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PubMed1977

The metabolism of trans-cyclohexan-1,2-diol by an Acinetobacter species.

1. Acinetobacter TD63 was one of some thirty organisms isolated by elective culture with trans-cyclohexan-1,2-diol as sole source of carbon. The great majority of these isolates displayed the same growth spectrum as Nocardia globerula CL1 and Acinetobacter NCIB 9871 being capable of utilizing trans-cyclohexan-1,2-diol, 2-hydroxycyclohexan-1-one, cyclohexanol, cyclohexanone,1-oxa-2oxocycloheptane and adipate and were assumed to use well described metabolic pathways. 2. Acinetobacter TD63 was distinctive in being incapable of growth with cyclohexanol, cyclohexanone or 1-oxa-2-oxocycloheptane and because of this it was hoped that it would display an alternative pathway for the oxidation of trans-cyclohexan-1,2-diol. 3. Studies with cell extracts have shown the presence of inducible dehydrogenase for the conversion of trans-cyclohexan-1,2-diol to 2-hydroxycyclohexan-1-one and cyclohexan-1,2-dione and of 6-oxohexanoate to adipate. These enzymes are linked into a metabolic sequence by the action of a monooxygenase of broad specificity but efficiently capable of converting 2-hydroxy-cyclohexan-1-one into the lactone 1-oxa-2-oxo-7-hydroxycycloheptane that spontaneously rearranges to yield 6-oxohexanoate. 4. An enzyme capable of attacking cyclohexan-1,2-dione (mono-enol) in the absence of an electron donor or oxygen has also been detected. Evidence has been presented indicating that this enzyme catalyses a keto-enol tautomerization between cyclohexan-1,2-dione (mono-enol) and cyclohexan-1,2-dione (mono-hydrate) and is not involved in the pathway of ring cleavage. 5. The failure of Acinetobacter TD63 to grow with cyclohexanol, cyclohexanone or 1-oxa-2-oxocycloheptane is due not to this organism possessing a distinctive metabolic sequence but to a narrow inducer specificity coupled with an inability to form a lactone hydrolase enabling it to cleave the stable 1-oxa-2-oxocycloheptane which is an intermediate in the established pathway of cyclohexanol and cyclohexanone oxidation.

Acinetobacter↗
PubMed1990

Organic acid and acylcarnitine profiles of glutaric aciduria type I.

Urinary organic acid and acylcarnitine profiles from a 2-month-old boy were studied by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry. The patient excreted large amounts of glutaric acid and significant amounts of 3-hydroxyglutaric acid, glutaconic acid and glutarylcarnitine, and his serum glutaric acid level was markedly elevated. Thus he was chemically diagnosed as having glutaric aciduria type I (GAI). In addition to the above metabolites previously described in GAI, significantly increased excretion of 2-ketoglutaric acid, succinic acid, adipic acid, adipylcarnitine, suberic acid and azelaic acid was found. 2-Ketoadipic acid methylsuccinic acid and ethylmalonic acid were also detectable, suberylcarnitine was not increased, and dehydroadipylcarnitine was decreased in his urine. These results suggest that excess glutaryl-CoA causes the competitive inhibition of the dehydrogenation of adipyl-CoA to dehydroadipyl-CoA and results in an increase of adipic acid and adipylcarnitine and a decrease of dehydroadipylcarnitine. It is also suggested that oxidative decarboxylation of 2-ketoglutaric acid to succinyl-CoA is inhibited by high levels of glutaryl-CoA, and that the dehydrogenation of succinic acid to fumaric acid is inhibited owing to the increased glutaric acid derived from excess glutaryl-CoA. These results indicate that gas chromatography-mass spectrometry is the most appropriate and accurate method for the differential chemical diagnosis of GAI and glutaric aciduria type II.

Acylation↗
PubMed1995

Gestational diabetes: do all women need to be tested?

The results of glucose tolerance testing in 1,185 consecutive women were examined with respect to historical risk factors for gestational diabetes mellitus (GDM). GDM was present in 79 of 1,185 (6.7%) of the women. GDM was present in 8.5% of women aged > or = 30 years, in 12.3% of women with a preconception BMI > or = 30 and in 11.6% of women with a family history of diabetes in a first degree relation. A combination of one or all of these risk factors predicted GDM in only 48 of 79 (60.8%) cases. GDM was present in 4.8% of women without risk factors. Testing for GDM on the basis of these historical risk factors alone, and using the Australasian Diabetes in Pregnancy Society (ADIPS) criteria for diagnosis, would miss more than one-third of all cases. This study supports the ADIPS recommendation that there should be universal testing.

Adult↗
PubMed1999

Gestational diabetes mellitus. At what time should the postprandial glucose level be monitored?

OBJECTIVE: To compare selected pregnancy outcomes for women with gestational diabetes mellitus (GDM) with management based on testing either 1 hour or 2 hours postprandially according to the ADIPS recommendations. METHODS: Prospective study of consecutive women referred for the medical management of their GDM. Women were allowed to select whether they would test either 1 hour postprandial with a target glucose of < 8.0 mmol/L or 2 hours postprandial with a target glucose of <7.0 mmol/L. Changes to diet and the introduction and adjustment of insulin therapy were designed to maintain postprandial glucose levels below these targets. RESULTS: 166 women elected to test 1 hour postprandial and 101 elected to test 2 hours postprandial. There were no significant demographic differences between these 2 groups. The fetal birthweight, percentage of women requiring insulin and the total daily dose of insulin were similar in both groups. CONCLUSIONS: For women with GDM, monitoring either 1 hour or 2 hours postprandially led to similar outcomes. This would suggest that the ADIPS recommendations are equivalent and therefore women can choose the most convenient time for their postprandial monitoring.

Adult↗
PubMed2001

Screening for gestational diabetes mellitus: can we be more efficient?

In a retrospective review of 471 patients screened for gestational diabetes mellitus (GDM) in a community laboratory, we compared 50 g polycose screening test results with those of the 75 g oral glucose tolerance test (GTT). The rate of GDM diagnosis was compared using criteria promulgated by the New Zealand Society for Study of Diabetes (NZSSD), Australian Diabetes in Pregnancy Society (ADIPS) and World Health Organisation (WHO). In those with borderline screening results (7.8-8 mmol/L) the rate of GDM diagnosis using NZSSD criteria was low (2.8%) compared with higher screening test results (> or = 8.1 mmol/L), where the rate was 7.4%. Corresponding rates were 7.5% and 13.5% using ADIPS criteria and 5.6% and 12.4% using WHO criteria. The predictive value of a positive 50 g screening test is therefore low, especially for the higher New Zealand criteria. In women with borderline screening results no subject had a two-hour plasma glucose of 9.0 mmol/L or more on oral GTT. This suggests that the current screening cut-off of 7.8 mmol/L might be raised to 8.1 mmol/L, resulting in a 25% reduction in the number of glucose tolerance tests. Those with significant risk factors such as macrosomia, however, still warrant greater clinical suspicion and closer follow-up.

Adult↗
PubMed1995

An attempt to clarify the mechanism of the penetration enhancing effects of lipophilic vehicles with differential scanning calorimetry (DSC).

In a previous in-vivo skin penetration study, it was observed that certain lipophilic liquid vehicles enhanced drug penetration, whilst others did not. To clarify the mechanism of skin penetration enhancement, isolated sheets of human stratum corneum were measured by differential scanning calorimetry (DSC), either untreated or after pretreatment with various lipophilic liquids (highly purified light mineral oil, isopropyl myristate, caprylic/capric acid triglycerides containing 5% phospholipids, dibutyl adipate, dimethicone 100, cetearyl iso-octanoate, caprylic/capric acid triglycerides), commonly used in ointment bases. All samples were analysed over a heating range of at least--10-130 degrees C. All DSC curves were evaluated with regard to the phase-transition enthalpies (peak areas) and peak maximum temperatures of the lipid-phase transitions at ca 75 and 85 degrees C. With the exception of dimethicone 100, cetearyl iso-octanoate and caprylic/capric acid triglycerides, all vehicles showed characteristic alterations of the phase-transition temperatures and enthalpies of the stratum corneum lipids. Mineral oil and isopropyl myristate caused a reduction of the enthalpy and a decrease of the phase-transition temperatures. These two vehicles are thought to fluidize the lamellar-gel phase of the stratum corneum lipids, and possibly partially dissolve the lipids. Dibutyl adipate and caprylic/capric acid triglycerides containing 5% phospholipids decreased the phase-transition enthalpy only, probably due to dissolution or extraction of the stratum corneum lipids. These DSC results provide an explanation for the in-vivo penetration-enhancing effects observed previously.

Calorimetry, Differential Scanning↗
PubMed1994

Preparation, characterization, and immunological properties in mice of Escherichia coli O157 O-specific polysaccharide-protein conjugate vaccines.

Escherichia coli O157 causes severe enteritis and the extraintestinal complication of hemolytic-uremic syndrome, with their highest incidence occurring in children. We postulated that serum immunoglobulin G (IgG) antibodies to the O-specific polysaccharide of lipopolysaccharide (LPS) may confer protective immunity to enteric pathogens by inducing bactericidal reactions against the ingested organisms in the jejunum (J. B. Robbins, C. Chu, and R. Schneerson, Clin. Infect. Dis. 15:346-361, 1992; S. C. Szu, R. Gupta, and J. B. Robbins, p. 381-394, in I. K. Wachsmuth, P. A. Blake, and O. Olsvik, ed., Vibrio cholerae, 1994). Because polysaccharide-protein conjugates induce serum IgG antibodies in infants, we bound the O-specific polysaccharide of E. coli O157 to proteins. E. coli O157 LPS, treated with acetic acid or hydrazine, was derivatized with adipic acid dihydrazide and bound to proteins by carbodiimide-mediated condensation. Conjugates of these adipic hydrazide derivative were prepared with bovine serum albumin, formalin-treated exotoxin C of Clostridium welchii (Pig Bel toxoid), or Pseudomonas aeruginosa recombinant exoprotein A. The conjugates had low levels of endotoxin and elicited serum antibodies with bactericidal activity to the O157 LPS. The largest increase in LPS antibodies was of the IgG class. Clinical evaluation of E. coli O157-toxoid conjugates is planned.

ADP Ribose Transferases↗
PubMed2002

Immunogenicity in a mouse model of a conjugate vaccine made with a synthetic single repeating unit of type 14 pneumococcal polysaccharide coupled to CRM197.

Oligosaccharides (OSs) related to the pneumococcal type 14 capsular polysaccharide (Pn14PS) were studied for their ability to inhibit the binding between anti-PS14 antisera and native PS14. A synthetic tetrasaccharide corresponding to the repeating unit of the Pn14PS, a hexasaccharide mimic, and an octasaccharide fragment obtained by Pn14PS depolymerization were good inhibitors. CRM197 conjugates of the tetrasaccharide and an octasaccharide mimic were prepared by using either adipic acid diester or diethyl squarate linkers. The conjugate with the tetrasaccharide chains induced anti-Pn14PS antibodies when injected subcutaneously into mice, as determined by an enzyme-linked immunosorbent assay, and antibody titers increased with oligosaccharide loading. The adipic acid-linked tetrasaccharide conjugates elicited higher antibody titers than those prepared with a squarate spacer. The lower anti-Pn14PS antibody response of the octasaccharide mimic conjugate indicates the importance of the backbone galactose residue for an appropriate antibody response. The OS-CRM197 conjugate prepared from a single repeat unit of the Pn14PS is a potential vaccine candidate.

Animals↗
PubMed1978

[Physiological study and taxonomy of Alcaligenes species: A denitrificans, A. odorans and A faecalis].

We have studied 43 strains of the species Alcaligenes dentrificans, A. odorans, and A. faecalis. Twenty-five of them were isolated by enrichment culture on minimal medium containing an organic acid (L-malate, succinate, tartrate, adipate, or itaconate) and N2O as a respiratory electron acceptor. These constitute a single phenon with the A. dentrificans strain type and 9 other strains isolated from clinical specimens. However, strain 4 differs from the other 34 strains in 12 nutritional characters, in its ability to effect a meta cleavage of diphenols, and by the absence of tetrathionate reductase. The percentages of G + C are the following: strains isolated from soil, 66.4 +/- 1.1; collection strains, 67.0 +/- 1.3. The 5 strains of A. odorans differ from the 34 strains of A. denitrificans (not including strain 4) in their inability to denitrify nitrate and use D-saccharate, adipate, pimelate, suberate, beta-hydroxy-beta-methylglutarate meso-tartrate, azelate, and itaconate. Their percentage of G + C is much lower: 56.1 +/- 0.4. From the nutritional point of view the 3 strains of A. faecalis resemble A. dentrificans. However, they differ from the latter by their inability to grow anaerobically on NO3-, NO2-, N2O, and by a slightly lower percentage of G+ C: 64.3 +/- 0.0. The 43 strains synthesize poly-beta-hydroxybutyric acid. None of them is chemolithotrophic.

Alcaligenes↗
PubMed2003

Effects of commonly consumed fruit juices and carbohydrates on redox status and anticancer biomarkers in female rats.

Administration of apple juice, black currant juice, or a 1:1 combination of the two juices significantly decreased the level of the lipid peroxidation biomarker malondialdehyde in plasma of female rats, whereas the protein oxidation biomarker 2-amino-adipic semialdehyde, was significantly increased following administration of orange juice, black currant juice, or the 1:1 combination of apple and black currant juice. A significant increase in 2-amino-adipic semialdehyde was also observed in control rats given sucrose, fructose, and glucose in the drinking water at concentrations approximating the average carbohydrate levels in the employed fruit juices. None of the fruit juices were found to affect the activities of antioxidant enzymes in red blood cells or hepatic glutathione S-transferase. Hepatic quinone reductase activity, on the other hand, was significantly increased by grapefruit juice, apple juice, and black currant juice. The total daily intake of a selected subset of flavonoid aglycones ranged from 0.2 to 4.3 mg, and quercetin was found to be a minor constituent of all the juices investigated. In a parallel study, rats were fed quercetin at doses ranging from 0.001 to 10 g/kg of diet. However, no effects were observed on hepatic glutathione S-transferase or quinone reductase activities, plasma redox status, or the activity of red blood cell antioxidant enzymes. Overall, the results of the present study suggest that commonly consumed fruit juices can alter lipid and protein oxidation biomarkers in the blood as well as hepatic quinone reductase activity, and that quercetin may not be the major active principle. The observation that natural carbohydrates are capable of mediating oxidative stress in vivo warrants further studies due to the central role refined and unrefined carbohydrates play in human nutrition.

Animals↗
PubMed1986

Type I diabetes is characterized by insulin resistance not only with regard to glucose, but also to lipid and amino acid metabolism.

Resistance to the metabolic effects of insulin has been reported with regard to glucose disposal in type I diabetic patients (IDDM) even when they were euglycemic. Our aim was to study glucose, lipid, and amino acid metabolism during glucose clamping at multiple levels of insulin in 10 normal (N) and 6 IDDM patients. Blood glucose was maintained constant (4.7 mmol/liter) at three insulin plateaus (160 min each) [42 +/- 6 (SD) 89 +/- 11, and 1255 +/- 185 microU/ml in N and 36 +/- 4, 80 +/- 13, and 1249 +/- 107 microU/liter in IDDM]. Mean glucose disposal was 34 +/- 11, 69 +/- 10, and 84 +/- 22 mumol kg-1 min-1 in N and 16 +/- 5, 40 +/- 18, and 65 +/- 27 in IDDM, respectively. Baseline concentrations of blood lactate, pyruvate, alanine, and branched chain amino acids were 560 +/- 130, 36 +/- 9, 212 +/- 44, and 451 +/- 19 mumol/liter, in N and 793 +/- 179 (P less than 0.05), 45 +/- 14, 195 +/- 50, and 439 +/- 33 in IDDM, respectively. The maximum percent change of lactate during the euglycemic clamp was +147 +/- 23% in N and +75 +/- 15% (P less than 0.05) in IDDM; that of branched chain amino acids was -61 +/- 5% in N and -48 +/- 7% (P less than 0.01) in IDDM. Baseline concentrations of glycerol, FFA, and adipate were 44 +/- 15, 449 +/- 152, and 8 - 8 mumol/liter in N and 39 +/- 14, 473 +/- 44, and 41 +/- 14 (P less than 0.01) in IDDM. The maximum percent change of glycerol during the euglycemic clamp was -50 +/- 8% in N and -16 +/- 8% (P less than 0.01) in IDDM, that of FFA -98 +/- 3% in N and -70 +/- 4% in IDDM (P less than 0.05). No significant differences were found between N and IDDM with regard to blood concentrations of ketone bodies, citrate, ketoglutarate, and hydroxymethylglutaryl coenzyme A both before and during the euglycemic clamp. The lactate percent increase was significantly correlated to glucose disposal rate (P less than 0.001). The lactate turnover rate increased during the euglycemic clamp and was lower in IDDM than in N. We conclude that during euglycemic-multiple insulin clamp studies the greater lactate increase suggests that the flux of glycolysis is higher in N than in IDDM, tricarboxylic acid concentrations are comparable in N and IDDM, and FFA, glycerol, and branched chain amino acid decreases were less in IDDM than in N, suggesting that IDDM patients are resistant to insulin with regard to lipid and protein metabolism. The higher adipate basal values demonstrate enhanced omega-oxidation in IDDM.

Adult↗
PubMed1995

Effect of vehicles on diclofenac permeation across excised rat skin.

The in vitro percutaneous permeation of diclofenac from various vehicles was examined using rat abdominal skin as a model membrane. The oleaginous vehicles used in this study consisted of three components: i.e. fatty acid, fatty acid ester and nonpolar oil. The solubilities of sodium diclofenac in formulated vehicles were above 0.2 M. The effect of each oleaginous component in the vehicle on the permeation of diclofenac across the skin was in the following order: oleic acid > isostearic acid, diisopropyl adipate = diethyl sebacate > Panasate 875 and squalane > liquid paraffin. To clarify the reason for the differences in permeation among the fatty acid esters, the release of diclofenac through either porous or lipoidal membranes from these vehicles in vitro and the solubility of sodium diclofenac in the vehicles were studied. However, no relationship was observed between the release rate or solubility and skin permeability. The skin permeation of diclofenac increased following pretreatment with diisopropyl adipate or diethyl sebacate, but not with middle chain triglyceride (Panasate 875). These results suggested that the main reason may be the enhancement effect of fatty acid esters. Emulsions and creams containing 3% sodium diclofenac were prepared using the above oleaginous vehicles. A large flux and short lag time were observed in these preparations compared with an aqueous suspension of sodium diclofenac. The incorporation of urea significantly enhanced the permeation of diclofenac from these preparations. These results suggest that the emulsion and cream prepared in this study are useful for development for practical purposes.

Animals↗
PubMed1992

Relationship between the effects on bacterial activity of selected disinfectants and the hydrophobic characters of dibasic acid diesters.

We prepared test solutions which contained 80% (v/v) ethanol and 0.2% (w/v) chlorhexidine (CH) or benzalkonium chloride (BC) with or without a dibasic acid diester. After complete evaporation of the ethanol from the solution on filter paper, an overnight broth culture (Staphylococcus aureus) was repeatedly inoculated onto the filter paper, and viable bacterial counts were measured at 5 min after the last inoculation. By comparison with viable counts for CH or BC alone, we estimated the potentiating effects of dibasic acid diester on the bactericidal activity of CH or BC, and confirmed that this activity of the two disinfectants was potentiated in the presence of certain compounds in the homologs of di-n-butyl esters of aliphatic dibasic acid, and di-alkyl esters of adipic and phthalic acid. Diisobutyl adipate, one of the most effective diesters, substantially enhanced the bactericidal activities of benzethonium chloride, cetyl pyridinium chloride and didecyl dimethyl ammonium chloride, as well as CH and BC, but not those of polyhexamethylene biguanide or alkyldiaminoethyl glycinate. The potentiating effects of dibasic acid diesters observed for both CH and BC seemed to be affected by the hydrophobic character of these diesters themselves and are also expressed well by a particular quadratic equation as a function of these characters: namely, capacity factors, as determined by high-performance liquid chromatography.

Chemical Phenomena↗
PubMed2003

Characterization of polyesters by matrix-assisted laser desorption/ionization and Fourier transform mass spectrometry.

Two homopolyesters, poly(neopentyl glycol-alt-isophthalic acid) and poly(hexanediol-alt-azelaic acid), and two copolyesters, poly(dipropoxylated bisphenol-A-alt-(isophthalic acid-co-adipic acid)) and poly(neopentyl glycol-alt-(adipic acid-co-isophthalic acid)) were analyzed by internal source matrix assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS). The high resolution and high mass accuracy provided by FTMS greatly facilitate the characterization of the polyester and copolyester samples. Isobaric resolution allows the ion abundances of overlapping isotopic envelopes to be assessed. Repeat units were confirmed and end functionality assigned. Single shot mass spectra of the entire polymeric distribution demonstrate that the dynamic range of this internal MALDI source instrument and the analyzer cell exceeds performance of those previously reported for higher field instruments. Corrections of space charge mass shift effects are demonstrated for the analytes using an external calibrant and (subsequent to confirmation of structure) via internal calibration which removes ambiguity due to space charge differences in calibrant and analyte spectra. Capillary gel permeation chromatography was used to prepare low polydispersity samples from a high polydispersity polyester, improving the measurement of molecular weight distribution two-fold while retaining the benefits of high resolution mass spectrometry for elucidation of oligomer identity.

Polyesters↗
PubMed1992

Specificity of basolateral organic anion exchanger in proximal tubule for cellular and extracellular solutes.

We used an epifluorimetric technique to study the mechanism of organic anion transport across the basolateral surface of isolated S2 segments of rabbit proximal tubules. Fluorescein influx and efflux rates across the basolateral surface of lumen-collapsed tubules were determined from serial measurements of cellular fluorescein content after its addition to or removal from the bathing medium. We examined the effect on fluorescein transport of monocarboxylic and dicarboxylic metabolic intermediates added to the bathing medium or preloaded into the cells. The presence of the monocarboxylates (octanoate, valerate, butyrate, propionate, and acetate) in the bathing medium inhibited fluorescein influx. The eight-carbon-chain fatty acid, octanoate, was nearly as potent an inhibitor as probenecid and was more potent than p-aminohippurate (PAH) (IC50 = 10, 6, and 141 microM, respectively); the shorter chain fatty acids were much less effective (IC50 greater than or equal to 1,000 microM). The dicarboxylates (succinate, adipate, and alpha-ketoglutarate) moderately inhibited fluorescein influx (IC50 = 505, 245, and 257 microM, respectively). To determine the effect of intracellular organic anions on fluorescein influx, tubules were preincubated with organic anions to load the cells; the compounds were then removed from the bath, and fluorescein influx was measured. Preincubation with monocarboxylates, octanoate, butyrate, acetate, and PAH had no effect. In contrast, the dicarboxylates alpha-ketoglutarate, glutarate, and adipate stimulated fluorescein influx by 58, 53, and 43%, respectively, but succinate had no effect. Fluorescein efflux was accelerated by medium octanoate, PAH, alpha-ketoglutarate, and succinate but not by acetate. Probenecid alone had no effect on fluorescein efflux, but it blocked the stimulation caused by medium PAH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

[Determination of alkylphenols, bisphenol A, benzophenone and phthalates in containers of baby food, and migration into food simulants].

Infants, whose growth and development are highly dependent upon the endocrine system, are particularly vulnerable to endocrine disruptor exposure. In our study, we examined whether or not alkylphenols, bisphenol A, benzophenone, di(2-ethylhexyl)adipate and 10 phthalates are present in containers of baby food. Furthermore, the migration into food-simulating solvents was also examined. Sixteen types of containers of baby food, obtained on the Japanese market in 2001, were examined: 8 glass bottle types, 1 plastic type, 1 metallic package (laminated with plastic) and 6 multilayered laminated film packages. Alkylphenols, benzophenone, bisphenol A and di(2-ethylhexyl)adipate were not detected in any of the samples. On the other hand, dibutylphthalate (DBP) was detected in 7 samples (1.2-9.1 micrograms/sample), and di(2-ethylhexyl)phthalate (DEHP) was detected in 15 samples (1.3-18 micrograms/sample). Migration tests were carried out for 5 samples, and the levels of DBP and DEHP that migrated into n-heptane were 0.68-1.7 micrograms/sample and 0.33-3.5 micrograms/sample, respectively. From these results, a baby's intake levels of DBP and DEHP were estimated to be about 1/2,500 and 1/90-300 of the tolerable daily intake (TDI), respectively.

Alkylation↗
PubMed2026

Broad-spectrum biodegradation of aliphatic and aliphatic-aromatic polyesters by Papiliotrema laurentii isolated from locust frass.

Biodegradable aliphatic and aliphatic-aromatic polyesters, such as poly(butylene adipate-co-terephthalate) (PBAT), polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), and polyhydroxyalkanoates (PHA), are increasingly used as sustainable alternatives to petrochemical plastics. However, their depolymerization outside industrial composting facilities is often incomplete. This study characterized Papiliotrema laurentii strain 62UF-13, isolated from migratory locust frass, for broad-spectrum polyester hydrolysis. Emulsion assays demonstrated hydrolytic activity across all five polymers, with PCL and PBS showing the highest clearance rates. Solid-film assays revealed substantial gravimetric mass loss of PCL, PLA, and PHA cast films, whereas a commercial PBAT-PLA mulch film in minimal medium, underwent progressive fragmentation/disintegration, as assessed by the remaining film area. Incubation with the PBAT-PLA film was accompanied by the release of adipic acid (49.60 mg/L, week 1) and terephthalic acid (maximum 21.62 mg/L, week 4), followed by a decrease to 0.26 mg/L by week 8, coinciding with the emergence of putative 3,4-dihydroxymandelic acid and a putative acetylated derivative. Scanning electron microscopy (SEM) revealed pronounced pitting and erosion, while Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) indicated ester-bond scission and changes in crystallinity/melting behavior. Whole-genome sequencing identified eight candidate polyesterases, including cutinases and esterases, with &#x2265; 60% amino acid identity to known hydrolases active on PCL, PBS, PHA, and PLA. This study is the first report of P. laurentii degrading a broad range of aliphatic and aliphatic-aromatic polyesters, including partial biotransformation of terephthalate moieties from PBAT. Integration of phenotypic assays and genomic evidence positions P. laurentii 62UF-13 as a viable biocatalyst for decentralized management of biodegradable plastic waste under mild environmental conditions.

Papiliotrema laurentii↗
PubMed1991

Metabolic conversion of dicarboxylic acids to succinate in rat liver homogenates. A stable isotope tracer study.

The metabolic conversion of dicarboxylic acids into succinate and other gluconeogenic intermediates in rat liver homogenates was investigated using [1,2,4-13C4]dodecanedioic acid as tracer. Isotope enrichments in 3-hydroxybutyrate, succinate, fumarate, and malate, as well as dicarboxylates (dodecanedioic, sebacic, suberic, and adipic acids) were measured with selected ion monitoring capillary column gas chromatograph-mass spectrometry. Significant enrichment in the M + 4 (four labeled carbons) ion of succinate (0.4-2.9%) was detected, unequivocally demonstrating the direct conversion of dicarboxylate into succinate. In addition, significant enrichment of the M + 2 ion of succinate was also observed. This labeled species was generated from labeled acetyl-CoA through the tricarboxylic acid cycle. The partition of acetyl-CoA into the tricarboxylic acid cycle relative to ketone body formation was higher in the beta oxidation of dicarboxylate than monocarboxylate. Therefore, in addition to the production of succinate, the beta oxidation of dodecanedioate resulted in the channeling of the acetyl-CoA produced to the tricarboxylic acid cycle instead of to acetoacetate production. The enrichments in lower chain dicarboxylates are consistent with a partial bidirectional beta oxidation of dodecanedioic acid. In addition to the expected M + 0 and M + 4 labels, significant M + 2 species were detected in suberic and adipic acids. These M + 2-labeled species were produced from the released free dicarboxylate intermediates which were then reactivated and metabolized. In these experiments, the overall succinate production was derived 4% from the direct conversion of dodecanedioic acid and 11% from the indirect route via acetyl-CoA through tricarboxylic acid.

Acetyl Coenzyme A↗