Degradation of monohydroxylated benzoates by strain KUFI-6N of the yeast-like fungus Exophiala jeanselmei

Strain KUFI-6N of Exophiala jeanselmei, a cyclohexanol-utilizing yeast-like fungus, was found to grow on 3 isomers of hydroxybenzoate that functioned as the sole carbon sources. Distinct and highly specific hydroxylases converted p- and m-hydroxybenzoate to protocatechuate and o-hydroxybenzoate to catechol.     

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     

Degradation of phenol via carboxylation to benzoate by a defined,obligate syntrophic consortium of anaerobic bacteria

Summary An obligate syntrophic culture was selected in mineral medium with phenol as the only carbon and energy source. The consortium consisted of a short and a long rod-shaped bacterium and of low numbers of Desulfovibrio cells, and grew only in syntrophy with methanogens, e. g. Methanospirillum hungatei. Under N₂/CO₂, phenol was degraded via benzoate to acetate, CH₄ and CO₂, while in the presence of H₂/CO₂ benzoate was formed, but not further degraded. When 4-hydroxybenzoate was fed to the mixed culture, it was decarboxylated to phenol prior to benzoate formation and subsequent ring cleavage. Isolation of pure cultures of the two rod-shaped bacteria failed. Microscopic observations during feeding of either 4-hydroxybenzoate, phenol or benzoate implied an obligate syntrophic interdependence of the two different rod-shaped bacteria and of the methanogen. The non-motile rods formed phenol from 4-hydroxybenzoate and benzoate from phenol, requiring an as yet unknown co-substrate or co-factor, probably cross-fed by the short, motile rod. The short, motile rodshaped bacterium grew only in syntrophy with methanogens and degraded benzoate to acetate, CO₂ and methane. Desulfovibrio sp., present in low numbers, apparently could not contribute to the degradation of phenol or 4-hydroxybenzoate.     

Fermentative degradation of monohydroxybenzoates by defined syntrophic cocultures

From anaerobic freshwater enrichment cultures with 3-hydroxybenzoate as sole substrate, a slightly curved rod-shaped bacterium was isolated in coculture with Desulfovibrio vulgaris as hydrogen scavenger. The new isolate degraded only 3-hydroxybenzoate or benzoate, and depended on syntrophic cooperation with a hydrogenoxidizing methanogen or sulfate reducer. 3-Hydroxybenzoate was degraded via reductive dehydroxylation to benzoate. With 2-hydroxybenzoate (salicylate), short coccoid rods were enriched from anaerobic freshwater mud samples, and were isolated in defined coculture with D. vulgaris. This isolate also fermented 3-hydroxybenzoate or benzoate in obligate syntrophy with a hydrogen-oxidizing anaerobe. The new isolates were both Gram-negative, non-sporeforming strict anaerobes. They fermented hydroxybenzoate or benzoate to acetate, CO₂, and, presumably, hydrogen which was oxidized by the syntrophic partner organism. With hydroxybenzoates, but not with benzoate, Acetobacterium woodii could also serve as syntrophic partner. Other substrates such as sugars, alcohols, fatty or amino acids were not fermented. External electron acceptors such as sulfate, sulfite, nitrate, or fumarate were not reduced. In enrichment cultures with 4-hydroxybenzoate, decarboxylation to phenol was the initial step in degradation which finally led to acetate, methane and CO₂.     

Degradation of 4-chlorophenol by enriched mixed cultures utilizing phenol and glucose as added growth substrate

Two mixed cultures, phenol-oxidizing (PO) and glucose-oxidizing (GO), were cultivated in two parallel chemostat reactors. The PO culture was enriched on phenol, and the GO culture was enriched on glucose. Batch biodegradation experiments were conducted to examine the degradation of 4-chlorophenol (4-CP) under various substrate conditions. The results indicate that in the absence of added growth substrate, 4-CP transformation by PO culture was complete at S _c ^o /X _o (initial 4-CP concentration/initial biomass concentration) 0.27 and that by GO culture was complete at S _c ^o /X _o = 0.09. In the presence of 5–500 mg phenol/l, the phenol dosage required to achieve the complete transformation of 4-CP was 60 mg/l at S _c ^o /X _o = 1, increasing to 120 mg/l at S _c ^o /X _o = 2, and to 180 mg/l at S _c ^o /X _o = 5. As glucose was added to the GO culture at a concentration of over 5–500 mg chemical oxygen demand (COD)/l, 4-CP was not completely transformed at S _c ^o /X _o = 5 [S _c ^o = 50 mg/l, X _o = 10 mg/l volatile suspended solids (VSS)]. These two cultures in utilizing added growth substrate were easily switched between glucose and phenol. Overall, the capacity of PO culture to degrade 4-CP, expressed as T _c (4-CP mass consumed /biomass inactivated, having unit of mg 4-CP/mg VSS), was 0.15–0.80, which compares with T _c values of 0.05–0.26 for GO culture. This work shows that adding phenol as a growth substrate is preferable over adding glucose, as it enhances 4-CP transformation, but a final choice should take into account both degradation efficiency and the risk of phenol toxicity.     

Anaerobic degradation of 3-aminobenzoate by a newly isolated sulfate reducer and a methanogenic enrichment culture

A new rod-shaped, gram-negative, non-sporing sulfate reducer, strain mAB1, was enriched and isolated from marine sediment samples with 3-aminobenzoate as sole electron and carbon source. Strain mAB1 degraded 3-aminobenzoate completely to CO₂ and NH₃ with stoichiometric reduction of sulfate to sulfide. Cells contained carbon monoxide dehydrogenase, cytochromes, and sulfite reductase P582. Strain mAB1 degraded also benzoate, 4-aminobenzoate, hydroxybenzoates, and some aliphatic compounds. Besides sulfates, also sulfite was reduced with 3-aminobenzoate as electron donor, but not thiosulfate, sulfur, nitrate, or fumarate. The strain grew in sulfide-reduced mineral medium supplemented with 7 vitamins. Strain mAB1 was tentatively affiliated with the genus Desulfobacterium. Experiments with dense cell supsensions showed benzoate accumulation during 3-aminobenzoate degradation under conditions of sulfate limitation or cyanide inhibition. 3-Aminobenzoate was activated to 3-aminobenzoyl-CoA by cell extracts in the presence of ATP, coenzyme A, and Mg²⁺. Acitivity of 3-aminobenzoyl-CoA synthetase was 16 nmol per min and mg protein, with a K_M for 3-aminobenzoate lower than 50 M. Cell extract of 3-aminobenzoate-grown cells activated also 3-hydroxybenzoate (31.7 nmol per min and mg protein) and benzoate (2.3 nmol per min and mg protein), but not 2-aminobenzoate or 4-aminobenzoate. In the presence of NADH of NADPH, 3-aminobenzoyl-CoA was further metabolized to a not yet identified reduced product.Freshwater enrichments with 3-aminobenzoate in the absence of an extenal electron acceptor led to a stable methanogenic enrichment culture consisting of three types of bacteria. 3-Aminobenzoate was degraded completely to CO₂ and stoichiometric amounts of CH₄, with intermediary acetate accumulation.     

Studies on the Utilization of Hydrocarbons by Microorganisms

In the course of study on the utilization of methyl-substituents of mono-cyclic aromatic hydrocarbons by Pseudomonas aeruginosa S668B2, some organic acids and phenolic compounds were found to be produced in culture broth.

Strain S668B2 was capable of producing ultraviolet absorbing and fluorescent substances from m-xylene. These substances were isolated in the form of crystal and identified as 3-methyl salicylic acid and m-toluic acid.

Strain S668B2 also produced ultraviolet absorbing and fluorescent substances from pseudocumene (1,2,4-trimethyl benzene). These substances were isolated in the crystalline form and identified as 3,4-dimethyl benzoic acid and 3,4-dimethyl phenol.

Strain S668B″ did not attack o-xylene. Under the similar conditions Pseudomonas desmolytica S449B3, which produced a large amount of cumic acid from p-cymene, did not oxidize o-xylene, but grew on p-xylene, m-xylene and 1,2,4-trimethyl benzene.

None out of 364 soil samples gave microorganisms which utilize o-xylene as a sole carbon source.     

Anaerobic degradation of phenol and phenol derivatives by Desulfobacterium phenolicum sp. nov.

A new sulfate-reducing bacterium was enriched and isolated from marine sediment with phenol as sole electron donor and carbon source. Strain Ph01 grew well in defined media without growth factors. Further aromatic compounds oxidized by strain Ph01 were benzoate, phenylacetate, 2-hydroxybenzoate, 4-hydroxybenzoate, 4-hydroxyphenylacetate, p-cresol, indole, anthranilic acid, and phenylalanine. Various fatty acids, alcohols and dicarboxylic acids were also utilized by strain Ph01. Sulfate and thiosulfate served as electron acceptors and were reduced to H₂S. Stoichiometric measurements with strain Ph01 showed complete oxidation of phenol to CO₂. Cytochromes and menaquinone MK-7(H₂) were present; desulfoviridin could not be detected. Strain Ph01 is described as type strain of the new species Desulfobacterium phenolicum.In further marine enrichments with 4-hydroxybenzoate, 4-hydroxyphenylacetate, p-cresol or o-cresol as substrates and sulfate as electron acceptor a variety of morphologically different sulfate-reducing bacteria developed. However, since the new isolate strain Ph01 was able to degrade all these aromatic compounds (except o-cresol) no further studies with the enrichment cultures were carried out.     

Anaerobic digestion of cellulose by pure and mixed bacterial cultures

Summary By enrichment technique, nine anaerobic mixed bacterial cultures were isolated, five of which showed stable cellulolysis. All cultures fermented cellulose and produced different fermentative products. Mixed culture BOC 25 yielded major levels of acetate and ethanol (39.6 and 12.0 mmol/l, respectively) and minor levels of propionate (2.5 mmol/l) and digested filter paper cellulose to the extent of 32.5% w/v. BOC 25 digested cellulosic and lignocellulosic substrates and produced filter paper cellulase, carboxymethyl cellulase, Avicelase and -glucosidase. Strain DC 25, a cellulolyticClostridium was purified from one of the mixed cultures. The fermentation products of DC 25 from cellulose, cellobiose or glucose were ethanol, acetate, formate, H₂ and CO₂.     

Biodegradation of 4-aminobenzenesulphonate by a newly isolated bacterial strain PNS-1

A bacterial strain PNS-1, isolated from activated sludge derived from a domestic wastewater treatment unit, could utilize 4-aminobenzenesulphonate (4-ABS) as a sole organic carbon and energy source under aerobic conditions. Degradation rate varied with the initial concentration of 4-ABS and maximum specific substrate removal rate was observed at 400mg 4-ABS l^–1 (2.3mM). Average biomass yield was 0.31mg/mg 4-ABS degraded. Biokinetic parameters for the degradation, determined using the Haldane relationship, were 0.26h^–1 (_max), 6mg\,l^–1 (K_S) and 4020mg\,l^–1 (K_i). Strain PNS-1 could not utilize other isomers of benzenesulphonate and 5-sulphosalicylate as growth substrates whereas protocatechuate, pyrocatechuate and p-hydroxybenzoate could be degraded. In mixed substrate batch cultivations, where 4-ABS was one of the component, protocatechuate and 4-ABS were simultaneously utilized. Presence of 2- or 3-ABS decreased the growth and substrate degradation rates of 4-ABS. With 4-ABS and pyrocatechuate, although a lag phase was observed prior to pyrocatechuate degradation, a diauxic growth pattern was not seen.     

ADRB2 Haplotype Is Associated With Glucose Tolerance and Insulin Sensitivity in Obese Postmenopausal Women

The β₂‐adrenergic receptor (ADRB2) mediates obesity, cardiorespiratory fitness, and insulin resistance. We examined the hypothesis that ADRB2 Arg16Gly‐Gln27Glu haplotype is associated with body composition, glucose tolerance, and insulin sensitivity in obese, postmenopausal women. Obese (>35% body fat), postmenopausal (age 45–75 years) women (n = 123) underwent genotyping, dual‐energy X‐ray absorptiometry, and computed tomography scans, exercise testing (VO_2max), 2‐h oral glucose tolerance tests (OGTTs), and hyperinsulinemic‐euglycemic clamps (80 mU/m²/min). Analysis of covariance (ANCOVA) tested for differences among haplotypes, with race, % body fat, and VO_2max as covariates. We found that ADRB2 haplotype was independently associated with % body fat, abdominal fat distribution, VO_2max, insulin sensitivity (M/ΔInsulin), and glucose tolerance (ANOVA, P < 0.05 for all). Women homozygous for Gly16–Gln27 haplotype had the highest % body fat (52.7 ± 1.9%), high abdominal fat, low M/ΔInsulin (0.49 ± 0.08 mg/kg/min/pmol/l/10²), and impaired glucose tolerance (IGT) during an OGTT (G₁₂₀ = 10.2 ± 0.9 mmol/l). Women homozygous for Gly16–Glu27 haplotype also had low M/ΔInsulin (0.51 ± 0.05 mg/kg/min/pmol/l/10²) and IGT (G₁₂₀ = 8.2 ± 0.7 mmol/l). Subjects with Arg16–Gln27/Gly16–Gln27 haplotype combination had the highest VO_2max (1.84 ± 0.07 l/min) and M/ΔInsulin (0.7 ± 0.04 mg/kg/min/pmol/l/10²), and normal glucose tolerance (G₁₂₀ = 6.4 ± 0.4 mmol/l), despite being obese. These data show associations of the ADRB2 Arg16Gly‐Gln27Glu haplotype with VO_2max and body composition, and an independent association with glucose metabolism, which persists after controlling for body composition and fitness. This suggests that ADRB2 haplotypes may mediate insulin action, glucose tolerance, and potentially risk for type 2 diabetes mellitus (T2DM) in obese, postmenopausal women.     

Anaerobic Biodegradation of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by <Emphasis Type="Italic">Acetobacterium malicum</Emphasis> Strain HAAP-1 Isolated from a Methanogenic Mixed Culture

In previous work, we studied the anaerobic biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by a methanogenic mixed culture that biodegrades RDX by using H₂ as the sole electron donor. Strain HAAP-1 was isolated after enriching for the homoacetogens in a mineral medium containing RDX and an H₂-CO₂ (80:20) headspace. Strain HAAP-1 degraded 29.0 M RDX in <14 days and formed 13.0 mM acetate when grown in a mineral medium with an H₂-CO₂ headspace. Methylenedinitramine was observed as a transient intermediate, indicating ring cleavage had occurred. In live cultures containing an N₂-CO₂ headspace, RDX was not degraded, and no acetate was formed. The 16S rRNA gene sequence for strain HAAP-1, consisting of 1485 base pairs, had a 99.2% and 99.1% sequence similarity to Acetobacterium malicum and A. wieringae, respectively. This is the first report of RDX degradation by a homoacetogen growing autotrophically and extends the number of genera known to carry out this transformation.     

Improved production of (R)-2-octanol via asymmetric reduction of 2-octanone with Oenococcus oeni CECT4730 in a biphasic system

Abstract

Oenococcus oeni CECT4730, which catalyses the asymmetric reduction of 2-octanone to (R)-2-octanol with high enantioselectivity, was further studied to exploit its potential for production of (R)-2-octanol in an aqueous/organic solvent biphasic system. Variables such as the volume ratio of aqueous to organic phase (V_a/V_o), buffer pH, reaction temperature, shaking speed, co-substrates and the ratio of biocatalyst to substrate were examined with respect to the molar conversion, the initial reaction rate and the product enantiomeric excess (e.e.). Under the optimized conditions (V_a/V_o=1:1 (v/v), buffer pH=8.0, reaction temperature=30°C, shaking speed=150 rev/min, ratio of glucose to biomass=5.4:l (w/w), ratio of biocatalyst to substrate=0.51:l (g/mol)), the highest space time yield of (R)-2-octanol, 24 mmol L^?1 per h, and >98% product e.e. were obtained at a substrate concentration close to 1.0 mol L^?1 after 24 h reduction.     

Complete oxidation of benzoate and 4-hydroxybenzoate by a new sulfate-reducing bacterium resembling Desulfoarculus

A new sulfate-reducer strain SAX was isolated from an anaerobic marine sediment [Saxild, Denmark]. The isolate was a gram-negative, motile and non-spore-forming rod which sometimes appeared as a curved rod. Strain SAX differed from all described Desulfovibrio-, Desulfobotulus- and Desulfoarculus-species by the ability to degrade aromatic compounds such as benzoate, 4-hydroxybenzoate and phenol completely to CO₂. Electron donors used included lactate, pyruvate, malate, fumarate, crotonate and butyrate, while pyruvate was fermented in the absence of an external electron acceptor. Sulfate, thiosulfate or sulfite served as electron acceptors with benzoate as the donor, while nitrate and nitrite did not. The sulfate-reducing bacterium required vitamins and NaCl-concentrations of about 20 g/l. The optimum temperature for growth of strain SAX was 30°C and the optimum pH value was 7.3. The DNA base composition was 62.4 mol% G+C. The strain possessed cytochrome c₃, but no desulfoviridin. On the basis of these characteristics and because strain SAX could not be ascribed to any of the existing species therefore assignment as a new species to the genus Desulfoarculus was suggested.Abbreviations G+C Guanine plus Cytosine     

A kinetic model and simulation of starch saccharification and simultaneous ethanol fermentation by amyloglucosidase and Zymomonas mobilis

A mathematical model is described for the simultaneous saccharification and ethanol fermentation (SSF) of sago starch using amyloglucosidase (AMG) and Zymomonas mobilis. By introducing the degree of polymerization (DP) of oligosaccharides produced from sago starch treated with -amylase, a series of Michaelis-Menten equations were obtained. After determining kinetic parameters from the results of simple experiments carried out at various substrate and enzyme concentrations and from the subsite mapping theory, this model was adapted to simulate the SSF process. The results of simulation for SSF are in good agreement with experimental results.List of Symbols g/g rate coefficient of production - _max 1/h maximum specific growth rate - E %, v/w AMG concentration - G ₁ mmol/l glucose concentration - G _c mmol/l glucose concentration consumed - G _f mmol/l glucose concentration formed - G _n mmol/l n-mer maltooligosaccharide concentration - K _i g/l ethanol inhibition constant for ethanol production - K _g mmol/l glucose inhibition constant for glucose production - K _p mmol/l glucose limitation constant for ethanol production - K _x mmol/l glucose limitation constant for cell growth - K _m,n mmol/l Michaelis-Menten constant for n-mer oligosaccharide - k _e %, v/w enzyme limitation constant - k _es proportional constant - k _{max, n} 1/s maximal velocity for n-mer digestion - k _s g/l substrate limitation constant - m _s g/g maintenance energy - MW _n g/mol molecular weight of n-mer oligosaccharide - P g/l ethanol concentration - P ₀ g/l initial ethanol concentration - P _m g/l maximal ethanol concentration - Q _pm g/(g · h) maximum specific ethanol production rate - S _n mmol/h branched n-mer oligosaccharide concentration - S ₀ g/l initial starch concentration - S _sta g/l starch concentration - S _tot g/l total sugar concentration - V _{max, n} 1/h maximum digestion rate of n-mer oligosaccharide - V ₀ g/(l · h) initial glucose formation rate - X g/l cell mass - X ₀ g/l initial cell mass - Y _p/s g/g ethanol yield - Y _x/s g/g cell mass yield     

Anaerobic oxidation of saturated hydrocarbons to CO2 by a new type of sulfate-reducing bacterium

n-Hexadecane added as electron donor and carbon source to an anaerobic enrichment culture from an oil production plant or to anoxic marine sediment samples allowed dissimilatory sulfate reduction to sulfide. The enrichment from the oil field was purified via serial dilutions in liquid medium under a hexadecane phase and in agar medium with caprylate. A pure culture of a sulfate-reducing bacterium, strain Hxd3, with relatively tiny cells (0.4–0.5 by 0.8–2 m) was isolated that grew anaerobically on hexadecane without addition of further organic substrates. Most of the cells were found to adhere to the hydrocarbon phase. It was verified that neither organic impurities in hexadecane nor residual oxygen were responsible for growth. Strain Hxd3 was grown with n-hexadecane of high purity (99.5%) in anoxic glass ampoules sealed by fusion. Of 0.4 ml hexadecane added per l (1.4 mmol per l), 90% was degraded with concomitant reduction of sulfate. Controls with pasteurized cells or a common Desulfovibrio species neither consumed hexadecane nor reduced sulfate. Incubation of cell-free medium with low reducing capacity and a redox indicator showed that the ampoules were completely oxygen-tight. Measured degradation balances and enzyme activities suggested a complete oxidation of the alkane to CO₂ via the carbon monoxide dehydrogenase pathway. However, the first step in anaerobic alkane oxidation is unknown. On hexadecane, strain Hxd3 produced as much as 15 to 20 mM H₂S, but growth was rather slow; with 5% inoculum, cultures were fully grown after 5 to 7 weeks. The new sulfate reducer grew on alkanes from C₁₂ to C₂₀, 1-hexadecene, 1-hexadecanol, 2-hexadecanol, palmitate and stearate. Best growth occurred on stearate (doubling time around 26 h). Growth on soluble fatty acids such as caprylate was very poor. Alkanes with chains shorter than C₁₂, lactate, ethanol or H₂ were not used. Strain Hxd3 is the first anaerobe shown to grow definitely on saturated hydrocarbons.Abbreviations CO dehydrogenase carbon monoxide dehydrogenase - DTE 1,4-dithioerythritol - Tris tris(hydroxymethyl)-aminomethane Dedicated to Dr. Ralph S. Wolfe on occasion of his 70th birthday     

Anaerobic aniline degradation via reductive deamination of 4-aminobenzoyl-CoA in Desulfobacterium anilini

The initial reactions involved in anaerobic aniline degradation by the sulfate-reducing Desulfobacterium anilini were studied. Experiments for substrate induction indicated the presence of a common pathway for aniline and 4-aminobenzoate, different from that for degradation of 2-aminobenzoate, 2-hydroxybenzoate, 4-hydroxybenzoate, or phenol. Degradation of aniline by dense cell suspensions depended on CO₂ whereas 4-aminobenzoate degradation did not. If acetyl-CoA oxidation was inhibited by cyanide, benzoate accumulated during degradation of aniline or 4-aminobenzoate, indicating an initial carboxylation of aniline to 4-aminobenzoate, and further degradation via benzoate of both substrates. Extracts of alinine or 4-aminobenzoategrown cells activated 4-aminobenzoate to 4-aminobenzoyl-CoA in the presence of CoA, ATP and Mg²⁺. 4-Aminobenzoyl-CoA-synthetase showed a K _m for 4-aminobenzoate lower than 10 M and an activity of 15.8 nmol · min^-1 · mg^-1. 4-Aminobenzoyl-CoA was reductively deaminated to benzoyl-CoA by cell extracts in the presence of low-potential electron donors such as titanium citrate or cobalt sepulchrate (2.1 nmol · min^-1 · mg^-1). Lower activities for the reductive deamination were measured with NADH or NADPH. Reductive deamination was also indicated by benzoate accumulation during 4-aminobenzoate degradation in cell suspensions under sulfate limitation. The results provide evidence that aniline is degraded via carboxylation to 4-aminobenzoate, which is activated to 4-aminobenzoyl-CoA and further metabolized by reductive deamination to benzoyl-CoA.     

Pentachlorophenol degradation by Pseudomonas aeruginosa

Five Pseudomonas species were tested for ability to degrade pentachlorophenol (PCP). Pseudomonas aeruginosa completely degraded PCP up to 800 mg/l in 6 days with glucose as co-substrate. With 1000 mg PCP/l, 53% was degraded. NH₄ ⁺ salts were better at enhancing degradation than organic nitrogen sources and shake-cultures promoted PCP degradation compared with surface cultures. Degradation was maximal at pH 7.6 to 8.0 and at 30 to 37°C. Only PCP induced enzymes that degraded PCP and chloramphenicol inhibited this process. The PCP was degraded to CO₂, with release of Cl^-.The authors are with the Bacteriology Laboratory, Central Leather Research Institute, Madras-600 020, India.     

The Occurrence of Ferredoxin-sulfite Reductase in Barley Roots

A simple method was established for determining 10 preservatives, butylhydroxyanisole and dibutylhydroxytoluene in food. Steam distillation was carried out, and the distillate was trapped with dichloromethane and distilled water. After acidification and addition of sodium chloride, food additives were extracted from aqueous phase with dichloromethane. The food additives were analyzed with a gas Chromatograph equipped with a dual column system of 10% FFAP and 5% DEGS + 1% H₃PO₄. Column temperature was increased from 140 to 210°C at the rate of 3°C/min, Fluorene was used as an internal standard.

Ethyl p-hydroxybenzoate and isopropyl p-hydroxybenzoate were not separated with the 10% FFAP column, but other food additives were simultaneously determined with this column. With the 5% DEGS + 1% H₃PO₄ column, isobutyl p-hydroxybenzoate and propyl p-hydroxybenzoate were not separated, but the others were simultaneously determined.

Added recovery tests were carried out on about 38 foods.     

Regulation of avilamycin biosynthesis in Streptomyces viridochromogenes: effects of glucose, ammonium ion, and inorganic phosphate

Effects of glucose, ammonium ions and phosphate on avilamycin biosynthesis in Streptomyces viridochromogenes AS4.126 were investigated. Twenty grams per liter of glucose, 10 mmol/L ammonium ions, and 10 mmol/L phosphate in the basal medium stimulated avilamycin biosynthesis. When the concentrations of glucose, ammonium ions, and phosphate in the basal medium exceeded 20 g/L, 10 mmol/L, and 10 mmol/L, respectively, avilamycin biosynthesis greatly decreased. When 20 g/L glucose was added at 32 h, avilamycin yield decreased by 70.2%. Avilamycin biosynthesis hardly continued when 2-deoxy-glucose was added into the basal medium at 32 h. There was little influence on avilamycin biosynthesis with the addition of the 3-methyl-glucose (20 g/L) at 32 h. In the presence of excess (NH₄)₂SO₄ (20 mmol/L), the activities of valine dehydrogenase and glucose-6-phosphate dehydrogenase were depressed 47.7 and 58.3%, respectively, of that of the control at 48 h. The activity of succinate dehydrogenase increased 49.5% compared to the control at 48 h. The intracellular adenosine triphosphate level and 6-phosphate glucose content of S. viridochromogenes were 128 and 129%, respectively, of that of the control at 48 h, with the addition of the 40 mmol/L of KH₂PO₄. As a result, high concentrations of glucose, ammonium ions, and inorganic phosphate all led to the absence of the precursors for avilamycin biosynthesis and affected antibiotic synthesis.