Operation of mixed-culture immobilized cell reactors for the metabolism of meta- and para-nitrobenzoate by comamonas sp. JS46 and comamonas sp. JS47

The treatment of meta- and para-nitrobenzoic acid in an industrial wastestream by Comamonas sp. JS46 and Comamonas sp. JS47 is investigated. The most important feature of the wastestream is the constantly changing concentration ratio of the two isomers. The most extreme occurrence is considered here: the complete change in feed carbon source from one isomer to the other. A series of immobilized cell airlift reactor experiments are described to examine the operation and response of the system to these changes in the feed carbon source. Separate reactors containing each species immobilized are compared with a reactor containing both species immobilized within the same bead, and to a reactor containing both species with each species confined to separate beads. On the basis of response time necessary to recover the appropriate activity, the reactor containing both species immobilized within the same bead offers the most effective arrangement. Interactions occurring between the two organisms in the coimmobilized system, mediated by the nitrobenzoate metabolites, are discussed relative to the improved response of this arrangement. Copyright 1998 John Wiley & Sons, Inc.     

Coupled reductive and oxidative degradation of 4-chloro-2-nitrophenol by a co-immobilized mixed culture system

Summary The restriction of oxygen transfer in Ca-alginate beads used for the immobilization of microbial cells was applied to a coupled reductive and oxidative microbial degradation of the xenobiotic 4-chloro-2-nitrophenol (CNP). The conversion of CNP by Enterobacter cloacae under anaerobic conditions led to the formation of 4-chloro-2-aminophenol (CAP, 81%) and 4-chloro-2-acetaminophenol (CAAP, 16%) after 50 h incubation. CAP, the main reduction product, was further degraded under aerobic conditions by Alcaligenes sp. TK-2, a hybrid strain isolated by conjugative in-vivo gene transfer. Whereas both degradation steps excluded one another in homogeneous systems with free cells, a coupled reductive and oxidative degradation of CNP was observed in one aerated reactor system after co-immobilization of both strains in Ca alginate. The diameter of the alginate beads used for immobilization was recognized as one main factor determining the properties of this mixed culture system. Offprint requests to: H.-J. Rehm     

Simultaneous degradation of 3-chlorobenzoate and phenolic compounds by a defined mixed culture ofPseudomonas spp.

A mixed culture of a chlorobenzoate-(3-CBA)-degradingPseudomonas aeruginosa, strain 3mT, and a phenol/cresols-degradingPseudomonas sp., strain CP4, simultaneously and efficiently degraded mixtures of 3-CBA and phenol/cresols. However, strains 3mT and CP4 usedortho- andmeta-ring cleavage pathways, respectively. Degradation of 3-CBA was complete when the 3-CBA was equal in amount to or less than that of phenol. CP4/3mT inoculum ratios (w/w) of 1:1 or 1:2 gave the most effective degradation of both the substrates in the mixture. The mixed culture degraded equimolar mixtures of 3-CBA/phenol up to 10mm. Equimolar mixtures of 3-CBA ando-, m- orp-cresol were also degraded by the mixed culture.The authors are with the Microbiology and Bioengineering Department, Central Food Technological Research Institute, Mysore-570013, India;     

Use of food additives to prevent contamination during fermentation using a co-immobilized mixed culture system

The use of natural food additives to prevent contamination during fermentation under nonsterile conditions was investigated. Direct ethanol production from raw starch with a co-immobilized mixed Aspergillus awamori, Rhizopus japonicus and Zymomonas mobilis cell system was used as an example. When 0.1% Neupectin-L was added to the medium, there was no contamination and the metabolic activities of the immobilized cells were not adversely affected.     

Degradation of mono-chlorophenols by a mixed microbial community via a meta- cleavage pathway

A mixed microbial community, specially designed todegrade a wide range of substituted aromaticcompounds, was examined for its ability to degrademono-chlorophenols as sole carbon source in aerobicbatch cultures. The mixed culture degraded 2-, 3-, and4 -chlorophenol (1.56 mM) via a meta- cleavagepathway. During the degradation of 2- and3-chlorophenol by the mixed culture, 3-chlorocatecholproduction was observed. Further metabolism was toxicto cells as it led to inactivation of the catechol2,3-dioxygenase enzyme upon meta- cleavage of3-chlorocatechol resulting in incomplete degradation.Inactivation of the meta- cleavage enzyme led toan accumulation of brown coloured polymers, whichinterfered with the measurement of cell growth usingoptical denstiy. Degradation of 4-chlorophenol by themixed culture led to an accumulation of5-chloro-2-hydroxymuconic semialdehyde, themeta- cleavage product of 4-chlorocatechol. Theaccumulation of this compound did not interfere withthe measurement of cell growth using optical density.5-chloro-2-hydroxymuconic semialdehyde was furthermetabolized by the mixed culture with a stoichiometricrelease of chloride, indicating complete degradationof 4-chlorophenol by the mixed culture via ameta- cleavage pathway.     

Biphenomycin A production by a mixed culture.

Production of biphenomycin A by Streptomyces griseorubiginosus 43708 was stimulated by a mixed culture with a partner strain, Pseudomonas maltophilia 1928. This stimulatory effect on biphenomycin A accumulation by the mixed culture was caused by the enzyme activity which strain 1928 possessed. It is suggested that in a mixed culture strain 43708 produces a precursor of biphenomycin A in culture broth and that strain 1928 converts the precursor to biphenomycin A.     

Biphenomycin A production by a mixed culture.

Production of biphenomycin A by Streptomyces griseorubiginosus 43708 was stimulated by a mixed culture with a partner strain, Pseudomonas maltophilia 1928. This stimulatory effect on biphenomycin A accumulation by the mixed culture was caused by the enzyme activity which strain 1928 possessed. It is suggested that in a mixed culture strain 43708 produces a precursor of biphenomycin A in culture broth and that strain 1928 converts the precursor to biphenomycin A.     

Biodegradation of chlorinated ethenes by a methane-utilizing mixed culture.

Chlorinated ethenes are toxic substances which are widely distributed groundwater contaminants and are persistent in the subsurface environment. Reports on the biodegradation of these compounds under anaerobic conditions which might occur naturally in groundwater show that these substances degrade very slowly, if at all. Previous attempts to degrade chlorinated ethenes aerobically have produced conflicting results. A mixed culture containing methane-utilizing bacteria was obtained by methane enrichment of a sediment sample. Biodegradation experiments carried out in sealed culture bottles with radioactively labeled trichloroethylene (TCE) showed that approximately half of the radioactive carbon had been converted to 14CO2 and bacterial biomass. In addition to TCE, vinyl chloride and vinylidene chloride could be degraded to products which are not volatile chlorinated substances and are therefore likely to be further degraded to CO2. Two other chlorinated ethenes, cis and trans-1,2-dichloroethylene, were shown to degrade to chlorinated products, which appeared to degrade further. A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions. The biodegradation of TCE was inhibited by acetylene, a specific inhibitor of methane oxidation by methanotrophs. This observation supported the hypothesis that a methanotroph is responsible for the observed biodegradations.     

Clonal propagation of Leptospermum spp. by tissue culture

Propagation by axillary and multiple axillary bud development was achieved in three native Leptospermum spp. when axillary buds derived from nodal tissues ex mature plants were placed in benzylaminopurine media (0.04–1.0 M) containing macro- and micro-nutrients, sucrose (0.06 M) and a vitamin/amino acid supplement. Reduction of agar concentration from 0.8 to 0.2% greatly stimulated axillary bud development and growth in L. flavescens and L. brachyandrum. Rooting of axillary shoots was stimulated by 2,4-dichlorophenoxyacetic acid and p-chlorophenoxy acetic acid in L. flavescens at concentrations of 5 and 1 M respectively. In L. petersonii ssp. root initiation and development was favoured by -naphthoxyacetic acid (1 M) and in L. brachyandrum indole butyric acid and -naphthalene acetic acid (1 M) were almost equally effective.     

Trypanosoma spp., Leishmania spp. and Leptomonas spp.: enzymes of ornithine-arginine metabolism

Eight species of trypanosomatid flagellates, Trypanosoma cruzi, T. mega, T. conorhini, Leishmania donovani, L. braziliensis, Leptomonas seymouri, L. collosoma, and L. samueli, were examined for the presence of enzymes of the arginine-ornithine metabolism. Arginase was found in species of the genera Leishmania and Leptomonas. Citrulline hydrolase was found only in species of Leptomonas. Trypanosoma spp. did not present any of the mentioned enzymes. Ornithine carbamoyltransferase and argininosuccinate lyase were found only in Leptomonas samueli, which also possessed arginine deiminase. With the sole exception of L. samueli the other species seem to present a uniform enzyme constitution, peculiar to their genera and different from the enzyme patterns of other genera of trypanosomatids already known. The potential usefulness of these findings for taxonomical purposes is discussed.     

Numerical modeling and uncertainties in rate coefficients for methane utilization and TCE cometabolism by a methane-oxidizing mixed culture

The rates of methane utilization and trichloroethylene (TCE) cometabolism by a methanotrophic mixed culture were characterized in batch and pseudo-steady-state studies. Procedures for determination of the rate coefficients and their uncertainties by fitting a numerical model to experimental data are described. The model consisted of a system of differential equations for the rates of Monod kinetics, cell growth on methane and inactivation due to TCE transformation product toxicity, gas/liquid mass transfer of methane and TCE, and the rate of passive losses of TCE. The maximum specific rate of methane utilization (k(CH(4) )) was determined by fitting the numerical model to batch experimental data, with the initial concentration of active methane-oxidizing cells (X(0) (a)) also used as a model fitting parameter. The best estimate of k(CH(4) ) was 2.2 g CH(4)/g cells-d with excess copper available, with a single-parameter 95% confidence interval of 2.0-2.4 mg/mg-d. The joint 95% confidence region for k(CH(4) ) and X(0) (a) is presented graphically. The half-velocity coefficient (K(S,CH(4) )) was 0.07 mg CH(4)/L with excess copper available and 0.47 mg CH(4)/L under copper limitation, with 95% confidence intervals of 0.02-0.11 and 0.35-0.59 mg/L, respectively. Unique values of the TCE rate coefficients k(TCE) and K(S,TCE) could not be determined because they were found to be highly correlated in the model fitting analysis. However, the ratio k(TCE)/K(S,TCE) and the TCE transformation capacity (T(C)) were well defined, with values of 0.35 L/mg-day and 0.21 g TCE/g active cells, respectively, for cells transforming TCE in the absence of methane or supplemental formate. The single-parameter 95% confidence intervals for k(TCE)/K(S,TCE) and T(C) were 0.27-0.43 L/mg-d and 0.18-0.24 g TCE/g active cells, respectively. The joint 95% confidence regions for k(TCE)/K(S,TCE) and T(C) are presented graphically. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 320-331, 1997.     

Effects of thymol and diphenyliodonium chloride against Campylobacter spp. during pure and mixed culture in vitro

Aims: To determine if the purported deaminase inhibitors diphenyliodonium chloride (DIC) and thymol reduce the growth and survivability of Campylobacter. Methods and Results: Growth rates of Campylobacter jejuni and Camp. coli were reduced compared to unsupplemented controls during culture in Muellar–Hinton broth supplemented with 0·25 μmol DIC or thymol ml^?1 but not with 0·01 μmol monensin ml^?1 or 1% ethanol. Recovery of Camp. jejuni and Camp. coli was reduced >5 log₁₀ CFU from controls after 24 h pure culture in Bolton broth supplemented with 0·25 or 1·0 μmol DIC ml^?1 or with 1·0 μmol thymol ml^?1. Similarly, each test Campylobacter strain was reduced >3 log₁₀ CFU from controls after 24 h mixed culture with porcine faecal microbes in Bolton broth supplemented with 0·25 or 1·0 μmol DIC ml^?1 or with 1·0 μmol thymol ml^?1. Treatments with 0·25 μmol thymol ml^?1, 0·01 μmol monensin ml^?1 or 1% ethanol were less effective. Ammonia production during culture or incubation of cell lysates was reduced by 0·25 or 1·0 μmol DIC ml^?1 but only intermittently reduced, if at all, by the other treatments. Conclusions: Diphenyliodonium chloride and thymol reduced growth, survivability and ammonia production of Camp. jejuni and Camp. coli. Significance and Impact of the Study: Results suggest a potential physiological characteristic that may be exploited to develop interventions.     

T-2 toxin and diacetoxyscirpenol metabolism by Baccharis spp.

Hybrids resulting from crosses between Baccharis sarothroides and B. pilularis (FS1), B. sarothroides (FS2) and B. megapotamica (FS3) were tested for their tolerance to trichothecenes as well as their ability to metabolize the toxins. B. sarothroides (desert broom) was placed in an aqueous solution containing 500 ppm of T-2 toxin and showed visible signs of toxicity on the twigs at 21 h after exposure but not at 6 h, indicating some resistance. Samples of the twigs harvested 6 and 21 h after treatment contained, respectively, T-2 (0.03 and 2.2 micrograms/g), HT-2 (0.09 and 7.6 micrograms/g), and T-2-tetraol (2.1 and 2.6 micrograms/g). The hybrid FS1 showed no signs of toxicity 6 h after treatment, and its twigs contained T-2 (0.8 micrograms/g), HT-2 (10.2 micrograms/g), and T-2-tetraol (10.8 micrograms/g). The leaves at 6 h contained 0.5 micrograms of T-2, 1.7 micrograms of HT-2, 0.01 microgram of 3'-hydroxy-HT-2, and 41 micrograms of T-2-tetraol per g. At 21 h, toxic signs were apparent and the twigs contained T-2 (39 micrograms/g), HT-2 (62 micrograms/g), 3'-hydroxy-HT-2 (0.8 microgram/g), and T-2-tetraol (22 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS)     

Biodegradation of chlorinated ethenes by a methane-utilizing mixed culture

Chlorinated ethenes are toxic substances which are widely distributed groundwater contaminants and are persistent in the subsurface environment. Reports on the biodegradation of these compounds under anaerobic conditions which might occur naturally in groundwater show that these substances degrade very slowly, if at all. Previous attempts to degrade chlorinated ethenes aerobically have produced conflicting results. A mixed culture containing methane-utilizing bacteria was obtained by methane enrichment of a sediment sample. Biodegradation experiments carried out in sealed culture bottles with radioactively labeled trichloroethylene (TCE) showed that approximately half of the radioactive carbon had been converted to 14CO2 and bacterial biomass. In addition to TCE, vinyl chloride and vinylidene chloride could be degraded to products which are not volatile chlorinated substances and are therefore likely to be further degraded to CO2. Two other chlorinated ethenes, cis and trans-1,2-dichloroethylene, were shown to degrade to chlorinated products, which appeared to degrade further. A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions. The biodegradation of TCE was inhibited by acetylene, a specific inhibitor of methane oxidation by methanotrophs. This observation supported the hypothesis that a methanotroph is responsible for the observed biodegradations.     

Biodegradation of polyvinyl alcohol by a mixed microbial culture

A mixed culture capable of degrading 1 g l⁻¹ polyvinyl alcohol (PVA) completely was screened from sludge samples at Pacific Textile Factory, Wuxi, China. This mixed culture had stronger capability of degrading PVA with low polymerization and high saponification than degrading PVA with high polymerization and low saponification. Inorganic nitrogen source was more suitable for the mixed culture to grow and degrade PVA than organic nitrogen source. Microorganisms and relative abundance of this mixed culture were explored by terminal restriction fragment length polymorphism (T-RFLP). Small PVA molecules were detected in cell extracts of the mixed culture. This indicated that PVA degradation in the mixed culture was in fact a combined action of extracellular and intracellular enzymes. Two strains producing extracellular PVA-degrading enzyme were isolated from the mixed culture. They could individually degrade PVA1799 with polymerization of 1700 from initial average molecular weight 112,981 to 98,827 Da and 84,803 Da, respectively. However, only small amount of PVA124 in polymerization of 400 could be degraded by these two strains.     

Degradation of phenol by a coimmobilized entrapped mixed culture

Summary The degradation of phenol by a defined mixed culture, consisting of Pseudomonas putida P8 and Cryptococcus elinovii H1, was studied. The microorganisms were entrapped either in 30 g·l^-1 calcium-alginate or in chitosan-alginate. Chitosan-alginate entrapment was suitable for a continuous culture. The coimmobilized mixed culture of Cryptococcus elinovii H1 which degrades phenol via an ortho pathway and of Pseudomonas putida P8 which uses the meta cleavage pathway was able to degrade high phenol concentrations up to 3.2 g·l^-1 in semicontinuous cultures. The degradation performance in continuous cultures could reach a maximum of 0.41 g·l^-1·h^-1 phenol. The mixed culture could be stored for up to six months without loss of phenol degradation capacity.Dedicated to Professor Dr. Dr. h. c. K. Esser on the occasion of his 65th birthday     

十七种虫草的子实体培育研究

在过去的12年间,分离得到20余种虫草无性型,对其中十七种虫草无性型进行了人工诱发虫草子座的试验,结果表明:蜂头虫草Cordycepssphecocephala、亚黄蜂虫草C.oxycephala、蚂蚁草C.myrmecophila、蛹虫草C.militaris、拟细虫草C.gracilioides和布氏虫草C.brongniatii等6种人工培养的虫草观察到了成熟的子囊壳并弹射了子囊孢子;古尼虫草小孢变种C.gunniivar.minor、球孢虫草C.bassiana、戴氏虫草C.taii、蚁虫草C.formicarum、蝽虫草C.nutans、长座虫草C.longissima、台湾虫草C.formosana和双梭孢虫草近似种C.bifusisporaaff.长出了许多的未成熟的子座或孢梗束;而冬虫夏草C.sinensis、沫蝉虫草C.tricentri和细虫草C.gracilis未能培育出子实体。其中蚁虫草和亚黄蜂虫草的人工成功培育子实体为首次报道。     

Biodegradation of 3-Nitrotyrosine by Burkholderia sp. Strain JS165 and Variovorax paradoxus JS171

The cascade of reactive nitrogen species generated from nitric oxide causes modification of proteins, lipids, and nucleic acids in a wide range of organisms. 3-Nitrotyrosine is one of the most common products of the action of reactive nitrogen species on proteins. Although a great deal is known about the formation of 3-nitrotyrosine, the subsequent metabolism of this compound is a mystery. Variovorax paradoxus JS171 and Burkholderia sp. strain JS165 were isolated from soil slurries when 3-nitrotyrosine was provided as the sole carbon, nitrogen, and energy source. During growth on 3-nitrotyrosine stoichiometric amounts of nitrite were released along with approximately one-half of the theoretically available ammonia. The catabolic pathway involving oxidative denitration is distinct from the pathway for tyrosine metabolism. The facile isolation and the specific, regulated pathway for 3-nitrotyrosine degradation in natural ecosystems suggest that there is a significant flux of 3-nitrotyrosine in such environments.