bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and Metabolism of Lactic Acid Bacteria during and after Malolactic Fermentation of Wines at Different pH
Authors: Davis C. R. , Wibowo D. J. , Lee T. H. , Fleet G. H.
Published: January 2020

Commercially produced red wines were adjusted to pH 3.0, 3.2, 3.5, 3.7, or 4.0 and examined during and after malolactic fermentation for growth of lactic acid bacteria and changes in the concentrations of carbohydrates, organic acids, amino acids, and acetaldehyde. With one exception,
Leuconostoc oenos
conducted the malolactic fermentation in all wines and was the only species to occur in wines at pH below 3.5. Malolactic fermentation by
L. oenos
was accompanied by degradation of malic, citric, and fumaric acids and production of lactic and acetic acids. The concentrations of arginine, histidine, and acetaldehyde also decreased at this stage, but the behavior of hexose and pentose sugars was complicated by other factors.
Pediococcus parvulus
conducted the malolactic fermentation in one wine containing 72 mg of total sulfur dioxide per liter. Fumaric and citric acids were not degraded during this malolactic fermentation, but hexose sugars were metabolized.
P. parvulus
and species of
Lactobacillus
grew after malolactic fermentation in wines with pH adjusted above 3.5. This growth was accompanied by the utilization of wine sugars and production of lactic and acetic acids.
Transport and Metabolism of Lactose, Glucose, and Galactose in Homofermentative Lactobacilli
Authors: Hickey Malcolm W. , Hillier Alan J. , Jago G. Richard
Published: January 2020

A number of species of lactobacilli were examined for their ability to ferment both the glucose and galactose moieties of lactose.
Lactobacillus helveticus
strains metabolized both the glucose and galactose moieties, whereas
L. bulgaricus, L. lactis
, and
L. acidophilus
strains metabolized only the glucose moiety and released galactose into the growth medium. All four species tested contained β-galactosidase activity, and no significant phospho-β-galactosidase activity was observed.
L. bulgaricus
and
L. helveticus
had a phosphoenolpyruvate (PEP):glucose phosphotransferase system for the uptake of glucose, but no evidence for a PEP:lactose phosphotransferase or PEP:galactose phosphotransferase system was obtained.
Evaluation of mixed cell types and 5-iodo-2'-deoxyuridine treatment upon plaque assay titers of human enteric viruses
Authors: Benton W H , Hurst C J
Published: January 2020

Four continuous cell lines, BGM, L-132, HEL-299, and RD, were compared both when cultured separately and as mixtures for use in plaque assay titrations of human adenovirus 1 and six human enterovirus serotypes. The effect of incubating these cell cultures in media containing 5-iodo-2'deoxyuridine (IDU) prior to inoculation with virus was also studied. The use of mixed-cell cultures revealed cell line-dependent synergistic effects as well as inhibitory effects. These effects were strongly virus dependent. In particular, enterovirus 69 did not form plaques on any of the four cell lines when cultured independently. However, it did form plaques on nearly all of the cell lines when cultured as mixtures. Contrary to this effect, when BGM cells were used in combination with the other cell lines, plaque counts for adenovirus 1 were greatly reduced. The effect of IDU pretreatment was also virus and cell line specific and enabled some viruses to form plaques on cell lines when they otherwise would not. Overall, IDU pretreatment resulted in an approximate twofold increase in plaque titers over those obtained without treatment.
Novel Method of Lactic Acid Production by Electrodialysis Fermentation
Authors: Hongo Motoyoshi , Nomura Yoshiyuki , Iwahara Masayoshi
Published: January 2020

In lactic acid fermentation by
Lactobacillus delbrueckii,
the produced lactic acid affected the lactic acid productivity. Therefore, for the purpose of alleviating this inhibitory effect, an electrodialysis fermentation method which can continuously remove produced lactic acid from the fermentation broth was applied to this fermentation process. As a result, the continuation of fermentation activity was obtained, and the productivity was three times higher than in non-pH-controlled fermentation. In electrodialysis fermentation, the amount of produced lactic acid was 82.2 g/liter, which was about 5.5 times greater than that produced in non-pH-controlled fermentation. It was concluded that these good results were obtained on account of alleviating the lactic acid inhibitory effect by electrodialysis fermentation. However, the fouling of anion-exchange membranes by cells was observed in electrodialysis fermentation.
Evaluation of methods for enumeration of Vibrio parahaemolyticus from seafood
Authors: Karunasagar I , Venugopal M N , Karunasagar I , Segar K
Published: January 2020

The efficiency of several enrichment broths in recovering Vibrio parahaemolyticus inoculated into fish homogenates was studied. Recovery by the most probable number technique was very low in all the broths, while direct plating on thiosulfate citrate bile salt sucrose agar yielded better recovery. A decrease in the enrichment time to 8 from 18 h did not improve recovery. At concentrations exceeding 2.5 micrograms/ml, polymyxin was inhibitory to V. parahaemolyticus.
Microbial degradation of 1,3-dichlorobenzene
Authors: de Bont J A , Vorage M J , Hartmans S , van den Tweel W J
Published: January 2020

A gram-negative, peritrichously flagellated rod, tentatively identified as an Alcaligenes sp., was isolated from a mixture of soil and water samples by using 1,3-dichlorobenzene as the sole carbon and energy source. During growth on 1,3-dichlorobenzene, almost stoichiometric amounts of chloride were released. Simultaneous adaptation studies, as well as enzyme studies, indicated that 1,3-dichlorobenzene was metabolized via 3,5-dichloro-cis-1,2-dihydroxycyclohexa-3,5-diene to 3,5-dichlorocatechol. Subsequently, the latter product was cleaved, yielding 2,4-dichloromuconate. No initial hydrolytic step yielding 3-chlorophenol was detected in this species.
Direct fermentation of potato starch to ethanol by cocultures of Aspergillus niger and Saccharomyces cerevisiae
Authors: Abouzied M M , Reddy C A
Published: January 2020

Direct fermentation of unhydrolyzed potato starch to ethanol by monocultures of an amylolytic fungus, Aspergillus niger, and cocultures of A. niger and Saccharomyces cerevisiae was investigated. Amylolytic activity, rate and amount of starch utilization, and ethanol yields increased several-fold in coculture versus the monoculture due to the synergistic metabolic interactions between the species. Optimal ethanol yields were obtained in the pH range 5 to 6 and amylolytic activity was obtained in the pH range 5 to 8. Ethanol yields were maximal when fermentations were conducted anaerobically. Increasing S. cerevisiae inoculum in the coculture from 4 to 12% gave a dramatic increase in the rate of ethanol production, and ethanol yields of greater than 96% of the theoretical maximum were obtained within 2 days of fermentation. These results indicate that simultaneous fermentation of starch to ethanol can be conducted efficiently by using cocultures of the amylolytic fungus A. niger and a nonamylolytic sugar fermenter, S. cerevisiae.
Factors Affecting High-Oxygen Survival of Heterotrophic Microorganisms from an Antarctic Lake
Authors: Mikell Alfred T. , Parker B. C. , Gregory E. M.
Published: January 2020

We sought to determine factors relating to the survival of heterotrophic microorganisms from the high-dissolved-oxygen (HDO) waters of Lake Hoare, Antarctica. This lake contains perpetual HDO about three times that of normal saturation (40 to 50 mg liter
−1
). Five isolates, one yeast and four bacteria, were selected from Lake Hoare waters by growth with the membrane filter technique with oxygen added to yield dissolved concentrations 14 times that in situ, 175 mg liter
−1
. One bacterial isolate was obtained from the microbial mat beneath the HDO waters. This organism was isolated at normal atmospheric oxygen saturation. The bacteria were gram-negative rods, motile, oxidase positive, catalase positive, and superoxide dismutase positive; they contained carotenoids. The planktonic isolates grew in media containing 10 mg of Trypticase soy (BBL Microbiology Systems)-peptone (2:1) liter
−1
but not at 10 g liter
−1
. Under low-nutrient levels simulating Lake Hoare waters (10 mg liter
−1
), two of the planktonic isolates tested were not inhibited by HDO. Growth inhibition by HDO increased as nutrient concentration was increased. A carotenoid-negative mutant of one isolate demonstrated a decreased growth rate, maximal cell density, and increased cell lysis in the death phase under HDO compared with the parent strain. The specific activity of superoxide dismutase was increased by HDO in four of the five bacterial isolates. The superoxide dismutase was of the manganese type on the basis of inhibition and electrophoretic studies. The bacterial isolates from Lake Hoare possess several adaptations which may aid their survival in the HDO waters, as well as protection due to the oligotrophic nature of the lake.
Palo Podrido: Model for Extensive Delignification of Wood by
Ganoderma applanatum
Authors: Dill Ingrid , Kraepelin Gunda
Published: January 2020

Chemical and micromorphological analysis revealed that South Chilean “palo podrido” results from a white-rot fungus that causes highly selective and extensive delignification. Palo podrido samples from 10 different hardwood trunks (
Eucryphia cordifolia, Drimys winteri
, and
Nothofagus dombeyi
) decayed by
Ganoderma applanatum
were analyzed. Of 14 samples, 11 had extremely low Klason lignin values, ranging from 6.1 to 0.4% (dry weight). The most remarkable and unusual feature was that delignification and defibration were not restricted to small pockets but extended throughout large areas in the interior of trunks subjected to undisturbed rotting over long periods of time. Comparative analysis of water content, swelling capacity, and lignin content led to the conclusion that besides lignin degradation, suppression of the cellulolytic activity of the rotting organisms plays a decisive role. Among various nutrients added to a palo podrido sample (3% residual Klason lignin), the nitrogen source was the only one leading to almost complete cellulose degradation. We suggest that the extremely low nitrogen content (0.037 to 0.073% [dry weight]) of the investigated wood species was the primary cause for the extensive delignification as well as the concomitant suppression of cellulose breakdown. The low temperatures, high humidity, and microaerobic conditions maintained within the decaying trunks are discussed as additional ecological factors favoring delignification in South Chilean rain forests.
Changes in Protein Composition of Three Bacterial Isolates from Marine Waters during Short Periods of Energy and Nutrient Deprivation
Authors: Jaan Åsa Jouper , Dahllöf Björn , Kjelleberg Staffan
Published: January 2020

Two-dimensional gel electrophoresis analysis of and total cell protein determination for three bacterial isolates from marine waters at the onset and after 24 h of energy and nutrient deprivation demonstrated that the three isolates exhibited different pathways of starvation survival. Two strains appeared to synthesize new proteins during starvation.
Root-Zone-Specific Oxygen Tolerance of
Azospirillum
spp. and Diazotrophic Rods Closely Associated with Kallar Grass
Authors: Hurek Thomas , Reinhold Barbara , Fendrik Istvan , Niemann Ernst-Georg
Published: January 2020

The effect of oxygen on N
2
-dependent growth of two
Azospirillum
strains and two diazotrophic rods closely associated with roots of Kallar grass (
Leptochloa fusca
) was studied. To enable precise comparison, bacteria were grown in dissolved-oxygen-controlled batch and continuous cultures. Steady states were obtained from about 1 to 30 μM O
2
, some of them being carbon limited. All strains needed a minimum amount of oxygen for N
2
-dependent growth. Nitrogen contents between 10 and 13% of cell dry weight were observed. The response of steady-state cultures to increasing O
2
concentrations suggested that carbon limitation shifted to internal nitrogen limitation when N
2
fixation became so low that the bacteria could no longer meet their requirements for fixed nitrogen. For
Azospirillum lipoferum
Rp5, increase of the dilution rate resulted in decreased N
2
fixation in steady-state cultures with internal nitrogen limitation. Oxygen tolerance was found to be strain specific in
A. lipoferum
with strain Sp59b as a reference organism. Oxygen tolerance of strains from Kallar grass was found to be root zone specific.
A. halopraeferens
Au 4 and
A. lipoferum
Rp5, predominating on the rhizoplane of Kallar grass, and strains H6a2 and BH72, predominating in the endorhizosphere, differed in their oxygen tolerance profiles. Strains H6a2 and BH72 still grew and fixed nitrogen in steady-state cultures at O
2
concentrations exceeding those which absolutely inhibited nitrogen fixation of both
Azospirillum
strains. It is proposed that root-zone-specific oxygen tolerance reflects an adaptation of the isolates to the microenvironments provided by the host plant.
Expression of cloned monkey metallothionein in Escherichia coli
Authors: Murooka Y , Nagaoka T
Published: January 2020

Expression vectors were constructed in which a cDNA specifying the monkey kidney metallothionein-II (MT-II) was linked directly to the lambda PR promoter. Enhanced expression of MT-II in Escherichia coli was observed when two initiation signals were tandemly linked to the MT-II gene and the lambda cI+ host cells were induced by nalidixic acid.
Isolation of Campylobacter spp. from pigeon feces by a combined enrichment-filtration technique
Authors: M�graud F
Published: January 2020

A technique combining enrichment in Preston enrichment broth and direct filtration onto chocolate agar was used to isolate Campylobacter species from pigeon feces. Campylobacter jejuni was isolated from 106 of 200 samples tested; 105 strains were isolated by enrichment-filtration, and 84 strains were isolated by direct plating. Most of the strains grew after 48 h at 37 degrees C.
Efficient Implementation of Consecutive Reactions by Peptidases at the Periphery of the
Streptococcus cremoris
Membrane
Authors: Exterkate Fred A. , de Veer Gerrie J. C. M.
Published: January 2020

Activities detectable in
Streptococcus cremoris
with the chymotrypsin substrate
N
-glutaryl-
l
-phenylalanine-4-nitroanilide and formerly designated endopeptidases P37 and P50 (F. A. Exterkate, Appl. Environ. Microbiol. 47:177-183, 1984) are both coupled peptidase reactions. These coupled reactions involve a membrane-bound, restricted
l
-α-glutamyl aminopeptidase which is responsible for the initial release of the glutaryl moiety. The subsequent reaction is catalyzed by either a so-called low-temperature or a high-temperature phenylalanyl aminopeptidase activity, both located at the outside surface of the membrane. Altered microenvironmental conditions created by the membrane-perturbing action of
n
-butanol or obtained by solubilization resulted in the removal of a restriction on the activity of
l
-α-glutamyl aminopeptidase and in a less efficient functioning of the coupled reactions; a long transient phase occurred before the steady state was reached. The results suggest that the in situ spatial organization is conducive to an efficient attuning of at least three peptidases which are located at the outer membrane surface and in the membrane. The possibility that peptidases in these locations exist as a cluster with physiological significance is discussed in relation to growth of
S. cremoris
in milk.
Optimization of Protoplast Formation and Regeneration in
Leuconostoc mesenteroides
Authors: Otts David R. , Day D. F.
Published: January 2020

Conditions are reported for efficient protoplast formation and regeneration in four strains of
Leuconostoc mesenteroides.
Protoplasts were produced from each strain at frequencies greater than 99%, although the rate of their production was variable from strain to strain. Bovine serum albumin and Mg
2+
were required for maximal regeneration, while the presence of Ca
2+
was inhibitory. Regeneration frequencies of 16% could be obtained with strain ATCC 10830. This frequency was four- to eightfold higher than the frequencies of the other strains examined.
Survival and virulence of copper- and chlorine-stressed Yersinia enterocolitica in experimentally infected mice
Authors: Singh A , McFeters G A
Published: January 2020

The effect of gastric pH on the viability and virulence of Yersinia enterocolitica O:8 after exposure to sublethal concentrations of copper and chlorine was determined in mice. Viability and injury were assessed with a nonselective TLY agar (tryptic soy broth containing lactose, yeast extract, and agar) and two selective media, TLYD agar (TLY agar plus sodium deoxycholate) and CIN agar (cefsulodin-Irgasan-novobiocin agar). Both copper and chlorine caused injury which was manifested by the inability of the cells to grow on selective media. CIN agar was more restrictive to the growth of injured cells than TLYD agar. Injury of the exposed cells was further enhanced in the gastric environment of mice. Besides injury, the low gastric pH caused extensive loss of viability in copper-exposed cells. Lethality in the chlorine-exposed cells was less extensive, and a portion of the inoculum (5.2 X 10(5) of 1 X 10(7) inoculated cells) reached the small intestine 5 min postinoculation. No adverse effect on the injured cells was apparent in the small intestine, and a substantial revival (approximately 70%) of the injury occurred in 3 to 4 h after intraluminal inoculation. The virulence of chlorine-stressed Y. enterocolitica in orally inoculated mice was similar to that of the control culture, but copper-stressed cells showed reduced virulence. Virulence was partly restored by oral administration of sodium bicarbonate before the inoculation of copper-exposed cells. Neutralization of gastric acidity had no effect on the virulence of the control or chlorine-stressed cells. The results of this study indicate that the extensive injury caused by the low gastric pH does not affect the virulence potential of chlorine-exposed cells. However, extensive cell death in the mouse stomach is responsible for the reduced virulence of the copper-stressed bacteria.
Influence of Lime and Phosphate on Nodulation of Soil-Grown
Trifolium subterraneum
L. by Indigenous
Rhizobium trifolii
Authors: Almendras Angela S. , Bottomley Peter J.
Published: January 2020

Previous research had identified four serogroups of
Rhizobium trifolii
indigenous to the acidic Abiqua soil (fine, mixed, mesic Cumulic Ultic Haploxeroll). Nodulation of subterranean clover (
Trifolium subterraneum
L.) by two of the serogroups, 6 and 36, was differentially influenced by an application of CaCO
3
which raised the pH of the soil from 5.0 to 6.5. These studies were designed to characterize this phenomenon more comprehensively. Liming the soil with either CaCO
3
, Ca(OH)
2
, MgO, or K
2
CO
3
significantly (
P
= 0.05) increased the percent nodule occupancy by serogroup 36, whereas the percent nodule occupancy by serogroup 6 was decreased, but the decrease was significant (
P
= 0.05) only after application of either CaCO
3
or Ca(OH)
2
. Application of KH
2
PO
4
(25 mg of P kg of soil
−1
), which did not change soil pH, also significantly (
P
= 0.05) increased the percent nodule occupancy by serogroup 36. Application of KH
2
PO
4
in combination with Ca(OH)
2
produced the same increase in nodule occupancy by serogroup 36 as did individual application of the two materials. Soil populations of serogroup 36 consistently, and in the majority of cases significantly (
P
= 0.05), outnumbered those of serogroup 6 before planting and after harvest regardless of soil treatment or the outcome of nodulation. Soil chemical and plant analyses provided no evidence that liming was simulating phosphate addition by increasing the availability and subsequent uptake of soil P
i
by the subclover plants. Liming did, however, result in a significant transformation (30 to 50 mg of P kg of soil
−1
) of P
i
from the residual soil P
i
fraction into an NaOH-extractable organic P fraction during the preplant equilibration period.
Isolation and Characterization of a Thermophilic Bacterium Which Oxidizes Acetate in Syntrophic Association with a Methanogen and Which Grows Acetogenically on H
2
-CO
2
Authors: Lee Monica J. , Zinder Stephen H.
Published: January 2020

We previously described a thermophilic (60�C), syntrophic, two-membered culture which converted acetate to methane via a two-step mechanism in which acetate was oxidized to H
2
and CO
2
. While the hydrogenotrophic methanogen
Methanobacterium
sp. strain THF in the biculture was readily isolated, we were unable to find a substrate that was suitable for isolation of the acetate-oxidizing member of the biculture. In this study, we found that the biculture grew on ethylene glycol, and an acetate-oxidizing, rod-shaped bacterium (AOR) was isolated from the biculture by dilution into medium containing ethylene glycol as the growth substrate. When the axenic culture of the AOR was recombined with a pure culture of
Methanobacterium
sp. strain THF, the reconstituted biculture grew on acetate and converted it to CH
4
. The AOR used ethylene glycol, 1,2-propanediol, formate, pyruvate, glycine-betaine, and H
2
-CO
2
as growth substrates. Acetate was the major fermentation product detected from these substrates, except for 1,2-propanediol, which was converted to 1-propanol and propionate.
N,N
-Dimethylglycine was also formed from glycine-betaine. Acetate was formed in stoichiometric amounts during growth on H
2
-CO
2
, demonstrating that the AOR is an acetogen. This reaction, which was carried out by the pure culture of the AOR in the presence of high partial pressures of H
2
, was the reverse of the acetate oxidation reaction carried out by the AOR when hydrogen partial pressures were kept low by coculturing it with
Methanobacterium
sp. strain THF. The DNA base composition of the AOR was 47 mol% guanine plus cytosine, and no cytochromes were detected.
Development of a new shuttle plasmid system for Escherichia coli and Clostridium perfringens
Authors: Roberts I , Holmes W M , Hylemon P B
Published: January 2020

We constructed a 7.9-kilobase-pair recombinant shuttle plasmid, designated pHR106, by combining desired segments of three plasmids: an Escherichia coli plasmid (pSL100) which provides a multiple cloning site, a Clostridium perfringens plasmid (pJU122) which provides a clostridial origin of replication, and an E. coli plasmid (pJIR62) which provides an E. coli origin of replication, an ampicillin resistance gene, and a chloramphenicol resistance gene of clostridial origin. The shuttle plasmid transformed E. coli HB101 with a frequency of 1 transformant per 10(4) viable cells and C. perfringens L-phase strain L-13 with a frequency of approximately 1 transformant per 10(6) viable cells. Because of the set of unique cloning sites and the chloramphenicol resistance marker, this shuttle plasmid should be particularly useful for studies of gene regulation and for enzyme production with C. perfringens.
Metabolism of glyphosate in Pseudomonas sp. strain LBr
Authors: Jacob G S , Garbow J R , Hallas L E , Kimack N M , Kishore G M , Schaefer J
Published: January 2020

Metabolism of glyphosate (N-phosphonomethylglycine) by Pseudomonas sp. strain LBr, a bacterium isolated from a glyphosate process waste stream, was examined by a combination of solid-state 13C nuclear magnetic resonance experiments and analysis of the phosphonate composition of the growth medium. Pseudomonas sp. strain LBr was capable of eliminating 20 mM glyphosate from the growth medium, an amount approximately 20-fold greater than that reported for any other microorganism to date. The bacterium degraded high levels of glyphosate, primarily by converting it to aminomethylphosphonate, followed by release into the growth medium. Only a small amount of aminomethylphosphonate (about 0.5 to 0.7 mM), which is needed to supply phosphorus for growth, could be metabolized by the microorganism. Solid-state 13C nuclear magnetic resonance analysis of strain LBr grown on 1 mM [2-13C,15N]glyphosate showed that about 5% of the glyphosate was degraded by a separate pathway involving breakdown of glyphosate to glycine, a pathway first observed in Pseudomonas sp. strain PG2982. Thus, Pseudomonas sp. strain LBr appears to possess two distinct routes for glyphosate detoxification.
Production of Vesicular-Arbuscular Mycorrhizal Fungus Inoculum in Aeroponic Culture
Authors: Hung Ling-Ling L. , Sylvia David M.
Published: January 2020

Bahia grass (
Paspalum notatum
) and industrial sweet potato (
Ipomoea batatas
) colonized by
Glomus deserticola, G. etunicatum
, and
G. intraradices
were grown in aeroponic cultures. After 12 to 14 weeks, all roots were colonized by the inoculated vesicular-arbuscular mycorrhizal fungi. Abundant vesicles and arbuscules formed in the roots, and profuse sporulation was detected intra-and extraradically. Within each fungal species, industrial sweet potato contained significantly more roots and spores per plant than bahia grass did, although the percent root colonization was similar for both hosts. Mean percent root colonization and sporulation per centimeter of colonized root generally increased with time, although with some treatments colonization declined by week 14. Spore production ranged from 4 spores per cm of colonized root for
G. etunicatum
to 51 spores per cm for
G. intraradices.
Infectivity trials with root inocula resulted in a mean of 38, 45, and 28% of bahia grass roots colonized by
G. deserticola, G. etunicatum
, and
G. intraradices
, respectively. The germination rate of
G. etunicatum
spores produced in soil was significantly higher than that produced in aeroponic cultures (64% versus 46%) after a 2-week incubation at 28°C. However, infectivity studies comparing
G. etunicatum
spores from soil and aeroponic culture indicated no biological differences between the spore sources. Aeroponically produced
G. deserticola
and
G. etunicatum
inocula retained their infectivity after cold storage (4°C) in either sterile water or moist vermiculite for at least 4 and 9 months, respectively.
Influence of
Glycine
spp. on Competitiveness of
Bradyrhizobium japonicum
and
Rhizobium fredii
Authors: Cregan P. B. , Keyser H. H.
Published: January 2020

The displacement of indigenous
Bradyrhizobium japonicum
in soybean nodules with more effective strains offers the possibility of enhanced N
2
fixation in soybean (
Glycine max
(L.) Merr.). Our objective was to determine whether the wild soybean (
G. soja
Sieb. & Zucc.) genotype PI 468397 would cause reduced competitiveness of important indigenous
B. japonicum
strains USDA 31, 76, and 123 and thereby permit nodulation by
Rhizobium fredii
, the fast-growing microsymbiont of soybean. In an initial experiment, PI 468397 nodulated and fixed moderate amounts of N
2
with USDA 31 and 76 but, despite the formation of nodules, fixed essentially no N
2
with USDA 123. In contrast, PI 468397 formed a highly effective symbiosis with
R. fredii
strain USDA 193. In two subsequent experiments, Williams soybean and PI 468397 were grown in a pasteurized soil mixture or in soybean rhizobium-free soil and inoculated with both USDA 123 and USDA 193. In each experiment, more than 90% of the nodules of Williams contained USDA 123, while only a maximum of 2% were occupied with USDA 193. In contrast, in the two experiments, 16 and 11%, respectively, of the nodules produced on PI 468397 were occupied by USDA 123, while in both experiments 87% contained USDA 193. Thus, in relation to the cultivar Williams, which is commonly grown and used as a parent in soybean breeding programs in the United States, PI 468397 substantially reduced the competitive ability of
B. japonicum
strain USDA 123 in relation to
R. fredii
strain USDA 193.
Growth of Clostridium perfringens in cooked chili during cooling
Authors: Blankenship L C , Craven S E , Leffler R G , Custer C
Published: January 2020

U.S. Department of Agriculture regulations require that brick chili be cooled from 48.9 degrees C to 4.4 degrees C within 2 h of cooking, but processors may not always be able to comply. Studies were conducted to evaluate the extent of bacterial multiplication resulting from outgrowth of germinated Clostridium perfringens spores experimentally inoculated into chili and incubated at various temperatures. Inoculated samples were heated (75 degrees C for 20 min) to activate spores, quickly equilibrated, and held at one of five desired temperatures for 6 h. No growth was observed for C. perfringens in samples held at 26.7 degrees C and below for 6 h, but growth was observed by 6 h in samples held at 32.2 degrees C and after 2 h in samples held at temperatures between 37.8 degrees C and 48.9 degrees C. Using isothermal growth data, we developed a simple model for predicting the growth of bacteria with time under exponential cooling conditions. The model predicts both the lag phase and the numbers of bacteria at specific times during the growth phase. It was developed by using isothermal growth data and tested by using temperature-varying growth data from experiments with spores of C. perfringens in chili. Actual data agreed closely with predicted results. The results should be useful for evaluating the hazard potential for growth of C. perfringens in chili.
A Proposed Pathway for Catabolism of Propionate in Methanogenic Cocultures
Authors: Robbins J. E.
Published: January 2020

A metabolic pathway for the catabolism of propionate is proposed. This pathway incorporates a transcarboxylation reaction involving propionyl coenzyme A and oxaloacetate and a carboxylation of pyruvate to regenerate oxaloacetate. Data indicated that the proposed pathway is reversible. The proposed pathway and its apparent reversibility provide a reasonable explanation of observations obtained from metabolism of labeled substrate.
Numerical Taxonomic Analysis of Some Strains of
Rhizobium
spp. That Uses a Qualitative Coding of Immunodiffusion Reactions
Authors: Dudman William F. , Belbin Lee
Published: January 2020

Antigenic relationships among seven strains of
Bradyrhizobium japonicum
were examined by immunodiffusion reactions, in which cells of each strain were reacted against each of the seven corresponding antisera. Similar analyses were performed with
Rhizobium trifolii
(28 strains),
Rhizobium meliloti
(9 strains), and rhizobia of the cowpea miscellany (13 strains). Antigens and antisera were reacted within each species only; serological interspecies cross-reactions were not performed. The results, scored qualitatively as reactions of identity, cross-reactions, or no reaction, were formed into datum matrices and used to analyze the relationships between strains by applying the association measure of Bray and Curtis (J. R. Bray and J. T. Curtis, Ecol. Monogr. 27:325-349, 1957) and the UPGMA clustering algorithm (P. H. A. Sneath and R. R. Sokal,
Numerical Taxonomy
, 1973). No two strains were regarded as being serologically identical unless each gave the same results as the other in each immunodiffusion reaction against every antiserum. Despite the high level of cross-reactions and reactions of identity (totalling 93% of all cell-antiserum combinations) among strains of
R. trifolii
and
R. meliloti
, no strains were identical by the criterion described above; however, the strains of these species clustered rapidly and fused at the 70% similarity level. The
B. japonicum
strains and the rhizobia of the cowpea miscellany were much less cross-reactive (67 and 86% of all combinations were negative, respectively), and they clustered more slowly. The strains of
B. japonicum
fused completely only at the 4% similarity level, whereas of the 13 cowpea-nodulating strains, 4 reacted as two pairs of identical strains and 6 remained unfused.
Genetic and Biochemical Characterization of Mutations Affecting the Ability of the Yeast
Pachysolen tannophilus
To Metabolize
d
-Xylose
Authors: James A. P. , Zahab D. M. , Mahmourides G. , Maleszka R. , Schneider H.
Published: January 2020

Induced mutants, selected for their defective growth on
d
-xylose while retaining the ability to grow normally on
d
-glucose, were studied in
Pachysolen tannophilus
, a yeast capable of converting
d
-xylose to ethanol. Fourteen of the mutations were found to occur at nine distinct loci, and data indicated that many more loci remain to be detected. Most of the mutations were pleiotropic in character, and the expression of some of them was much affected by nutritional conditions and by genetic background. Mutations at several loci resulted in poor growth on at least one compound that was either an intermediate of the tricarboxylic acid cycle, succinate or α-ketoglutarate, or on compounds metabolizable via this cycle, ethanol or glycerol. An initial biochemical characterization of the mutants was undertaken. Analysis for xylose reductase, xylitol dehydrogenase, and xylulose kinase activity showed that one or more of these activities was affected in 12 of 13 mutants. However, drastic reduction in activity of a single enzyme was confined to that of xylitol dehydrogenase by mutations at three different loci and to that of
d
-xylose reductase by mutation at another locus. Growth of these latter four mutants was normal on all carbon sources tested that were not five-carbon sugars.
Comparison of ozone inactivation, in flowing water, of hepatitis A virus, poliovirus 1, and indicator organisms
Authors: Herbold K , Flehmig B , Botzenhart K
Published: January 2020

In steadily flowing water at 20 degrees C and pH 7, five organisms had the following order of resistance to ozone (at constant levels of ozone): poliovirus 1 (PV1) less than Escherichia coli less than hepatitis A virus (HAV) less than Legionella pneumophila serogroup 6 less than Bacillus subtilis spores. The tests were repeated at 10 degrees C with HAV, PV1, and E. coli. Ozone inactivation of HAV and E. coli was faster at 10 degrees C than at 20 degrees C. At 20 degrees C, 0.25 to 0.38 mg of O3 per liter was required for complete inactivation of HAV but only 0.13 mg of O3 per liter was required for complete inactivation of PV1.
Characterization of a
Pseudomonas
sp. Capable of Aniline Degradation in the Presence of Secondary Carbon Sources
Authors: Konopka Allan , Knight Deborah , Turco Ronald F.
Published: January 2020

Pseudomonas
strain K1 is a gram-negative rod which grows aerobically on minimal media containing aniline with a doubling time of 2 h at 30°C. The half-saturation parameter for aniline metabolism by aniline-grown cells was 3.8 μmol · liter
−1
. Concentrations of aniline as low as 50 nM were metabolized. Neither substituted anilines nor other aromatic compounds (other than aromatic amino acids) supported growth. Cells grew as fast on aniline as on nonaromatic substrates such as lactate. The aromatic ring was cleaved via the
meta
pathway. Catechol 2,3-oxygenase activity was induced by aniline, even in cultures containing alternative carbon sources such as lactate. Cultures grown on a mixture of aniline and lactate mineralized aniline in the presence of the second substrate. Lactate-grown cultures lacked catechol oxygenase activity, and resting cells from these cultures did not respire aniline. Resting cells from aniline-grown cultures exhibited high respiratory activity upon the addition of aniline or catechol, some activity with toluidine, and no activity after addition of a wide variety of other aromatic compounds, including dihydroxybenzylamine, chloroanilines, ethylanilines, aminophenols, aminobenzoates, and dihydroxybenzoates. Although substituted anilines were not metabolized, 3-or 4-chloroaniline did induce the enzymes for aniline oxidation.
Effect of thermal additions on the density and distribution of thermophilic amoebae and pathogenic Naegleria fowleri in a newly created cooling lake
Authors: Tyndall R L , Ironside K S , Metler P L , Tan E L , Hazen T C , Fliermans C B
Published: January 2020

Pathogenic Naegleria fowleri is the causative agent of fatal human amoebic meningoencephalitis. The protozoan is ubiquitous in nature, and its presence is enhanced by thermal additions. In this investigation, water and sediments from a newly created cooling lake were quantitatively analyzed for the presence of thermophilic amoebae, thermophilic Naegleria spp., and the pathogen Naegleria fowleri. During periods of thermal additions, the concentrations of thermophilic amoebae and thermophilic Naegleria spp. increased as much as 5 orders of magnitude, and the concentration of the pathogen N. fowleri increased as much as 2 orders of magnitude. Concentrations of amoebae returned to prior thermal perturbation levels within 30 to 60 days after cessation of thermal additions. Increases in the thermophilic amoeba concentrations were noted in Savannah River oxbows downriver from the Savannah River plant discharge streams as compared with oxbows upriver from the discharges. Concentrations of thermophilic amoebae and thermophilic Naegleria spp. correlated significantly with temperature and conductivity. Air samples taken proximal to the lake during periods of thermal addition showed no evidence of thermophilic Naegleria spp. Isoenzyme patterns of the N. fowleri isolated from the cooling lake were identical to patterns of N. fowleri isolated from other sites in the United States and Belgium.
Dehalogenation of lindane by a variety of porphyrins and corrins
Authors: Marks T S , Allpress J D , Maule A
Published: January 2020

The dehalogenation of lindane by a range of hemoproteins, porphyrins, and corrins has been tested under reducing conditions in the presence of dithiothreitol. In addition, a series of porphyrin-metal ion complexes have been prepared and have also been screened for the capacity to dehalogenate lindane. Hemoglobin, hemin, hematin, and chlorophyll alpha all catalyzed the dehalogenation of lindane, as did all of the corrins tested. The porphyrins which did not contain metal centers--coproporphyrin, hematoporphyrin, protoporphyrin, and uroporphyrin--were inactive. However, when these porphyrins were then complexed with Co, Fe, Mg, Mo, Ni, or V, lindane dehalogenation was observed. In all cases, the reaction proceeded by an initial dechlorination to produce tetrachlorocyclohexene, which was further dehalogenated to yield chlorobenzene as the end product.
Germination of
Clostridium cylindrosporum
Spores on Medium Containing Uric Acid
Authors: Smith M. , Sullivan C.
Published: January 2020

Clostridium cylindrosporum
spores germinated rapidly under reducing conditions when bicarbonate, uric acid, and calcium were present. Germination rates on 10 mM urate increased with increasing Ca
2+
(maximum rate at 5 mM Ca
2+
or greater). Germination rates on urate (limiting Ca
2+
) increased with increasing urate concentrations to 10 mM urate. At 10 mM Ca
2+
, germination rates reached a maximum at 1 mM urate and remained constant thereafter. Cations (Na
+
, K
+
, Li
+
, and Mg
2+
), purines, purine analogs, and EDTA inhibited germination at limiting calcium concentrations but not (except for 10 mM adenine) at 10 mM Ca
2+
. Methyl viologen or formate did not inhibit germination. Germination was not observed in solutions containing xanthine, hypoxanthine, caffeine, theophylline, 6,8-dihydroxypurine, adenine, allopurinol, formate, glycine, or acetate, even though some of the purines are growth substrates.
Survival of Vibrio anguillarum and Vibrio salmonicida at different salinities
Authors: Hoff K A
Published: January 2020

The fish pathogenic bacteria Vibrio anguillarum and V. salmonicida showed the capacity to survive for more than 50 and 14 months, respectively, in seawater microcosms. A salinity of 5% proved lethal to V. anguillarum harvested in the late-exponential growth phase, whereas a salinity of 9% was lethal to the bacterium after it had been starved at a salinity of 30% for 67 days. The lethal salinity for V. salmonicida harvested in the late-exponential growth phase was probably in the vicinity of 10%. V. anguillarum and V. salmonicida were very sensitive to nalidixic acid. Direct determination of viable cells after incubation with nalidixic acid was not possible, since the cells did not elongate. Samples of V. salmonicida were double stained with fluorescein isothiocyanate-labeled antibodies and 4',6-diamidino-2-phenylindole. After 3 or 4 days of starvation, there was a discrepancy between the total numbers of cells as determined by immunofluorescence versus by staining with 4',6-diamidino-2-phenylindole. The immunofluorescence counts remained high, which indicated the presence of intact cell envelopes but leakage of DNA and other cytoplasm components. After 2 weeks of starvation, for some of the cells, the region stained with 4',6-diamidino-2-phenylindole (i.e., DNA) was markedly smaller than the cell envelope. I attributed this to a shrinkage of the cytoplasm or a confined nucleoid or both. V. anguillarum lost its exoproteolytic activity before 11 days of starvation.
Insect virus: assays for toxic effects and transformation potential in mammalian cells
Authors: Hartig P C , Chapman M A , Hatch G G , Kawanishi C Y
Published: January 2020

The nuclear polyhedrosis virus of Autographa californica (AcNPV) was evaluated by using in vitro test systems for toxicity and transforming potential in mammalian cells. Mass cell cultures of CV-1 and WI38 cells appeared unaffected by AcNPV at a multiplicity of infection of 5. Human foreskin cells grew more slowly after inoculation but eventually produced healthy monolayers. The sensitivities of the inhibition of reproductive survivability assays were greater and demonstrated slight AcNPV toxicity to CV-1, WI38, and human foreskin cells. Toxicity was not ameliorated when gradient-purified or psoralen-inactivated virus was used, suggesting that the toxic component of the preparation is part of the virion or copurifies with it. AcNPV was not toxic to and did not transform BALB/c 3T3 cells or primary cell cultures derived from Syrian hamster embryo cells (SHE). Unlike the BALB/c 3T3 transformation assay, the SHE assay detected no spontaneous transformants. The SHE transformation assay can employ simian adenovirus 7 as a positive control. SHE are transformed by numerous viruses and so are useful in assessment protocols. This study suggests that in vitro assessment of viral pesticide toxicity should employ the inhibition of reproductive survivability assay and that transformation assessment is best done with the SHE-simian adenovirus 7 procedure.
Mechanisms of microbial movement in subsurface materials
Authors: Reynolds P J , Sharma P , Jenneman G E , McInerney M J
Published: January 2020

The biological factors important in the penetration of Escherichia coli through anaerobic, nutrient-saturated, Ottawa sand-packed cores were studied under static conditions. In cores saturated with galactose-peptone medium, motile strains of E. coli penetrated four times faster than mutants defective only in flagellar synthesis. Motile, nonchemotactic mutants penetrated the cores faster than did the chemotactic parental strain. This, plus the fact that a chemotactic galactose mutant penetrated cores saturated with peptone medium at the same rate with or without a galactose gradient, indicates that chemotaxis may not be required for bacterial penetration through unconsolidated porous media. The effect of gas production on bacterial penetration was studied by using motile and nonmotile E. coli strains together with their respective isogenic non-gas-producing mutants. No differences were observed between the penetration rates of the two motile strains through cores saturated with peptone medium with or without galactose. However, penetration of both nonmotile strains was detected only with galactose. The nonmotile, gas-producing strain penetrated cores saturated with galactose-peptone medium five to six times faster than did the nonmotile, non-gas-producing mutant, which indicates that gas production is an important mechanism for the movement of nonmotile bacteria through unconsolidated porous media. For motile strains, the penetration rate decreased with increasing galactose concentrations in the core and with decreasing inoculum sizes. Also, motile strains with the faster growth rates had faster penetration rates. These results imply that, for motile bacteria, the penetration rate is regulated by the in situ bacterial growth rate.(ABSTRACT TRUNCATED AT 250 WORDS)
Degradation of the Ferric Chelate of EDTA by a Pure Culture of an
Agrobacterium
sp
Authors: Lauff John J. , Steele D. Bernie , Coogan Louise A. , Breitfeller James M.
Published: January 2020

A pure culture of an
Agrobacterium
sp. (deposited as ATCC 55002) that mineralizes the ferric chelate of EDTA (ferric-EDTA) was isolated by selective enrichment from a treatment facility receiving industrial waste containing ferric-EDTA. The isolate grew on ferric-EDTA as the sole carbon source at concentrations exceeding 100 mM. As the degradation proceeded, carbon dioxide, ammonia, and an unidentified metabolite(s) were produced; the pH increased, and iron was precipitated from solution. The maximum rate of degradation observed with sodium ferric-EDTA as the substrate was 24 mM/day. At a substrate concentration of 35 mM, 90% of the substrate was degraded in 3 days and 70% of the associated chemical oxygen demand was removed from solution. Less than 15% of the carbon initially present was incorporated into the cell mass. Significant growth of this strain was not observed with uncomplexed EDTA as the sole carbon source at comparable concentrations; however, the ferric chelate of propylenediaminetetraacetic acid (ferric-PDTA) did support growth.
Increased sensitivity of the rapid hydrophobic grid membrane filter enzyme-labeled antibody procedure for Escherichia coli O157 detection in foods and bovine feces
Authors: Szabo R , Todd E , MacKenzie J , Parrington L , Armstrong A
Published: January 2020

Several strains of Escherichia coli O157:H7 artificially inoculated into vegetables and dairy products were recovered on hydrophobic grid membrane filters and enumerated by an enzyme-labeled antibody assay. The mean of the recoveries from 12 fresh vegetables was 108.8%, whereas that from 10 dairy products was 93.2%. Modified tryptic soy broth at 43 degrees C with shaking at 100 rpm provided optimum recovery of the organism from meat, with a sensitivity of less than or equal to 1 CFU/g, which is 10 times more sensitive than direct plating. The method performed equally well with vegetable and dairy products. Tryptic soy broth, however, under the same conditions gave the best results for fecal samples. Of 22 asymptomatic dairy cattle, reported as having positive Brucella titers when assayed with polyclonal antibodies, eight were found to contain E. coli O157 in their feces as demonstrated by the enzyme-labeled antibody assay by using monoclonal antibodies. This finding may explain some of the false-positive Brucella tests.