyacetic acid - 2,4,5-TCP 2,4,5-trichlorophenol     

Physiological and cellular responses of the 2,4-D degrading bacterium,Burkholderia cepacia YK-2, to the phenoxyherbicides 2,4-D and 2,4,5-T

Our previous research has demonstrated that novel 43-kDa DnaK and 41-kDa GroEL proteins are synthesized in Burkholderia sp. YK-2 in response to sublethal concentrations of 2,4-D stress [Cho et al. (2000) Curr Microbiol 41:33-38]. In this study, we have extended this work to examine the cellular responses of strain YK-2 to stresses induced in response to the phenoxyherbicides 2,4-D or 2,4,5-T. Strain YK-2 exhibited a more sensitive response to 2,4,5-T stress than to 2,4-D stress, as shown in physiological and morphological changes, suggesting a greater cytotoxic effect of 2,4,5-T. SEM analyses revealed the presence of perforations and irregular rod forms with wrinkled surfaces for cells treated with either herbicide. These irregularities were found more frequently for 2,4,5-T-treated cells than for 2,4-D-treated cells. Analysis of cellular fatty acids showed similar effects in the shifts of total cellular fatty acid composition in response to 2,4-D and 2,4,5-T. Strain YK-2 could degrade 2.25 m M 2,4-D completely during 28 h of incubation with transient production of 2,4-dichlorophenol as a metabolite; however, 2,4,5-T was not catabolized at any of the concentrations tested. BIOLOG and 16S rDNA analyses revealed that strain YK-2 was 98% similar to the Burkholderia cepacia species cluster; therefore, we have designated this strain as B. cepacia YK-2.     

Biodegradation of 2,4,5-trichlorophenoxyacetic acid in liquid culture and in soil by the white rot fungus Phanerochaete chrysosporium

Summary Extensive biodegradation of [¹⁴C]-2,4,5-trichlorophenoxyacetic acid ([¹⁴C]-2,4,5-T) by the white rot fungus Phanerochaete chrysosporium was demonstrated in nutrient nitrogen-limited aqueous cultures and in [¹⁴C]-2,4,5-T-contaminated soil inoculated with this fungus and supplemented with ground corn cobs. After incubation of [¹⁴C]-2,4,5-T with aqueous cultures of the fungus for 30 days, 62.0%±2.0% of the [¹⁴C]-2,4,5-T initially present was degraded to ¹⁴CO₂. Mass balance analysis demonstrated that water soluble metabolites were formed during degradation, and HPLC and thin layer chromatography (TLC) of methylene chloride-extractable material revealed the presence of polar and non-polar [¹⁴C]-2,4,5-T metabolites. It was also shown that only 5% of the [¹⁴C]-2,4,5-T initially present in cultures remained as undegraded [¹⁴C]-2,4,5-T. In incubations composed of [¹⁴C]-2,4,5-T-contaminated soil, ground corn cobs, and 40% (w/w) water, 32.5%±3.6% of the [¹⁴C]-2,4,5-T initially present was converted to ¹⁴CO₂ after 30 days of incubation. These results suggest that it may be possible to develop practical systems based on the use of this fungus to detoxify 2,4,5-T-contaminated water and soil.     

Chlorinated phenoxyacetic acids and chlorophenols in the modified Allium test

The chlorinated phenoxyacetic acids 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4,5-T butoxyethyl ester and the chlorophenols 2,4-dichlorophenol and 2,4,5-trichlorophenol were tested for genotoxicity in the modified Allium test, which is based on exposure to the test chemicals of growing onions. The mean length of growing roots were measured and chromosome damage was recorded. Of the substances tested, MCPA was the most toxic and the chlorophenoxyacetic acids were more toxic than the chlorophenols. The lower threshold values for growth retardation were below 0.1 ppm for the acids, approx. at 0.1 ppm for the ester and less than 5 ppm for the phenols. Though a monocotyledon, Allium cepa was sensitive enough to respond to even low concentrations of these dicotyledon-selecting pesticides.     

<Emphasis Type="Italic">Raoultella</Emphasis> spp.—clinical significance,infections and susceptibility to antibiotics

The genus Raoultella belongs to the family of Enterobacteriaceae. Raoultella spp. are Gram-negative, aerobic, non-motile rods. This genus can be distinguished from the genus Klebsiella, in that genus use histamine as the only source of carbon in the medium. Also, Raoultella grow at 4 °C and do not produce gas from lactose at 44.5 °C. Raoultella sp. is known to inhabit natural environments (water, soil, plants). The reservoir of Raoultella is the gastrointestinal tract and upper respiratory tract. Raoultella spp. are opportunistic bacteria, which usually cause infections of the biliary tract, pneumonia and bacteraemia in oncologic and with lower immunity patients. Raoultella planticola and Raoultella ornithinolytica are the most frequently encountered human pathogens among the genus Raoultella. In this review, the current knowledge on Raoultella infections is summarized.     

Interaction of coumarin, gibberellic acid and abscisic acid in the translocation of auxin in bean seedlings

The effects of coumarin on the translocation of 2,4,5-trichlorophenoxyaceticacid (2,4,5-T) in bean (Phaseolus vulgaris L. cv. StringlessGreenpod) seedlings was determined. ¹⁴C-labeled 2,4,5-T wasinjected in the stem tissue at the cotyledonary node along withthe coumarin or the coumarin was added to the nutrient solutionprior to, or at the time of, 2,4,5-T treatment. The amount oftranslocation of radioactive 2,4,5-T to plant parts was thendetermined at various times after treatment. An immediate effectof coumarin was to enhance acropetal 2,4,5-T translocation tothe young shoots. This effect occurred at low 2,4,5-T treatmentlevels and appeared to be specific for 2,4,5-T since sucrosetranslocation was not affected. Prolonged treatment with coumarininhibited acropetal and basipetal 2,4,5-T translocation in amanner similar to prolonged treatment with abscisic acid (ABA).Gibberellin A₃ (GA) reversed the inhibitory effects of coumarinand ABA on 2,4,5-T acropetal translocation. ¹ Journal article 3244 of the Agricultural Experiment Station,Oklahoma State University. (Received December 6, 1976; )     

How to identify Raoultella spp. including R. ornithinolytica isolates negative for ornithine decarboxylase? The reliability of the chromosomal bla gene

Although Raoultella planticola and Raoultella ornithinolytica were described more than 20 years ago, identifying them remains difficult. The reliability of the chromosomal bla gene for this identification was evaluated in comparison with that of the 16S rDNA and rpoB genes in 35 Raoultella strains from different origins. Of the 26 strains previously identified as R. planticola by biochemical tests alone or in association with molecular methods, 21 harboured a bla gene with 99.8% identity with the bla gene of two reference R. ornithinolytica strains (bla_ORN gene) and 5 harboured a bla gene with 99.2% identity with the bla gene of two reference R. planticola strains (bla_PLA gene). The 9 isolates previously identified as R. ornithinolytica harboured a bla_ORN gene. The bla gene-based identification was confirmed by 16S rDNA and rpoB sequencing. The 21 isolates newly identified as R. ornithinolytica had a test negative for ornithine decarboxylase (ODC). Molecular experiments suggested one copy of ODC-encoding gene in both ODC-negative R. ornithinolytica and R. planticola strains and two copies in ODC-positive R. orninthinolytica strains. Analysis of the 35 bla genes allowed us (i) to confirm an identity of only 94% between the bla genes of the two Raoultella species while this identity was > 98% for rpoB and > 99% for 16S rDNA genes and (ii) to develop and successfully apply a bla PCR RFLP assay for Raoultella spp. identification.Overall, this study allowed us to discover ODC-negative R. ornithinolytica and to provide a reliable Raoultella identification method widely available as not requiring sequencing equipment.     

The mycoflora of adult worker honeybees,Apis mellifera: Effects of 2,4,5-T and caging of bee colonies

The guts of 195 adult worker honeybees, Apis mellifera, from free-flying control colonies fed sucrose, from caged control colonies fed sucrose, from free-flying colonies fed 2,4,5-T, and from caged colonies fed 2,4,5-T were examined for yeasts and molds. Only 25% of the bee guts contained fungi. Torulopsis magnoliae, T. glabrata, Hansenula anomala, Penicillium cyclopium, and P. cyclopium var. echinulatum were the most frequent isolates. Molds were most prevalent in bees from free-flying control colonies fed sucrose, and yeasts were found most often in bees from caged colonies fed 2,4,5-T.     

Histidine Decarboxylases and Their Role in Accumulation of Histamine in Tuna and Dried Saury

Histamine-producing bacteria (HPB) such as Photobacterium phosphoreum and Raoultella planticola possess histidine decarboxylase (HDC), which converts histidine into histamine. Histamine fish poisoning (HFP) is attributable to the ingestion of fish containing high levels of histamine produced by HPB. Because freezing greatly decreases the histamine-producing ability of HPB, especially of P. phosphoreum, it has been speculated that HFP is caused by HDC itself from HPB cells autolyzing during frozen storage, even when HPB survive frozen storage. Here we constructed recombinant HDCs of P. phosphoreum, Photobacterium damselae, R. planticola, and Morganella morganii and investigated the ability of HDCs to produce sufficient histamine to cause HFP. To elucidate the character of these HDCs, we examined the specific activity of each recombinant HDC at various temperatures, pH levels, and NaCl concentrations. Further, we also investigated the stability of each HDC under different conditions (in reaction buffer, tuna, and dried saury) at various temperatures. P. damselae HDC readily produced sufficient histamine to cause HFP in fish samples. We consider that if HDC is implicated as an independent cause of HFP in frozen-thawed fish, the most likely causative agent is HDC of P. damselae.     

The Uptake of Growth Substances: VI. A COMPARATIVE STUDY OF THE FACTORS DETERMINING THE PATTERNS OF UPTAKE OF PHENOXYACETIC ACID AND 2,4,5-TRICHOLOROPHEN-OXYACETIC ACID, WEAK AND STRONG AUXINS, BY GOSSYPIUM TISSUES2

Using segments of etiolated hypocotyls of Gossypium, a comparativestudy has been made of the processes which determine the patternsof uptake of a very weak auxin, phenoxyacetic acid (POA), anda very powerful one, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). When segments are placed in solutions of POA-1-¹⁴C, a continuousincrease in the radioactivity of the tissues is accompaniedby the formation of radioactive metabolities which can be separatedfrom POA by techniques of paper chromatography. At the sametime there is a progressive increase in the amount of radio-activitywhich cannot be removed by transferring the tissues to buffer.Uptake is inhibited by low temperature, anaerobiosis, 2,4-dinitrophenol,and iodoacetate. It is concluded that the accumulation of POAinvolves its metabolic conversion to products which do not readilydiffuse out into the external medium. With 2,4,5-T-1-¹⁴C the radioactivity of the segments at firstincreases rapidly but this is followed after two hours by aphase of rapid decrease. No radioactive metoabolites can bedetected by paper chromatography and all of the ¹⁴C taken upcan be rapidly removed by transfer to buffer. The magnitudeof the decrease in radioctivity during the second phase of uptakeis balanced by a release to the medium of a matched amount ofradioactive 2,4,5-T. Uptake of 2,4,5-T is somewhat less sensitiveto temperature and anaerobiosis than uptake of POA and is bycontrast only slightly inhibited by 2,4-dinitrophenol and iodoacetate. Pretreatment of segments in buffer markedly alters the patternof uptake of 2,4,5-T but not that of POA. It reduces both theamount of 2,4,5-T initially taken up and the amount subsequentlyreleased to the medium. In addition, both net loss of radioactivityduring the course of uptake of 2,4,5-T and the reduction inthe extent of uptake following pretreatment are both arrestedby adding streptomycin, but not by the addition of pencillinor chloramphenicol. It is concluded that the uptake of 2,4,5-T involves reversibleaccumulation by a process whose efficiency decreases with time:the most likely systems are a metabolically linked mechanismfor the active transport across a membrane or reversible adsorptionon specific binding sites.     

The Uptake of Growth Substances: XI. VARIATIONS IN THE ACCUMULATION OF SUBSTITUTED PHENOXYACETIC ACIDS OF DIFFERING PHYSIOLOGICAL ACTIVITY BY SEGMENTS OF AVENA MESOCOTYL

An examination has been made of the phase of continuous accumulationof phenoxyacetic acid (POA) and the 2-, 4-, 2,4-, 2,6-, and2,4,5-chloro-derivatives, containing carbon-14 in the carboxylgroup, by segments of the Avena mesocotyl. On the basis of previousfindings to eliminate the initial transient components of uptake(Type I processes) the segments were pretreated for 13 to 18h in buffer or buffer containing the respective non-radioactivecompound. For five of the compounds the relationship between the rateof uptake and the external concentration takes the form of arectangular hyperbola, but for the sixth, 2,4,5-T, this relationshipdoes not hold. The data, except those for 2,4,5-T, have beenevaluated as linear regressions of rate of uptake against thequotient of rate over concentration. From each regression equationtwo constants have been derived: the point ‘B’ wherethe line intersects the rate axis (the theoretically maximumrate) and the slope of the regression ‘K’, whichcan alternatively be expressed as the concentration at whichthe observed rate equals half the value of ‘B’. The calculated values of B and K for POA are approximately twiceas great as the corresponding values for 2-CPA, and about 25times greater than for 4-CPA. The values for 2,4-D are closeto those for 4-CPA, and 2,6-D is intermediate between 2-CPAand 4-CPA. Although the constants for 2,4,5-T could not be calculatedprecisely, the rates of accumulation are about one-fourth ofthose measured for 2,4-D at equivalent concentrations. The uptake of radioactive 2,4-D is slightly depressed in thepresence of nonradioactive POA. Greater reductions are causedby 2-CPA or 2,6-D, and 2,4-D or 2,4,5-T are even more inhibitory.The pattern of inhibition caused by 2,4,5-T indicates competitionfor common sites of uptake, while POA appears not to be competitive.In corresponding experiments with POA, the presence of the otherregulators only caused small inhibitions and the order was different. Earlier work showed that in Avena accumulation is accompaniedby the conversion to a varying degree of the individual substitutedphenoxyacetic acids to conjugated derivatives. It is suggestedthat the variation between compounds in their rates of accumulationis in part due to differences in the stability of the conjugatedderivatives, and that the facility of conversion is a factorin determining physiological activity.     

Abscisic acid and gibberellic acid as factors in the translocation of auxin

The effects of abscisic acid (ABA) and gibberellic acid (GA)on the translocation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)in beans (Phaseolus vulgaris L. cv. Stringless Greenpd) seedlingswere determined. ¹⁴C-labeled 2,4,5-T was injected in the stemtissue at the cotyledonary node in 1-µl amounts alongwith the AB or GA. ABA caused an enhancement of 2,4,5-T translocationto the lower hypocotyl and roots and promoted a decrease inthe accumulation of 2,4,5-T in the young expanding shoots andprimary leaves. GA promoted the accumulation of 2,4,5-T in youngshoots. The enhanced basipetal translocation of 2,4,5-T wasmeasurable after a few hours of treatment and was partiallyeffective even in the presence of the protein synthesis inhibitorcychloheximide. The GA effects on 2,4,5-T translocation werenullified by cycloheximide and were also noted after only afew hours of treatment. ¹Journal Article 2618 of the Agricultural Experiment Station,Oklahoma State University. (Received October 1, 1973; )     

Mineralization of 2,4-Dichlorophenoxyacetic Acid (2,4-D) and Mixtures of 2,4-D and 2,4,5-Trichlorophenoxyacetic Acid by Phanerochaete chrysosporium

Evidence is presented for mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) in nutrient-rich media (high-nitrogen and malt extract media) by wild-type Phanerochaete chrysosporium and by a peroxidase-negative mutant of this organism. Mass balance analysis of [U-ring-¹⁴C]2,4-D mineralization in malt extract cultures showed 82.7% recovery of radioactivity. Of this, 38.6% was released as ¹⁴CO₂ and 27.0, 11.2, and 5.9% were present in the aqueous, methylene chloride, and mycelial fractions, respectively. 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were simultaneously mineralized when presented as a mixture, and mutual inhibition of degradation was not observed. In contrast, a relatively higher rate of mineralization of 2,4-D and 2,4,5-T was observed when these compounds were tested as mixtures than when they were tested alone.