bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation of Extracellular β-(1,3)(1,6)-
d
-Glucan by
Botrytis cinerea
Authors: Stahmann K.-Peter , Pielken Petra , Schimz Karl-Ludwig , Sahm Hermann
Published: January 2020

During growth on glucose,
Botrytis cinerea
produced extracellular β-(1,3)(1,6)-
d
-glucan (cinerean), which formed an adhering capsule and slime. After glucose was exhausted from the medium, cinereanase activity increased from <0.4 to 30 U/liter, effecting a striking loss in the viscosity of the culture. Cinerean was cleaved into glucose and gentiobiose. Gentiobiose was then hydrolyzed to glucose. While cinereanase activity was strongest in the culture supernatant, gentiobiase activity was located mainly in the cell wall fraction. The addition of extra glucose or cycloheximide prevented the cinerean degradation caused by an effect on cinereanase formation. Cinerean degradation was accompanied by microconidiation and sclerotium formation.
B. cinerea
was found to grow on cinerean with the latter as its single carbon and energy source. In this case, cinerean degradation occurred during hyphal growth, and no microconidiation or sclerotium formation was observed. Growth experiments with various carbon sources indicated that cinerean had a positive effect on the formation of cinerean-degrading enzymes.
Lysogeny in
Bradyrhizobium japonicum
and Its Effect on Soybean Nodulation
Authors: Abebe H. M. , Sadowsky M. J. , Kinkle B. K. , Schmidt E. L.
Published: January 2020

Rhizobiophage V, isolated from soil in the vicinity of soybean roots, was strongly lytic on
Bradyrhizobium japonicum
123B (USDA 123) but only mildly lytic on strain L4-4, a chemically induced small-colony mutant of 123. Numerous bacteriophage-resistant variants were isolated from L4-4 infected with phage V; two were studied in detail and shown to be lysogenic. The two, L4-4 (V5) and L4-4 (V12), are the first reported examples of temperate-phage infection in
B. japonicum.
Phage V and its derivative phages V5 and V12 were closely related on the basis of common sensitivity to 0.01 M sodium citrate and phage V antiserum, phage immunity tests, and apparently identical morphology when examined by electron microscopy. However, the three phages differed in host range and in virulence. Lysogens L4-4 (V5) and L4-4 (V12) were immune to infection by phages V and V5 but not to infection by V12. Southern hybridization analysis confirmed the incorporation of phage V into the genomes of strains L4-4(V5) and L4-4(V12) and also demonstrated the incorporation of phage V into the genome of a phage V-resistant derivative of USDA 123 designated 123 (V2). None of the three lysogens, L4-4(V5), L4-4(V12), or 123B(V2), was able to nodulate soybean plants. However, Southern hybridization profile data indicated that phage V had not incorporated into any of the known
B. japonicum
nodulation genes.
Enumeration and Characterization of Bacterial Colonists of a Submersed Aquatic Plant, Eurasian Watermilfoil (
Myriophyllum spicatum
L.)
Authors: Chand T. , Harris R. F. , Andrews J. H.
Published: January 2020

A simple procedure for enumerating and grouping the bacterial colonists of Eurasian watermilfoil (
Myriophyllum spicatum
L.) is described. Colony characteristics of bacteria associated with
M. spicatum
were better defined and more stable on nutrient-poor, diluted nutrient broth agar than on high-nutrient media.
Acinetobacter, Cytophaga, Flavobacterium, Moraxella, Pseudomonas
and/or
Alcaligenes
, and
Vibrio/Aeromonas
spp., as well as two highly fastidious unidentified bacterial groups (gram-negative rods and gram-negative cocci), were associated with cultured watermilfoil during January, February, May, June, July, and August 1988. In Lake Wingra (Madison, Wis.),
Micrococcus
spp. and enterobacters were also associated with Eurasian watermilfoil during July, August, and October 1987.
Stereospecific hydroxylation of indan by Escherichia coli containing the cloned toluene dioxygenase genes from Pseudomonas putida F1
Authors: Brand J M , Cruden D L , Zylstra G J , Gibson D T
Published: January 2020

Escherichia coli JM109(pDTG601), containing the todC1C2BA genes encoding toluene dioxygenase from Pseudomonas putida F1, oxidizes indan to (-)-(1R)-indanol (83% R) and trans-1,3-indandiol. Under similar conditions, P. putida F39/D oxidizes indan to (-)-(1R)-indanol (96% R), 1-indanone, and trans-1,3-indandiol. The differences in the enantiomeric composition of the 1-indanols formed by the two organisms are due to the presence of a 1-indanol dehydrogenase in P. putida F39/D that preferentially oxidizes (+)-(1S)-indanol.
Occurrence of tributyltin-tolerant bacteria in tributyltin- or cadmium-containing seawater
Authors: Suzuki S , Fukagawa T , Takama K
Published: January 2020

Tributyltin chloride (TBTCl)-tolerant bacteria accounted for 90% of the flora in natural seawater to which TBTCl was added. These tolerant bacteria were insensitive to 250 nmol of TBTCl per disc, and all were Vibrio species. Total counts of viable bacteria did not decrease upon storage of the TBTCl-treated seawater, indicating that enrichment of tolerant strains took place. Addition of CdSO4 to seawater resulted in the occurrence of TBTCl-tolerant bacteria as well as Cd-tolerant bacteria, suggesting some correlation of Cd tolerance and TBTCl tolerance.
Amplification of DNA from native populations of soil bacteria by using the polymerase chain reaction
Authors: Bruce K D , Hiorns W D , Hobman J L , Osborn A M , Strike P , Ritchie D A
Published: January 2020

Specific DNA sequences from native bacterial populations present in soil, sediment, and sand samples were amplified by using the polymerase chain reaction with primers for either "universal" eubacterial 16S rRNA genes or mercury resistance (mer) genes. With standard amplification conditions, 1.5-kb rDNA fragments from all 12 samples examined and from as little as 5 micrograms of soil were reproducibly amplified. A 1-kb mer fragment from one soil sample was also amplified. The identity of these amplified fragments was confirmed by DNA-DNA hybridization.
Differential amplification of rRNA genes by polymerase chain reaction
Authors: Reysenbach A L , Giver L J , Wickham G S , Pace N R
Published: January 2020

The polymerase chain reaction (PCR) is used widely to recover rRNA genes from naturally occurring communities for analysis of population constituents. We have found that this method can result in differential amplification of different rRNA genes. In particular, rDNAs of extremely thermophilic archaebacteria often cannot be amplified by the usual PCR methods. The addition of 5% (wt/vol) acetamide to a PCR mixture containing both archaebacterial and yeast DNA templates minimized nonspecific annealing of the primers and prevented preferential amplification of the yeast small-subunit rRNA genes.
Methods Involving Light Variation for Isolation of Cyanobacteria: Characterization of Isolates from Central Australia
Authors: de Chazal Nola M. , Smaglinski Silke , Smith Geoffrey D.
Published: January 2020

We report the isolation of organisms belonging to a range of cyanobacterial genera from the remote arid region of central Australia, together with a preliminary characterization of their temporal modes of nitrogen fixation. We rendered unialgal
Dermocarpa
and
Myxosarcina
spp. (Section II organisms), LPP group B: type X (Section III), and
Scytonema
and
Nostoc
spp. (Section IV). We developed an isolation procedure based on a combination of published methods and applicable to a broad spectrum of cyanobacterial genera. We found light intensity to be a critical variable in our methodology; it was also an important determinant of the proportions of different organisms growing in stable mixtures.
Influence of aromatic substitution patterns on azo dye degradability by Streptomyces spp. and Phanerochaete chrysosporium
Authors: Pasti-Grigsby M B , Paszczynski A , Goszczynski S , Crawford D L , Crawford R L
Published: January 2020

Twenty-two azo dyes were used to study the influence of substituents on azo dye biodegradability and to explore the possibility of enhancing the biodegradabilities of azo dyes without affecting their properties as dyes by changing their chemical structures. Streptomyces spp. and Phanerochaete chrysosporium were used in the study. None of the actinomycetes (Streptomyces rochei A10, Streptomyces chromofuscus A11, Streptomyces diastaticus A12, S. diastaticus A13, and S. rochei A14) degraded the commercially available Acid Yellow 9. Decolorization of monosulfonated mono azo dye derivatives of azobenzene by the Streptomyces spp. was observed with five azo dyes having the common structural pattern of a hydroxy group in the para position relative to the azo linkage and at least one methoxy and/or one alkyl group in an ortho position relative to the hydroxy group. The fungus P. chrysosporium attacked Acid Yellow 9 to some extent and extensively decolorized several azo dyes. A different pattern was seen for three mono azo dye derivatives of naphthol. Streptomyces spp. decolorized Orange I but not Acid Orange 12 or Orange II. P. chrysosporium, though able to transform these three azo dyes, decolorized Acid Orange 12 and Orange II more effectively than Orange I. A correlation was observed between the rate of decolorization of dyes by Streptomyces spp. and the rate of oxidative decolorization of dyes by a commercial preparation of horseradish peroxidase type II, extracellular peroxidase preparations of S. chromofuscus A11, or Mn(II) peroxidase from P. chrysosporium. Ligninase of P. chrysosporium showed a dye specificity different from that of the other oxidative enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)
Incorporation of [
3
H]Leucine and [
3
H]Valine into Protein of Freshwater Bacteria: Field Applications
Authors: J�rgensen Niels O. G.
Published: January 2020

Incorporation of leucine and valine into proteins of freshwater bacteria as a measure of bacterial production was tested in two eutrophic Danish lakes and was related to bacterial production measured by thymidine incorporation. In a depth profile (0 to 8 m) in Frederiksborg Castle Lake, incorporation of 100 nM leucine and valine gave similar rates of protein production. In terms of carbon, this production was about 50% lower than incorporation of 10 nM thymidine. In another depth profile in the same lake, incorporations of 10 nM valine and 100 nM leucine were identical, but differed from incorporations of 10 nM leucine and 100 nM valine. Bacterial carbon production calculated from incorporations of 10 nM thymidine and 10 nM leucine was similar, whereas 10 nM valine and 100 nM leucine and valine indicated an up to 2.4-fold-higher rate of carbon production. In a diel study in Lake Bagsvaerd, incorporation of 100 nM leucine and valine indicated a similar protein production, but the calculated carbon production was about 1.9-fold higher than the production based on uptake of 10 nM thymidine. Different diel changes in incorporation of the two amino acids and in incorporation of thymidine were observed. In both lakes, concentrations of naturally occurring leucine and valine were <5 nM in most samples. This means that the specific activity of a
3
H isotope added at a concentration of 100 nM usually was diluted a maximum of 5%. Net assimilation of natural free amino acids in the lakes sustained 8 to 69% of the net bacterial carbon requirement, estimated from incorporation of leucine, valine, or thymidine. The present results indicate that incorporation of leucine and valine permits realistic measurements of bacterial production in freshwater environments.
Development of monoclonal antibodies that identify Vibrio species commonly isolated from infections of humans, fish, and shellfish
Authors: Chen D , Hanna P J , Altmann K , Smith A , Moon P , Hammond L S
Published: January 2020

Monoclonal antibodies (MAbs) against Vibrio species that infect humans, fish, and shellfish were developed for application in rapid identifications. The pathogens included Vibrio alginolyticus, V. anguillarum, V. carchariae, V. cholerae, V. damsela, V. furnissii, V. harveyi, V. ordalii, V. parahaemolyticus, and V. vulnificus. Three types of MAbs were selected. The first important group included MAbs that reacted with only a single species. A second group comprised a number of MAbs that reacted with two, taxonomically closely related Vibrio species. For example, of 22 MAbs raised against V. alginolyticus, 6 recognized a 52-kDa flagellar H antigen common to both V. alginolyticus and V. parahaemolyticus; V. anguillarum and V. ordalii also shared antigens. A third group included three genus-specific MAbs that reacted with almost all Vibrio species but did not react with other members of the family Vibrionaceae (e.g., members of the Aeromonas, Photobacterium, and Plesiomonas genera) or a wide range of gram-negative bacteria representing many genera. This last group indicated the possible existence of an antigenic determinant common to Vibrio species. Two of these three genus-specific MAbs reacted with heat-stable antigenic determinants of Vibrio species as well as lipopolysaccharide extracted from Vibrio species. The use of the MAbs in blind tests and diagnosis of clinical isolates indicated that three different types of bacteria, viz., live, formalin-fixed, and sodium azide-killed bacteria, were detected consistently. Overall, it was found that the genus-specific MAbs were very useful for rapidly identifying vibrios in the screening of acute infections, while the species-specific MAbs and others were useful for completing the diagnosis.
Release of Bacterial DNA by Marine Nanoflagellates, an Intermediate Step in Phosphorus Regeneration
Authors: Turk Valentina , Rehnstam Ann-Sofi , Lundberg Erik , Hagstr�m �ke
Published: January 2020

The concentrations of dissolved DNA and nanoflagellates were found to covary during a study of diel dynamics of the microbial food web in the Adriatic Sea. This observation was further investigated in a continuous seawater culture when nanoflagellates were fed bacteria grown in filtered seawater. Analysis of dissolved organic phosphorus and dissolved DNA showed a sixfold increase of dissolved DNA in the presence of the nanoflagellates (
Ochromonas
sp.). The amount of DNA released suggested that the majority of the consumed bacterial DNA was ejected. Phagotrophic nanoflagellates thus represent an important source of origin for dissolved DNA. The rate of breakdown of dissolved DNA and release of inorganic phosphorus in the pelagic ecosystem is suggested to be dependent on the ambient phosphate pool. In the P-limited northern Adriatic Sea, rapid degradation of the labelled DNA could be demonstrated, whereas the N-limited southern California bight water showed a much lower rate. Phosphorus originating from dissolved DNA was shown to be transferred mainly to organisms in the <3-μm-size fractions. On the basis of the C/P ratios, we suggest that a significant fraction of the phosphorus demand by the autotrophs may be sustained by the released DNA during stratified conditions. Thus, the nucleic acid-rich bacterial biomass grazed by protozoa plays an important role in the biogeochemical cycling of phosphorus in the marine environment.
Isolation of a Pseudomonas solanacearum-specific DNA probe by subtraction hybridization and construction of species-specific oligonucleotide primers for sensitive detection by the polymerase chain reaction
Authors: Seal S E , Jackson L A , Daniels M J
Published: January 2020

A subtraction hybridization technique was employed to make a library enriched for Pseudomonas solanacearum-specific sequences. One cloned fragment, PS2096, hybridized under stringent conditions to DNA of 82 P. solanacearum strains representing all subgroups of the species. Other plant-associated bacteria, including closely related species such as Pseudomonas capacia, Pseudomonas picketti, or Pseudomonas syzygii, did not hybridize to PS2096. A minimum number of between 4 x 10(5) and 4 x 10(6) P. solanacearum cells could routinely be detected with PS2096 labelled either with [32P]dCTP or with digoxigenin-11-dUTP. To improve the sensitivity of detection, PS2096 was sequenced to allow the construction of specific oligonucleotide primers to be used for polymerase chain reaction (PCR) amplification. After 50 cycles of amplification, 5 to 116 cells, depending on the strain, could reproducibly be detected by visualization of a 148-bp PCR product on an agarose gel. A preliminary field trial in Burundi with the probe and PCR primers has confirmed that they are sensitive tools for specifically detecting low-level infections of P. solanacearum in potato tubers.
Effect of Light and Organic Acids on Oxygen Uptake by BTAi 1, a Photosynthetic Rhizobium
Authors: Wettlaufer S. H. , Hardy R. W. F.
Published: January 2020

A photosynthetic rhizobium, strain BTAi 1, was cultured ex planta to investigate its photosynthetic-respiratory system and the response of this interactive system to light quantity and quality and to the addition of organic acids. Oxygen uptake, as measured with an oxygen electrode, is diminished upon illumination, with the amount of decrease related to light intensity. This oxygen-sparing effect is correlated with the wavelengths of light that are associated with bacteriochlorophyll absorbance. Increasing concentrations of glutamic, succinic, and malic acids enhance the oxygen-sparing effect of light until a threshold concentration is reached, beyond which succinic and malic acids decrease the effect. The photobiology of this unique rhizobium is similar to the photobiology of both anaerobic and aerobic photosynthetic bacteria.
Gene probe analysis of soil microbial populations selected by amendment with 2,4-dichlorophenoxyacetic acid
Authors: Holben W E , Schroeter B M , Calabrese V G , Olsen R H , Kukor J K , Biederbeck V O , Smith A E , Tiedje J M
Published: January 2020

Soils with a history of 2,4-dichlorophenoxyacetic acid (2,4-D) treatment at field application rates and control soils with no prior exposure to 2,4-D were amended with 2,4-D in the laboratory. Before and during these treatments, the populations of 2,4-D-degrading bacteria were monitored by most-probable-number (MPN) enumeration and hybridization analyses, using probes for the tfd genes of plasmid pJP4, which encode enzymes for 2,4-D degradation. Data obtained by these alternate methods were compared. Several months after the most recent field application of 2,4-D (approximately 1 ppm), soils with a 42-year history of 2,4-D treatment did not have significantly higher numbers of 2,4-D-degrading organisms than did control soils with no prior history of treatment. In response to laboratory amendments with 2,4-D, both the previously treated soils and those with no prior history of exposure exhibited a dramatic increase in the number of 2,4-D-metabolizing organisms. The MPN data indicate a 4- to 5-log population increase after one amendment with 250 ppm of 2,4-D and ultimately a 6- to 7-log increase after four additional amendments, each with 400 ppm of 2,4-D. Similarly, when total bacterial DNA from the soil microbial community of these samples was analyzed by using a probe for the tfdA gene (2,4-D monoxygenase) or the tfdB gene (2,4-dichlorophenol hydroxylase) a dramatic increase in the level of hybridization was observed in both soils.(ABSTRACT TRUNCATED AT 250 WORDS)
Resistance of proline-containing peptides to ruminal degradation in vitro
Authors: Yang C M , Russell J B
Published: January 2020

Mixed ruminal bacteria utilized an enzymatic digest of casein at a rate faster than that for an enzymatic digest of gelatin, but neither amino acid source was completely utilized even when the incubation period was as long as 96 h. Since the reaction of ninhydrin with the residual nonammonia, nonprotein nitrogen was more than twofold stronger when the samples were hydrolyzed with 6 N HCl, it appeared that much of the residual nitrogen was from peptides. Approximately 66% of the nonammonia, nonprotein, ninhydrin-reactive material could not be recovered as amino acids, but there was a significant decrease in total amino acid nitrogen when the samples were pretreated with a C18 Sep-Pak column to remove peptides. The resistant peptides had an abundance of proline, and subsequent incubations showed that synthetic dipeptides which contained proline were hydrolyzed slowly. Lysine appears to be the amino acid which is most apt to limit ruminant production. Dipeptides containing proline and lysine were hydrolyzed at least fivefold slower than lysine-alanine. Methionine, another potentially limiting amino acid, was also degraded at a slower (2.5-fold) rate when it was present as part of a proline dipeptide.
Purification and properties of NADP-dependent glutamate dehydrogenase from Ruminococcus flavefaciens FD-1
Authors: Duncan P A , White B A , Mackie R I
Published: January 2020

Glutamate dehydrogenase (GDH) (L-glutamate:NADP+ oxidoreductase, deaminating, EC 1.4.1.4) from the cellulolytic ruminal bacterium Ruminococcus flavefaciens has been purified and characterized. The native enzyme and subunit are 280 and 48 kDa, respectively, suggesting that the native enzyme is a hexamer. The enzyme requires 0.5 M KCl for optimal activity and has a pH optimum of 6.9 to 7.0. The Kms for ammonia, alpha-ketoglutarate, and glutamate are 19, 0.41, and 62 mM, respectively. The sigmoidal NADPH saturation curve revealed positive cooperativity for the binding of this coenzyme. The first residue in the N-terminal amino acid sequence from R. flavefaciens GDH was alanine, suggesting that the protein may be modified posttranslationally. Comparison of the N-terminal sequence with those of Escherichia coli, Salmonella typhimurium, and Clostridium symbiosum revealed only 39% amino acid homologies. The GDH from R. flavefaciens was unique in that its specific activity was highest during ammonia-limited growth but was not affected by ammonia shock treatment (20 mM).
High-level expression of the Streptomyces clavuligerus isopenicillin N synthase gene in Escherichia coli
Authors: Durairaj M , Doran J L , Jensen S E
Published: January 2020

The pcbC gene, which encodes isopenicillin N synthase (IPNS), was subcloned from Streptomyces clavuligerus into Escherichia coli by using the pT7 series of plasmid vectors. The polymerase chain reaction was used to introduce an NdeI site at the translation initiation codon of pcbC, allowing the gene to be inserted behind an E. coli type of ribosome binding site. This construction directed high-level expression of IPNS, but the IPNS was in an inactive form in inclusion bodies. Active IPNS was recovered by solubilizing and renaturing the protein.
Toxicity of Pentachlorophenol to Six Species of White Rot Fungi as a Function of Chemical Dose
Authors: Alleman Bruce C. , Logan Bruce E. , Gilbertson Robert L.
Published: January 2020

The growth of six species of white rot fungi was a function of pentachlorophenol (PCP) dose, expressed as mass of PCP per mass of mycelia, at PCP doses ≤35 μg mg of mycelium
-1
, and not concentration. At higher doses,
Inonotus dryophilus, Perenniporia medulla-panis
, and
Ganoderma oregonense
removed less PCP than three other species of white rot fungi.
Phanerochaete chrysosporium
grown under nitrogen-deficient conditions was inactivated at PCP doses that under nitrogen-sufficient conditions resulted in only 2-day lag periods in growth.
Trametes versicolor
was the fastest-growing species that remained viable at higher PCP doses. Both
Trametes versicolor
and
Phellinus badius
were able to degrade PCP at higher PCP doses.
Cloning and sequence analysis of genes for dehalogenation of 4-chlorobenzoate from Arthrobacter sp. strain SU
Authors: Schmitz A , Gartemann K H , Fiedler J , Grund E , Eichenlaub R
Published: January 2020

Strains of Arthrobacter catalyze a hydrolytic dehalogenation of 4-chlorobenzoate (4-CBA) to p-hydroxybenzoate. The reaction requires ATP and coenzyme A (CoA), indicating activation of the substrate via a thioester, like that reported for Pseudomonas sp. strain CBS3 (J. D. Scholten, K.-H. Chang, P. C. Babbit, H. Charest, M. Sylvestre, and D. Dunaway-Mariano, Science 253:182-185, 1991). The dehalogenase genes of Arthrobacter sp. strain SU were cloned and expressed in Escherichia coli. Analyses of deletions indicate that dehalogenation depends on three open reading frames (ORFs) which are organized in an operon. There is extensive sequence homology to corresponding gene products in Pseudomonas sp. strain CBS3, suggesting that ORF1 and ORF2 encode a 4-CBA-CoA-ligase and a 4-CBA-CoA dehalogenase, respectively. ORF3 possibly represents a thioesterase, although no homology to the enzyme from Pseudomonas sp. strain CBS3 exists.
Enzymatic iron oxidation by Leptothrix discophora: identification of an iron-oxidizing protein
Authors: Corstjens P L , de Vrind J P , Westbroek P , de Vrind-de Jong E W
Published: January 2020

An iron-oxidizing factor was identified in the spent culture medium of the iron- and manganese-oxidizing bacterial strain Leptothrix discophora SS-1. It appeared to be a protein, with an apparent molecular weight of approximately 150,000. Its activity could be demonstrated after fractionation of the spent medium by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A spontaneous mutant of L. discophora SS-1 was isolated which excreted neither manganese- nor iron-oxidizing activity, whereas excretion of other proteins seemed to be unaffected. Although the excretion of both metal-oxidizing factors was probably linked, the difference in other properties suggests that manganese and iron oxidation represent two different pathways. With a dot-blot assay, it was established that different bacterial species have different metal-oxidizing capacities. Whereas L. discophora oxidized both iron and manganese, Sphaerotilus natans oxidized only iron and two Pseudomonas spp. oxidized only manganese.
Molecular cloning of genes related to aflatoxin biosynthesis by differential screening
Authors: Feng G H , Chu F S , Leonard T J
Published: January 2020

A differential hybridization strategy was used to clone genes associated with aflatoxin biosynthesis. A genomic library, formed between nuclear DNA and the pUC19 plasmid, was screened with three different cDNA probes by the colony hybridization procedure. Nineteen clones were selected; all were positively correlated with and presumably enriched with genes associated with aflatoxin production. Some of these clones were further characterized by using them as probes in Northern (RNA blot) hybridizations. Five clones hybridized strongly with some polyadenylated RNAs formed during the transition to or during idiophase when aflatoxin was produced. However, little or no corresponding hybridization occurred with polyadenylated RNAs formed in early and mid-log growth phase. Two of the clones were further used as probes to hybridize with polyadenylated RNAs formed under aflatoxin-permissive and nonpermissive temperatures. Hybridization occurred with RNA species formed under the permissive temperature only.
Identification of two proline transport systems in Staphylococcus aureus and their possible roles in osmoregulation
Authors: Bae J H , Miller K J
Published: January 2020

The food-borne pathogen Staphylococcus aureus is distinguished from other food-borne pathogens by its ability to grow at water activity values below 0.90. Previous studies have indicated that proline accumulation mediated by transport represents a primary osmoregulatory strategy utilized by this bacterium (C. B. Anderson and L. D. Witter, Appl. Environ, Microbiol. 43:1501-1503, 1982; I. Koujima, H. Hayashi, K. Tomochika, A. Okabe, and Y. Kanemasa, Appl. Environ. Microbiol. 35:467-470, 1978; K. J. Miller, S. C. Zelt, and J.-H. Bae, Curr. Microbiol. 23:131-137, 1991). In this study, we demonstrate the presence of two proline transport systems within whole cells of S. aureus, a high-affinity transport system (Km, 7 microM) and a low-affinity transport system (Km, 420 microM). Our results indicate that the low-affinity proline transport system is osmotically activated and is the primary system responsible for the accumulation of proline by this pathogen during growth at low water activity.
Development of a lactococcal integration vector by using IS981 and a temperature-sensitive lactococcal replication region
Authors: Polzin K M , McKay L L
Published: January 2020

A vector (pKMP10) capable of Campbell-like integration into the Lactococcus lactis subsp. lactis LM0230 chromosome via homologous recombination with chromosomal IS981 sequences was constructed from the replication region of lactococcal plasmid pSK11L, an internal fragment of IS981, and the erythromycin resistance gene and Escherichia coli replication origin of pVA891. The pSK11L replication region is temperature sensitive for maintenance in L. lactis subsp. lactis LM0230, resulting in loss of unintegrated pKMP10 during growth at greater than 37 degrees C. pKMP10 integrants made up 8 to 75% of LM0230(pKMP10) erythromycin-resistant cells following successive growth at 25 degrees C with selection, 39 degrees C without selection, and 39 degrees C with selection. pKMP10 integrants were also isolated from L. lactis subsp. lactis MG1363(pKMP10) but at a 10-fold-lower frequency (4%). No integrants were isolated form L. lactis subsp. lactis MMS368(pKMP10) (a Rec-deficient strain) or LM0230(pKMP1-E) (the corresponding plasmid lacking the IS981 fragment). Examination of 17 LM0230 integrants by Southern hybridization revealed pKMP10 integration into five different chromosomal sites. Four of the integration sites appeared to be chromosomal IS981 sequences, while one was an uncharacterized chromosomal sequence. The four IS981 integrants seemed to have pKMP10 integrated in a tandem repeat structure of undetermined length. Integrated pKMP10 was more stable (0 to 2% plasmid loss) than unintegrated pKMP10 (100% plasmid loss) when grown for 100 generations at 32 degrees C without selection.
Stromal Development and Mating System of
Balansia epichloë
, a Leaf-Colonizing Endophyte of Warm-Season Grasses
Authors: White James F. , Owens James R.
Published: January 2020

Studies of the stromal development and mating system of
Balansia epichloë
were conducted. Early development of the stroma consists of both endophytic and epiphytic phases of growth. As development progresses, the epiphytic stromal subiculum on the upper surface of leaves is linked with endophytic mycelium within leaves by hyphal bridges, which may provide carbohydrates for stromal development. Sugar utilization studies suggest that
Balansia epichloë
is excluded from growth within inflorescence primordia of grasses by the presence of high levels of sugars that are inhibitory to growth of the endophyte. Studies of the mating system of
B. epichloë
were conducted, and the fungus was shown to be heterothallic, with ephelidial conidia functioning as spermatia. Insect vectoring of ephelidial spermatia is suggested to account for the irregular pattern of perithecial development on stromata.
Characterization of an extracellular protease inhibitor of Bacillus brevis HPD31 and nucleotide sequence of the corresponding gene
Authors: Shiga Y , Hasegawa K , Tsuboi A , Yamagata H , Udaka S
Published: January 2020

A novel proteinaceous protease inhibitor was isolated from the culture supernatant of Bacillus brevis HPD31. The protease inhibitor of B. brevis (designated BbrPI) was produced extracellularly in multiple forms having at least three different molecular weights. One of them, BbrPI-a, was purified to near homogeneity and only showed inhibitory activity toward serine proteases, such as trypsin, chymotrypsin, and subtilisin. BbrPI was presumed to form a trypsin-inhibitor complex in a molar ratio of 1:1. The inhibitor was found to be heat resistant at neutral and acidic pHs. The gene coding for BbrPI was cloned into Escherichia coli, and its nucleotide sequence was determined. The sequence suggested that BbrPI is produced with a signal peptide of 24 amino acid residues. The amino acid sequence of the protein deduced from the DNA sequence contained the amino acid sequences of amino termini of the inhibitors, a, b, and c, and their putative precursor determined chemically. The molecular weight of the precursor was about 33,000, and the molecular weights of inhibitors a, b, and c were about 22,000, 23,500, and 24,000, respectively. It is presumed that the secreted precursor protein, which is probably inactive, is cleaved by protease into several active protease inhibitor molecules. BbrPI shows no significant homology to the protease inhibitors described previously and is unique in not having any cysteine residues in its molecule.
Bacterial Oxidation of Sulfide Minerals in Column Leaching Experiments at Suboptimal Temperatures
Authors: Ahonen Lasse , Tuovinen Olli H.
Published: January 2020

The purpose of the work was to quantitatively characterize temperature effects on the bacterial leaching of sulfide ore material containing several sulfide minerals. The leaching was tested at eight different temperatures in the range of 4 to 37°C. The experimental technique was based on column leaching of a coarsely ground (particle diameter, 0.59 to 5 mm) ore sample. The experimental data were used for kinetic analysis of chalcopyrite, sphalerite, and pyrrhotite oxidation. Chalcopyrite yielded the highest (73 kJ/mol) and pyrrhotite yielded the lowest (25 kJ/mol) activation energies. Especially with pyrrhotite, diffusion contributed to rate limitation. Arrhenius plots were also linear for the reciprocals of lag periods and for increases of redox potentials (
d
mV/
dt
). Mass balance analysis based on total S in leach residue was in agreement with the highest rate of leaching at 37 and 28°C. The presence of elemental S in leach residues was attributed to pyrrhotite oxidation.
Inhibition of Listeria monocytogenes by fatty acids and monoglycerides
Authors: Wang L L , Johnson E A
Published: January 2020

Fatty acids and monoglycerides were evaluated in brain heart infusion broth and in milk for antimicrobial activity against the Scott A strain of Listeria monocytogenes. C12:0, C18:3, and glyceryl monolaurate (monolaurin) had the strongest activity in brain heart infusion broth and were bactericidal at 10 to 20 micrograms/ml, whereas potassium (K)-conjugated linoleic acids and C18:2 were bactericidal at 50 to 200 micrograms/ml. C14:0, C16:0, C18:0, C18:1, glyceryl monomyristate, and glyceryl monopalmitate were not inhibitory at 200 micrograms/ml. The bactericidal activity in brain heart infusion broth was higher at pH 5 than at pH 6. In whole milk and skim milk, K-conjugated linoleic acid was bacteriostatic and prolonged the lag phase especially at 4 degrees C. Monolaurin inactivated L. monocytogenes in skim milk at 4 degrees C, but was less inhibitory at 23 degrees C. Monolaurin did not inhibit L. monocytogenes in whole milk because of the higher fat content. Other fatty acids tested were not effective in whole or skim milk. Our results suggest that K-conjugated linoleic acids or monolaurin could be used as an inhibitory agent against L. monocytogenes in dairy foods.
Characterization of Fluorescent Siderophore-Mediated Iron Uptake in
Pseudomonas
sp. Strain M114: Evidence for the Existence of an Additional Ferric Siderophore Receptor
Authors: Morris John , O'Sullivan Daniel J. , Koster Margot , Leong John , Weisbeek Peter J. , O'Gara Fergal
Published: January 2020

In
Pseudomonas
sp. strain M114, the outer membrane receptor for ferric pseudobactin M114 was shown to transport ferric pseudobactins B10 and A225, in addition to its own. The gene encoding this receptor, which was previously cloned on pCUP3, was localized by Tn
5
mutagenesis to a region comprising >1.6 kb of M114 DNA. A mutant (strain M114R1) lacking this receptor was then created by a marker exchange technique. Characterization of this mutant by using purified pseudobactin M114 in radiolabeled ferric iron uptake studies confirmed that it was completely unable to utilize this siderophore for acquisition of iron. In addition, it lacked an outer membrane protein band of 89 kDa when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. As a result, growth of the mutant was severely restricted under low-iron conditions. However, this phenotype was reversed in the presence of another fluorescent siderophore (pseudobactin MT3A) from
Pseudomonas
sp. strain MT3A, suggesting the presence of a second receptor in strain M114. Furthermore, wild-type
Pseudomonas
sp. strain B24 was not able to utilize ferric pseudobactin MT3A, and this phenotype was not reversed upon expression of the M114 receptor encoded on pCUP3. However, a cosmid clone (pMS1047) that enabled strain B24 to utilize ferric pseudobactin MT3A was isolated from an M114 gene bank. Radiolabel transport assays with purified pseudobactin MT3A confirmed this event. Plasmid pMS1047 was shown to encode an outer membrane protein of 81 kDa in strain B24 under iron-limiting conditions; this protein corresponds to a similar protein in strain M114.
Construction of a 3-chlorobiphenyl-utilizing recombinant from an intergeneric mating
Authors: Adams R H , Huang C M , Higson F K , Brenner V , Focht D D
Published: January 2020

Recombinant Pseudomonas sp. strain CB15, which grows on 3-chlorobiphenyl (3CB), was constructed from Pseudomonas sp. strain HF1, which grows on 3-chlorobenzoate, and from Acinetobacter sp. strain P6, which grows on biphenyl, by using a continuous amalgamated culture apparatus. DNA from strains CB15 and HF1 hybridized very strongly to each other, while hybridization between both parental strains, HF1 and P6, was negligible. However, DNA from the recombinant CB15 hybridized moderately to strongly with three specific fragments of parental strain P6. Strains HF1 and P6 did not grow on 3CB, but recombinant strain CB15 mineralized this compound and released inorganic chloride. When growing on 3CB, strain CB15 accumulated brown products, one of which was identified as 3-chloro-5-(2'-hydroxy-3'-chlorophenyl)-1,2-benzoquinone by mass spectrometry. Emulsification and mechanical fragmentation greatly increased the rate of 3CB mineralization by strain CB15. At least three methods of inhibition from catecholic intermediates may account for slow growth on 3CB. The meta fission of 2,3-dihydroxybiphenyl (the nonchlorinated analog of the metabolic intermediate 3-chloro-2',3'-dihydroxybiphenyl) was affected by substrate inhibition (Vmax = 359 nmol.min-1.mg-1, Km = 114 microM, Kss [the inhibition constant] = 951 microM) and was also inhibited by 3-chlorocatechol. The ortho fission of 3-chlorocatechol, a degradation product, followed Michaelis-Menten kinetics (Vmax = 365 nmol.min-1.mg-1, Km = 1 microM), but the addition of 2,3-dihydroxybiphenyl inhibited the reaction (Ki = 0.87 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
Development and Use of Field Application Vectors To Express Nonadaptive Foreign Genes in Competitive Environments
Authors: Lajoie C. A. , Chen S. -Y. , Oh K. -C. , Strom P. F.
Published: January 2020

Many potential applications of genetically engineered microorganisms in environmental and agricultural biotechnology involve introducing genetic capabilities into nonsterile competitive environments in which they provide no advantage to the host. Field application vectors have been designed for the purpose of creating a temporary niche for the host in such environments. This technique involves the addition to the target environment of a selective substrate readily utilizable by the host microorganism but unavailable to most indigenous species. Thirteen nonionic and anionic detergents, representing a wide range of structural complexities and molecular weights, were screened as potential selective substrates. Competition experiments in soil, using Warburg respirometry, indicated that isolates from six different detergent enrichment cultures were more active on their corresponding detergents than the indigenous microorganisms. Detergents of intermediate structural complexities and molecular weights were most effective for use as selective substrates. A field application vector that utilizes 1.0% Igepal CO-720 (detergent) as the selective substrate and
Pseudomonas paucimobilis
1IGP4 as the host was tested for its ability to increase the presence of nonadaptive tetracycline resistance marker genes in soil. In soil amended with the selective substrate, strain 1IGP4 plate counts increased by three orders of magnitude and tetracycline-resistant transformant (pRK293) counts increased from 1.8 × 10
6
/g of soil to 4.3 × 10
8
/g in 2 days. Inoculation in the absence of substrate amendment or amendment with a nonselective substrate did not result in growth of strain 1IGP4. These results demonstrate the effectiveness of field application vectors for increasing the concentration of nonadaptive genes in competitive environments.
Genetic characterization of Legionella pneumophila serogroup 1 associated with respiratory disease in Australia
Authors: Lanser J , Adams M , Doyle R , Hewitt P , Sangster N
Published: January 2020

Techniques were developed for genetic characterization of Legionella pneumophila serogroup 1 by using restriction fragment length polymorphism analysis. Allozyme analysis provided an index of the discrimination achieved by restriction fragment length polymorphism. Isolates from human cases of legionellosis were examined by both methods, and their profiles were compared with reference strains of L. pneumophila serogroup 1 obtained from the American Type Culture Collection. Eighteen distinct clones were evident among the isolates examined. Both methods could be used to trace the source of an outbreak of legionellosis caused by L. pneumophila serogroup 1.
Use of colistin-polymyxin B-cellobiose agar for isolation of Vibrio vulnificus from the environment
Authors: Oliver J D , Guthrie K , Preyer J , Wright A , Simpson L M , Siebeling R , Morris J G
Published: January 2020

Colistin-polymyxin B-cellobiose agar was employed for the isolation of Vibrio vulnificus from shellfish. Isolates were examined phenotypically and with a gene probe and monoclonal antibody specific for V. vulnificus. Results indicated that colistin-polymyxin B-cellobiose agar is superior to both sodium dodecyl sulfate-polymyxin B-sucrose agar and thiosulfate-citrate-bile salts-sucrose agar in its ability to select and differentiate this species from background vibrios.
Selective Medium for Quantitation of
Bacillus popilliae
in Soil and in Commercial Spore Powders
Authors: Stahly D. P. , Takefman D. M. , Livasy C. A. , Dingman D. W.
Published: January 2020

A medium consisting of MYPGP agar supplemented with vancomycin was found to be highly selective for
Bacillus popilliae
, especially for strains originally isolated from Japanese beetle larvae. The medium has proven to be useful for the quantitation of
B. popilliae
spores in commercial spore powder and in soil.
The plasmid-encoded lactococcal envelope-associated proteinase is encoded by a chromosomal gene in Lactococcus lactis subsp. cremoris BC101
Authors: Nissen-Meyer J , Lillehaug D , Nes I F
Published: January 2020

The plasmid-free strain Lactococcus lactis subsp. cremoris BC101 produced an extracellular proteinase physicochemically similar to the proteinase encoded by the plasmid-linked prtP gene of other lactococcal strains. The absence of detectable plasmids in strain BC101 indicated that the prtP proteinase gene may be chromosomally located. The chromosomal linkage of the prtP proteinase gene in BC101 was confirmed by pulsed-field electrophoresis of chromosomal DNA and hybridization, using as a probe the plasmid-linked prtP gene from L. lactis subsp. cremoris Wg2. The prtM gene necessary for the maturation of the proteinase was also chromosomally located adjacent to prtP in BC101. By using as a hybridization probe the ISS1-like element ISS1W, which is found adjacent to the proteinase genes in both pWV05 and pSK111, specific homology to the chromosomal fragment containing the proteinase gene was found. DNA sequencing of a polymerase chain reaction product of chromosomal DNA upstream from prtM revealed a 123-nucleotide sequence which was 100% identical to the equivalent sequence in the ISS1W-containing plasmid. The terminal inverted repeat (18 nucleotides) of the ISS1W element was found in this sequenced DNA. These findings suggest that the chromosomal proteinase gene is organized in a fashion similar to that of the plasmid-linked proteinase gene.
Toxicity of some Fusarium section Sporotrichiella strains in relation to mycotoxin production
Authors: Visconti A , Minervini F , Solfrizzo M , Bottalico C , Lucivero G
Published: January 2020

The relationship between the toxicities of crude extracts and purified toxins of Fusarium spp. belonging to the section Sporotrichiella has been assessed. Toxicity was determined on the basis of death of Artemia salina larvae and of viability and blastogenic response of bovine and human lymphocytes. Trichothecene-producing strains of Fusarium sporotrichioides and Fusarium poae were toxic to A. salina and to lymphocyte blastogenesis. A strain of Fusarium tricinctum, producing visoltricin and chlamydosporol, induced differentiated activity in different bioassays (toxicity to A. salina but only minor activity against lymphocyte blastogenesis). Other, non-toxin-producing strains of Fusarium chlamydosporum, F. poae, and F. tricinctum were not active in the tested biosystems.
Use of Inorganic Membrane Filters (Anopore) for Epifluorescence and Scanning Electron Microscopy of Nanoplankton and Picoplankton
Authors: McKenzie Cynthia H. , Helleur Robert , Deibel Don
Published: January 2020

Inorganic membrane filters (Anopore) were examined qualitatively by epifluorescence and scanning electron microscopy to determine their suitability for the study of nanoplankton and picoplankton. Compared with filters currently used, the Anopore filters allowed for increased resolution of the specimen with epifluorescence microscopy because of filter flatness and increased illumination caused by the large number of pores cm
-2
. The inorganic filters had a lower filtration rate than polycarbonate filters. For scanning electron microscopy, the metal oxide (Anopore) filters were efficient support for the plankton, with little charging of cells or background.
Solid-Phase Products of Bacterial Oxidation of Arsenical Pyrite
Authors: Carlson Liisa , Lindström E. Börje , Hallberg Kevin B. , Tuovinen Olli H.
Published: January 2020

Bacterial leaching of an As-containing pyrite concentrate produced acidic (pH < 1) leachates. During the leaching, the bacteria solubilized both As and Fe, and these two elements were distributed in solution-phase and solid-phase products. Jarosite and scorodite were the exclusive crystalline products in precipitate samples from the bacterial leaching of the sulfide concentrate.
Genetic Analysis of
Rhizobium leguminosarum
bv. Phaseoli Mutants Defective in Nodulation and Nodulation Suppression
Authors: George Maria Luz C. , Robert Françoise M. , Borthakur Dulal
Published: January 2020

Nodulation-defective rhizobia and their nodule-forming derivatives containing cloned DNA from the wild type were used to study nodulation suppression in
Phaseolus vulgaris
L. Non-nitrogen-fixing derivatives which formed rhizobia-containing white nodules induced partial suppression. Comparison of this with the complete suppression by Fix
+
derivatives and a Fix
-
mutant which formed rhizobia-containing pink nodules suggests that the extent of suppression may be related to successive stages of nodule development.