bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors relevant in bacterial pyrroloquinoline quinone production
Authors: van Kleef M A , Duine J A
Published: January 2020

Quinoprotein content and levels of external pyrroloquinoline quinone (PQQ) were determined for several bacteria under a variety of growth conditions. From these data and those from the literature, a number of factors can be indicated which are relevant for PQQ production. Synthesis of PQQ is only started if synthesis of a quinoprotein occurs, but quinoprotein synthesis does not depend on PQQ synthesis. The presence of quinoprotein substrates is not necessary for quinoprotein and PQQ syntheses. Although the extent of PQQ production was determined by the type of organism and quinoprotein produced, coordination between quinoprotein and PQQ syntheses is loose, since underproduction and overproduction of PQQ with respect to quinoprotein were observed. The results can be interpreted to indicate that quinoprotein synthesis depends on the growth rate whereas PQQ synthesis does not. In that view, the highest PQQ production can be achieved under limiting growth conditions, as was shown indeed by the much higher levels of PQQ produced in fed-batch cultures compared with those produced in batch experiments. The presence of nucleophiles, especially amino acids, in culture media may cause losses of PQQ due to transformation into biologically inactive compounds. Some organisms continued to synthesize PQQ de novo when this cofactor was administered exogenously. Most probably PQQ cannot be taken up by either passive diffusion or active transport mechanisms and is therefore not able to exert feedback regulation on its biosynthesis in these organisms.
Microzonation of Denitrification Activity in Stream Sediments as Studied with a Combined Oxygen and Nitrous Oxide Microsensor
Authors: Christensen Peter Bondo , Nielsen Lars Peter , Revsbech Niels Peter , S�rensen Jan
Published: January 2020

Microzonation of denitrification was studied in stream sediments by a combined O
2
and N
2
O microsensor technique. O
2
and N
2
O concentration profiles were recorded simultaneously in intact sediment cores in which C
2
H
2
was added to inhibit N
2
O reduction in denitrification. The N
2
O profiles were used to obtain high-resolution profiles of denitrification activity and NO
3
−
distribution in the sediments. O
2
penetrated about 1 mm into the dark-incubated sediments, and denitrification was largely restricted to a thin anoxic layer immediately below that. With 115 μM NO
3
−
in the water phase, denitrification was limited to a narrow zone from 0.7 to 1.4 mm in depth, and total activity was 34 nmol of N cm
−2
h
−1
. With 1,250 μM NO
3
−
in the water, the denitrification zone was extended to a layer from 0.9 to 4.8 mm in depth, and total activity increased to 124 nmol of N cm
−2
h
−1
. Within most of the activity zone, denitrification was not dependent on the NO
3
−
concentration and the apparent

K
m

for NO
3
−
was less than 10 μM. Denitrification was the only NO
3
−
-consuming process in the dark-incubated stream sediment. Even in the presence of C
2
H
2
, a significant N
2
O reduction (up to 30% of the total N
2
O production) occurred in the reduced, NO
3
−
-free layers below the denitrification zone. This effect must be corrected for during use of the conventional C
2
H
2
inhibition technique.
Metal Interactions with Microbial Biofilms in Acidic and Neutral pH Environments
Authors: Ferris F. G. , Schultze S. , Witten T. C. , Fyfe W. S. , Beveridge T. J.
Published: January 2020

Microbial biofilms were grown on strips of epoxy-impregnated filter paper submerged at four sites in water contaminated with metals from mine wastes. At two sample stations, the water was acidic (pH 3.1); the other sites were in a lake restored to a near neutral pH level by application of a crushed limestone slurry. During a 17-week study period, planktonic bacterial counts increased from 10
1
to 10
3
CFU/ml at all sites. Biofilm counts increased rapidly over the first 5 weeks and then leveled to 10
4
CFU/cm
2
in the neutral pH system and 10
3
CFU/cm
2
at the acidic sites. In each case, the biofilms bound Mn, Fe, Ni, and Cu in excess of the amounts adsorbed by control strips covered with nylon filters (pore size, 0.22 μm) to exclude microbial growth; Co bound under neutral conditions but not under acidic conditions. Conditional adsorption capacity constants, obtained graphically from the data, showed that biofilm metal uptake at a neutral pH level was enhanced by up to 12 orders of magnitude over acidic conditions. Similarly, adsorption strength values were usually higher at elevated pH levels. In thin sections of the biofilms, encapsulated bacterial cells were commonly found enmeshed together in microcolonies. The extracellular polymers often contained iron oxide precipitates which generated weak electron diffraction patterns with characteristic reflections for ferrihydrite (Fe
2
O
3
� H
2
O) at
d
equaling 0.15 and 0.25 nm. At neutral pH levels, these deposits incorporated trace amounts of Si and exhibited a granular morphology, whereas acicular crystalloids containing S developed under acidic conditions.
Uptake and Incorporation of Thymidine by Bacterial Isolates from an Upwelling Environment
Authors: Davis C. L.
Published: January 2020

Thymidine uptake and incorporation by marine bacterial isolates from an upwelling environment were studied. Of 17 isolates each from upwelled and downwelled water, 1 and 6 isolates, respectively, were found to be negative for [
3
H]thymidine incorporation at a substrate concentration of 19 μM. Strains lacking the ability to take up thymidine were not confined to one genus. The measurable rates of uptake and incorporation by the 34 isolates varied greatly. Studies carried out using starved
Vibrio, Pseudomonas,
and
Cytophaga
cells showed that these isolates transported and incorporated thymidine after periods of as long as 5 weeks of nutrient deprivation. This occurred in the absence of any other exogenously supplied nutrients. Overall, these results indicate that not all marine bacteria take up thymidine and that those that do incorporate the nucleoside may do so at very different rates. The assumption that only actively growing or dividing cells incorporate thymidine must be viewed with caution.
Growth of the syntrophic anaerobic acetogen, strain PA-1, with glucose or succinate as energy source
Authors: Brulla W J , Bryant M P
Published: January 2020

Strain PA-1 (S. Barik, W.J. Brulla, and M.P. Bryant, Appl. Environ. Microbiol. 50:304-310, 1985) is an anaerobic, gram-negative rod that in pure culture decarboxylates succinate to propionate and that grows syntrophically as an acetogen with the H2 utilizer Methanospirillum hungatei if glucose, pyruvate, aspartate, or fumarate is provided. In pure culture, strain PA-1 grows optimally in a medium containing 5% ruminal fluid, 0.1% yeast extract, a 4:1 N2-CO2 gas phase, and 20 mM succinate. With the PA-1 plus M. hungatei coculture, good growth was obtained with 7.5 mM glucose and tryptophan could replace the yeast extract. Strain PA-1 in pure culture grew quite well in glucose medium if the large headspace was flushed intermittently with N2. Flushing with H2 inhibited this growth.
Excretion of amino acids by 1,2,4-triazole-3-alanine-resistant mutants of Methanococcus voltae
Authors: Sment K A , Konisky J
Published: January 2020

In contrast to wild-type cells, it was found that triazole-alanine-resistant mutants of Methanococcus voltae excreted histidine, proline, phenylalanine, and tyrosine in various combinations. These results suggest that a form of general amino acid biosynthetic control may operate in this methanogen. We also show that wild-type M. voltae excretes methionine.
Isolation, Growth Characteristics, and Long-Term Storage of Fungi Cultivated by Attine Ants
Authors: Cazin John , Wiemer David F. , Howard Jerome J.
Published: January 2020

Seven pure-culture strains of fungi cultivated by attine ants (ant-garden fungi) were isolated from locally maintained leaf-cutting ant colonies. An ant-garden fungus strain obtained from an
Atta cephalotes
colony, when offered to ants of the colony from which the fungus was isolated, was accepted as their own. Young fungus cultures were harvested and incorporated into the fungus garden, and cultures of intermediate age were used to begin a new fungus garden; old cultures were simply harvested. To facilitate further research on this fungus, growth characteristics of the different isolates were studied under a variety of conditions. They grew better at 24°C than at 30°C, and growth did not occur at an incubation temperature of 37°C. In a broth culture medium, growth was enhanced by aeration of the culture and by addition of yeast extract, olive oil, sesame oil, peanut oil, soybean oil, corn oil, sunflower oil, cottonseed oil, walnut oil, safflower oil, or mineral oil. Glycerol did not noticeably affect growth, but Tween 80 inhibited growth. These fungi were extremely sensitive to cycloheximide, growth being totally inhibited at cycloheximide concentrations ranging from 0.4 to 4.0 μg/ml. To date, the ant-garden fungus isolates have remained viable in long-term mineral oil-overlay storage cultures for up to 4 years.
Role of DNA Superhelicity in Regulation of Bacteroid-Associated Functions of
Bradyrhizobium
sp. Strain 32H1
Authors: Gober James W. , Kashket Eva R.
Published: January 2020

Bradyrhizobium
sp. strain 32H1 cells express a number of bacteroid-associated functions and repress some functions related to the free-living state when grown ex planta under conditions of low (0.2%) oxygen tension and relatively high levels (>8 mM) of medium K
+
. Expression of the bacteroid-associated phenotype was blocked by the DNA gyrase inhibitor novobiocin. Because the degree of negative supercoiling of DNA is the result of the activities of both DNA gyrase and topoisomerase I, we measured these enzymes in cells grown under nitrogen-fixing (low O
2
, high K
+
) and non-nitrogen-fixing conditions (low O
2
, low [50 μM] K
+
or high O
2
, high K
+
). Lower topoisomerase I activities were seen in extracts from nitrogen-fixing cells than in those from non-nitrogen-fixing cells. In contrast, DNA gyrase levels were lower in high-O
2
-grown cells than under the other conditions tested. These differences are consistent with an increase in DNA superhelicity associated with growth under low-O
2
, high-K
+
conditions. A spontaneous mutant resistant to the DNA gyrase inhibitor ciprofloxacin was found to be constitutive with respect to the K
+
requirement, because it expressed the bacteroid-associated phenotype when grown under low-O
2
, low-K
+
conditions. The mutant cells gave rise to effective nodules on
Macroptilium atropurpureum
and possessed the low topoisomerase I activities and high DNA gyrase levels of low-O
2
-, high-K
+
-grown wild-type cells. Our data suggest that changes in DNA supercoiling resulting from low O
2
tension and a high K
+
concentration exert a major influence on the expression of the bacteroid-associated phenotype.
Plasmid transformation by electroporation of Leuconostoc paramesenteroides and its use in molecular cloning
Authors: David S , Simons G , De Vos W M
Published: January 2020

In this report, we demonstrate the utility of electroporation as an efficient method for genetic transformation of Leuconostoc paramesenteroides. We optimized several factors which determine the transformation frequency, resulting in transformation efficiencies of up to 4 x 10(3) transformants per micrograms of pNZ12 DNA, which contains the promiscuous Lactococcus lactis pSH71 replicon. Slightly lower efficiencies were obtained with a deletion derivative of the broad-host-range plasmid pAM beta 1. These plasmids could be stably maintained in L. paramesenteroides NZ6009 for more than 100 generations, even in the absence of selective pressure. In order to show the use of the developed host-vector system, we cloned the Lactococcus lactis gene encoding phospho-beta-galactosidase in L. paramesenteroides. Expression of this heterologous gene in L. paramesenteroides under control of Lactococcus lactis expression signals was evident from the presence, in transformants, of phospho-beta-galactosidase activity and a specific phospho-beta-galactosidase protein band on Western blots (immunoblots). In addition, we transformed a lactose-deficient derivative of L. paramesenteroides with a plasmid carrying a Lactococcus lactis-Escherichia coli lacZ gene fusion. The resulting transformants synthesized high levels of beta-galactosidase, indicating the efficiency of heterologous gene expression signals in L. paramesenteroides.
Comparative recovery of uninjured and heat-injured Listeria monocytogenes cells from bovine milk
Authors: Crawford R G , Beliveau C M , Peeler J T , Donnelly C W , Bunning V K
Published: January 2020

The standard selective enrichment protocols of the Food and Drug Administration (FDA) and U.S. Department of Agriculture (USDA) were compared with an experimental nonselective broth enrichment (NSB) protocol and variations of the standard cold-enrichment (CE) protocol for the recovery of heat-injured Listeria monocytogenes. Bacterial cells (10(7)/ml) were suspended in sterile milk and heated at 71.7 degrees C in a slug-flow heat exchanger for holding times ranging from 1 to 30 s. Surviving cells were determined (50% endpoint) by the given protocols, and the following D values were obtained: NSB, D = 2.0 +/- 0.5 s; FDA, D = 1.4 +/- 0.3 s; USDA, D = 0.6 +/- 0.2 s; CE, D less than or equal to 1.2 s. The respective direct-plating media used in these enrichments were also analyzed for recovery, and the following D values were calculated from the enumeration of surviving cells; NSB, D = 2.7 +/- 0.8 s; FDA, D = 1.3 +/- 0.4 s; USDA, D = 0.7 +/- 0.2 s. The low levels of heat-injured L. monocytogenes cells which were detected at inactivation endpoints on the optimal nonselective media (25 degrees C for 7 days) failed to recover and multiply during experimental CEs (4 degrees C for 28 days). Initial inactivation experiments in which raw whole milk was used as the heating menstruum gave much lower recoveries with all protocols. The detectable limits for uninjured cells that were suspended in raw milk were similar (0.35 to 3.2 cells per ml) for the standard CE, FDA, and USDA protocols.(ABSTRACT TRUNCATED AT 250 WORDS)
Enzyme immunoassay for macrolide antibiotics: characterization of an antibody to 23-amino-O-mycaminosyltylonolide
Authors: Yao R C , Mahoney D F
Published: January 2020

An enzyme-linked immunosorbent assay was developed for the detection of macrolide antibiotics by using a polyclonal antibody generated in rabbits immunized with 23-amino-O-mycaminosyltylonolide (23-amino-OMT) covalently linked to keyhole limpet hemocyanin. The specificity and sensitivity of this antibody were characterized by using 23-amino-OMT coupled to alkaline phosphatase as an enzyme-linked label in a direct competitive enzyme-linked immunosorbent assay. The assay sensitivity was as low as 0.3 ng/ml for 23-amino-OMT, with a 50% inhibitory concentration of 8 ng/ml. This antibody exhibited good reactivity with 12-, 14- or 16-membered macrolides possessing amino-substituted sugar moieties, regardless of the presence of neutral sugar residues. Little or no cross-reactivity was observed with the macrocyclic lactone ring structure (tylactone) or macrolides containing only neutral sugars. No cross-reaction was observed with polyenes or nonmacrolide antibiotics. Known macrolide-producing cultures grown in fermentation broth also showed good reactivity, indicating that this assay is useful in detecting this class of metabolites in fermentation.
Regulation of Bacterioplankton Production and Cell Volume in a Eutrophic Estuary
Authors: Bjørnsen Peter Koefoed , Riemann Bo , Pock-Steen Jan , Nielsen Torkel Gissel , Horsted Steen Jesper
Published: January 2020

During three periods of 16 to 25 days, bacterioplankton production, bacterial cell volume, chlorophyll
a
, CO
2
assimilation, and particulate organic carbon were measured in enclosures situated in the eutrophic estuary Roskilde Fjord, Denmark. The enclosures were manipulated with respect to sediment contact and contents of inorganic nutrients, planktivorous fish, and suspension-feeding bivalves. Nutrient enrichment, the presence of suspension feeders, and sediment contact induced pronounced changes in bacterial production, as well as minor changes in bacterial cell volume; however, these effects seemed to be indirect, transmitted via phytoplankton. Bacterial production, measured as [
3
H]thymidine incorporation, closely followed changes in phytoplankton biomass and production, with time lags of 5 to 10 days. Good correlations of mean bacterioplankton production to chlorophyll
a
concentration and CO
2
assimilation suggested phytoplankton to be the dominating source of bacterial substrate, apparently independent of nutrient stress. Zooplankton >140 μm, bivalves, and sediment seemed to provide insignificant, if any, substrate for bacterioplankton, and benthic suspension feeders seemed not to act as direct competitors for dissolved organic carbon. The bacterioplankton mean cell volume, measured by image analysis, changed seasonally, with the smallest cells during the summer. Within each period, the bacterial cell volume correlated positively to growth rate and negatively to temperature.
Regulation of neurotoxin and protease formation in Clostridium botulinum Okra B and Hall A by arginine
Authors: Patterson-Curtis S I , Johnson E A
Published: January 2020

Supplementation of a minimal medium with high levels of arginine (20 g/liter) markedly decreased neurotoxin titers and protease activities in cultures of Clostridium botulinum Okra B and Hall A. Nitrogenous nutrients that are known to be derived from arginine, including proline, glutamate, and ammonia, also decreased protease and toxin but less so than did arginine. Proteases synthesized during growth were rapidly inactivated after growth stopped in media containing high levels of arginine. Separation of extracellular proteins by electrophoresis and immunoblots with antibodies to toxin showed that the decrease in toxin titers in media containing high levels of arginine was caused by both reduced synthesis of protoxin and impaired proteolytic activation. In contrast, certain other nutritional conditions stimulated protease and toxin formation in C. botulinum and counteracted the repression by arginine. Supplementation of the minimal medium with casein or casein hydrolysates increased protease activities and toxin titers. Casein supplementation of a medium containing high levels of arginine prevented protease inactivation. High levels of glucose (50 g/liter) also delayed the inactivation of proteases in both the minimal medium and a medium containing high levels of arginine. These observations suggest that the availability of nitrogen and energy sources, particularly arginine, affects the production and proteolytic processing of toxins and proteases in C. botulinum.
Effect of Yeast Hulls on Stuck and Sluggish Wine Fermentations: Importance of the Lipid Component
Authors: Munoz Eeva , Ingledew W. M.
Published: January 2020

The effect of yeast hulls (yeast ghosts) on sluggish or stuck white wine fermentations was studied. The enhancing effect on yeast growth and fermentation rate displayed by the hulls was shown to be similar to the effect provided by lipid extract from the same hulls. Unsaturated fatty acids and sterols were incorporated into the yeast from lipid extracts during fermentation carried out under oxygen-limited conditions. Adsorption of toxic medium-chain fatty acid (decanoic acid) onto the yeast hulls took place through a dialysis membrane. However, when the hulls were placed inside a dialysis bag, the increase in yeast growth and fermentation rate seen when freely suspended hulls were used did not occur. Accordingly, the effect of yeast hulls in preventing stuck fermentations cannot be attributed only to the adsorption and consequent removal of medium-chain fatty acids from the juice.
Fate of Listeria monocytogenes in processed meat products during refrigerated storage
Authors: Glass K A , Doyle M P
Published: January 2020

The fate of Listeria monocytogenes during refrigerated storage was determined on several processed meat products, including ham, bologna, wieners, sliced chicken, sliced turkey, fermented semidried sausage, bratwurst, and cooked roast beef. The meats were surface inoculated with a five-strain mixture of less than or equal to 200 or ca. 10(5) L. monocytogenes cells per package, vacuum packaged, and stored at 4.4 degrees C. Survival or growth of listeriae was determined for up to 12 weeks of storage or until the product was spoiled. The organism survived but did not grow on summer sausage, grew only slightly on cooked roast beef, grew well on some wiener products but not on others, grew well (10(3) to 10(5) CFU/g increase within 4 weeks) on ham, bologna, and bratwurst, and grew exceptionally well (10(3) to 10(5) CFU/g increase within 4 weeks) on sliced chicken and turkey. The rate of growth depended largely upon the type of product and the pH of the product. Growth was most prolific on processed poultry products. The organism generally grew well on meats near or above pH 6 and poorly or not at all on products near or below pH 5. These results indicate the importance of preventing postprocessing contamination of L. monocytogenes in a variety of ready-to-eat meat products.
Metabolism and some characteristics of ruminal strains of Megasphaera elsdenii
Authors: Marounek M , Fliegrova K , Bartos S
Published: January 2020

Megasphaera elsdenii belongs to the group comprising the ruminal and intestinal lactate- and sugar-fermenting species. In the present study the fermentation characteristics, metabolism of glucose and lactate, and susceptibility to antimicrobial agents of four ruminal strains were investigated. Particular attention was given to the mixed-substrate fermentation pattern and resultant fermentation acid profile. Lactate was utilized more rapidly than glucose in media with both carbon sources. Interaction of the two substrates changed the composition of fermentation end products toward more valerate and less propionate in cultures with glucose and lactate. Contrary to the indications in Bergey's Manual of Systematic Bacteriology, butyrate, not caproate, was the main end product of glucose metabolism. The strains examined were rather insensitive to many antimicrobial compounds, especially to ionophores and other antimicrobial feed additives.
Ecology of Vibrio cholerae non-O1 and Salmonella spp. and role of zooplankton in their seasonal distribution in Fukuyama coastal waters, Japan
Authors: Venkateswaran K , Takai T , Navarro I M , Nakano H , Hashimoto H , Siebeling R J
Published: January 2020

Seasonal variation of human pathogens such as Vibrio Cholerae non-01 and Salmonella spp. in Fukuyama coastal waters and the role of zooplankton in their distribution were studies for a period of 1 year. Comparison of two established methods, viz., the elevated temperature method and the two-step enrichment method of enumerating V. cholerae, showed that the former is superior in the recoveries of V. cholerae non-01. Isolation of this pathogen on a wider range of salinities (0.4 to 32.5%) revealed that these organisms are apparently an autochthonous component of the aquatic environment. Temperature appears to be the most crucial element in governing the distribution of V. cholerae non-01. Among the 69 isolates serotyped, 22 different serovars were identified, while one isolate failed to react with any of the known Louisiana State University antisera tested. Zooplankton samples did not harbor more V. Cholerae non-01 than the water column did. Better isolation of an allochthonous pathogen, viz., Salmonella spp., was noticed from the water samples when swabs were employed. Of the 251 isolates serotyped, 18 serotypes with three variants of Salmonella spp. were identified. A high amount of nutrients in the water column increased the survival rate of these pathogens in saline waters as evidenced by a higher incidence of various serotypes in polluted Fukuyama port than in clean marine waters. Salmonella spp. association between V. cholerae non-01 of Salmonella spp. with zooplankton could be noticed as influencing their seasonal distribution.
Competition among Strains of
Rhizobium leguminosarum
biovar
trifolii
and Use of a Diallel Analysis in Assessing Competition
Authors: Ames-Gottfred N. P. , Christie B. R.
Published: January 2020

Competition between indigenous
Rhizobium leguminosarum
biovar
trifolii
strains and inoculant strains or between mixtures of inoculant strains was assessed in field and growth-room studies. Strain effectiveness under competition was compared with strain performance in the absence of competition. Field inoculation trials were conducted at Elora, Ontario, Canada, with soil containing indigenous
R. leguminosarum
biovar
trifolii.
The indirect fluorescent-antibody technique was used for the identification of nodule occupants. Treatments consisted of 10 pure strains, a commercial peat inoculant containing a mixture of strains, and an uninoculated control. Inoculant strains occupied 17.5 to 85% of nodules and resulted in increased dry weight and nitrogen content, as compared with the uninoculated control. None of the strains was capable of completely overcoming resident rhizobia, which occupied, on average, 50% of the total nodules tested. In growth-room studies single commercial strains were mixed in all possible two-way combinations and assessed in a diallel mating design. Significant differences in plant dry weight of red clover were observed among strain combinations. Specific combining ability effects were significant at the 10% level, suggesting that the effectiveness of strain mixtures depended on the specific strain combinations. Strains possessing superior effectiveness and competitive abilities were identified by field and growth-room studies. No relationship was detected between strain effectiveness and competitive ability or between strain recovery and host cultivar. The concentration of indigenous populations was not considered to be a limiting factor in the recovery of introduced strains at this site.
Pectin Lyase Production by a
Penicillium italicum
Strain
Authors: Alaña Aitor , Gabilondo Ane , Hernando Fernando , Moragues Maria D. , Dominguez Juan B. , Llama Maria J. , Serra Juan L.
Published: January 2020

Growth and concomitant production of an extracellular pectin lyase (PL) [poly(methoxylgalactosiduronate) endolyase; EC 4.2.2.10] were investigated in a group of 16 fungi grown in liquid medium containing pectin as a supplementary carbon source. Culture filtrates of both
Penicillium italicum
(CECT 2294) and
P. expansum
(CECT 2275) showed the highest PL activity and contained polygalacturonase but not pectinesterase activity. The effect of the inoculum size, the carbon source (sucrose and glucose syrup), and the presence of pectin on the production of PL by
P. italicum
was studied. The presence of 2.6 mM glycerophosphate in the culture medium enhanced the appearance of PL but was not inhibitory for the in vitro activity. However, glycerol inhibited the enzyme nearly 50% at such a concentration.
Freon 11 Extraction of Volatile Metabolites Formed by Certain Lactic Acid Bacteria
Authors: Tracey Ralph P. , Britz Trevor J.
Published: January 2020

The volatile metabolites formed by 18 lactic acid bacteria, representing three genera, were extracted from a complex medium by using a Freon 11 extraction method. The Freon extracts were then analyzed by capillary gas chromatography, and certain extracts were analyzed by gas chromatography-mass spectrometry. A total of 35 major peaks, of which 20 were positively identified, were used to differentiate between the various strains. On the basis of the results obtained, it was possible to differentiate between the members of the genera
Lactobacillus, Pediococcus
, and
Leuconostoc
, as well as between various species within the genus
Leuconostoc.
Of the 10
Leuconostoc oenos
strains included in this study, 9 yielded similar results, but it was still possible to differentiate between the various strains.
L. oenos
B66 differed from the other
L. oenos
strains. Use of the Freon 11 extraction technique to determine volatile metabolites formed by lactic acid bacteria was shown to be highly reproducible and of great value. Furthermore, certain compounds not previously known to be formed by lactic acid bacteria were found.
Inducible bacteriophages from ruminal bacteria
Authors: Klieve A V , Hudman J F , Bauchop T
Published: January 2020

The incidence of temperate bacteriophage in a wide range of ruminal bacteria was investigated by means of induction with mitomycin C. Supernatant liquid from treated cultures was examined for phagelike particles by using transmission electron microscopy. Of 38 ruminal bacteria studied, nine organisms (23.7%) representing five genera (Eubacteria, Bacteroides, Butyrivibrio, Ruminococcus, and Streptococcus) produced phagelike particles. Filamentous particles from Butyrivibrio fibrisolvens are the first of this morphological type reported from ruminal bacteria. All of the other particles obtained possessed polyhedral heads and long, noncontractile tails (group B-type phage). The limited range of morphological types produced by mitomycin C induction cannot yet account for the much wider range of types found in ruminal contents by direct examination. The presence of viral genetic material in a significant percentage of the bacteria tested, as well as in a range of different genera, indicates that viral genetic material may be a normal constituent of the genome of appreciable numbers of ruminal bacteria.
Degradation of Lignin-Related Compounds by Actinomycetes
Authors: Ball A. S. , Betts W. B. , McCarthy A. J.
Published: January 2020

Evidence for activity against the lignin fraction of straw was produced for a range of actinomycete strains. Decolorization of the polymeric dye Poly R and oxidation of veratryl alcohol, indicators of ligninolytic activity in white rot fungi, and utilization of fractionated Kraft lignin and low-molecular-weight methoxylated aromatic compounds were the criteria used. The relationships between these activities and the solubilization of native lignin are discussed.
Complete nucleotide sequence and characterization of a cryptic plasmid from Lactobacillus helveticus subsp. jugurti
Authors: Takiguchi R , Hashiba H , Aoyama K , Ishii S
Published: January 2020

A small cryptic plasmid, pLJ1, was isolated from Lactobacillus helveticus subsp. jugurti and was cloned into Escherichia coli HB101 by using pBR329 as a vector. Plasmid pLJ1 was 3,292 base pairs long and had single restriction endonuclease sites for PvuII, KpnI, AvaII, Acci, HindIII, and EcoRI. In a maxicell system, pLJ1 produced a protein of about 41 kilodaltons.
Localization, cloning, and expression of genetic determinants for bacteriophage resistance (Hsp) from the conjugative plasmid pTR2030
Authors: Hill C , Romero D A , McKenney D S , Finer K R , Klaenhammer T R
Published: January 2020

Genetic determinants for a bacteriophage resistance mechanism (Hsp+) encoded by plasmid pTR2030 (46.2 kilobases [kb]) were localized by mapping an 11.5-kb deletion that accompanied the transition of Lactococcus lactis LMA12-4 transconjugants (M. E. Sanders, P. J. Leonard, W. D. Sing, and T. R. Klaenhammer, Appl. Environ. Microbiol. 52:1001-1007, 1986) from phage resistance to phage sensitivity. The deleted 34.7-kb replicon (pTR2023, Hsp-) retained its conjugative ability, demonstrating that the phage resistance and conjugal transfer determinants were genetically distinct. The Hsp region of pTT2030, which was contained within a 13.6-kb BglII fragment, was cloned into the BamHI site of bacteriophage lambda EMBL3, and Hsp was subcloned into the Escherichia coli-Streptococcus shuttle vector pSA3. The recombinant plasmids pTK6 and pTK9 were recovered in E. coli HB101 and contained a 13.6-kb insert in opposite orientations. L. Lactis MG1363 transformants carrying pTK6 or pTK9 exhibited a significant reduction in plaque size, in addition to a slight reduction in the efficiency of plaquing for both prolate and small isometric phages. Phenotypic reactions observed for the recombinant plasmids suggest that pTR2030-encoded Hsp acts similarly against both prolate and small isometric phages. Tn5 mutagenesis was used to define the region essential for the expression of the Hsp+ phenotype. Any of four insertions within a 3-kb region resulted in the loss of phage resistance, whereas a further 26 insertions outside this locus had no effect on Hsp expression. In vitro deletion analysis confirmed that the 3-kb region contained all the information necessary for the observed resistance.
Survival of Ice Nucleation-Active and Genetically Engineered Non-Ice-Nucleating
Pseudomonas syringae
Strains after Freezing
Authors: Buttner Mark P. , Amy Penny S.
Published: January 2020

The survival after freezing of ice nucleation-active (INA) and genetically engineered non-INA strains of
Pseudomonas syringae
was compared. Each strain was applied to oat seedlings and allowed to colonize for 3 days, and the plants were subjected to various freezing temperatures. Plant leaves were harvested before and after freezing on two consecutive days, and bacterial populations were determined. Populations of the INA wild-type strain increased 15-fold in the 18 h after the oat plants incurred frost damage at −5 and −12°C. Plants colonized by the non-INA strain were undamaged at −5°C and exhibited no changes in population size after two freeze trials. As freezing temperatures were lowered (−7, −9, and −12°C), oat plants colonized by the non-INA strain suffered increased frost damage concomitant with bacterial population increases following 18 h. At −12°C, both strains behaved identically. The data show a relationship between frost damage to plants and increased bacterial population size during the following 18 h, indicating a potential competitive advantage of INA strains of
P. syringae
over non-INA strains in mild freezing environments.
Influence of Pseudomonas syringae culture conditions on initiation of the hypersensitive response of culture tobacco cells
Authors: Yucel I , Xiao Y X , Hutcheson S W
Published: January 2020

The inhibitor sensitivity and timing of the ionic response of suspension-cultured tobacco cells were used as a bioassay for the Pseudomonas syringae signal that elicits the hypersensitive response in resistant plants. The ionic response of tobacco cell suspensions inoculated with P. syringae pv. syringae 61 and P. syringae pv. pisi grown in rich media was inhibited by rifampin, tetracycline, and streptomycin during a 2- to 2.5-h induction stage. Coculturing the bacteria with tobacco cells for 3 h or more before inoculating fresh tobacco cells specifically abolished the sensitivity of the ionic response to these inhibitors and reduced the response time of the tobacco cells from 3 to 1 h. The apparent activation of the bacteria during coculture was not dependent on the plant cells and could be achieved by incubating the bacteria in a nitrogen-deficient medium containing a metabolizable carbon source. Addition of proteose peptone and Casamino Acids to this medium suppressed activation of the bacteria. The results suggest that the hypersensitive response-eliciting signal forms late in the induction stage, perhaps as a result of the derepression of some of the P. syringae genes functional in elicitation of the hypersensitive response. The nature of the activated state remains elusive but is consistent with the accumulation of protein(s) whose activity indirectly elicits the ionic response.
Comparison of Two Methods for Enumeration of Anaerobe Numbers on Forages and Evaluation of Ethylene Oxide Treatment for Forage Sterilization
Authors: Shockey W. L. , Dehority B. A.
Published: January 2020

Experiments were conducted to (i) compare most-probable-number (MPN) procedures with roll tube procedures for enumeration of forage anaerobic bacteria and (ii) evaluate the efficacy of using ethylene oxide to sterilize wet herbage. Alfalfa, corn, and alfalfa-orchardgrass silages and alfalfa and orchardgrass herbages were analyzed for total anaerobic bacteria (medium pH, 6.8) and acid-tolerant anaerobic bacteria (medium pH, 4.5) by both roll tube and MPN procedures. No difference was found between the roll tube and MPN procedures for total bacteria; however, higher counts were obtained for acid-tolerant bacteria when the MPN procedure was used. Although MPN procedures require less time to obtain an estimate of bacterial numbers, isolation and identification of the microbial population is not possible. Alfalfa herbage was treated with ethylene oxide for 12, 24, or 36 h, incubated for 7 days at 37°C with or without addition of a bacterial inoculant, and analyzed for total bacteria by MPN procedures. Microbial growth after inoculation of ethylene oxide-treated herbage indicated that there was insufficient residual ethylene oxide to inhibit subsequent microbial growth. The results also indicated that 24 h was required to adequately sterilize fresh herbage. Thus, ethylene oxide can be used to sterilize wet herbage for use as a substrate for pure cultures of silage bacteria.
Phenotypic and genomic studies of "Cytophaga psychrophila" isolated from diseased rainbow trout (Oncorhynchus mykiss) in France
Authors: Bernardet J F , Kerouault B
Published: January 2020

Five strains of gliding bacteria were isolated in France from farmed diseased rainbow trouts reared at low water temperature. The resemblance of these bacteria to the known fish pathogen "Cytophaga psychrophila" led to their comparative study with reference strain NCMB 1947 and with an American isolate. Morphological, physiological, and biochemical characteristics of the seven strains proved to be similar. Comparison of their DNA by the S1 nuclease DNA-DNA hybridization method showed that the seven strains formed a tight genomic species with DNA relatedness above 90%. This is the first identification of this fish pathogen in a European country. The main phenotypic characteristics differentiating this bacterium from other nonpathogenic gliding bacteria of fish origin include a poor gliding movement, yellow compact or weakly rhizoid colonies on solid media, and the presence of flexirubin-type pigments. The inability to metabolize any carbohydrates, the strong proteolytic activity, the absence of growth in more than 0.5% NaCl, and the tolerance to a maximum temperature of 25 degrees C are also useful characteristics of this group of bacteria.
Annual Pattern of Denitrification and Nitrate Ammonification in Estuarine Sediment
Authors: Jørgensen Kirsten Schannong
Published: January 2020

The seasonal variation and depth distribution of the capacity for denitrification and dissimilatory NO
3
−
reduction to NH
4
+
(NO
3
−
ammonification) were studied in the upper 4 cm of the sediment of Norsminde Fjord estuary, Denmark. A combination of C
2
H
2
inhibition and
15
N isotope techniques was used in intact sediment cores in short-term incubations (maximum, 4 h). The denitrification capacity exhibited two maxima, one in the spring and one in the fall, whereas the capacity for NO
3
−
ammonification was maximal in the late summer, when sediments were progressively reduced. The denitrification capacity was always highest in the uppermost 1 cm of the sediment and declined with depth. The NO
3
−
ammonification was usually higher with depth, but the maximum activity in late summer was observed within the upper 1 cm. The capacity for NO
3
−
incorporation into organic material was investigated on two occasions in intact sediment cores and accounted for less than 5% of the total NO
3
−
reduction. Denitrification accounted for between 13 and 51% of the total NO
3
−
reduction, and NH
4
+
production accounted for between 4 and 21%, depending on initial rates during the time courses. Changes of the rates during the incubation were observed in the late summer, which reflected synthesis of denitrifying enzymes. This time lag was eliminated in experiments with mixed sediment because of preincubation with NO
3
−
and alterations of the near-environmental conditions. The initial rates obtained in intact sediment cores therefore reflect the preexisting enzyme content of the sediment.
Plasmid expression and maintenance during long-term starvation-survival of bacteria in well water
Authors: Caldwell B A , Ye C , Griffiths R P , Moyer C L , Morita R Y
Published: January 2020

Strains of enteric bacteria and pseudomonads containing plasmid R388::Tnl721 (Tpr, Tcr) or pRO101 (Hgr, Tcr) were starved for over 250 days in sterile well water to evaluate effects of starvation-survival on plasmid expression and maintenance. Viable populations dropped to between approximately 0.1 and 1% of the initial populations. Escherichia coli(pRO101) and Pseudomonas cepacia(pRO101) lost both viability and plasmid expression at a lower rate than strains containing R388::Tnl721. Three patterns of host-plasmid interaction were detected: (i) no apparent loss of plasmid expression, (ii) loss of plasmid expression on initial recovery with subsequent expression upon resuscitation, and (iii) loss of capability to produce functional plasmid resistance.
Production of extracellular nucleic acids by genetically altered bacteria in aquatic-environment microcosms
Authors: Paul J H , David A W
Published: January 2020

The factors which affect the production of extracellular DNA by genetically altered strains of Escherichia coli, Pseudomonas aeruginosa, Pseudomonas cepacia, and Bradyrhizobium japonicum in aquatic environments were investigated. Cellular nucleic acids were labeled in vivo by incubation with [3H]thymidine or [3H]adenine, and production of extracellular DNA in marine waters, artificial seawater, or minimal salts media was determined by detecting radiolabeled macromolecules in incubation filtrates. The presence or absence of the ambient microbial community had little effect on the production of extracellular DNA. Three of four organisms produced the greatest amounts of extracellular nucleic acids when incubated in low-salinity media (2% artificial seawater) rather than high-salinity media (10 to 50% artificial seawater). The greatest production of extracellular nucleic acids by P. cepacia occurred at pH 7 and 37 degrees C, suggesting that extracellular-DNA production may be a normal physiologic function of the cell. Incubation of labeled P. cepacia cells in water from Bimini Harbor, Bahamas, resulted in labeling of macromolecules of the ambient microbial population. Collectively these results indicate that (i) extracellular-DNA production by genetically altered bacteria released into aquatic environments is more strongly influenced by physiochemical factors than biotic factors, (ii) extracellular-DNA production rates are usually greater for organisms released in freshwater than marine environments, and (iii) ambient microbial populations can readily utilize materials released by these organisms.
Chemotaxis toward Nitrogenous Compounds by Swimming Strains of Marine
Synechococcus
spp
Authors: Willey J. M. , Waterbury J. B.
Published: January 2020

Many of the open-ocean isolates of the marine unicellular cyanobacterium
Synechococcus
spp. are capable of swimming motility, whereas coastal isolates are nonmotile. Surprisingly, the motile strains do not display phototactic or photophobic responses to light, but they do demonstrate positive chemoresponses to several nitrogenous compounds. The chemotactic responses of
Synechococcus
strain WH8113 were investigated using blind-well chemotaxis chambers fitted with 3.0-μm-pore-size Nuclepore filters. One well of each chamber contained cells suspended in aged Sargasso Sea water, and the other well contained the potential chemoattractant in seawater. The number of cells that crossed the filter into the attractant-seawater mixture was measured by direct cell counts and compared with values obtained in chambers lacking gradients. Twenty-two compounds were tested, including sugars, amino acids, and simple nitrogenous substrates, at concentrations ranging from 10
−5
to 10
−10
M. Strain WH8113 responded positively only to ammonia, nitrate, β-alanine, glycine, and urea. Typically, there was a 1.5- to 2-fold increase in cell concentrations above control levels in chambers containing these compounds, which is comparable to results from similar experiments using enteric and photoheterotrophic bacteria. However, the threshold levels of 10
−9
to 10
−10
M found for
Synechococcus
spp. chemoresponses were lower by several orders of magnitude than those reported for other bacteria and fell within a range that could be ecologically significant in the oligotrophic oceans. The presence of chemotaxis in motile
Synechococcus
spp. supports the notion that regions of nutrient enrichment, such as the proposed microzones and patches, may play an important role in picoplankton nutrient dynamics.
Occurrence of the hepatotoxic cyanobacterium Nodularia spumigena in the Baltic Sea and structure of the toxin
Authors: Sivonen K , Kononen K , Carmichael W W , Dahlem A M , Rinehart K L , Kiviranta J , Niemela S I
Published: January 2020

Water blooms formed by potentially toxic species of cyanobacteria are a common phenomenon in the Baltic Sea in late summer. Twenty-five cyanobacterial bloom samples were collected from open and coastal waters of the Baltic Sea during 1985 to 1987, and their toxicity was determined by mouse bioassay. All of 5 bloom samples from the southern Baltic Sea, 6 of 6 from the open northern Baltic Sea (Gulf of Finland), and 7 of 14 Finnish coastal samples were found to contain hepatotoxic cyanobacteria. Nodularia spumigena and Aphanizomenon flos-aquae occurred together in high amounts in blooms from the open-sea areas. In addition, coastal samples contained the species Anabaena lemmermannii, Microcystis aeruginosa, and Oscillatoria agardhii. Eighteen hepatotoxic N. spumigena cultures were isolated from water bloom and open-sea water samples. High-pressure liquid chromatographic analysis of both hepatotoxic bloom samples and Nodularia strains showed a single toxic fraction. The toxin concentrations of the blooms were less than or equal to 2.4 mg/g of freeze-dried material, and those of laboratory-grown cultures were 2.5 to 8.0 mg/g of freeze-dried cells. A single toxin was isolated from three N. spumigena-containing bloom samples and three N. spumigena laboratory isolates. Amino acid analysis and low- and high-resolution fast-atom bombardment mass spectroscopy indicated that the toxin from all of the sources was a cyclic pentapeptide (molecular weight, 824) containing glutamic acid, beta-methylaspartic acid, arginine, N-methyldehydrobutyrine, and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
Shifts in Methanogenic Subpopulations Measured with Antibody Probes in a Fixed-Bed Loop Anaerobic Bioreactor Treating Sulfite Evaporator Condensate
Authors: Macario Alberto J. L. , de Macario Everly Conway , Ney Ulrich , Schoberth Siegfried M. , Sahm Hermann
Published: January 2020

A fixed-bed loop, high-rate anaerobic bioreactor treating sulfite evaporator condensate was sampled when it reached steady state and afterwards following perturbations during a 14-month period. By using immunotechnology, it was observed that shifts in methanogenic subpopulations occurred in association with perturbations, such as restarting and relocating the biomass into a different tank. Methanogens related to
Methanobacterium bryantii
MoHG and
Methanobrevibacter smithii
ALI were numerous throughout the observation period, while
Methanosarcina mazei
S6 and
Methanosarcina thermophila
TM1 were found in the early and late samples, respectively. Also,
Methanobacterium formicicum
was more numerous at the top portion of the bioreactor, while
Methanobrevibacter arboriphilus
AZ and DC were at the bottom. Sample formalinization required for prolonged storage proved suitable for antigen preservation.