bluuebunny/crossref_metadata_2025_split huggingface dataset:
Truncation of Peptide Deformylase Reduces the Growth Rate and Stabilizes Solvent Production in
Clostridium beijerinckii
NCIMB 8052
Authors: Evans Victoria J. , Liyanage Hemachandra , Ravagnani Adriana , Young Michael , Kashket Eva R. 
Published: December 2019

ABSTRACT

The wild-type strain of
Clostridium beijerinckii
NCIMB 8052 tends to degenerate (i.e., lose the ability to form solvents) after prolonged periods of laboratory culture. Several Tn
1545
mutants of this organism showing enhanced long-term stability of solvent production were isolated. Four of them harbor identical insertions within the
fms
(
def
) gene, which encodes peptide deformylase (PDF). The
C. beijerinckii fms
gene product contains four diagnostic residues involved in the Zn
2+
coordination and catalysis found in all PDFs, but it is unusually small, because it lacks the dispensable disordered C-terminal domain. Unlike previously characterized PDFs from
Escherichia coli
and
Thermus thermophilus
, the
C. beijerinckii
PDF can apparently tolerate N-terminal truncation. The Tn
1545
insertion in the mutants is at a site corresponding to residue 15 of the predicted gene product. This probably removes 23 N-terminal residues from PDF, leaving a 116-residue protein. The mutant PDF retains at least partial function, and it complements an
fms
(Ts) strain of
E. coli
. Northern hybridizations indicate that the mutant gene is actively transcribed in
C. beijerinckii
. This can only occur from a previously unsuspected, outwardly directed promoter located close to the right end of Tn
1545
. The Tn
1545
insertion in
fms
causes a reduction in the growth rate of
C. beijerinckii
, and, associated with this, the bacteria display an enhanced stability of solvent production. The latter phenotype can be mimicked in the wild type by reducing the growth rate. Therefore, the observed amelioration of degeneration in the mutants is probably due to their reduced growth rates.
Antibiotic Resistance Patterns of Enterococci and Occurrence of Vancomycin-Resistant Enterococci in Raw Minced Beef and Pork in Germany
Authors: Klein Günter , Pack Alexander , Reuter Gerhard 
Published: December 2019

ABSTRACT
The food chain, especially raw minced meat, is thought to be responsible for an increase in the incidence of vancomycin-resistant enterococci (VRE) in human nosocomial infections. Therefore, 555 samples from 115 batches of minced beef and pork from a European Union-licensed meat-processing plant were screened for the occurrence of VRE. The processed meat came from 45 different slaughterhouses in Germany. Enterococci were isolated directly from Enterococcosel selective agar plates and also from Enterococcosel selective agar plates supplemented with 32 mg of vancomycin per liter. In addition, peptone broth was used in a preenrichment procedure, and samples were subsequently plated onto Enterococcosel agar containing vancomycin. To determine resistance, 209 isolates from 275 samples were tested with the glycopeptides vancomycin, teicoplanin, and avoparcin and 19 other antimicrobial substances by using a broth microdilution test. When the direct method was used, VRE were found in 3 of 555 samples (0.5%) at a concentration of 1.0 log CFU/g of minced meat. When the preenrichment procedure was used, 8% of the samples were VRE positive. Our findings indicate that there is a low incidence of VRE in minced meat in Germany. In addition, the resistance patterns of the VRE isolates obtained were different from the resistance patterns of clinical isolates. A connection between the occurrence of VRE in minced meat and nosocomial infections could not be demonstrated on the basis of our findings.
Oxidation of Methyl-Substituted Naphthalenes: Pathways in a Versatile
Sphingomonas paucimobilis
Strain
Authors: Dutta Tapan K. , Selifonov Sergey A. , Gunsalus Irwin C. 
Published: December 2019

ABSTRACT

Aromatic compounds with alkyl substituents are abundant in fossil fuels. These compounds become important environmental sources of soluble toxic products, developmental inhibitors, etc. principally through biological activities. To assess the effect of methyl substitution on the completeness of mineralization and accumulation of pathway products, an isolate from a phenanthrene enrichment culture,
Sphingomonas paucimobilis
2322, was used. Washed cell suspensions containing cells grown on 2,6-dimethylnaphthalene in mineral medium were incubated with various mono-, di-, and trimethylnaphthalene isomers, and the products were identified and quantified by gas chromatography and mass spectrometry. The data revealed enzymes with relaxed substrate specificity that initiate metabolism either by methyl group monoxygenation or by ring dioxygenation. Congeners with a methyl group on each ring initially hydroxylate a methyl, and this is followed by conversion to a carboxyl; when there are two methyl groups on a single ring, the first reaction is aryl dioxygenation of the unsubstituted ring. Intermediates are channeled to primary ring fission via dihydrodiols to form methyl-substituted salicylates. Further evidence that there are multiple pathways comes from the fact that both phthalate and (methyl)salicylate are formed from 2-methylnaphthalene.
Rapid Benzene Degradation in Methanogenic Sediments from a Petroleum-Contaminated Aquifer
Authors: Weiner Jonathan M. , Lovley Derek R. 
Published: December 2019

ABSTRACT

In methanogenic sediments from a petroleum-contaminated aquifer, [
14
C]benzene was converted to
14
CH
4
and
14
CO
2
without an apparent lag. Phenol, acetate, and propionate were intermediates in benzene mineralization. These results suggest that alternative electron acceptors need not be available for there to be significant natural attenuation of benzene in some petroleum-contaminated aquifers.
Structures of Homologous Composite Transposons Carrying
cbaABC
Genes from Europe and North America
Authors: Di Gioia Diana , Peel Michelle , Fava Fabio , Wyndham R. Campbell 
Published: December 2019

ABSTRACT

IS
1071
is a class II transposable element carrying a
tnpA
gene related to the transposase genes of the Tn
3
family. Copies of IS
1071
that are conserved with more than 99% nucleotide sequence identity have been found as direct repeats flanking a remarkable variety of catabolic gene sequences worldwide. The sequences of chlorobenzoate catabolic transposons found on pBRC60 (Tn
5271
) in Niagara Falls, N.Y., and on pCPE3 in Bologna, Italy, show that these transposons were formed from highly homologous IS
1071
and
cbaABC
components (levels of identity, >99.5 and >99.3%, respectively). Nevertheless, the junction sequences between the IS
1071L
and IS
1071R
elements and the internal DNA differ by 41 and 927 bp, respectively, suggesting that these transposons were assembled independently on the two plasmids. The formation of the right junction in both transposons truncated an open reading frame for a putative aryl-coenzyme A ligase with sequence similarity to benzoate- and
p
-hydroxybenzoate-coenzyme A ligases of
Rhodopseudomonas palustris.
Diversity of European Lyme Disease Spirochetes at the Southern Margin of Their Range
Authors: Matuschka Franz-Rainer , Klug Birte , Schinkel Thomas W. , Spielman Andrew , Richter Dania 
Published: December 2019

ABSTRACT
We determined whether the genospecies diversity of Lyme disease spirochetes in vector ticks questing on a subtropical island is as broad as that in Central Europe. Although spirochetes infected <1% of the ticks sampled on Madeira Island, these infections included all three genospecies implicated in human disease. Therefore, spirochetal diversity is as great at the southern margin as it is in the center of this pathogen’s range.
Two Nearly Identical Aromatic Compound Hydrolase Genes in a Strong Polychlorinated Biphenyl Degrader,
Rhodococcus
sp. Strain RHA1
Authors: Yamada Akihiro , Kishi Hidekazu , Sugiyama Katsumi , Hatta Takashi , Nakamura Kanji , Masai Eiji , Fukuda Masao 
Published: December 2019

ABSTRACT

The two 2-hydroxy-6-oxohepta-2,4-dienoate (HOHD) hydrolase genes,
etbD1
and
etbD2
, were cloned from a strong polychlorinated biphenyl (PCB) degrader,
Rhodococcus
sp. strain RHA1, and their nucleotide sequences were determined. The
etbD2
gene was located in the vicinity of
bphA
gene homologs and encoded an enzyme whose amino-terminal sequence was very similar to the amino-terminal sequence of the HOHD hydrolase which was purified from RHA1. Using the
etbD2
gene fragment as a probe, we cloned the
etbD1
gene encoding the purified HOHD hydrolase by colony hybridization. Both genes encode a product having 274 amino acid residues and containing the nucleophile motif conserved in α/β hydrolase fold enzymes. The deduced amino acid sequences were quite similar to the amino acid sequences of the products of the single-ring aromatic hydrolase genes, such as
dmpD
,
cumD
,
todF
, and
xylF
, and not very similar to the amino acid sequences of the products of
bphD
genes from PCB degraders, including RHA1. The two HOHD hydrolase genes and the RHA1 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate (HPDA) hydrolase gene,
bphD
, were expressed in
Escherichia coli
, and their relative enzymatic activities were examined. The product of
bphD
was very specific to HPDA, and the products of
etbD1
and
etbD2
were specific to HOHD. All of the gene products exhibited poor activities against the
meta
-cleavage product of catechol. These results agreed with the results obtained for BphD and EtbD1 hydrolases purified from RHA1. The three hydrolase genes exhibited similar induction patterns both in an RNA slot blot hybridization analysis and in a reporter gene assay when a promoter probe vector was used. They were induced by biphenyl, ethylbenzene, benzene, toluene, and
ortho
-xylene. Strain RCD1, an RHA1 mutant strain lacking both the
bphD
gene and the
etbD2
gene, grew well on ethylbenzene. This result suggested that the
etbD1
gene product is involved in the
meta
-cleavage metabolic pathway of ethylbenzene.
The
gal
Genes for the Leloir Pathway of
Lactobacillus casei
64H
Authors: Bettenbrock Katja , Alpert Carl-Alfred 
Published: December 2019

ABSTRACT

The
gal
genes from the chromosome of
Lactobacillus casei
64H were cloned by complementation of the
galK2
mutation of
Escherichia coli
HB101. The pUC19 derivative pKBL1 in one complementation-positive clone contained a 5.8-kb DNA
Hin
dIII fragment. Detailed studies with other
E. coli
K-12 strains indicated that plasmid pKBL1 contains the genes coding for a galactokinase (GalK), a galactose 1-phosphate-uridyltransferase (GalT), and a UDP-galactose 4-epimerase (GalE). In vitro assays demonstrated that the three enzymatic activities are expressed from pKBL1. Sequence analysis revealed that pKBL1 contained two additional genes, one coding for a repressor protein of the LacI-GalR-family and the other coding for an aldose 1-epimerase (mutarotase). The gene order of the
L. casei gal
operon is
galKETRM
. Because parts of the gene for the mutarotase as well as the promoter region upstream of
galK
were not cloned on pKBL1, the regions flanking the
Hin
dIII fragment of pKBL1 were amplified by inverse PCR. Northern blot analysis showed that the
gal
genes constitute an operon that is transcribed from two promoters. The
galKp
promoter is inducible by galactose in the medium, while
galEp
constitutes a semiconstitutive promoter located in
galK
.
Female Fertility and Mating Type Distribution in a South African Population of
Fusarium subglutinans
f. sp.
pini
Authors: Britz H. , Wingfield M. J. , Coutinho T. A. , Marasas W. F. O. , Leslie J. F. 
Published: December 2019

ABSTRACT

Fusarium subglutinans
f. sp.
pini
is the causal agent of pitch canker disease of pines. The initial occurrence of
F. subglutinans
f. sp.
pini
in South Africa was limited to a single nursery, and isolates from this population are capable of reproducing sexually. We determined the effective population number,

N
e

, of this population by using mating type and male/hermaphrodite polymorphisms as indicators. The effective population number for mating type,

N
e(mt)

, is 99% of the count (total population), and that for male/hermaphrodite status,

N
e(f)

, is 42 to 46% of the count (total population). The number of strains that can function as the female parent limits the effective population number of this population. If this population is stable, then, depending upon assumptions about mutation and selection, sexual reproduction need occur only once per 26 to 153 asexual generations to maintain this level of sexual fertility.
Characterization of Metabolites in the Biotransformation of 2,4,6-Trinitrotoluene with Anaerobic Sludge: Role of Triaminotoluene
Authors: Hawari Jalal , Halasz A. , Paquet L. , Zhou E. , Spencer B. , Ampleman G. , Thiboutot S. 
Published: December 2019

ABSTRACT

The present study describes the biotransformation of 2,4,6-trinitrotoluene (TNT) (220 μM) by using anaerobic sludge (10%, vol/vol) supplemented with molasses (3.3 g/liter). Despite the disappearance of TNT in less than 15 h, roughly 0.1% of TNT was attributed to mineralization (
14
CO
2
). A combination of solid-phase microextraction–gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry identified two distinctive cycles in the degradation of TNT. One cycle was responsible for the stepwise reduction of TNT to eventually produce triaminotoluene (TAT) in relatively high yield (160 μM). The other cycle involved TAT and was responsible for the production of azo derivatives, e.g., 2,2′,4,4′-tetraamino-6,6′-azotoluene (2,2′,4,4′-TA-6,6′-azoT) and 2,2′,6,6′-tetraamino-4,4′-azotoluene (2,2′,6,6′-TA-4,4′-azoT) at pH 7.2. These azo compounds were also detected when TAT was treated with the anaerobic sludge but not with an autoclaved sludge, suggesting the biotic nature of their formation. When the anaerobic conditions in the TAT-containing culture medium were removed by aeration and/or acidification (pH 3), the corresponding phenolic compounds, e.g., hydroxy-diaminotoluenes and dihydroxy-aminotoluenes, were observed at room temperature. Trihydroxytoluene was detected only after heating TAT in water at 100°C. When
13
CH
3
-labeled TNT was used as the N source in the above microcosms, we were unable to detect
13
C-labeled
p
-cresol or [
13
CH
3
]toluene, indicating the absence of denitration or deamination in the biodegradation process. The formation and disappearance of TAT were not accompanied by mineralization, suggesting that TAT acted as a dead-end metabolite.
Randomly Amplified Polymorphic DNA PCR Analysis of Bovine
Cryptosporidium parvum
Strains Isolated from the Watershed of the Red River of the North
Authors: Shianna Kevin V. , Rytter Russell , Spanier Jonathan G. 
Published: December 2019

ABSTRACT

Cryptosporidium parvum
is a protozoan parasite that causes the disease cryptosporidiosis in a variety of mammals, including neonatal calves and humans. Millions of oocysts are shed during acute cryptosporidiosis, and zoonotic transmission is inferred, though not proven, to be a general phenomenon. Very little is known about the degree of strain variation exhibited by bovine and human isolates, though such knowledge would enable the amount of bovine-to-human transmission to be more precisely analyzed. This research was initiated to determine whether variations exist among bovine strains isolated from a localized geographic area, the watershed of the Red River of the North. Sixteen strains were isolated and compared to each other and to two human and two calf strains from Australia by randomly amplified polymorphic DNA PCR. A statistical analysis of the data indicated that the isolates belonged to four different groups of strains.
Antagonistic Activity of
Lactobacillus plantarum
C11: Two New Two-Peptide Bacteriocins, Plantaricins EF and JK, and the Induction Factor Plantaricin A
Authors: Anderssen Erlend L. , Diep Dzung Bao , Nes Ingolf F. , Eijsink Vincent G. H. , Nissen-Meyer Jon 
Published: December 2019

ABSTRACT

Six bacteriocinlike peptides (plantaricin A [PlnA], PlnE, PlnF, PlnJ, PlnK, and PlnN) produced by
Lactobacillus plantarum
C11 were detected by amino acid sequencing and mass spectrometry. Since purification to homogeneity was problematic, all six peptides were obtained by solid-phase peptide synthesis and were tested for bacteriocin activity. It was found that
L. plantarum
C11 produces two two-peptide bacteriocins (PlnEF and PlnJK); a strain-specific antagonistic activity was detected at nanomolar concentrations when PlnE and PlnF were combined and when PlnJ and PlnK were combined. Complementary peptides were at least 10
3
times more active when they were combined than when they were present individually, and optimal activity was obtained when the complementary peptides were present in approximately equal amounts. The interaction between complementary peptides was specific, since neither PlnE nor PlnF could complement PlnJ or PlnK, and none of these peptides could complement the peptides constituting the two-peptide bacteriocin lactococcin G. Interestingly, PlnA, which acts as an extracellular signal (pheromone) that triggers bacteriocin production, also possessed a strain-specific antagonistic activity. No bacteriocin activity could be detected for PlnN.
Method Detection Limits of PCR and Immunofluorescence Assay forCryptosporidium parvumin Soil
Authors: Walker Mark J. , Montemagno Carlo , Bryant Juliet C. , Ghiorse William C. 
Published: December 2019

ABSTRACTWe determined and compared the method detection limits (MDLα) of a PCR and an immunofluorescence assay (IFA) for detection ofCryptosporidium parvumoocysts in soils. Based on the MDLαand the quantitative nature and stability of the IFA, PCR analysis is not a useful screening step for soil studies of oocyst transport.
Detection of
Cyclospora cayetanensis
in Wastewater
Authors: Sturbaum Gregory D. , Ortega Ynes R. , Gilman Robert H. , Sterling Charles R. , Cabrera Lilia , Klein Donald A. 
Published: December 2019

ABSTRACT

Cyclospora cayetanensis
causes diarrheal disease worldwide without a confirmed mode of transmission. Wastewater was examined for the presence of this organism. Oocysts were detected microscopically, and their identity was confirmed by molecular techniques. These findings verify that current techniques can isolate
Cyclospora
oocysts and suggest that fecally contaminated water may act as a vehicle of transmission.
Bioencapsulation of Two DifferentVibrioSpecies in Nauplii of the Brine Shrimp (Artemia franciscana)
Authors: Gomez-Gil Bruno , Herrera-Vega Maria A. , Abreu-Grobois F. Alberto , Roque Ana 
Published: December 2019

ABSTRACTTwo groups of nauplii from the brine shrimp (Artemia franciscana) were enriched with different bacteria, and the dynamics of bacterial uptake by the nauplii were observed. This study showed that the efficiency ofArtemia naupliiin bioencapsulating bacteria strongly depends on the type of bacteria used, time of exposure, and status (live or dead) of the bacteria.
Isolation and Entomotoxic Properties of the
Xenorhabdus nematophilus
F1 Lecithinase
Authors: Thaler Jacques-Olivier , Duvic Bernard , Givaudan Alain , Boemare Noël 
Published: December 2019

ABSTRACT

Xenorhabdus
spp. and
Photorhabdus
spp., entomopathogenic bacteria symbiotically associated with nematodes of the families Steinernematidae and Heterorhabditidae, respectively, were shown to produce different lipases when they were grown on suitable nutrient agar. Substrate specificity studies showed that
Photorhabdus
spp. exhibited a broad lipase activity, while most of the
Xenorhabdus
spp. secreted a specific lecithinase.
Xenorhabdus
spp. occur spontaneously in two variants, phase I and phase II. Only the phase I variants of
Xenorhabdus nematophilus
and
Xenorhabdus bovienii
strains produced lecithinase activity when the bacteria were grown on a solid lecithin medium (0.01% lecithin nutrient agar; 24 h of growth). Five enzymatic isomers responsible for this activity were separated from the supernatant of a
X. nematophilus
F1 culture in two chromatographic steps, cation-exchange chromatography and C
18
reverse-phase chromatography. The substrate specificity of the
X. nematophilus
F1 lecithinase suggested that a phospholipase C preferentially active on phosphatidylcholine could be isolated. The entomotoxic properties of each isomer were tested by injection into the hemocoels of insect larvae. None of the isomers exhibited toxicity with the insects tested,
Locusta migratoria
,
Galleria mellonella
,
Spodoptera littoralis
, and
Manduca sexta
. The possible role of lecithinase as either a virulence factor or a symbiotic factor is discussed.
Detoxification of Benzoxazolinone Allelochemicals from Wheat by
Gaeumannomyces graminis
var.
tritici
,
G. graminis
var.
graminis
,
G. graminis
var.
avenae
, and
Fusarium culmorum
Authors: Friebe A. , Vilich V. , Hennig L. , Kluge M. , Sicker D. 
Published: December 2019

ABSTRACT

The ability of phytopathogenic fungi to overcome the chemical defense barriers of their host plants is of great importance for fungal pathogenicity. We studied the role of cyclic hydroxamic acids and their related benzoxazolinones in plant interactions with pathogenic fungi. We identified species-dependent differences in the abilities of
Gaeumannomyces graminis
var.
tritici
,
Gaeumannomyces graminis
var.
graminis
,
Gaeumannomyces graminis
var.
avenae
, and
Fusarium culmorum
to detoxify these allelochemicals of gramineous plants. The
G. graminis
var.
graminis
isolate degraded benzoxazolin-2(3
H
)-one (BOA) and 6-methoxy-benzoxazolin-2(3
H
)-one (MBOA) more efficiently than did
G. graminis
var.
tritici
and
G. graminis
var.
avenae. F. culmorum
degraded BOA but not MBOA.
N
-(2-Hydroxyphenyl)-malonamic acid and
N
-(2-hydroxy-4-methoxyphenyl)-malonamic acid were the primary
G. graminis
var.
graminis
and
G. graminis
var.
tritici
metabolites of BOA and MBOA, respectively, as well as of the related cyclic hydroxamic acids. 2-Amino-3
H
-phenoxazin-3-one was identified as an additional
G. graminis
var.
tritici
metabolite of BOA. No metabolite accumulation was detected for
G. graminis
var.
avenae
and
F. culmorum
by high-pressure liquid chromatography. The mycelial growth of the pathogenic fungi was inhibited more by BOA and MBOA than by their related fungal metabolites. The tolerance of
Gaeumannomyces
spp. for benzoxazolinone compounds is correlated with their detoxification ability. The ability of
Gaeumannomyces
isolates to cause root rot symptoms in wheat (cultivars Rektor and Astron) parallels their potential to degrade wheat allelochemicals to nontoxic compounds.
Role of Organic Acids in the Manganese-Independent Biobleaching System of
Bjerkandera
sp. Strain BOS55
Authors: Moreira María Teresa , Feijoo Gumersindo , Mester Tünde , Mayorga Pablo , Sierra-Alvarez Reyes , Field Jim A. 
Published: December 2019

ABSTRACT

Bjerkandera
sp. strain BOS55 is a white rot fungus that can bleach EDTA-extracted eucalyptus oxygen-delignified kraft pulp (OKP) without any requirement for manganese. Under manganese-free conditions, additions of simple physiological organic acids (e.g., glycolate, glyoxylate, oxalate, and others) at 1 to 5 mM stimulated brightness gains and pulp delignification two- to threefold compared to results for control cultures not receiving acids. The role of the organic acids in improving the manganese-independent biobleaching was shown not to be due to pH-buffering effects. Instead, the stimulation was attributed to enhanced production of manganese peroxidase (MnP) and lignin peroxidase (LiP) as well as increased physiological concentrations of veratryl alcohol and oxalate. These factors contributed to greatly improved production of superoxide anion radicals, which may have accounted for the more extensive biobleaching. Optimum biobleaching corresponded most to the production of MnP. These results suggest that MnP from
Bjerkandera
is purposefully produced in the absence of manganese and can possibly function independently of manganese in OKP delignification. LiP probably also contributed to OKP delignification when it was present.