Undefined Medium Research Articles

The role of FIS protein in the physiological control of the expression of the Escherichia coli meta-hpa operon

Expression from the Escherichia coli W meta-hpa operon promoter (Pg) is under a strict catabolic repression control mediated by the cAMP-catabolite repression protein (CRP) complex in a glucose-containing medium. The Pg promoter is also activated by the integration host factor (IHF) and repressed by the specific transcriptional regulator HpaR when 4-hydroxyphenylacetate (4HPA) is not present in the medium. Expression from the hpa promoter is also repressed in undefined rich medium such as LB, but the molecular basis of this mechanism is not understood. We present in vitro and in vivo studies to demonstrate the involvement of FIS protein in this catabolic repression. DNase I footprinting experiments show that FIS binds to multiple sites within the Pg promoter. FIS-site I overlaps the CRP-binding site. By using an electromobility shift assay, we demonstrated that FIS efficiently competes with CRP for binding to the Pg promoter, suggesting an antagonist/competitive mechanism. RT-PCR showed that the Pg repression effect is relieved in a FIS deleted strain. The repression role of FIS at Pg was further demonstrated by in vitro transcription assays. These results suggest that FIS contributes to silencing the Pg promoter in the exponential phase of growth in an undefined rich medium when FIS is predominantly expressed.

Endospore dipicolinic acid detection during Bacillus thuringiensis culture

The aim of this work was to detect Bacillus thuringiensis endospore production during fermentation under conditions hindering endospore detection, i.e. in a complex undefined industrial medium with a high content of solids in suspension. Bacterial endospore production was measured using the photoluminescence of dipicolinate (DPA) with Tb3+. The high temperature and pressure of a conventional autoclave was used to release DPA from the endospores. The endospore was obtained from B. thuringiensis var. kurstaki HD-73 fermentations in industrial-type media with 25.1 and 54.1 g l(-1) glucose, 4.4 and 35.3 g l(-1) soybean meal, 5.8 g l(-1) yeast extract, 9.2 g l(-1) corn steep solids and mineral salts. In this study, we successfully determined the DPA concentrations during the culture of B. thuringiensis in high-concentration soybean meal media. A good correlation was found between microscope endospore counting and DPA measurements in the cultures. Because of synergy between Cry protein and endospore in B. thuringiensis bioinsecticides formulation, it is important to be able to determine endospore development during B. thuringiensis industrial-type fermentation, in order to ascertain the beginning of sporulation.

Copper deficiency in potato dextrose agar causes reduced pigmentation in cultures of various fungi

Potato dextrose agar (PDA) is one of the most commonly used media for the isolation and cultivation of fungi, with morphological features and pigmentation in culture often being important for identification of cultures. Cultivation of various fungi on different brands and batches of powdered (commercial) potato dextrose media revealed deficient pigmentation in five of 10 media tested. Reduced pigmentation on these media was correlated with low levels of copper and colony colour was restored by the addition of copper. Deficient pigmentation was most pronounced when copper levels in the medium were below 50 ng mL(-1) (50 p.p.b.; 0.8 microM). Differences in pigmentation and laccase activity of spore and mycelial preparations were quantified for representative species belonging to the genera Aspergillus, Fusarium, Trichoderma, Cladosporium and Penicillium grown on PDA containing different amounts of copper. A strong positive correlation between laccase activity and copper levels was observed. Differences were also found between batches of raw potatoes, with organically cultivated tubers having higher copper levels than those grown by conventional methods, possibly because of the use of copper-based fungicides in the former case. Routine addition of 1000 ng mL(-1) copper (or standard trace element solutions) to PDA and other undefined media is advised to avoid atypical culture pigmentation and possibly other consequences of reduced activity of copper-requiring enzymes.

Impact of carbon sources on growth and oxalate synthesis by the phytopathogenic fungus Sclerotinia sclerotiorum

The impact of various supplemental carbon sources (oxalate, glyoxylate, glycolate, pyruvate, formate, malate, acetate, and succinate) on growth and oxalate formation (i.e., oxalogenesis) by Sclerotinia sclerotiorum was studied. With isolates D-E7, 105, W-B10, and Arg-L of S. sclerotiorum, growth in an undefined broth medium (0.1% soytone; pH 5) with 25 mM glucose and 25 mM supplemental carbon source was increased by the addition of malate and succinate. Oxalate accumulation occurred in the presence of glucose and a supplemental carbon source, with malate, acetate, and succinate supporting the most oxalate synthesis. With S. sclerotiorum Arg-L, oxalate-to-biomass ratios, an indicator of oxalogenic potential, were dissimilar when the organism was grown in the presence of different carbon sources. The highest oxalate-to-biomass ratios were observed with pyruvate, formate, malate, acetate, and succinate. Time-course studies with acetate-supplemented cultures revealed that acetate and glucose consumption by S. sclerotiorum D-E7 coincided with oxalogenesis and culture acidification. By day 5 of incubation, oxalogenesis was halted when cultures reached a pH of 3 and were devoid of acetate. In succinate-supplemented cultures, oxalogenesis essentially paralleled glucose and succinate utilization over the 9-day incubation period; during this time period, culture pH declined but never fell below 4. Overall, these results indicate that carbon sources can regulate the accumulation of oxalate, a key pathogenicity determinant for S. sclerotiorum.

Improved in vitro bovine embryo development and increased efficiency in producing viable calves using defined media

In this study, we developed a defined culture medium that supported improved in vitro bovine embryo development and calving rate after embryo transfer (ET). In vitro-matured bovine oocytes from abbatoir-derived ovaries from Korean native, HanWoo cattle were fertilized with frozen–thawed spermatozoa and embryos were cultured in two-step culture media. In Experiment 1, embryos were cultured in media supplemented with 8 mg/mL BSA, or 0.1 mg/mL PVA and 8 mg/mL BSA + 2.77 mM myo-inositol or 0.1 mg/mL PVA + 2.77 mM myo-inositol. Although defined culture media containing PVA supported lower developmental competence compared to undefined media (containing BSA; 8% versus 34%, respectively), defined culture media containing 2.77 mM myo-inositol increased rates of blastocyst formation up to 28%. In Experiment 2, the effect of energy substrate (1.5 mM glucose or 1.2 mM phosphate) in PVA–myo-inositol defined culture medium on in vitro embryo development was investigated. Defined culture media containing PVA, myo-inositol and phosphate supported better embryo development to blastocysts compared to medium supplemented with both glucose and phosphate (43% versus 31%). In Experiment 3, the effect of epidermal growth factor (EGF) in PVA + myo-inositol–phosphate two-step culture medium on in vitro embryo development was investigated. Among 0, 1, 10 and 100 ng/mL EGF concentrations, the maximal effect was observed with 10 ng/mL EGF (52% blastocyst formation). In Experiment 4, total cell number and calving rate were compared between defined PVA–myo-inositol–phosphate–EGF medium and undefined medium containing BSA, glucose and phosphate. No differences in total cell number of blastocysts obtained from the two groups were observed, however, the rate of viable offspring production was increased using the defined culture medium, compared to the undefined culture medium. In Experiment 5, the relative abundance of mRNA transcripts [interferon-tau (If-τ), glucose transporter-1 (glut-1) and insulin like growth factor 2 receptor (Igf2r)] were analyzed in blastocysts derived from undefined or defined culture media. Gene expression of If-τ, glut-1 was significantly increased in defined culture medium compared to undefined medium. In conclusion, chemically defined culture media without BSA or FBS improved developmental competence of in vitro cultured bovine embryos and delivery of viable calves after ET.

Effect of Glucose or Glycerol as the Sole Carbon Source on Gene Expression from the Salmonella prpBCDE Promoter in Escherichia coli

We have developed an expression system (Salmonella-based pPro system) containing the Salmonella enterica prpBCDE promoter (PprpB) and prpR encoding the positive transcriptional regulator of this promoter. In this study, the transcriptional efficiency of the pPro expression system was measured by placing the gene encoding the green fluorescent protein (gfp) under the control of PprpB and growing cells containing this construct in minimal medium supplemented with glucose or glycerol as a sole carbon source. In wild-type Escherichia coli (E. coli) BL21, the system exhibited high induced expression as well as high background expression; however, in E. coli JSB, a sbm-ygfDGHI deletion mutant of E. coli BL21(DE3), the system showed low background expression and high induced expression. The system exhibited homogeneous expression at the single-cell level, highly regulatable expression over a wide range of propionate concentrations, and fully induced expression at a low propionate concentration relative to that needed to induce the system in rich, undefined medium. The expression system is comparable to the widely used T7 promoter-driven expression systems in glucose or glycerol minimal medium.

Insights into Actinobacillus succinogenes Fermentative Metabolism in a Chemically Defined Growth Medium

Chemically defined media allow for a variety of metabolic studies that are not possible with undefined media. A defined medium, AM3, was created to expand the experimental opportunities for investigating the fermentative metabolism of succinate-producing Actinobacillus succinogenes. AM3 is a phosphate-buffered medium containing vitamins, minerals, NH4Cl as the main nitrogen source, and glutamate, cysteine, and methionine as required amino acids. A. succinogenes growth trends and end product distributions in AM3 and rich medium fermentations were compared. The effects of NaHCO3 concentration in AM3 on end product distribution, growth rate, and metabolic rates were also examined. The A. succinogenes growth rate was 1.3 to 1.4 times higher at an NaHCO3 concentration of 25 mM than at any other NaHCO3 concentration, likely because both energy-producing metabolic branches (i.e., the succinate-producing branch and the formate-, acetate-, and ethanol-producing branch) were functioning at relatively high rates in the presence of 25 mM bicarbonate. To improve the accuracy of the A. succinogenes metabolic map, the reasons for A. succinogenes glutamate auxotrophy were examined by enzyme assays and by testing the ability of glutamate precursors to support growth. Enzyme activities were detected for glutamate synthesis that required glutamine or alpha-ketoglutarate. The inability to synthesize alpha-ketoglutarate from glucose indicates that at least two tricarboxylic acid cycle-associated enzyme activities are absent in A. succinogenes.

Nitrite as an energy-conserving electron sink for the acetogenic bacterium Moorella thermoacetica.

Nitrite served as an energy-conserving electron acceptor for the acetogenic bacterium Moorella thermoacetica. Growth occurred in an undefined (0.1% yeast extract) medium containing 20 m M glyoxylate and 5 m M nitrite and was essentially equivalent to that observed in the absence of nitrite. In the presence of nitrite, acetate (the normal product of glyoxylate-derived acetogenesis) was not detected during growth. Instead, growth was coupled to nitrite dissimilation to ammonium, and acetogenesis was limited to the stationary phase. Furthermore, membranes from glyoxylate-grown cells under nitrite-dissimilating conditions were deficient in the b-type cytochrome that is typically found in the membranes of acetogenic cells. Unlike glyoxylate, other acetogenic substrates (fructose, oxalate, glycolate, vanillin, and hydrogen) were not growth supportive in the undefined medium containing nitrite, and glyoxylate-dependent growth did not occur in a nitrite-supplemented, basal (without yeast extract) medium. Glyoxylate-dependent growth by Moorella thermoautotrophica was not observed in the undefined medium containing nitrite.

진탕배양에서 Acetobacter sp. A9로부터 셀룰로오스 생산에 대한 완충성분 및 Bead의 효과

Acetobacter strains는 포도당을 함유한 복합배지에서 셀룰로오스를 합성할 수 있는 세균이다. 본 연구에서는 Acetobacter sp. A9에 의한 셀룰로오스 생산에 영향을 미치는 몇 가지 배양 환경요인을 진탕배양을 통하여 조사하였다. 배지에 3-(N-morpholino) propanesulfonir acid (MOPS)와 CaCO<TEX>$_3$</TEX> 등과 같은 완충성분의 첨가는 hcetobacter sp. A9에 의한 셀룰로오스 생산량을 증가시켰다. 따라서 배양시간 경과에 따른 배양액의 수소이온농도 조절이 경제적인 셀룰로오스 대량생산에 중요한 요인임을 알 수 있었다. 배지에 직경 10 mm의 bead를 첨가함으로써 다양한 기능을 가진 'disintegrated bacterial cellulose'가 생산되었다. Acetobacter strains are bacteria that can synthesize cellulose when grown on an undefined medium containing glucose. Several culture conditions affecting cellulose production by Acetobacter sp. A9 were examined by cultivating cells under shaking cultures. The addition of buffering agents, such as 3-(N-morpholino) propanesulfonic acid (MOPS) and CaCO<TEX>$_3$</TEX>, increased cellulose production. It suggests that pH of culture medium is important to an economical mass cellulose production. Addition of bead (Ф10 w) to culture medium stimulated 'disintegrated bacterial cellulose' production.

Some Nutritional Factors Affecting Production of Biomass and Antifungal Metabolites of Coniothyrium minitans

The ability of the mycoparasite Coniothyrium minitans to utilize a range of C and N sources and vitamins for growth, pycnidial formation and antifungal metabolite production was examined using a defined liquid medium. Coniothyrium minitans was able to use all the C sources tested, with the exception of D -xylose, and all the N sources tested, although growth was generally better on organic N sources rather than NO 3 -N. Increasing C:N ratios from 9:1-202:1 with N constant (2.0 g L -l L -alanine) resulted in steadily increasing yields, whereas increasing C:N ratios with C constant (40.0 g L -l D -glucose) gradually decreased yield. Addition of thiamine to the glucose-alanine basal medium resulted in the greatest increase in growth but biomass was still less than that achieved using an undefined molasses-yeast medium. Pycnidial production was generally low or failed to occur in the basal medium + C + N sources in the absence of vitamins, but addition of thiamine consistently led to abundant pycnidial formation. Molasses-yeast static culture provided greater biomass and conidial yields than molasses-yeast shaken culture. Incorporation of C. minitans culture medium into potato dextrose broth (10% v/v) resulted in consistent reduction in growth of Sclerotinia sclerotiorum irrespective of C, N or vitamin content of the basal medium or whether molasses-yeast medium was used. This is the first report of consistent production of antifungal metabolites by C. minitans .

Influence of the culture medium on antibiotic susceptibility testing of food-associated lactic acid bacteria with the agar overlay disc diffusion method.

To investigate the influence of the culture medium on antibiotic susceptibility testing of food-associated lactic acid bacteria (LAB) with the agar overlay disc diffusion (DD) method. The antibiotic resistance profile of 39 food-associated lactobacilli and enterococci was determined with the agar overlay DD method using a defined medium (i.e. Iso-sensitest agar; ISA) or an undefined medium (i.e. de Man, Rogosa, Sharpe or MRS agar). The study revealed that ampicillin discs and, although to a lesser extent, also tetracycline discs consistently produced larger zones on MRS medium compared to ISA medium. For the antibiotics gentamicin, bacitracin and erythromycin, the radius of the inhibition zones produced on MRS medium was significantly smaller in relation to ISA. For categorizing LAB isolates into resistant, intermediate and susceptible groups, it was demonstrated that major errors can occur in determining bacitracin and gentamicin resistance if MRS medium instead of ISA medium is used. On the other hand, the performance of both media was found to be equivalent for testing tetracycline resistance. Despite the fact that MRS medium generally supports the growth of lactic acid bacteria much better than the nutrient-poor ISA medium, the present study clearly demonstrates that both media are not compatible in susceptibility testing against various classes of antibiotics. These results may stimulate future discussions on a generally recommended DD method for susceptibility testing of food LAB strains.

Anaerobic biotransformation of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) by aquifer bacteria using hydrogen as the sole electron donor

RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) is a nitramine explosive that has contaminated soil and groundwater at military installations throughout the US. Although anaerobic RDX metabolism has been reported, the process is not well understood, as past studies have typically involved complex, undefined media with multiple potential electron donors and acceptors. In this study, bacteria enriched from RDX-contaminated aquifer sediments consumed RDX in a defined, bicarbonate-buffered, anaerobic medium containing hydrogen as the sole electron donor and RDX as a potential electron acceptor and sole nitrogen source. RDX was not consumed in live controls that did not contain hydrogen. Transient formation of mononitroso- and dinitroso-RDX metabolites (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine and hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine, respectively) was documented by liquid chromatography-mass spectrometry. However, studies with 14C-labeled RDX suggested that mineralization to carbon dioxide was negligible (<2%), which is consistent with cometabolic transformation. Several lines of evidence suggest that the RDX-transforming bacteria under study were homoacetogens, including correlations between RDX consumption and acetate production. Methanogens were unlikely to be responsible for RDX metabolism, as the presence of 2-bromoethanesulfonate, an inhibitor of methanogenesis, did not appear to affect RDX metabolism. The presence of nitrate reversibly halted RDX metabolism, whereas ammonium had no discernible effect, which implies that: (i) nitrate, which commonly occurs in RDX-contaminated groundwater, may inhibit in situ RDX metabolism, and (ii) although RDX may act as both a nitrogen source and cometabolic electron sink, the latter role predominates, as RDX reduction will proceed regardless of whether or not a more favorable nitrogen source is present.

A comparison of human dental plaque microcosm biofilms grown in an undefined medium and a chemically defined artificial saliva

The growth and pathogenic properties of dental plaque result from interactions between the microbiota and the oral environment and have been studied in laboratory experimental systems ranging from single or a few species (such as in chemostats) to dental plaque microcosms. Microcosm plaque is an in vitro version of natural plaque and has been explored as a microflora model because it is sited a more manipulable and controllable environment. It is obtained as microcosm biofilms in an ‘artificial mouth’ plaque culture system by culturing the bacteria in natural plaque-enriched saliva (i.e. salivary bacteria where a whole-saliva donor has abstained from oral hygiene for 24 h to increase the plaque bacteria in the saliva). The aim here was to examine whether a new, chemically defined analogue of saliva (defined medium mucin, DMM) could substitute for a previously used, chemically undefined medium (basal medium mucin, BMM) as an analogue of saliva for large-scale biofilm culturing. DMM contains various ions, mucin, amino acids, vitamins and growth factors at concentrations generally similar to those in saliva, whereas BMM contains yeast extract, peptones and mucin. To model the nutrient functions of salivary proteins, amino acids equivalent to 5 g/l casein were also included in DMM. In earlier studies, BMM-grown plaques were similar to natural plaques in structure, composition, growth rate and pH response to substrates. Their doubling-time patterns over a 20-day period were similar, except that the DMM-grown plaques showed biphasic growth patterns that were more pronounced than with BMM. Variation in enzyme profiles between BMM- and DMM-grown plaque, measured using the API-ZYM technique, provided evidence of nutritional effects on plaque composition. It was concluded that realistic growth rates and patterns are generated in microcosm plaque biofilms by supplying both DMM and BMM. However, the use of DMM enables specific modifications to be made to nutrient conditions during large-scale culture in our ‘artificial mouth’ biofilm system.

Maintenance and culture of yeasts.

AbstractYeasts generally are very easy to maintain, store, cultivate in almost any size of batch, and isolate from most habitats, but if a few elementary methods are understood, their isolation, storage, and culture, for day-to-day use in the laboratory is greatly simplified. Furthermore, the same methods can be used for maintenance of a stock collection for use in a production plant in a yeast-based industry. Being a group of unicellular organisms, yeasts can be handled in the same way as most bacteria, except that their nutritional and environmental requirements are, with few exceptions, much simpler. The techniques used will be considered under the following headings: 1. For short-term maintenance, for daily use. Rich, undefined media, such as yeast extract-peptone-glucose agar, YM agar, or malt agar, are commonly used (see Section 3.); 2. For medium-term storage; 3. For long-term preservation, as in a culture collection, where immediate access is less important, but maintenance of the characteristics of the species and strain is the primary objective; and 4. Methods for cultivation of yeasts, in small-, medium-, and large-scale volumes. KeywordsGlycerol SolutionMalt AgarCorn Meal AgarRice AgarUndefined MediumThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Proliferative Response of English Sole Splenic Leukocytes to Mitogens

Abstract The mitogenic response and mixed leukocyte reaction (MLR) were studied to determine the ability of a benthic marine fish, English sole Pleuronectes vetulus, to produce leukoproliferative (LP) responses. The mitogenic response of English sole leukocytes was assessed for a variety of mitogens. In vitro culture conditions for English sole leukocytes that would maintain cellular viability and allow leukocytes to proliferate were initially determined with an undefined medium. Factors that were varied to create an effective mitogen assay included mitogen type (pokeweed mitogen, concanavalin A, phytohemagglutinin, and lipopolysaccharide), mitogen concentrations, incubation time and temperature, medium supplementation, and number of leukocytes per culture. A leukocyte concentration of 1 × 107 leukocytes/mL provided for the greatest proliferation; cell concentrations above or below this level resulted in less proliferation. A higher degree of proliferation occurred when the leukocytes were incubated with ...

Media replenishment: A tool for the analysis of high-cell density perfusion systems

A simple method to analyze media consumption and by-product build-up in high-cell-density perfusion cultures has been developed. This technique makes use of a media replenishment strategy which can be used to decouple the two phenomena. Also, the replenished media method can be used to identify limitation by complex and undefined media components such as bovine serum.

Fumarate dissimilation and differential reductant flow by Clostridium formicoaceticum and Clostridium aceticum

Methanol and the O-methyl group of vanillate did not support the growth of Clostridium formicoaceticum in defined medium under CO2-limited conditions; however, they were growth supportive when fumarate was provided concomitantly. Fumarate alone was not growth supportive under these conditions. Fumarate reduction (dissimilation) to succinate was the predominant electron-accepting, energy-conserving process for methanol-derived reductant under CO2-limited conditions. However, when both reductant sinks, i.e., fumarate and CO2, were available, reductant was redirected towards CO2 in defined medium. In contrast, in undefined medium with both reductant sinks available, C. formicoaceticum simultaneously engaged fumarate dismutation and the concomitant usage of CO2 and fumarate as reductant sinks. With Clostridium aceticum, fumarate also substituted for CO2, and H2 became growth supportive under CO2-limited conditions. Fumarate dissimilation was the predominant electron-accepting process under CO2-limited conditions; however, when both reductant sinks were available, H2-derived reductant was routed towards CO2, indicating that acetogenesis was the preferred electron-accepting process when reductant flow originated from H2. Collectively, these findings indicate that fumarate dissimilation, not dismutation, is selectively used under certain conditions and that such usage of fumarate is subject to complex regulation.

Formaldehyde lacks genotoxicity in formaldehyde-hyperresistant strains of the yeast Saccharomyces cerevisiae

Formaldehyde is a weak mutagen and recombinagen in wild type strains of Saccharomyces cerevisiae. Genotoxicity of formaldehyde is influenced by the activity of the SFA yeast gene. Yeast transformants containing multiple copies of the plasmid-contained SFA gene are hyperresistant to the chemical and grow in the presence of 5 mM formaldehyde, a concentration lethal for the wild type. The SFA-encoded protein mediates the degradation of formaldehyde and its activity is most probably responsible for the low or absent genotoxic effects in formaldehyde-treated cells. Multi-copy vectors containing the SFA gene are retained in yeast transformations growing in complex media supplemented with 5 mM formaldehyde. Cells harboring such multi-copy vectors may, therefore, be propagated in large batch cultures in undefined media in the presence of formaldehyde concentrations toxic to the wild type.

Vector YFRp1 allows transformant selection in Saccharomyces cerevisiae via resistance to formaldehyde.

Formaldehyde (FA), a chemical with low toxic potential, is used as sole selective agent for transformation in the yeast Saccharomyces cerevisiae. Neither stable auxotrophic markers in recipient cells nor defined synthetic media are needed when multicopy vector YFRp1, containing the yeast SFA gene, is employed for yeast transformation. The SFA gene gives stability to the vector and its yeast (and other) passenger genes when transformants are propagated in complex media supplemented with 3-5 mM-FA. Use of inexpensive FA and non-synthetic, undefined media will lower the cost of yeast transformant propagation considerably and thus make feasible large-volume industrial application of transformants containing YFRp1 derivatives.

Re-examination of thee metabolic potentials of the acetogensClostridium aceticumandClostridium formicoaceticum: chemolithoautotrophic and aromatic-dependent growth

Both Clostridium formicoaceticum and Clostridium aceticum grew chemolithoautotrophically on carbon monoxide plus CO2 in defined medium in the absence of carbohydrates, amino acids, or other carbon and energy sources. Formate supported the growth of both organisms as well in both defined and undefined media (both of which also contained CO2). Hydrogen was stimulatory to the growth of C. formicoaceticum upon first transfer into H2-enriched formate medium; however, neither chemolithoautotrophic growth at the expense of H2 plus CO2 nor hydrogenase could be demonstrated with this acetogen. Consistent with recent findings with other acetogens, numerous aromatic compounds were utilized by C. aceticum and C. formicoaceticum: (i) aromatic methoxyl groups were O-demethylated; (ii) aromatic acrylates were reduced; and (iii) aromatic aldehydes were oxidized. These findings demonstrate that the metabolic potentials of these two acetogens are greater than previously recognized.