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J C Gottschal

Publications and source records attributed to J C Gottschal.

At least 37 records · Page 2Linked to original sources
PubMed1995

Degradation of 2,5-dichlorobenzoic acid by Pseudomonas aeruginosa JB2 at low oxygen tensions.

From long-term chemostat experiments, variants of Pseudomonas aeruginosa JB2 were obtained which exhibited altered properties with respect to the metabolism of 2,5-dichlorobenzoic acid (2,5-DBA). Thus, unlike the original strain JB2-WT, strain JB2-var1 is able to grow in continuous culture on 2,5-DBA as the sole limiting carbon and energy source. Yet, at a dilution rate of 0.07 h-1 and a dissolved oxygen concentration of < or = 12 microM, even with this strain no steady states with 2,5-DBA alone could be established in continuous cultures. Yet another strain was obtained after prolonged continuous growth of JB2-var1 in the chemostat. It has improved 2,5-DBA degrading capabilities which become apparent only during growth in continuous culture: a lower apparent Km for 2,5-DBA and lowered steady-state residual concentrations of 2,5 DBA. Although with this strain steady states were obtained at oxygen concentrations as low as 11 microM, at further lowered concentrations this was no longer possible. In C-limited continuous cultures of JB2-var1 or JB2-var2, addition of benzoic acid (BA) to the feed reduced the amounts of 2,5-DBA degraded, which was most apparent at low oxygen concentrations (< 30 microM). At higher dissolved oxygen concentrations the addition of BA resulted in increasing cell-densities but did not affect the residual steady state concentration of 2,5-DBA. Indeed, whole cell suspensions from chemostat cultures grown on BA plus 2,5-DBA did show a lower apparent affinity for 2,5-DBA than those from cultures grown on 2,5-DBA alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzoates↗
PubMed1995

Complete degradation of tetrachloroethene by combining anaerobic dechlorinating and aerobic methanotrophic enrichment cultures.

Degradation of tetrachloroethene (perchloroethylene, PCE) was investigated by combining the metabolic abilities of anaerobic bacteria, capable of reductive dechlorination of PCE, with those of aerobic methanotrophic bacteria, capable of co-metabolic degradation of the less-chlorinated ethenes formed by reductive dechlorination of PCE. Anaerobic communities reductively dechlorinating PCE, trichloroethene (TCE) and dichloroethenes were enriched from various sources. The maximum rates of dechlorination observed for various chloroethenes in these batch enrichments were: PCE to TCE (341 mumol l-1 day-1), TCE to cis-dichloroethene (159 mumol l-1 day-1), cis-dichloroethene to chloroethene (99 mumol l-1 day-1) and trans-dichloroethene to chloroethene (22 mumol l-1 day-1). A mixture of these enrichments was inoculated into an anoxic fixed-bed upflow column. In this column PCE was converted mainly into cis-1,2-dichloroethene, small amounts of TCE and chloroethene, and chloride. Enrichments of aerobic methanotrophic bacteria were grown in an oxic fixed-bed downflow column. Less-chlorinated ethenes, formed in the anoxic column, were further metabolized in this oxic methanotrophic column. On the basis of analysis of chloride production and the disappearance of chlorinated ethenes it was demonstrated that complete degradation of PCE was possible by combining these two columns. Operation of the two-column system under various process conditions indicated that the sensitivity of the methanotrophic bacteria to chlorinated intermediates represented the bottle-neck in the sequential anoxic/oxic degradation process of PCE.

Bacteria, Aerobic↗
PubMed1995

Substrate uptake and utilization by a marine ultramicrobacterium.

A facultatively oligotrophic ultramicrobacterium (strain RB2256) isolated from an Alaskan fjord by extinction dilution in seawater, was grown in batch culture and under single- and dual-substrate-limitation of alanine and glucose in a chemostat. The nature of the uptake systems, and the uptake kinetics and utilization patterns of alanine and glucose were investigated. Glucose uptake was inducible, the system exhibited a narrow substrate specificity, and part of the uptake system was osmotic-shock-sensitive. Half-saturation constants for glucose were between 7 and 74 microM during glucose limitation. The initial step in glucose metabolism was the synthesis of sugar polymers, even during glucose-limited growth. The alanine uptake system was constitutively expressed and was binding-protein-dependent. In addition to L-alanine, nine other amino acids inhibited accumulation of [14C]L-alanine, indicating broad substrate specificity of the alanine transporter. Half-saturation constants between 1.3 and 1.8 microM were determined for alanine uptake during alanine limitation. Simultaneous utilization of glucose and alanine occurred during substrate-limited growth in the chemostat, and during growth in batch culture at relatively high (mM) substrate concentrations. However, the half-saturation constant for alanine transport during dual-substrate-limitation, i.e. in the presence of glucose, increased almost fivefold. We conclude that mixed substrate utilization is an inherent property of this organism.

Alanine↗
PubMed1994

Anaerobic degradation of halogenated benzoic acids by photoheterotrophic bacteria.

From light-exposed enrichment cultures containing benzoate and a mixture of chlorobenzoates, a pure culture was obtained able to grow with 3-chlorobenzoate (3-CBA) or 3-bromobenzoate (3-BrBA) as the sole growth substrate anaerobically in the light. The thus isolated organism is a photoheterotroph, designated isolate DCP3. It is preliminarily identified as a Rhodopseudomonas palustris strain. It differs from Rhodopseudomonas palustris WS17, the only other known photoheterotroph capable of using 3-CBA for growth, in its independence of benzoate for growth with 3-CBA and in its wider substrate range: if grown on 3-CBA, it can also use 2-CBA, 4-CBA or 3,5-CBA.

Anaerobiosis↗
PubMed1993

Characterization of hydrogenosomes and their role in glucose metabolism of Neocallimastix sp. L2.

In the anaerobic fungus Neocallimastix sp. L2 fermentation of glucose proceeds via the Embden-Meyerhof-Parnas pathway. Enzyme activities leading to the formation of succinate, lactate, ethanol, and formate are associated with the cytoplasmic fraction. The enzymes 'malic enzyme,' NAD(P)H:ferredoxin oxidoreductase, pyruvate:ferredoxin oxidoreductase, hydrogenase, acetate:succinate CoA transferase and succinate thiokinase leading to the formation of H2,CO2, acetate, and ATP are localized in microbodies. Thus, these organelles are identified as hydrogenosomes. In addition, the microbodies contain the O2-scavenging enzymes NADH- and NADPH oxidase, while NAD(P)H peroxidase, catalase, or superoxide dismutase could not be detected. In cell-free extracts from zoospores of Neocallimastix sp. L2 the specific activities of hydrogenosomal enzymes as well as the quantities of these proteins are 2- to 6-fold higher than in mycelium extracts. These findings suggest that hydrogenosomes perform an important role--especially in zoospores--as H2-evolving, ATP-generating and O2-scavenging organelles.

Adenylate Kinase↗
PubMed1993

Growth kinetics and competition--some contemporary comments.

Results of competition experiments with one growth-limiting factor under idealized experimental conditions have been reported extensively, and usually provide ample support for the conclusion that 'complete competitors cannot coexist'. However, under conditions of multiple substrate limitation and discontinuous or alternating supply of nutrients, coexistence of species is quite common. Since such patterns of nutrient supply may be expected to prevail in many natural environments the mechanisms ruling the survival and growth of bacteria under such conditions need to be understood. However, it appears that surprisingly little is known of the physiological state of individual competing species grown in mixed cultures. Unfortunately, basic information such as the actual concentration of limiting nutrients is lacking in most cases. But perhaps the recent development of new and powerful techniques to explore the physiological properties even of individual cells will further stimulate studies into the mechanisms behind the competitiveness of microbial species.

Bacteria↗
PubMed1993

Isolation of Typical Marine Bacteria by Dilution Culture: Growth, Maintenance, and Characteristics of Isolates under Laboratory Conditions.

Marine bacteria in Resurrection Bay near Seward, Alaska, and in the central North Sea off the Dutch coast were cultured in filtered autoclaved seawater following dilution to extinction. The populations present before dilution varied from 0.11 x 10 to 1.07 x 10 cells per liter. The mean cell volume varied between 0.042 and 0.074 mum, and the mean apparent DNA content of the cells ranged from 2.5 to 4.7 fg of DNA per cell. All three parameters were determined by high-resolution flow cytometry. All 37 strains that were obtained from very high dilutions of Resurrection Bay and North Sea samples represented facultatively oligotrophic bacteria. However, 15 of these isolates were eventually obtained from dilution cultures that could initially be cultured only on very low-nutrient media and that could initially not form visible colonies on any of the agar media tested, indicating that these cultures contained obligately oligotrophic bacteria. It was concluded that the cells in these 15 dilution cultures had adapted to growth under laboratory conditions after several months of nutrient deprivation prior to isolation. From the North Sea experiment, it was concluded that the contribution of facultative oligotrophs and eutrophs to the total population was less than 1% and that while more than half of the population behaved as obligately oligotrophic bacteria upon first cultivation in the dilution culture media, around 50% could not be cultured at all. During one of the Resurrection Bay experiments, 53% of the dilution cultures obtained from samples diluted more than 2.5 x 10 times consisted of such obligate oligotrophs. These cultures invariably harbored a small rod-shaped bacterium with a mean cell volume of 0.05 to 0.06 mum and an apparent DNA content of 1 to 1.5 fg per cell. This cell type had the dimensions of ultramicrobacteria. Isolates of these ultramicrobacterial cultures that were eventually obtained on relatively high-nutrient agar plates were, with respect to cell volume and apparent DNA content, identical to the cells in the initially obligately oligotrophic bacterial dilution culture. Determination of kinetic parameters from one of these small rod-shaped strains revealed a high specific affinity for the uptake of mixed amino acids (a degrees (A), 1,860 liters/g of cells per h), but not for glucose or alanine as the sole source of carbon and energy (a degrees (A), +/- 200 liters/g of cells per h). The ultramicrobial strains obtained are potentially a very important part of picoplankton biomass in the areas investigated.

Journal Article↗
PubMed1993

Influence of Metronidazole, CO, CO(2), and Methanogens on the Fermentative Metabolism of the Anaerobic Fungus Neocallimastix sp. Strain L2.

The effects of metronidazole, CO, methanogens, and CO(2) on the fermentation of glucose by the anaerobic fungus Neocallimastix sp. strain L2 were investigated. Both metronidazole and CO caused a shift in the fermentation products from predominantly H(2), acetate, and formate to lactate as the major product and caused a lower glucose consumption rate and cell protein yield. An increased lactate dehydrogenase activity and a decreased hydrogenase activity were observed in cells grown under both culture conditions. In metronidazole-grown cells, the amount of hydrogenase protein was decreased compared with the amount in cells grown in the absence of metronidazole. When Neocallimastix sp. strain L2 was cocultured with the methanogenic bacterium Methanobrevibacter smithii, the fermentation pattern changed in the opposite direction: H(2) and acetate production increased at the expense of the electron sink products lactate, succinate, and ethanol. A concomitant decrease in the enzyme activities leading to these electron sink products was observed, as well as an increase in the glucose consumption rate and cell protein yield, compared with those of pure cultures of the fungus. Low levels of CO(2) in the gas phase resulted in increased H(2) and lactate formation and decreased production of formate, acetate, succinate, and ethanol, a decreased glucose consumption rate and cell protein yield, and a decrease in most of the hydrogenosomal enzyme activities. None of the tested culture conditions resulted in changed quantities of hydrogenosomal proteins. The results indicate that manipulation of the pattern of fermentation in Neocallimastix sp. strain L2 results in changes in enzyme activities but not in the proliferation or disappearance of hydrogenosomes.

Journal Article↗
PubMed1993

The hydrogenosomal enzyme hydrogenase from the anaerobic fungus Neocallimastix sp. L2 is recognized by antibodies, directed against the C-terminal microbody protein targeting signal SKL.

The question was addressed whether antibodies directed against the general microbody C-terminal protein targeting signal SKL recognized hydrogenosomal proteins from Neocallimastix sp. L2. Immunofluorescence, immunocytochemistry and Western blotting experiments using these antibodies indicated the presence of hydrogenosomal proteins containing SKL-COOH. One of these proteins, the hydrogenase, was purified to homogeneity. It has a native molecular mass of 87 kDa and consists of two subunits of approximately 30 and 60 kDa, both cross-reacting with anti-SKL antibodies. Its activity could be inhibited by CO, NO2-, and acetylene, suggesting a (Ni-Fe-Se) hydrogenase. Immunocytochemistry using polyclonal antibodies raised against the hydrogenase revealed the location of this protein in the hydrogenosomal matrix. The results described in this paper suggest that hydrogenosomes from Neocallimastix sp. L2 are related to microbodies from aerobic eukaryotes and support the idea of a common evolutionary origin for these organelles.

Amino Acid Sequence↗
PubMed1992

Specific removal of chlorine from the ortho-position of halogenated benzoic acids by reductive dechlorination in anaerobic enrichment cultures.

Anaerobic enrichment cultures catalysing the reductive dechlorination of chlorinated benzoic acids were obtained from three fresh-water sediments collected from seven different locations. Sub-cultures from these enrichments specifically removed ortho-substituted chlorine from 2,3,6-, 2,3,5- and 2,4,6-trichlorobenzoic acid, yielding chloride and 2,5-, 3,5-, and 2,4-dichlorobenzoic acids, respectively. These reductive dehalogenations were stimulated by the addition of benzoate and/or volatile organic acids. In one of these enrichments dehalogenation of ortho- and/or para-chlorine substituents was also observed from 2,3-, 2,4-, 2,5-, and 3,4-dichlorobenzoic acid, yielding 3- and 4-chlorobenzoate. Removal of meta-chlorines was not observed in any of the enrichments.

Bacteria, Anaerobic↗
PubMed1992

Characterization of an anaerobic fungus from llama faeces.

An anaerobic fungus was isolated from llama faeces. Based on its morphological characteristics, polyflagellated zoospores, extensive rhizoid system and the formation of monocentric colonies, the fungus is assigned to the genus Neocallimastix. Neocallimastix sp. L2 is able to grow on several poly-, oligo- and monosaccharides. It differs from other Neocallimastix isolates in its inability to ferment inulin. Neocallimastix sp. L2 requires CO2 for growth. In the presence of 100% CO2 in the gas phase glucose is fermented to H2, CO2, formate, acetate, lactate, succinate and ethanol (33.8, 15.4, 74.3, 69.2, 26.7, 8.2, and 28.7 mmol per 100 mmol glucose, respectively). Reduced sulphur compounds can be used as sulphur source and ammonium or amino acids as nitrogen source. The temperature range for glucose fermentation is from 37 to 42 degrees C with an optimum of around 38 degrees C. The pH range for glucose fermentation is from pH 6 to pH 8 with a broad optimum between pH 6.5 and pH 7.5. The zoospores of Neocallimastix sp. L2 contain ribosomal 'globules' and hydrogenosomes. In the kinetosomes of the zoospores spurs, scoops and skirts are visible. In both the rhizoids and the sporangia 'crystal bodies' and hydrogenosomes are present. Mitochondria were not detected in either of these life stages.

Anaerobiosis↗
PubMed1992

Modelling of mixed chemostat cultures of an aerobic bacterium, Comamonas testosteroni, and an anaerobic bacterium, Veillonella alcalescens: comparison with experimental data.

A mathematical model of mixed chemostat cultures of the obligately aerobic bacterium Comamonas testosteroni and the anaerobic bacterium Veillonella alcalescens grown under dual limitation of L-lactate and oxygen was constructed. The model was based on Michaelis-Menten-type kinetics for the consumption of substrates, with noncompetitive inhibition of V. alcalescens by O2. The growth characteristics of the aerobic and anaerobic organisms were determined experimentally with pure cultures of the individual species in (oxygen-limited) chemostats. Using these pure-culture data in the model of the mixed culture resulted in a good description of the actual mixed cultures of the two bacteria. In the actual mixed-culture experiments, coexistence of the two species occurred only when the cultures were oxygen limited. With increasing oxygen supply (the actual oxygen concentration in the culture remaining at less than 0.2 microM), the biomass of C. testosteroni increased, whereas that of V. alcalescens decreased. Apparently, C. testosteroni protected V. alcalescens from inhibition by oxygen by maintaining sufficiently low oxygen concentrations. The model calculations indicated that competition between the aerobic and the anaerobic bacterium for common substrates (L-lactate and oxygen) occurred and that the anaerobe was the better competitor. Analysis of the culture fluid indicated that C. testosteroni grew primarily at the expense of the fermentation products of V. alcalescens, i.e., propionate and acetate. The model further indicated that with different values of several growth parameters (e.g., substrate affinity and/or inhibition constants), the affinity of the aerobic organism for oxygen and the sensitivity of the anaerobic organism for oxygen were the most important properties determining the coexistence of these two physiologically different types of bacteria.

Acetates↗
PubMed1991

Aspartate and asparagine as electron acceptors for Wolinella recta.

Since fumarate and nitrate are not usually available in the oral ecosystem, it was investigated whether aspartate and asparagine could be used as alternative electron acceptors by Wolinella recta, which is strictly dependent on a respiratory metabolism with formate or H2 as electron donors. Both aspartate and asparagine were indeed shown to support growth of W. recta with formate as electron donor. Fermentative growth with aspartate alone was not possible. Succinate was the major end-product and was formed in equimolar quantities with respect to the amount of formate consumed. The consumption of aspartate and asparagine, on a molar basis, was 10-30% higher than that of formate. Cell-free extracts were prepared from cells grown with formate + fumarate, formate + aspartate, formate + asparagine, and formate + fumarate + aspartate. All these extracts contained high activities of asparaginase, aspartate ammonia-lyase and fumarate-reductase, but no significant activity of aspartate aminotransferase was detected, indicating that fumarate was synthesized directly from aspartate and subsequently reduced to succinate. Based on these results it seems likely that aspartate and asparagine can serve as natural electron acceptors for W. recta in periodontal lesions in which proteolytic bacteria abound.

Asparaginase↗
PubMed1991

Fermentation of Inulin by Clostridium thermosuccinogenes sp. nov., a Thermophilic Anaerobic Bacterium Isolated from Various Habitats.

Four closely related strains of thermophilic bacteria were isolated via enrichment in batch and continuous culture with inulin as the sole source of carbon and energy by using inoculations from various sources. These new strains were isolated from beet pulp from a sugar refinery, soil around a Jerusalem artichoke, fresh cow manure, and mud from a tropical pond in a botanical garden. The cells of this novel species of strictly anaerobic, gram-positive bacteria were rod shaped and nonmotile. Growth on inulin was possible between 40 and 65 degrees C, with optimum growth at 58 degrees C. All strains were capable of fermenting a large number of sugars. Formate, acetate, ethanol, lactate, H(2), and succinate were the main organic fermentation products after growth on fructose, glucose, or inulin. Synthesis of inulinase in batch culture closely paralleled growth, and the enzyme was almost completely cell bound. Strain IC is described as the type strain of a new species, Clostridium thermosuccinogenes sp. nov., with a G+C content of 35.9 mol%.

Journal Article↗
PubMed1990

Comparison of the chitinolytic properties of Clostridium sp. strain 9.1 and a chitin-degrading bacterium from the intestinal tract of the plaice, Pleuronectes platessa (L.).

The chitinolytic properties of a facultatively anaerobic bacterium isolated from the hindgut of plaice were compared with those of Clostridium sp. strain 9.1, a bacterium isolated from anoxic estuarine sediment. The chitinolytic enzyme systems of the gut isolate and strain 9.1 both released N,N'-diacetylchitobiose (NAG2) as the major hydrolysis end-product. During the hydrolysis of chitin, there was transient accumulation of a non-sedimentary chitin fraction which was not detectable by high-performance liquid chromatography. Growth on NAG2 repressed chitinase synthesis in the gut isolate but not in the Clostridium species. Thiol reagents were strongly inhibitory to the chitinase of the strict anaerobe but did not affect the hydrolytic enzymes of the gut isolate. When the two bacteria were cocultured with chitin as the sole carbon and energy source, Clostridium sp. strain 9.1 was always outcompeted. Experiments with batch and phauxostat cultures showed that the competitiveness of strain 9.1 could be improved dramatically by the inclusion in the cocultures of a non-chitinolytic bacterium capable of fermenting chitin oligomers. The cooperation between the oligomer-fermenting species and the Clostridium sp. is discussed in relation to the regulation of chitinolytic activity in the latter organism.

Animals↗