bluuebunny/crossref_metadata_2025 huggingface dataset:
Conjugal Strategy for Construction of Fast Acid-Producing, Bacteriophage-Resistant Lactic Streptococci for Use in Dairy Fermentations
Authors: Sanders M. E. , Leonhard P. J. , Sing W. D. , Klaenhammer T. R.
Published: January 2020

Bacteriophage-resistant dairy streptococci were obtained following conjugal transfer of pTR2030 from a lactose-negative donor,
Streptococcus lactis
TEK12, to lactose-positive recipient strains,
Streptococcus cremoris
LMA13 and 924 and
S. lactis
LMA12. Fast acid-producing, phage-resistant transconjugants were selected by challenge with homologous phage on fast-slow differential agar or lactose indicator agar. Acquisition of pTR2030 by the transconjugants was confirmed by DNA-DNA hybridization. Resistance of transconjugants to homologous phage was complete. Curing or deletion of pTR2030 in the transconjugants confirmed that phage resistance was due to pTR2030 acquisition and not to coincident background mutation. Phage-sensitive pTR2030 deletion derivatives of LMA12 transconjugants were isolated in vivo. The
Hin
dIII fragment B of pTR2030 was subcloned into pBR322 to yield a recombinant plasmid, pMET2, useful as a source of pTR2030 DNA. A specific, chemically synthesized oligomer useful as a pTR2030 probe was derived from the sequence of a small portion of pTR2030. The conjugal strategy presented here was effective in yielding fast acid-producing, phage-resistant
S. cremoris
and
S. lactis
strains without the use of antibiotic resistance markers and without interfering with the acid-producing ability of the recipient strain.
Use of Differential Scanning Calorimetry for Structural Analysis of Fungally Degraded Wood
Authors: Reh Ursula , Kraepelin Gunda , Lamprecht Ingolf
Published: January 2020

This paper assesses the potential use of differential scanning calorimetry for analyzing sound and decayed wood. With sound wood, this method permitted the detection of cellulose, hemicellulose, and lignin components as discrete peaks of combustion at defined temperatures. Characteristic changes in the calorimetric thermogram of birchwood (temperature of maxima, peak height, and peak area) were obtained from wood samples degraded by the basidiomycetes
Fomes fomentarius
and
Piptoporus betulinus.
Additional peaks in the thermograms of white rotted birchwood were assigned to lignin degradation products and to mycelium. Results obtained by the differential scanning calorimetry method are compared with those of chemical determination, with particular emphasis on Klason lignin.
Toxicity of paraquat to microorganisms
Authors: Carr R J , Bilton R F , Atkinson T
Published: January 2020

The biochemical response of the microorganisms Lipomyces starkeyi (Lod & Rij), Escherichia coli K-12 W3110, Bacillus subtilis 168 (Marburg) and Pseudomonas sp. strain TTO1 to the presence of growth-inhibitory concentrations of paraquat was studied. Paraquat was added to each culture at a concentration previously determined to reduce the culture growth rate by up to 50%. The changes in activity of a number of enzymes previously shown to be associated with the defense of the mammalian system against the action of paraquat were studied. While the response of E. coli was in agreement with that found in other studies of this microorganism and supports a commonly accepted mechanism for paraquat toxicity, the results obtained with L. starkeyi, B. subtilis, and Pseudomonas sp. strain TTO1 suggest that other mechanisms exist for protection against the toxicity of paraquat.
Comparative Study of Action of Cell Wall Proteinases from Various Strains of
Streptococcus cremoris
on Bovine α
s1
-, β-, and κ-Casein
Authors: Visser Servaas , Exterkate Fred A. , Slangen Charles J. , de Veer Gerrie J. C. M.
Published: January 2020

Partially purified cell wall proteinases of eight strains of
Streptococcus cremoris
were compared in their action on bovine α
s1
-, β-, and κ-casein, as visualized by starch gel electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and thin-layer chromatography. Characteristic degradation profiles could be distinguished, from which the occurrence of two proteinases, represented by strain HP and strain AM
1
, was concluded. The action of the HP-type proteinase P
1
(also detectable in strains Wg
2
, C
13
, and TR) was established by electrophoretic methods to be directed preferentially towards β-casein. The AM
1
-type proteinase P
III
(also detectable in strain SK
11
) was also able to degrade β-casein, but at the same time split α
s1
- and κ-casein more extensively than did P
I
. Strain FD
27
exhibited mainly P
I
activity but also detectable P
III
degradation characteristics. The cell wall proteinase preparation of strain E
8
showed low P
I
as well as low P
III
activity. All proteinase preparations produced from κ-casein positively charged degradation products with electrophoretic mobilities similar to those of degradation products released by the action of the milk-clotting enzyme chymosin. The differences between P
I
and P
III
in mode of action, as detected by gel electrophoresis and thin-layer chromatography, were reflected by the courses of the initial degradation of
methyl
-
14
C-labeled β-casein and by the effect of α
s1
- plus κ-casein on these degradations. The results are discussed in the light of previous comparative studies of cell wall proteinases in strains of
S. cremoris
and with respect to the growth of this organism in milk.
Thymidine Incorporation by the Microbial Community of Standing Dead
Spartina alterniflora
Authors: Fallon Robert D. , Newell Steven Y.
Published: January 2020

Thymidine incorporation by the microbial community on standing dead leaves of
Spartina alterniflora
did not obey many of the assumptions inherent in the use of the technique in planktonic systems. Incorporation rates of [
methly
-
3
H]thymidine were nonsaturable over a wide concentration range (10
1
to 10
5
nM). Owing to metabolism by both fungi and bacteria, a major fraction of the radiolabel (mean, 48%) appeared in protein. Extraction of the radiolabeled macromolecules was inefficient, averaging 8.8%. Based on an empirically derived conversion factor, 4 × 10
18
cells · mol of thymidine
−1
, doubling times ranged from 4 to 69 h for the epiphytic bacterial assemblage.
Improved Listeria monocytogenes selective agar
Authors: Lee W H , McClain D
Published: January 2020

By increasing the LiCl concentration to 5 g/liter and adding 20 mg of moxalactam per liter to modified McBride agar base, it was possible to inhibit the growth of many bacteria which interfered with the recovery of Listeria monocytogenes from beef.
Production and Rheological Properties of the Extracellular Polysaccharide Synthesized by
Pseudomonas
sp. Strain EPS-5028
Authors: Marqués Ana M. , Estañol Inmaculada , Alsina Joan M. , Fusté Carmen , Simon-Pujol Dolores , Guinea Jesús , Congregado Francisco
Published: January 2020

During batch aerobic submerged fermentation, the exopolysaccharide synthesis by
Pseudomonas
sp. strain EPS-5028 occurred in growth- and non-growth-linked processes. Polysaccharide formation increased when the pH was controlled at 7 during fermentation. Exopolysaccharide production depended on the phosphate content of the medium. The polymer exhibited a pseudoplastic nature, had good thermostability, and was affected neither by pH nor by high concentrations of salt.
Depth Distribution of Bacterial Production in a Stratified Lake with an Anoxic Hypolimnion
Authors: McDonough Robert J. , Sanders Robert W. , Porter Karen G. , Kirchman David L.
Published: January 2020

The purpose of this study was to determine the depth distribution of bacterial biomass and production in a stratified lake and to test techniques to measure bacterial production in anaerobic waters. Bacterial abundance and incorporation of both [
3
H]thymidine and [
3
H]leucine into protein were highest in the metalimnion, at the depth at which oxygen first became unmeasurable. In contrast, [
3
H]thymidine incorporation into DNA was highest in the epilimnion. The ratios of incorporation into DNA/protein averaged 2.2, 0.49, and 0.95 for the epilimnion, metalimnion, and hypolimnion, respectively. Low incorporation into DNA was not due to artifacts associated with the DNA isolation procedure. Recovery of added [
3
H]DNA was about 90% in waters in which the portion of [
3
H]thymidine incorporation into DNA was about 40%. At least some obligate anaerobic bacteria were capable of assimilating thymidine since aeration of anaerobic hypolimnion waters substantially inhibited thymidine incorporation. The depth profile of bacterial production estimated from total thymidine and leucine incorporation and the frequency of dividing cells were all similar, with maximal rates in the metalimnion. However, estimates of bacterial production based on frequency of dividing cells and leucine incorporation were usually significantly higher than estimates based on thymidine incorporation (using conversion factors from the literature), especially in anaerobic hypolimnion waters. These data indicate that the thymidine approach must be examined carefully if it is to be applied to aquatic systems with low oxygen concentrations. Our results also indicate that the interface between the aerobic epilimnion and anaerobic hypolimnion is the site of intense bacterial mineralization and biomass production which deserves further study.
Nature and reactivity of staphylococcal enterotoxin A monoclonal antibodies
Authors: Edwin C , Tatini S R , Maheswaran S K
Published: January 2020

Monoclonal antibodies from four clones (C5, C3, B2II, and B2I) directed against staphylococcal enterotoxin A were tested by the indirect enzyme-linked immunosorbent assay and double-gel immunodiffusion (micro-Ouchterlony) assay for the nature of heavy and light chain types. The reactivities of monoclonal antibodies were also tested by indirect enzyme-linked immunosorbent assay with various levels of purified staphylococcal enterotoxin A and various levels (dilutions) of monoclonal antibodies and saturation analysis-competitive indirect enzyme-linked immunosorbent assay. The heavy-chain isotype of monoclonal antibodies was found to be an unspecified subclass of immunoglobulin G1, and the light chain was the kappa type. Monoclonal antibodies from all of the clones exhibited high reactivity and nearly the same affinity to staphylococcal enterotoxin A in saturation analysis-competitive enzyme-linked immunosorbent assay. Purified immunoglobulin G from B2I yielded very high absorbance (1.2) at 405 nm with 1 ng of staphylococcal enterotoxin A as the coating antigen in the enzyme-linked immunosorbent assay. Monoclonal antibodies from B2I also neutralized the biological activity of staphylococcal enterotoxin A when tested by the kitten bioassay.
Specificity and cross-reactivity of staphylococcal enterotoxin A monoclonal antibodies with enterotoxins B, C1, D, and E
Authors: Edwin C , Tatini S R , Maheswaran S K
Published: January 2020

The cross-reactivity of monoclonal antibodies produced against staphylococcal enterotoxin A with purified and crude enterotoxins B, C1, D, and E and the specificity of such reactions were evaluated by the indirect enzyme-linked immunosorbent assay and immunoblotting of Western blots (from sodium dodecyl sulfate-polyacrylamide gel electrophoresis) followed by autoradiography. Purified and crude enterotoxins B were also tested with polyclonal antibodies. Specificity of reactivity was demonstrated by immunoblotting of crude enterotoxin A, crude enterotoxin A treated with trypsin, crude enterotoxin E, and also with crude A, B, C1, and D that were pretreated with Sepharose-4B-linked normal rabbit immunoglobulin G to remove protein A. A band corresponding to each staphylococcal enterotoxin was seen with monoclonal antibodies under all conditions tested and also with crude and purified enterotoxin B with two different (rabbit and goat) polyclonal antisera.
Distinguishing between Nitrification and Denitrification as Sources of Gaseous Nitrogen Production in Soil
Authors: Davidson Eric A. , Swank Wayne T. , Perry Thomas O.
Published: January 2020

The source of N
2
O produced in soil is often uncertain because denitrification and nitrification can occur simultaneously in the same soil aggregate. A technique which exploits the differential sensitivity of these processes to C
2
H
2
inhibition is proposed for distinguishing among gaseous N losses from soils. Denitrification N
2
O was estimated from 24-h laboratory incubations in which nitrification was inhibited by 10-Pa C
2
H
2
. Nitrification N
2
O was estimated from the difference between N
2
O production under no C
2
H
2
and that determined for denitrification. Denitrification N
2
was estimated from the difference between N
2
O production under 10-kPa C
2
H
2
and that under 10 Pa. Laboratory estimates of N
2
O production were significantly correlated with in situ N
2
O diffusion measurements made during a 10-month period in two forested watersheds. Nitrous oxide production from nitrification was most important on well-drained sites of a disturbed watershed where ambient NO
3
−
was high. In contrast, denitrification N
2
O was most important on poorly drained sites near the stream of the same watershed. Distinction between N
2
O production from nitrification and denitrification was corroborated by correlations between denitrification N
2
O and water-filled pore space and between nitrification N
2
O and ambient NO
3
−
. This technique permits qualitative study of environmental parameters that regulate gaseous N losses via denitrification and nitrification.
Production and Turnover of Planktonic Bacteria in Two Southeastern Blackwater Rivers
Authors: Edwards Richard T. , Meyer Judith L.
Published: January 2020

Production by attached and free-living planktonic bacteria in two blackwater rivers in the Southeastern United States was measured over a period of 14 months by using the rate of incorporation of [
methyl
-
3
H]thymidine into DNA. Production rates and biomass dynamics were compared to determine the potential for in situ production to supply planktonic biomass. Bacterial production in these rivers was moderate and varied seasonally. Rates varied from 0.058 to 2.120 mg of C m
−3
h
−1
in the Ogeechee River and from 0.002 to 2.418 mg of C m
−3
h
−1
in Black Creek. Regressions of growth rate on various environmental variables showed that temperature and total dissolved organic carbon concentration were the best predictors of growth. Although attached bacteria were <21% of the total biomass, they accounted for up to 53% of the total production. Turnover times for attached bacteria ranged from <1 day to >3 years depending on season. Turnover times of free-living bacteria varied from 4.4 days to 11.8 years. Comparisons of biomass with production indicated that during most seasons, the majority of bacterial biomass in these rivers was of allochthonous origin. During summer, when water temperatures were high, bacterial growth in the river may have supplied a greater percentage of the standing stock of bacteria than allochthonous inputs.
Effect of phenolic monomers on ruminal bacteria
Authors: Borneman W S , Akin D E , VanEseltine W P
Published: January 2020

Ruminal bacteria were subjected to a series of phenolic compounds in various concentrations to acquire fundamental information on the influence on growth and the potential limits to forage utilization by phenolic monomers. Ruminococcus albus 7, Ruminococcus flavefaciens FD-1, Butyrivibrio fibrisolvens 49, and Lachnospira multiparus D-32 were tested against 1, 5, and 10 mM concentrations of sinapic acid, syringaldehyde, syringic acid, ferulic acid, vanillin, vanillic acid, p-coumaric acid, p-hydroxybenzaldehyde, p-hydroxybenzoic acid, and hydrocinnamic acid. Responses were variable and dependent on the phenolic compound and microbial species. Compounds especially toxic (i.e., resulting in poor growth, effect on several species, dose-related response) were p-coumaric acid and p-hydroxybenzaldehyde, and adaptation to the toxins did not occur after three 24-h periods. Syringic, p-hydroxybenzoic, and hydrocinnamic acids stimulated growth of all four species and also stimulated filter paper degradation by R. flavefaciens. None of the stimulatory compounds supported microbial growth in the absence of carbohydrates. In vitro dry matter digestibility of cellulose (Solka-Floc) was not stimulated by any of the phenolic compounds (10 mM), but the cinnamic acids and benzoic aldehydes (10 mM) reduced (P less than 0.05) digestion by the mixed population in ruminal fluid. Growth of R. flavefaciens in the presence of p-hydroxybenzoic acid (10 mM) or p-coumaric acid (5 mM) resulted in recognizable alterations in cell ultrastructure. Both phenolics caused a reduction in cell size (P less than 0.05), and p-coumaric acid caused a reduction in capsular size (P less than 0.05) and produced occasional pleomorphic cells.
Phosphoenolpyruvate-dependent phosphorylation of hexoses by ruminal bacteria: evidence for the phosphotransferase transport system
Authors: Martin S A , Russell J B
Published: January 2020

Six species of ruminal bacteria were surveyed for the phosphoenolpyruvate (PEP)-dependent phosphorylation of glucose. Selenomonas ruminantium HD4, Streptococcus bovis JB1, and Megasphaera elsdenii B159 all showed significant activity, but Butyrivibrio fibrisolvens 49, Bacteroides succinogenes S85, and Bacteroides ruminicola B1(4) showed low rates of PEP-dependent phosphorylation and much higher rates in the presence of ATP. S. ruminantium HD4, S. bovis JB1, and M. elsdenii B159 also used PEP to phosphorylate the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DG). Rates of 2-DG phosphorylation with ATP were negligible for S. bovis JB1 and M. elsdenii B159, but toluene-treated cells of S. ruminantium HD4 phosphorylated 2-DG in the presence of ATP as well as PEP. Cell-free extracts of S. ruminantium HD4 used ATP but not PEP to phosphorylate glucose and 2-DG. Since PEP could serve as a phosphoryl donor in toluene-treated cells but not in cell-free extracts, there was evidence for membrane and hence phosphotransferase system involvement in the PEP-dependent activity. The ATP-dependent phosphorylating enzymes from S. ruminantium HD4 and S. bovis JB1 had molecular weights of approximately 48,000 and were not inhibited by glucose 6-phosphate. Based on these criteria, they were glucokinases rather than hexokinases. The S. ruminantium HD4 glucokinase was competitively inhibited by 2-DG and mannose, sugars that differ from glucose in the C-2 position. Since 2-DG was a competitive inhibitor of glucose, the same enzyme probably phosphorylates both sugars. The S. bovis JB1 glucokinase was not inhibited by either 2-DG or mannose and had a higher Km and Vmax for glucose.
Cloning and expression of a Streptomyces cholesterol oxidase gene in Streptomyces lividans with plasmid pIJ702
Authors: Murooka Y , Ishizaki T , Nimi O , Maekawa N
Published: January 2020

The cholesterol oxidase gene (cho) of Streptomyces sp. was cloned into Streptomyces lividans with the vector pIJ702. Deletion analysis of the recombinant plasmid showed that entire coding sequence of the cho gene was located within a 2.5-kilobase segment of the chromosomal DNA obtained from the cholesterol oxidase-producing strain. When cloned cells of S. lividans were grown in an appropriate medium, the cells produced severalfold more cholesterol oxidase extracellularly than did the producing strain.
Ingestion and Adsorption of
Bacillus thuringiensis
subsp.
israelensis
by
Gammarus lacustris
in the Laboratory
Authors: Brazner John C. , Anderson Richard L.
Published: January 2020

Several groups of
Gammarus lacustris
adults were exposed to solutions containing 0.5 and 5.0 mg of
Bacillus thuringiensis
subsp.
israelensis
per liter for 1- or 24-h periods by using traditional static bioassay exposure procedures. During a postexposure holding period, fecal pellets were removed and plated on tryptic soy agar to determine
B. thuringiensis
subsp.
israelensis
spore content. The experiments verified that traditional exposure procedures assure ingestion of
B. thuringiensis
subsp.
israelensis
spores and provided a mean dose estimate of 1,948 spores ingested per test animal with a 95% confidence interval ranging from 891 to 4,296 (1-h exposure, 5.0 mg/liter). It was also found that dose level is highly dependent upon both exposure duration and concentration and that relatively short exposures can result in a relatively long-term retention of spores postexposure (≥30 days). Body burden experiments established that large numbers of spores adsorb to the bodies of test animals during exposure and may in part explain the long-term retention of spores in the test system postexposure. These results imply that in field applications of microbial control agents, toxicologically unaffected but exposed organisms might transport the agent to untreated sites, expanding the effective treatment area and the number of organisms exposed.
Bacterial Enhancement of Vinyl Fouling by Algae
Authors: Holmes Paul E.
Published: January 2020

The role of bacteria in the development of algae on low-density vinyl was investigated. Unidentified bacterial contaminants in unialgal stock cultures of
Phormidium faveolarum
and
Pleurochloris pyrenoidosa
enhanced, by 1 to 2 orders of magnitude, colonization of vinyl by these algae, as determined by epifluorescence microscopy counts and chlorophyll
a
in extracts of colonized vinyl. Colonization by bacteria always preceded that by algae. Scanning electron microscopy of the colonized
Phormidium
-bacteria mixture revealed the presence of a slime matrix engulfing both bacteria and algae that may have facilitated algal attachment. Slime was not evident in the
Pleurochloris
-bacteria mixture, suggesting that the attachment mechanisms differ for the two algae.
Thermal resistance of intracellular Listeria monocytogenes cells suspended in raw bovine milk
Authors: Bunning V K , Crawford R G , Bradshaw J G , Peeler J T , Tierney J T , Twedt R M
Published: January 2020

The thermal resistance of Listeria monocytogenes associated with a milk-borne outbreak of listeriosis was determined in parallel experiments by using freely suspended bacteria and bacteria internalized by phagocytes. The latter inoculum was generated by an in vitro phagocytosis reaction with immune-antigen-elicited murine peritoneal phagocytes. The heat suspension medium was raw whole bovine milk. Both suspensions were heated at temperatures ranging from 52.2 to 71.7 degrees C for various periods of time. Mean D values for each temperature and condition of heated suspension revealed no significant differences. The extrapolated D71.7 degrees C (161 degrees F) value for bacteria internalized by phagocytes was 1.9 s. Combined tube and slug-flow heat exchanger results yielded an estimated D71.7 degrees C value of 1.6 s for freely suspended bacteria. The intracellular position did not protect L. monocytogenes from thermal inactivation.
Microbial Oxidation of Hydrocarbons and Related Compounds by Whole-Cell Suspensions of the Methane-Oxidizing Bacterium H-2
Authors: Imai Takeo , Takigawa Hirofumi , Nakagawa Satoshi , Shen Gwo-Jenn , Kodama Tohru , Minoda Yasuji
Published: January 2020

Previously, a thermophilic obligate methane-oxidizing bacterium, H-2 (type I), was isolated in our laboratory. H-2 is a new type of methylotroph because of the G+C content of DNA; it uses both the ribulose monophosphate pathway and the serine pathway for carbon assimilation and possesses a new quinone. In addition, we found that resting cell suspensions of H-2 had the ability to oxidize a variety of compounds different from the other methane-oxidizing bacteria as follows. (i) C
1
to C
8
n
-alkanes are hydroxylated and further oxidized, yielding mixtures of the corresponding alcohols, aldehydes, acids, and ketones. Liquid alkanes are transformed through a different oxidative pathway from that of gaseous ones. (ii) Both gaseous (C
2
to C
4
) and liquid (C
5
, C
6
)
n
-alkenes are oxidized to their corresponding 1,2-epoxides. (iii) Liquid monochloro and dichloro
n
-alkanes (C
5
, C
6
) are oxidized, yielding their corresponding acids or haloacids. (iv) Diethyl ether is oxidized to acetic acid; no ethanol and acetaldehyde are detected. (v) Cyclic and aromatic compounds are also oxidized. (vi) Secondary alcohols (C
3
to C
10
) are oxidized to their corresponding methyl ketones.
End Products of Anaerobic Chitin Degradation by Salt Marsh Bacteria as Substrates for Dissimilatory Sulfate Reduction and Methanogenesis
Authors: Boyer Joseph N.
Published: January 2020

The anaerobic pathway of chitin decomposition by chitinoclastic bacteria was examined with an emphasis on end product coupling to other salt marsh bacteria. Actively growing chitinoclastic bacterial isolates produced primarily acetate, H
2
, and CO
2
in broth culture. No sulfate-reducing or methanogenic isolates grew on chitin as sole carbon source or produced any measurable degradation products. Mixed cultures of chitin degraders with sulfate reducers resulted in positive sulfide production. Mixed cultures of chitin-degrading isolates with methanogens resulted in the production of CH
4
with reductions in headspace CO
2
and H
2
. The combination of all three metabolic types resulted in the simultaneous production of methane and sulfide, with more methane being produced in mixed cultures containing CO
2
-reducing methanogens and acetoclastic sulfate reducers because of less interspecific H
2
competition.
Comparative Growth of Natural Bacterial Isolates on Various Lignin-Related Compounds
Authors: Gonzalez B. , Merino A. , Almeida M. , Vicña R.
Published: January 2020

Bacterial strains were isolated on the basis of their ability to proliferate in a minimal medium containing one of a series of lignin-related compounds as the sole carbon and energy source. These included the aromatic monomers guaiacol, vanillic and coumaric acids, a dimer and a trimer possessing the arylglycerol-β-aryl ether linkage, anisoin, and both the ether-soluble and -insoluble fractions of kraft lignin. The growth of the strains on each of these compounds was measured. The results showed that the metabolic properties of the strains varied according to the structure of the carbon sources used for their selection. Spectrophotometric tracings of the culture medium during the log phase of growth of one of the strains on the β-
O
-4 dimer revealed decomposition with the release of guaiacol.
Plasmid transformation of Streptomyces tendae after heat attenuation of restriction
Authors: Engel P
Published: January 2020

Streptomyces tendae ATCC 31160 produces nikkomycin, a fungicide and insecticide that inhibits chitin synthases. Exposure of S. tendae protoplasts to 50 degrees C for 30 min is required for transformation (10(2) thiostrepton-resistant transformants micrograms of DNA-1) with plasmid pIJ702 or pIJ680 from Streptomyces lividans. pIJ702 and pIJ680 DNA isolated from the S. tendae transformants is efficient (10(6) to 10(7) transformants micrograms of DNA-1) in subsequent transformations of S. tendae protoplasts generated at 30 degrees C. PstI fails to cut the single PstI site in pIJ702 and cuts only one of the two PstI sites in pIJ680 DNA isolated from S. tendae transformants. Digests of plasmid DNA mixtures showed that plasmid DNA from S. tendae does not inhibit PstI activity. pIJ702 and pIJ680 DNA from S. tendae transformants was used to transform S. lividans to show that plasmid DNA remains unchanged, except for modification at some PstI sites in S. tendae, as a consequence of passage through S. tendae. The DNA modification is lost when S. lividans is transformed with plasmid DNA from S. tendae transformants. Since S. tendae modifies only some PstI sites, it appears the modification (presumably restriction activity also) activity in S. tendae recognizes a sequence that includes or overlaps the PstI hexanucleotide recognition sequence.
Seasonal changes in the cecal microflora of the high-arctic Svalbard reindeer (Rangifer tarandus platyrhynchus)
Authors: Mathiesen S D , Orpin C G , Greenwood Y , Blix A S
Published: January 2020

The dominant cecal bacteria in the high-arctic Svalbard reindeer were characterized, their population densities were estimated, and cecal pH was determined in summer, when food quality and availability is good, and in winter, when it is very poor. In summer the total culturable viable bacterial population was (8.9 +/- 5.3) X 10(8) cells ml-1, whereas in winter it was (1.5 +/- 0.7) X 10(8) cells ml-1, representing a decrease to 17% of the summer population density. Of the dominant species of cultured bacteria, Butyrivibrio fibrisolvens represented 23% in summer and 18% in winter. Streptococcus bovis represented 17% in summer and 5% in winter. Bacteroides ruminicola represented 10% in summer and 26% in winter. In summer and winter, respectively, the proportion of the viable population showing the following activities was as follows: fiber digestion, 36 and 48%; cellulolysis, 10 and 6%; xylanolysis, 33 and 48%; and starch utilization, 77 and 71%. The most abundant cellulolytic species in summer was Butyrivibrio fibrisolvens, representing 62% of the total cellulolytic population, and in winter it was Ruminococcus albus, representing 80% of the total cellulolytic population. The most abundant xylanolytic species in summer was Butyrivibrio fibrisolvens, and in winter it was Bacteroides ruminicola, representing 59 and 54% of the xylanolytic isolates in summer and winter, respectively. The cecal bacterial of the Svalbard reindeer have the ability to digest starch and the major structural carbohydrates of the diet that are not digested in the rumen. The cecum in these animals has the potential to contribute very substantially to the digestion of the available plant material in both summer and winter.
Production and characterization of antibodies against HT-2 toxin and T-2 tetraol tetraacetate
Authors: Fan T S , Zhang G S , Chu F S
Published: January 2020

Three new immunogens which were prepared by conjugation of the carboxymethyl oxime (CMO) derivatives of HT-2 toxin, T-2 tetraol (T-2 4ol), and T-2 tetraol tetraacetate (T-2 4Ac) to bovine serum albumin (BSA) were tested for the production of antibodies against the major metabolites of T-2 toxin. Antibodies against HT-2 toxin and T-2 4Ac were obtained from rabbits 5 to 10 weeks after immunizing the animals with CMO-HT-2-BSA and CMO-T-2 4Ac-BSA conjugates. Immunization with CMO-T-2 4ol-BSA resulted in no antibody against T-2 4ol. The antibody produced against HT-2 toxin had great affinity for HT-2 toxin as well as good cross-reactivity with T-2 toxin. The relative cross-reactivities of anti-HT-2 toxin antibody with HT-2 toxin, T-2 toxin, iso-T-2 toxin, acetyl-T-2 toxin, 3'-OH HT-2, 3'-OH T-2, T-2 triol, and 3'-OH acetyl-T-2, were 100, 25, 10, 3.3, 0.25, 0.15, 0.12 and 0.08%, respectively. Antibody against CMO-T-2 4Ac was very specific for T-2 4Ac and had less than 0.1% cross-reactivity with T-2 toxin, HT-2 toxin, acetyl-T-2 toxin, diacetoxyscirpenol, deoxynivalenol, and deoxynivalenol triacetate as compared with T-2 4Ac. The detection limits for HT-2 toxin and T-2 4ol by radioimmunoassay were approximately 0.1 and 0.5 ng per assay, respectively.
Rhizobial Ecology of the Woody Legume Mesquite (
Prosopis glandulosa
) in the Sonoran Desert
Authors: Jenkins Michael B. , Virginia Ross A. , Jarrell Wesley M.
Published: January 2020

Soil samples were collected from the surface (0 to 0.6 m) and phreatic (3.9 to 4.5 m) root systems of a
Prosopis glandulosa
woodland in the Sonoran Desert of southern California.
P. glandulosa
seedlings were inoculated with these soils, and rhizobia were isolated from nodules. The phreatic soil, characterized by constant moisture and temperature but low nutrient availability, favored slow-growing (SG) isolates as nodule occupants (85%). SG isolates from the surface and phreatic soil were distinct based on differences in colony morphology. Isolates from the surface soil, characterized by high nutrient availability and widely fluctuating water content and temperature, were equally represented by fast-growing and SG rhizobia. Most SG isolates (83%) had nodule relative efficiencies of <0.80, whereas 54% of the fast-growing isolates had relative efficiency values of >0.80.
Variation in Phospholipid Ester-Linked Fatty Acids and Carotenoids of Desiccated
Nostoc commune
(Cyanobacteria) from Different Geographic Locations
Authors: Potts Malcolm , Olie Jaap J. , Nickels Janet S. , Parsons John , White David C.
Published: January 2020

Profiles of phospholipid fatty acids and carotenoids in desiccated
Nostoc commune
(cyanobacteria) collected from China, Federal Republic of Germany, and Antarctica and in axenic cultures of the desiccation-tolerant strains
N. commune
UTEX 584 and
Hydrocoleum
strain GOEI were analyzed. The phospholipid fatty acid contents of the three samples of desiccated
Nostoc
species were all similar, and the dominant compounds were 16:1ω7c, 16:0, 18:2ω6, 18:3ω3, and 18:1ω7c. In comparison with the field materials,
N. commune
UTEX 584 had a much higher ratio of 18:2ω6 to 18:3ω3 (5.36) and a significantly lower ratio of 18:1ω7c to 18:1ω9c (1.86). Compound 18:3 was present in large amounts in the samples of desiccated
Nostoc
species which had been subject, in situ, to repeated cycles of drying and rewetting, but represented only a small fraction of the total fatty acids of the strains grown in liquid culture. This finding is in contrast to the data obtained from studies on the effects of drought and water stress on higher plants. Field materials of
Nostoc
species contained, in contrast to the axenic strains, significant amounts of apocarotenoids and a P384 pigment which, upon reduction with NaBH
4
, yielded a mixture of a chlorophyll derivative and a compound with an absorption maximum of 451 nm. A clear distinction can be made between the carotenoid contents of the axenic cultures and the desiccated field materials. In the former, β-carotene and echinenone predominate; in the latter, canthaxanthin and the β-γ series of carotenoids are found.
Characteristics of the endoglucanase encoded by a cel gene from Bacteroides succinogenes expressed in Escherichia coli
Authors: Taylor K A , Crosby B , McGavin M , Forsberg C W , Thomas D Y
Published: January 2020

A cel gene from Bacteroides succinogenes inserted into the vector pUC8 coded for an enzyme which exhibited high hydrolytic activity on carboxymethylcellulose, p-nitrophenylcellobioside, and lichenan and low activity on laminarin and xylan. The enzyme was not synthesized by the Escherichia coli host when cells were cultured in complex medium containing added glucose. In the absence of added glucose, the endoglucanase and cellobiosidase activities synthesized were partitioned into the periplasmic space during growth, and practically all enzyme was located in the periplasm when the stationary phase of growth was reached. The enzyme exhibited 17- and sixfold higher Km values for the hydrolysis of carboxymethylcellulose and lichenan, respectively, than did the extracellular endoglucanase complex from B. succinogenes. The Cel endoglucanase had a pH optimum similar to that of the B. succinogenes enzyme except that the range was narrower, and the Cel endoglucanase was more readily inactivated on exposure to high temperature, detergents, and certain metals. Its activity was stimulated by calcium and magnesium. Nondenaturing polyacrylamide gel electrophoresis at different acrylamide concentrations revealed the presence of three endoglucanase components, two with molecular weights of 43,000 and one with a molecular weight of 55,000.
Effects of Hydrogen Pressure during Growth and Effects of Pregrowth with Hydrogen on Acetate Degradation by
Methanosarcina
Species
Authors: Boone David R. , Menaia Jos� A. G. F. , Boone Jane E. , Mah Robert A.
Published: January 2020

Methanosarcina barkeri
227 and
Methanosarcina mazei
S-6 grew with acetate as the substrate; we found little effect of H
2
on the rate of aceticlastic growth in the presence of various H
2
pressures between 2 and 810 Pa. We used physical (H
2
addition or flushing the headspace to remove H
2
) and biological (H
2
-producing or -utilizing bacteria in cocultures) methods for controlling H
2
pressure in
Methanosarcina
cultures growing on acetate. Added H
2
(ca. 100 Pa) was removed rapidly (a few hours) by
M. barkeri
and slowly (within a day) by
M. mazei
. When the H
2
produced by the aceticlastic methanogens was removed by coculturing with an H
2
-using
Desulfovibrio
sp., the H
2
pressure was about 2.2 Pa. Under these conditions the stoichiometry of aceticlastic methanogenesis did not change. H
2
-grown inocula of
M. barkeri
grew with acetate as the sole catabolic substrate if the inoculum culture was transferred during logarithmic growth to acetate-containing medium or if the transfer was accomplished within 1 or 2 days after exhaustion of H
2
. H
2
-grown cultures incubated for 4 or more days after exhaustion of H
2
were able to grow with H
2
but not with acetate as the sole catabolic substrate. Addition of small quantities of H
2
to acetate-containing medium permitted these cultures to initiate growth on acetate.
Betaine Transport Imparts Osmotolerance on a Strain of
Lactobacillus acidophilus
Authors: Hutkins Robert W. , Ellefson William L. , Kashket Eva R.
Published: January 2020

Unlike most
Lactobacillus acidophilus
strains, a specific strain,
L. acidophilus
IFO 3532, was found to grow in rich medium containing 1 M sodium acetate, KCl, or NaCl. This strain could also grow with up to 1.8 M NaCl or 3 M nonelectrolytes (fructose, xylose, or sorbitol) added. Thus, this strain was tolerant to osmotic pressures up to 2.8 osM. A search for an intracellular solute which conferred osmoprotection led to the identification of glycine betaine (betaine). Betaine was accumulated to high concentrations in cells growing in MRS medium supplemented with 1 M KCl or NaCl. Uptake of [
14
C]betaine by
L. acidophilus
3532 cells suspended in buffer was stimulated by increasing the medium osmotic pressure with 1 M KCl or NaCl. The accumulated betaine was not metabolized further; transport was relatively specific for betaine and was dependent on an energy source. Other lactobacilli, more osmosensitive than strain 3532, including
L. acidophilus
strain E4356,
L. bulgaricus
8144, and
L. delbrueckii
9649, showed lower betaine transport rates in response to an osmotic challenge than
L. acidophilus
3532. Experiments with chloramphenicol-treated
L. acidophilus
3532 cells indicated that the transport system was not induced but appeared to be activated by an increase in osmotic pressure.
Multiplication and Virulence in Plant Tissues of
Escherichia coli
Clones Producing Pectate Lyase Isozymes PLb and PLe at High Levels and of an
Erwinia chrysanthemi
Mutant Deficient in PLe
Authors: Payne John H. , Schoedel Christianne , Keen Noel T. , Collmer Alan
Published: January 2020

The phytopathogenic enterobacterium
Erwinia chrysanthemi
strain EC16 produces four isozymes of pectate lyase (PL), an extracellular enzyme that macerates parenchymatous plant tissues and kills plant cells. A 1.8-kilobase
Eco
RI DNA fragment containing the entire
pelE
gene was deleted from the
E. chrysanthemi
chromosome by marker exchange of a cloned fragment that had been modified in vitro. The resulting mutant, UM1001, produced the isozymes PLa, PLb, and PLc, but not PLe. Mutant UM1001 was compared with wild-type
E. chrysanthemi
, with
Escherichia coli
JA221, and with JA221 containing expression vectors with cloned
pel
genes producing high levels of PLe (pPEL748) or PLb (pPEL343) for the ability to multiply and cause symptoms in intact potato tubers. Tubers were injected with less than 100 bacteria per inoculation site and incubated aerobically or anaerobically. While maceration occurred only in anaerobically incubated tubers, all of the bacteria, including nonpectolytic
E. coli
controls, multiplied substantially under all conditions.
E. coli
JA221(pPEL748) caused significantly more maceration than
E. coli
JA221(pPEL343) or wild-type
E. chrysanthemi.
Mutant UM1001 caused significantly less maceration than the wild-type
E. chrysanthemi.
The results establish the importance of PLe in the pectolytic arsenal of
E. chrysanthemi
by demonstrating that production of PLe can enable
E. coli
to aggressively macerate tuber tissue and that deletion of
pelE
significantly diminishes the virulence of
E. chrysanthemi.
Frequency of antibiotic and heavy metal resistance, pigmentation, and plasmids in bacteria of the marine air-water interface
Authors: Hermansson M , Jones G W , Kjelleberg S
Published: January 2020

A field investigation of marine coastal waters revealed that the frequency of pigmented bacteria and the occurrence of bacterial antibiotic resistance were higher at the air-water interface than in the bulk water. The differences in the frequency of pigmented colonies at the surface and in the bulk-water samples could not be explained by the degree of cell surface hydrophobicity or by bacterial adhesion to air-water interfaces. Pigmented strains exhibited a higher degree of multiple drug resistance than did nonpigmented strains. However, the frequency of multiple drug resistance in nonpigmented strains was also substantial. An average of 91% of all strains were resistant to more than one antibiotic, and 21% of the bacteria isolated were resistant to five of the eight antibiotics tested. High numbers of plasmid-carrying strains were found among selected surface isolates, but the presence of detectable plasmids could not be correlated with either pigmentation or multiple drug resistance. Furthermore, selected surface isolates were significantly more resistant to mercury than were bulk-water bacteria. The higher frequency of pigmented, antibiotic-resistant, and mercury resistant strains at the air-water interface than in the bulk water are discussed in terms of various forms of selective pressure and genetic exchange at the surface.
Transport and phosphorylation of disaccharides by the ruminal bacterium Streptococcus bovis
Authors: Martin S A , Russell J B
Published: January 2020

Toluene-treated cells of Streptococcus bovis JB1 phosphorylated cellobiose, glucose, maltose, and sucrose by the phosphoenolpyruvate-dependent phosphotransferase system. Glucose phosphorylation was constitutive, while all three disaccharide systems were inducible. Competition experiments indicated that separate phosphotransferase systems (enzymes II) existed for glucose, maltose, and sucrose. [14C]maltose transport was inhibited by excess (10 mM) glucose and to a lesser extent by sucrose (90 and 46%, respectively). [14C]glucose and [14C]sucrose transports were not inhibited by an excess of maltose. Since [14C]maltose phosphorylation in triethanolamine buffer was increased 160-fold as the concentration of Pi was increased from 0 to 100 mM, a maltose phosphorylase (Km for Pi, 9.5 mM) was present, and this activity was inducible. Maltose was also hydrolyzed by an inducible maltase. Glucose 1-phosphate arising from the maltose phosphorylase was metabolized by a constitutive phosphoglucomutase that was specific for alpha-glucose 1-phosphate (Km, 0.8 mM). Only sucrose-grown cells possessed sucrose hydrolase activity (Km, 3.1 mM), and this activity was much lower than the sucrose phosphotransferase system and sucrose-phosphate hydrolase activities.
Seasonal and Spatial Variations in Mercury Methylation and Demethylation in an Oligotrophic Lake
Authors: Korthals Eric T. , Winfrey Michael R.
Published: January 2020

Microbial mercury methylation and methylmercury decomposition were examined in Lake Clara, an oligotrophic northern Wisconsin seepage lake, using radioisotopic tracers. Methylation activity was near background in the water column, was greatest in the profundal surficial sediments, and decreased with depth in sediment cores. Active demethylation occurred in the water column but was variable. Demethylation was greatest in the surficial sediments and decreased slightly with sediment depth. The methylation/demethylation ratio (M/D) was >1 in the water column, exhibited a sharp peak in surface sediments, and decreased in deeper sediments. Methylation and demethylation activity varied in surface sediments collected along a lake transect. The M/D ratio in surface sediments ranged from 1.4 to 5.8. Methylation in attached microbial communities was near background, while demethylation was high. The M/D ratios in the attached communities were all <0.20. Methylation activity in surface sediments incubated at in situ temperature increased from spring to late summer and decreased in the fall. Demethylation increased from early to midsummer and then declined. The M/D ratio in surface sediments increased from mid- to late summer, and decreased in the fall. These results indicate that the greatest potential for methylation in Lake Clara occurs in the surficial sediments and that methylation in surficial sediments is greatest from mid-July through September. In addition, the net rate of methylmercury production may be significantly affected by demethylation.
Difference in sporogenous bacterial populations in thermophilic (55 degrees C) and mesophilic (35 degrees C) anaerobic sewage digestion
Authors: Chen M
Published: January 2020

Spores, sporeforming vegetative cells, and asporogenous populations were enumerated in two semicontinuous anaerobic fermentors digesting municipal primary sludge at 35 and 55 degrees C for more than 87 days. In the 35 degrees C fermentor, the anaerobic total population was 312.5 X 10(6)/ml, with 25.0 X 10(6)/ml being sporogenous. The populations that digest casein, starch, pectin, and cellulose were 23.1 X 10(6), 59.2 X 10(6), 26.2 X 10(6), and 7.3 X 10(6)/ml, respectively, with 2.8 X 10(6), 6.7 X 10(6), 3.4 X 10(6), and 1.5 X 10(6)/ml being sporogenous, respectively. The sporeformers accounted for 8.0 to 20.0% of each of the respective populations. In the 55 degrees C fermentor, the anaerobic total population was 512.5 X 10(6)/ml, with 336.6 X 10(6)/ml being sporogenous. The populations that digest casein, starch, pectin, and cellulose were 97.7 X 10(6), 190.7 X 10(6), 75.8 X 10(6), and 11.2 X 10(6)/ml, respectively, with 47.8 X 10(6), 110.6 X 10(6), 43.3 X 10(6), and 5.1 X 10(6)/ml, respectively, being sporogenous. The sporeformers represented 45.5 to 65.7% of each of the respective populations. The numbers of thermophilic sporeforming vegetative cells in the 55 degrees C fermentor were 9.0 to 19.8 times higher than their counterparts in the 35 degrees C fermentor. Most sporeformers were in the vegetative state in the 35 and 55 degrees C fermentors. After 18 days of fermentation at 55 degrees C, sporeformers carried out most of the digestion; however, the digestion was shared by both sporeformers and asporogenous bacteria after 87 days of fermentation. In the 35 degrees C fermentor, asporogenous bacteria digested most of the sludge. During the 18- and 87-day experimental periods, sporeformers were never predominant.