bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between lactic acid concentration and bacterial spoilage in ground beef
Authors: Nassos P S , King A D , Stafford A E
Published: January 2020

Lactic acid concentration correlated with organoleptic spoilage of refrigerated, coarsely ground beef stored in casings with low oxygen permeability. The samples were assayed over time for lactic acid concentration, total aerobic plate count, percentage of gram-positive organisms, and pH. Lactic acid increased in all samples, as did the bacterial counts and percentage of gram-positive organisms in the total microflora, the latter representing an increase in the lactic acid-producing bacteria. pH was found to decrease in all samples, with the smallest decrease in pH being observed in the meat sample which maintained the lowest proportion of gram-positive organisms. With samples evaluated by a sensory panel, lactic acid levels were found to correlate inversely with odor acceptability.
Possible Involvement of a Megaplasmid in Nodulation of Soybeans by Fast-Growing Rhizobia from China
Authors: Sadowsky Michael J. , Bohlool B. Ben
Published: January 2020

Several isolates from a newly described group of fast-growing acid-producing soybean rhizobia,
Rhizobium japonicum
, were analyzed for plasmid content. All contained from one to four plasmids with molecular weights of 100 × 10
6
or larger. Although most of the isolates shared plasmids of similar size, the restriction endonuclease (
Bam
HI,
Eco
RI, and
Hin
dIII) patterns of the plasmids from three of the isolates were vastly different. Growth in the presence of acridine orange was effective in producing mutants cured of the largest plasmid in one of the strains. These mutants also lost the ability to form nodules on soybeans. High-temperature curing of a smaller plasmid in another strain did not lead to loss of nodulating ability or alteration of symbiotic effectiveness on soybean cultivars. The identities of all of the isolates and mutants were ascertained by immunofluoresence and immunodiffusion. The new fast-growing strains of
R. japonicum
may provide a better genetic system for the study of the soybean symbiosis than the slow-growing
R. japonicum
, not all of which can be shown to contain plasmids.
Comparison of cytotoxicity and thin-layer chromatography methods for detection of mycotoxins
Authors: Robb J , Norval M
Published: January 2020

Thirty-three standard mycotoxins were assayed by thin-layer chromatography and by cytotoxicity in HEp-2 and Chang cells. Various levels of detection were found. The cytotoxicity test was significantly more sensitive than thin-layer chromatography for the trichothecenes and should be useful for screening extracts from animal feedstuffs for the presence of unknown mycotoxins.
Effect of UV Light on Spore Viability and Mosquito Larvicidal Activity of
Bacillus sphaericus
1593
Authors: Burke William F. , McDonald Karen Orzech , Davidson Elizabeth W.
Published: January 2020

UV light from a germicidal lamp rapidly reduced the viability of
Bacillus sphaericus
1593 spores, but insecticidal activity was resistant to inactivation by continuous exposure to UV light for 4 h.
Effect of Storm Events on Benthic Nitrifying Activity
Authors: Cooper A. Bryce
Published: January 2020

Storm events resulted in a marked reduction in the benthic nitrifying activity of a stream receiving geothermal inputs of ammonium. Subsequently, nitrifying activity demonstrated a logarithmic increase until a stable activity was reached 10 to 12 days after the storm event. The rate of increase of poststorm nitrifying activity was used to calculate the nitrifier growth rate in situ (0.0075 to 0.0116 h
−1
) which was lower than the growth rates observed for laboratory cultures of nitrifying bacteria isolated from the sediments (0.0233 to 0.0990 h
−1
).
Ecology and Physiology of the Competition for Light Between
Chlorobium limicola
and
Chlorobium phaeobacteroides
in Natural Habitats
Authors: Montesinos Emilio , Guerrero Ricardo , Abella Carlos , Esteve Isabel
Published: January 2020

Accurate studies of the pigment composition and isolation in pure cultures of
Chlorobiaceae
from samples of eight Spanish lakes show that there are two main coexisting groups of green and brown
Chlorobium
spp. represented respectively by
Chlorobium limicola
and
Chlorobium phaeobacteroides
. Laboratory experiments with pure and mixed cultures of the isolated strains show that light quality plays a selective role on the species composition among
Chlorobiaceae
. This selection depends on the pigment composition which determines the in vivo absorption spectrum of the cells as well as on their ability to adjust the intracellular concentration of light-harvesting pigments to the spectral distribution and energy of light. Correlation analysis performed with field data resulted in significant, but low, correlation coefficients. Nevertheless, they were consistent with laboratory data showing that brown
Chlorobiaceae
were dominant in deep layers in meromictic lakes, whereas green
Chlorobiaceae
dominated in layers nearer the surface or underneath plates of
Chromatiaceae
. The combination of laboratory and field observations stress the role of biological light filtering in determining the species composition among
Chlorobiaceae
in lakes.
System Development for Linked-Fermentation Production of Solvents from Algal Biomass
Authors: Nakas J. P. , Schaedle M. , Parkinson C. M. , Coonley C. E. , Tanenbaum S. W.
Published: January 2020

Five species of the genus
Dunaliella
(
D. tertiolecta, D. primolecta, D. parva, D. bardawil
, and
D. salina
) were examined for glycerol accumulation, growth rate, cell density, and protein and chlorophyll content. The suitability of each algal species for use as a fermentation substrate was judged according to glycerol accumulation and quantities of neutral solvents produced after sequential bacterial fermentations. When grown in 2 M NaCl, with 24 mM NaHCO
3
or 3% CO
2
at 28°C and with 10,000 to 15,000 lx of incident light on two sides of a glass aquarium, four of the five species tested produced ca. 10 to 20 mg of glycerol per liter of culture.
Clostridium pasteurianum
was found to convert an algal biomass mixture supplemented with 4% glycerol to ca. 16 g of mixed solvents (
n
-butanol, 1,3-propanediol, and ethanol) per liter. Acetone was not detected. Additionally, it has been demonstrated that
Dunaliella
concentrates of up to 300-fold can be directly fermented to an identical pattern of mixed solvents. Overall solvent yields were reduced by >50% when fermentations were performed in the presence of 2% NaCl. These results are discussed in terms of practical application in tropical coastal zones.
Degradation of chlorophenols by a defined mixed microbial community
Authors: Schmidt E , Hellwig M , Knackmuss H J
Published: January 2020

Synthetic sewage containing phenol, acetone, and alkanols plus 4-chlorophenol or a mixture of isomeric chlorophenols is completely degraded by a defined mixed culture with Pseudomonas sp. strain B13 as a chlorocatechol-dissimilating member of the community. Total degradation of the organic carbon was indicated by release of stoichiometric amounts of chloride and low content of dissolved organic carbon in the cell-free effluents. During adaptation to high loads of chlorophenols the initial meta-cleavage activity was completely replaced by ortho-cleavage activity of type I and II. In the fully acclimated culture, hybrid strains such as Alcaligenes sp. strain A7-2 were detected, which are more competitive than Pseudomonas sp. strain B13 with respect to chlorophenol degradation.
Alternative prey: a mechanism for elimination of bacterial species by protozoa
Authors: Mallory L M , Yuk C S , Liang L N , Alexander M
Published: January 2020

Antibiotic-resistant strains of Salmonella typhimurium and Klebsiella pneumoniae died readily after their addition to raw sewage, but they grew in sterilized sewage. The decline was not a result of abiotic stresses, and because the bacteria were able to survive in large numbers for at least 15 days in solutions containing no organic nutrients, it was not a result of competition. Toxin production, bacteriophages, and Bdellovibrio sp. did not cause the disappearance of the two bacterial species. A decline was also evident if the sewage was first passed through a 3-micron (pore size) filter or treated with cycloheximide or cycloheximide plus nystatin, but protozoa developed under these conditions. Little or no decline occurred if the sewage was filtered and treated with the eucaryotic inhibitors before the addition of S. typhimurium or K. pneumoniae, and protozoa were not detected. S. typhimurium increased in abundance if cycloheximide, streptomycin, and erythromycin or large amounts of glucose were added to sewage. Tetrahymena thermophilus did not significantly reduce the population of S. typhimurium in buffer when the density of the bacterium was about 10(4)/ml. However, when more than 10(8) Enterobacter agglomerans cells per ml were added to the buffer, T. thermophilus reduced the abundance of E. agglomerans and S. typhimurium to 10(6) and 10/ml, respectively. The density of S. typhimurium was further decreased by a second increment of E. agglomerans cells. The disappearance of S. typhimurium and K. pneumoniae from sewage thus is the result of predation by protozoa.(ABSTRACT TRUNCATED AT 250 WORDS)
Isolation and enumeration of Campylobacter jejuni from poultry products by a selective enrichment method
Authors: Wesley R D , Swaminathan B , Stadelman W J
Published: January 2020

A direct selective enrichment procedure was developed for the isolation of Campylobacter jejuni from poultry products. The selective enrichment medium (ATB) consisted of (per liter) tryptose (20 g), yeast extract (2.5 g), sodium chloride (5 g), FBP supplement (ferrous sulfate [0.25 g], sodium metabisulfite [0.25 g], sodium pyruvate [0.25 g]), bicine (10 g), and agar (1 g). Hematin solution (6.25 ml; prepared by dissolving 0.032 g of bovine hemin in 10 ml of 0.15 N sodium hydroxide solution and autoclaving at 0.35 kg/cm2 for 30 min), rifampin (25 mg), cefsulodin (6.25 mg), and polymyxin B sulfate (20,000 IU) were added after the medium was sterilized. The pH was adjusted to 8.0. Samples were enriched in the above medium at 42 degrees C for 48 h under an atmosphere of 5% O2, 10% CO2, and 85% N2. Enrichment cultures were streaked on a plating medium composed of Brucella agar, hematin solution, FBP supplement, and the above antibiotics. Plates were incubated under the same conditions as above. Suspect colonies from the plates were confirmed to be C. jejuni by morphological examination, growth characteristics, and biochemical tests. The above method yielded 25 isolates of C. jejuni from 50 samples of retail cut-up chicken and chicken parts, whereas a more complex method involving filtration, centrifugation, selective enrichment under a flowing atmosphere, and membrane filtration yielded only 6 positives from the same samples. The new isolation procedure was particularly effective in isolating C. jejuni in the presence of large numbers of Pseudomonas aeruginosa.(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of ambient temperature storage on potable water coliform population estimations
Authors: Standridge J H , Delfino J J
Published: January 2020

The effect of the length of time between sampling potable water and performing coliform analyses has been a long-standing controversial issue in environmental microbiology. The issue is of practical importance since reducing the sample-to-analysis time may substantially increase costs for water analysis programs. Randomly selected samples (from those routinely collected throughout the State of Wisconsin) were analyzed for total coliforms after being held at room temperature (20 +/- 2 degrees C) for 24 and 48 h. Differences in results for the two holding times were compared with differences predicted by probability calculations. The study showed that storage of the potable water for up to 48 h had little effect on the public health significance of most samples containing more than two coliforms per 100 ml.
Characterization of Phage-Sensitive Mutants from a Phage-Insensitive Strain of
Streptococcus lactis
: Evidence for a Plasmid Determinant that Prevents Phage Adsorption
Authors: Sanders Mary Ellen , Klaenhammer Todd R.
Published: January 2020

A phage-insensitive strain of
Streptococcus lactis
, designated ME2, was used as a prototype strain for the study of mechanisms and genetics of phage resistance in the lactic streptococci. Mutants sensitive to a
Streptococcus cremoris
phage, ϕ18, were isolated at a level of 17% from cultures of ME2 after sequential transfer at 30°C. Phage-sensitive mutants of ME2 were not fully permissive to ϕ18. The efficiency of plating of ϕ18 on the mutants was 5 × 10
−7
as compared with <10
−9
for ϕ18 on ME2. Further characterization of the mutants showed that they efficiently adsorbed ϕ18 at levels of >99.8%, whereas ME2 adsorbed only 20 to 40% of ϕ18. These results suggest that increased phage susceptibility of the mutants may result from the loss of a mechanism that inhibits phage adsorption. Moreover, the high frequency of spontaneous mutation in ME2 indicates the involvement of an unstable genetic determinant in this phage defense mechanism. ME2 was shown to possess 13 plasmids ranging in size from 1.6 to 34 megadaltons. Of 40 mutants examined that had increased efficiencies of plating, all were missing a 30-megadalton plasmid, pME0030. These data suggest that pME0030 codes for a function that prevents phage adsorption. Further phenotypic characterization of the phage-sensitive mutants showed that some mutants were deficient in the ability to ferment lactose (Lac) and hydrolyze milk proteins (Prt). However, the Lac
+
and Prt
+
phenotype segregated independently of the phage-sensitivity phenotype. One phage-sensitive adsorption mutant, designated N1, was tested for susceptibility to 14 different phages. N1 showed increased capacity to adsorb 4 and to replicate 2 of these 14 phages, thereby indicating a phage resistance mechanism in ME2 that generalizes to phage interactions other than the specific ϕ18-ME2 phage-host interaction. These data provide evidence for a unique plasmid-linked phage defense mechanism in phage-insensitive strains of lactic streptococci.
Relationship Between Lignin Degradation and Production of Reduced Oxygen Species by
Phanerochaete chrysosporium
Authors: Faison Brendlyn D. , Kirk T. Kent
Published: January 2020

The relationship between the production of reduced oxygen species, hydrogen peroxide (H
2
O
2
), superoxide (O
2
∸
), and hydroxyl radical (·OH), and the oxidation of synthetic lignin to CO
2
was studied in whole cultures of the white-rot fungus
Phanerochaete chrysosporium
Burds. The kinetics of the synthesis of H
2
O
2
coincided with the appearance of the ligninolytic system; also, H
2
O
2
production was markedly enhanced by growth under 100% O
2
, mimicking the increase in ligninolytic activity characteristic of cultures grown under elevated oxygen tension. Lignin degradation by whole cultures was inhibited by a specific H
2
O
2
scavenger, catalase, implying a role for H
2
O
2
in the degradative process. Superoxide dismutase also inhibited lignin degradation, suggesting that O
2
∸
is also involved in the breakdown of lignin. The production of ·OH was assayed in whole cultures by a benzoate decarboxylation assay. Neither the kinetics of ·OH synthesis nor the final activity of its producing system obtained under 100% O
2
correlated with that of the lignin-degrading system. However, lignin degradation was inhibited by compounds which react with ·OH. It is concluded that H
2
O
2
, and perhaps O
2
∸
, are involved in lignin degradation; because these species are relatively unreactive per se, their role must be indirect. Conclusions about a role for ·OH in ligninolysis could not be reached.
Energetics of Growth of a Defined Mixed Culture of
Desulfovibrio vulgaris
and
Methanosarcina barkeri
: Interspecies Hydrogen Transfer in Batch and Continuous Cultures
Authors: Traore Alfred S. , Fardeau Marie-Laure , Hatchikian Claude E. , Le Gall Jean , Belaich Jean-Pierre
Published: January 2020

Interspecies hydrogen transfer was studied in
Desulfovibrio vulgaris-Methanosarcina barkeri
mixed cultures. Experiments were performed under batch and continuous growth culture conditions. Lactate or pyruvate was used as an energy source. In batch culture and after 30 days of simultaneous incubation, these organisms were found to yield 1.5 mol of methane and 1.5 mol of carbon dioxide per mol of lactate fermented. When
M. barkeri
served as the hydrogen acceptor, growth yields of
D. vulgaris
were higher compared with those obtained on pyruvate without any electron acceptor other than protons. In continuous culture, all of the carbon derived from the oxidation of lactate was recovered as methane and carbon dioxide, provided the dilution rate was minimal. Increasing the dilution rate induced a gradual accumulation of acetate, causing acetate metabolism to cease at above μ = 0.05 h
−1
. Under these conditions all of the methane produced originated from carbon dioxide. The growth yields of
D. vulgaris
were measured when sulfate or
M. barkeri
was the electron acceptor. Two key observations resulted from the present study. First, although sulfate was substituted by
M. barkeri
, metabolism of
D. vulgaris
was only slightly modified. The coculture-fermented lactate produced equimolar quantities of carbon dioxide and methane. Second, acetogenesis and methane formation from acetate were completely separable.
Predominant Bacteria in an Activated Sludge Reactor for the Degradation of Cutting Fluids
Authors: Baker C. A. , Claus G. W. , Taylor P. A.
Published: January 2020

For the first time, an activated sludge reactor, established for the degradation of cutting fluids, was examined for predominant bacteria. In addition, both total and viable numbers of bacteria in the reactor were determined so that the percentage of each predominant type in the total reactor population could be determined. Three samples were studied, and a total of 15 genera were detected. In each sample, the genus
Pseudomonas
and the genus
Microcyclus
were present in high numbers. Three other genera,
Acinetobacter, Alcaligenes
, and
Corynebacterium
, were also found in every sample but in lower numbers. In one sample, numerous appendaged bacteria were present, and one of these, the genus
Seliberia
, was the most predominant organism in that sample. However, in the other two samples no appendaged bacteria were detected. Six genera were found in this reactor which have not been previously reported in either cutting fluids in use or in other activated sludge systems. These genera were
Aeromonas, Hyphomonas, Listeria, Microcyclus, Moraxella
, and
Spirosoma.
None of the predominant bacteria belonged to groups of strict pathogens.
Influence of a Calcium-Specific Chelant on Biofilm Removal
Authors: Turakhia M. H. , Cooksey K. E. , Characklis W. G.
Published: January 2020

This paper describes the influence of ethylene glycol-bisβ-aminoethyl ether)- N, N-tetraacetic acid (EGTA) on biofilm removal. The addition of EGTA resulted in the immediate detachment of biofilm which suggests that the chelant removed essential calcium from the biofilm, causing it to detach.
Effects of Environmental Toxicants on Metabolic Activity of Natural Microbial Communities
Authors: Barnhart Carole L. H. , Vestal J. Robie
Published: January 2020

Two methods of measuring microbial activity were used to study the effects of toxicants on natural microbial communities. The methods were compared for suitability for toxicity testing, sensitivity, and adaptability to field applications. This study included measurements of the incorporation of
14
C-labeled acetate into microbial lipids and microbial glucosidase activity. Activities were measured per unit biomass, determined as lipid phosphate. The effects of various organic and inorganic toxicants on various natural microbial communities were studied. Both methods were useful in detecting toxicity, and their comparative sensitivities varied with the system studied. In one system, the methods showed approximately the same sensitivities in testing the effects of metals, but the acetate incorporation method was more sensitive in detecting the toxicity of organic compounds. The incorporation method was used to study the effects of a point source of pollution on the microbiota of a receiving stream. Toxic doses were found to be two orders of magnitude higher in sediments than in water taken from the same site, indicating chelation or adsorption of the toxicant by the sediment. The microbiota taken from below a point source outfall was 2 to 100 times more resistant to the toxicants tested than was that taken from above the outfall. Downstream filtrates in most cases had an inhibitory effect on the natural microbiota taken from above the pollution source. The microbial methods were compared with commonly used bioassay methods, using higher organisms, and were found to be similar in ability to detect comparative toxicities of compounds, but were less sensitive than methods which use standard media because of the influences of environmental factors.
Factors Determining Annual Changes in Bacterial Photosynthetic Pigments in Holomictic Lake Cisó, Spain
Authors: Pedrós-Alió Carlos , Montesinos Emilio , Guerrero Ricardo
Published: January 2020

The pigments and biomass of anoxygenic phototrophic bacteria were measured during a year cycle in Lake Cisó (Girona, Spain). Two genera,
Chromatium
and
Chlorobium
, accounted for most of the bacterial population. The bacteria were present throughout the year despite complete mixing of the lake during fall and winter. This was possible because the sulfide production in the sediment was high enough to make the lake anaerobic to the very surface. Solar radiation, temperature, and biomass of
Chromatium
sp. were found to be important in determining pigment concentrations by correlation analysis. Sulfide concentration and biomass of
Chlorobium
spp. were found to be unimportant. A path analysis was performed to determine what percentage of the variability of pigments could be explained by the variables studied. Since a high percentage could be explained, it was possible to conclude that solar radiation, temperature, and biomass of
Chromatium
sp. were the main variables.
Malachite green-INT (MINT) method for determining active bacteria in sewage
Authors: Dutton R J , Bitton G , Koopman B
Published: January 2020

A membrane filtration method was developed to determine the proportion of active (respiring) bacteria at various stages of sewage treatment. Samples were incubated in the presence of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) and, after fixation, passed through membrane filters. Filters were counterstained with malachite green and then were examined by bright-field microscopy. The contrast between bacteria and the filter background was greatly improved by drying and then clearing the filter before counterstaining. By this method, it was found that active bacterial fractions in raw sewage, settled sewage, and secondary effluent were 40, 29, and 58%, respectively, whereas the proportion of respiring bacteria in chlorinated secondary effluent was 6.1%. The active bacterial fraction of activated sludge was found to be 16%. The proposed method represents a significant improvement in speed and simplicity over existing methods for determining active bacteria in sewage.
Aerobic and Anaerobic Catabolism of Vanillic Acid and Some Other Methoxy-Aromatic Compounds by
Pseudomonas
sp. Strain PN-1
Authors: Taylor Barrie F.
Published: January 2020

Vanillic acid (4-hydroxy-3-methoxybenzoic acid) supported the anaerobic (nitrate respiration) but not the aerobic growth of
Pseudomonas
sp. strain PN-1. Cells grown anaerobically on vanillate oxidized vanillate,
p
-hydroxybenzoate, and protocatechuic acid (3,4-dihydroxybenzoic acid) with O
2
or nitrate. Veratric acid (3,4-dimethoxybenzoic acid) but not isovanillic acid (3-hydroxy-4-methoxybenzoic acid) induced cells for the oxic and anoxic utilization of vanillate, and protocatechuate was detected as an intermediate of vanillate breakdown under either condition. Aerobic catabolism of protocatechuate proceeded via 4,5-
meta
cleavage, whereas anaerobically it was probably dehydroxylated to benzoic acid. Formaldehyde was identified as a product of aerobic demethylation, indicating a monooxygenase mechanism, but was not detected during anaerobic demethylation. The aerobic and anaerobic systems had similar but not identical substrate specificities. Both utilized
m
-anisic acid (3-methoxybenzoic acid) and veratrate but not
o
- or
p
-anisate and isovanillate. Syringic acid (4-hydroxy-3,5-dimethoxybenzoic acid), 3-
O
-methylgallic acid (3-methoxy-4,5-dihydroxybenzoic acid), and 3,5-dimethoxybenzoic acid were attacked under either condition, and formaldehyde was liberated from these substrates in the presence of O
2
. The anaerobic demethylating system but not the aerobic enzyme was also active upon guaiacol (2-methoxyphenol), ferulic acid (3-[4-hydroxy-3-methoxyphenyl]-2-propenoic acid), 3,4,5-trimethoxycinnamic acid (3-[3,4,5-trimethoxyphenyl]-2-propenoic acid), and 3,4,5-trimethoxybenzoic acid. The broad specificity of the anaerobic demethylation system suggests that it probably is significant in the degradation of lignoaromatic molecules in anaerobic environments.
Mechanism of chlorine inactivation of DNA-containing parvovirus H-1
Authors: Churn C C , Bates R C , Boardman G D
Published: January 2020

An investigation was undertaken to determine the effect of chlorine on a small DNA-containing enteric virus. Parvovirus H-1 was exposed to sodium hypochlorite in a phosphate-buffered saline solution at pH 7. Then, the whole virion, the protein capsid, or the nucleic acid was subjected to analysis. The sedimentation rate of the chlorine-treated whole virus decreased from 110S to 43S. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the virus demonstrated the formation of higher-molecular-weight aggregates resulting from covalent cross-linking of the capsid proteins. Electron microscopic examination revealed that the DNA was extruded as a taillike structure which remained attached to the virus particle. Furthermore, the DNA was intact and still capable of in vitro replication. The adsorption of the chlorine-treated virions to host cells was inhibited, presumably due to the effect of chlorine on the particular spatial arrangement of the capsid proteins required for adsorption. Specific sites on these proteins had become highly reactive, indicating that the initial action of chlorine on parvovirus H-1 was on the viral capsid.
Production of cyclopiazonic acid by Aspergillus tamarii Kita
Authors: Dorner J W
Published: January 2020

Production of the mycotoxin cyclopiazonic acid by Aspergillus tamarii Kita is reported for the first time. Examination of 23 isolates of the fungus showed that 22 produced the toxin under the culture conditions utilized.
Bacterial chemotaxis to effluent from a rum distillery in tropical near-shore coastal waters
Authors: Fuentes F A , Biamon E J , Hazen T C
Published: January 2020

Pseudomonas aeruginosa and Vibrio cholerae showed a strong positive chemotactic response towards rum distillery wastewaters (mostos) and a high oxygen uptake rate in the presence of this complex substrate. Rum slops stimulated only motility in Aeromonas hydrophila and Escherichia coli. The A. hydrophila and E. coli isolates were unable to oxidize mostos significantly.
Anaerobic degradation of coniferyl alcohol by methanogenic consortia
Authors: Grbić-Galić D
Published: January 2020

Coniferyl alcohol was shown to be completely biodegradable to carbon dioxide and methane under strictly anaerobic culture conditions. The mineralization of 300 mg of the substrate per liter was observed in acclimated ferulic acid-degrading methanogenic consortia, as well as in anaerobic enrichments on coniferyl alcohol seeded with sewage sludge. Ferulic and phenylpropionic acids were detected in the cultures degrading coniferyl alcohol as the sole carbon and energy source, suggesting that this compound is oxidized to ferulic acid, which is then degraded as previously described.
Failure of nisin to inhibit outgrowth of Clostridium botulinum in a model cured meat system
Authors: Rayman K , Malik N , Hurst A
Published: January 2020

Up to 550 ppm (550 micrograms/ml) of nisin in combination with 60 ppm (60 micrograms/ml) of nitrite failed to prevent outgrowth of Clostridium botulinum spores in pork slurries adjusted to pH 5.8. Reducing the pH enhanced nisin activity. Proteolytic and nonproteolytic type B spores were equally resistant to nisin.
Methanogenesis from Sucrose by Defined Immobilized Consortia
Authors: Jones W. Jack , Guyot Jean-Pierre , Wolfe Ralph S.
Published: January 2020

A bacterial consortium capable of sucrose degradation primarily to CH
4
and CO
2
was constructed, with acetate as the key methanogenic precursor. In addition, the effect of agar immobilization on the activity of the consortium was determined. The primary fermentative organism,
Escherichia coli
, produced acetate, formate, H
2
, and CO
2
(known substrates for methanogens), as well as ethanol and lactate, compounds that are not substrates for methanogens. Oxidation of the nonmethanogenic substrates, lactate and ethanol, to acetate was mediated by the addition of
Acetobacterium woodii
and
Desulfovibrio vulgaris
. The methanogenic stage was accomplished by the addition of the acetophilic methanogen
Methanosarcina barkeri
and the hydrogenophilic methanogen
Methanobacterium formicicum
. Results of studies with low substrate concentrations (0.05 to 0.2% [wt/vol]), a growth-limiting medium, and the five-component consortium indicated efficient conversion (40%) of sucrose carbon to CH
4
. Significant decreases in yields of CH
4
and rates of CH
4
production were observed if any component of the consortium was omitted. Approximately 70% of the CH
4
generated occurred via acetate. Agar-immobilized cells of the consortium exhibited yields of CH
4
and rates of CH
4
production from sucrose similar to those of nonimmobilized cells. The rate of CH
4
production decreased by 25% when cysteine was omitted from reaction conditions and by 40% when the immobilized consortium was stored for 1 week at 4°C.
Cloning and sequencing of the xylose isomerase and xylulose kinase genes of Escherichia coli
Authors: Lawlis V B , Dennis M S , Chen E Y , Smith D H , Henner D J
Published: January 2020

A 4.2-kilobase-pair fragment of the Escherichia coli chromosome which contains the genes for xylose isomerase and xylulose kinase was cloned into plasmid pBR322. The hybrid plasmid (designated pECX14) complements strains deficient in either or both of the two enzymes. Deletion derivatives of pECX14 were used to localize the two genes on the cloned fragment. The entire nucleotide sequence of the cloned fragment was determined. Open reading frames which, if translated, would encode proteins of molecular weights 54,000 and 52,000 were found. These were identified as the isomerase and kinase structural genes, respectively.
Bacteriological analysis of water by potentiometric measurement of lipoic acid reduction: preliminary assays for selective detection of indicator organisms
Authors: Charriere G , Jouenne T , Lemeland J F , Selegny E , Junter G A
Published: January 2020

The practical task of adapting an original potentiometric technique to the bacteriological analysis of water is discussed. Various laboratory strains of organisms belonging to the usual aquatic flora were inoculated one by one in a minimal lactose broth supplied with lipoic (thioctic) acid. The time evolution of the redox potential of the cultures was followed during incubation by combined gold versus reference electrodes. When the incubation temperature was regulated at 36 degrees C, most organisms were able to grow and to reduce the coenzyme, generating changes in the redox potential of the culture. However, very few organisms developed significant reductive activity when the temperature was increased to 41 degrees C and when the broth was provided with sodium deoxycholate. Among the fecal coliform organisms, only Escherichia coli and Klebsiella pneumoniae exhibited early but reproducible potential-time responses. Positive potentiometric responses were also recorded with Acinetobacter calcoaceticus. E. coli showed rapid potentiometric signals as compared with K. pneumoniae. The time required for 100-mV shift of potential to be detected was related to the logarithm of the initial concentration of E. coli or K. pneumoniae in the culture broth. Experiments on natural surface water samples showed the the potentiometric method, associated with the selective incubation conditions, mainly detected E. coli among the bacterial flora of the tested environmental water. The calibration curve relating the time required for a 100-mV shift of potential to be detected to the number of fecal coliforms, as determined by control fecal coliform-selective plate counts, was consistent with the composite standard curve of detection times obtained with six different laboratory strains of E. coli.(ABSTRACT TRUNCATED AT 250 WORDS)
Some characteristics and antibiotic resistance of anaerobic bacteria from the ceca and colons of pigs fed chlortetracycline-containing and unmedicated diets
Authors: Dawson K A , Langlois B E , Stahly T S , Cromwell G L
Published: January 2020

Morphology and end product patterns were used to group 112 bacterial isolates from the ceca and colons of pigs fed unmedicated and chlortetracycline-containing diets. Most of the isolates (68%) were resistant to chlortetracycline (greater than 4 micrograms/ml). Chlortetracycline resistance was associated with all groups of anaerobic and facultative bacteria.
Cellulolytic bacteria from pig large intestine
Authors: Varel V H , Fryda S J , Robinson I M
Published: January 2020

An anaerobic, cellulose-degrading, gram-negative rod and a gram-positive coccus, identified as Bacteroides succinogenes and Ruminococcus flavefaciens, respectively, were isolated from pig fecal samples. These organisms were isolated from cellulolytic most-probable-number dilutions which represented 4 or 6% of the viable bacterial count when pigs were fed a low- or high-fiber diet, respectively.
Biotransformation of linoleic acid and bile acids by Eubacterium lentum
Authors: Eyssen H , Verhulst A
Published: January 2020

Eubacterium lentum is a gram-positive, nonsporeforming, nonmotile, asaccharolytic anaerobe. In the present investigations, 3 E. lentum strains (group E) isolated from rat feces were compared with 30 E. lentum strains (groups A, B, C, and D) previously studied by Macdonald et al. (I. A. Macdonald, J. F. Jellet, D. E. Mahony, and L. V. Holdeman, Appl. Environ. Microbiol. 37:992-1000, 1979). All strains alkalized (pH 8 to 8.5) arginine-containing (2 to 15 mg/ml) culture media, and growth of the majority of the strains was stimulated by arginine. All strains converted linoleic acid into transvaccenic acid by shifting the 12,13-cis double bond of linoleic acid into an 11,12-trans(?) double bond followed by biohydrogenation of the 9,10-cis double bond. Hence, biohydrogenation of linoleic acid is a new general characteristic of E. lentum. The 33 strains were also studied for bile acid deconjugase and hydroxysteroid dehydrogenase (HSDH) activities. The 6 strains in group D were steroid inactive; the 27 strains in groups A, B, C, and E were steroid active. The steroid-active group contained bile acid deconjugase-producing strains (groups C and E, plus strain 116 in group A) and nondeconjugating strains. All nondeconjugating strains of groups A and B developed 7 alpha- and 12 alpha-HSDH activities and contained 3 alpha-HSDH-positive strains and 3 alpha-HSDH-negative strains. Deconjugating strains varied in HSDH activities.
Nitrogen-Fixing Bacteria from Warty Lenticellate Bark of a Mangrove Tree,
Bruguiera gymnorrhiza
(L.) Lamk
Authors: Uchino Fuji , Hambali Gregori G. , Yatazawa Michihiko
Published: January 2020

Detached warty lenticellate bark of a mangrove tree species,
Bruguiera gymnorrhiza
(L.) Lamk. from Iriomote Island, Okinawa, a subtropical region of Japan, showed development of acetylene reduction activity when incubated in a mineral nutrient solution lacking nitrogen under an atmosphere consisting of 5% O
2
, 90% N
2
, and 5% C
2
H
2
. The bacteria responsible for nitrogen fixation were isolated from the bark, and their capacity for acetylene reduction and the incorporation of
15
N
2
into the bacterial cells was confirmed. Four representative strains of the isolates were subjected to taxonomic classification. Two strains were similar to
Enterobacter cloacae
, and another resembled
Enterobacter aerogenes
. The characteristics of the fourth strain were similar to those of
Klebsiella planticola
(Bagley et al., Curr. Microbiol. 6:105-109, 1981). The results of this investigation suggest that the acetylene reduction activity of lenticellate warts of mangrove trunk bark is due to the presence in the warts of nitrogen-fixing bacteria belonging to the family
Enterobacteriaceae.
Pasteurization of naturally contaminated water with solar energy
Authors: Ciochetti D A , Metcalf R H
Published: January 2020

A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. On clear or partly cloudy days, with the SBC facing magnetic south in Sacramento, bottom water temperatures of at least 65 degrees C could be obtained in 11.1 liters of water during the 6 weeks on either side of the summer solstice, in 7.4 liters of water from mid-March through mid-September, and in 3.7 liters of water an additional 2 to 3 weeks at the beginning and end of the solar season. Periodic repositioning of the SBC towards the sun, adjusting the back reflective lid, and preheating water in a simple reflective device increased final water temperatures. Simultaneous cooking and heating water to pasteurizing temperatures was possible. Additional uses of the SBC to pasteurize soil and to decontaminate hospital materials before disposal in remote areas are suggested.
Fermentation of 6-Deoxyhexoses by
Bacillus macerans
Authors: Weimer Paul J.
Published: January 2020

Under anaerobic conditions
Bacillus macerans
ATCC 7068 fermented 6-deoxyhexoses (
l
-rhamnose,
l
-fucose, and
d
-fucose) to a mixture of 1,2-propanediol (PD), acetone, H
2
, CO
2
, and ethanol. The final PD concentration was proportional to the amount of
l
-rhamnose fermented (∼0.9 mol of PD per mol of rhamnose). PD was not produced from hexoses (e.g.,
d
-glucose or
l
-mannose), despite active fermentation of these substrates. Relative to the fermentation of
d
-glucose, the fermentation of
l
-rhamnose was accompanied by a twofold reduction in yield of H
2
, CO
2
, and cell mass. Exposure of cell extracts to
l
-rhamnose resulted in the transient appearance of an aldehyde intermediate. Cell extracts contained a pyridine nucleotide-linked lactaldehyde reductase activity which converted synthetic
d
- or
l
-lactaldehyde to PD. The data suggest an Embden-Meyerhof pathway for 6-deoxyhexose catabolism, with the formation of lactaldehyde by a conventional aldolase cleavage reaction and subsequent reduction to PD.
Anaerobic biodegradation of chlorophenols in fresh and acclimated sludge
Authors: Boyd S A , Shelton D R
Published: January 2020

We investigated the anaerobic biodegradation of mono- and dichlorophenol isomers by fresh (unacclimated) sludge and by sludge acclimated to either 2-chlorophenol, 3-chlorophenol, or 4-chlorophenol. Biodegradation was evaluated by monitoring substrate disappearance and, in selected cases, production of 14CH4 from labeled substrates. In unacclimated sludge, each of the monochlorophenol isomers was degraded. The relative rates of disappearance were in this order: ortho greater than meta greater than para. For the dichlorophenols in unacclimated sludge, reductive dechlorination of the Cl group ortho to phenolic OH was observed, and the monochlorophenol compounds released were subsequently degraded. 3,4-Dichlorophenol and 3,5-dichlorophenol were persistent. Sludge acclimated to 2-chlorophenol cross-acclimated to 4-chlorophenol but did not utilize 3-chlorophenol. This sludge also degraded 2,4-dichlorophenol. Sludge acclimated to 3-chlorophenol cross-acclimated to 4-chlorophenol but not to 2-chlorophenol. This sludge degraded 3,4- and 3,5-dichlorophenol but not 2,3- or 2,5-dichlorophenol. The specific cross-acclimation patterns observed for monochlorophenol degradation demonstrated the existence of two unique microbial activities that were in turn different from fresh sludge. The sludge acclimated to 4-chlorophenol could degrade all three monochlorophenol isomers and 2,4- and 3,4-dichlorophenol. The active microbial population in this sludge appeared to be a mixture of populations present in the 2-chlorphenol- and 3-chlorophenol-acclimated sludges, both of which could utilize 4-chlorophenol. Experiments with 14C-radiolabeled p-chlorophenol, o-chlorophenol, and 2,4-dichlorophenol demonstrated that these compounds were converted to 14CH4 and 14CO2.
Cloning the Gene for the Malolactic Fermentation of Wine from
Lactobacillus delbrueckii
in
Escherichia coli
and Yeasts
Authors: Williams Steven A. , Hodges Robert A. , Strike Terry L. , Snow Richard , Kunkee Ralph E.
Published: January 2020

The gene responsible for the malolactic fermentation of wine was cloned from the bacterium
Lactobacillus delbrueckii
into
Escherichia coli
and the yeast
Saccharomyces cerevisiae
. This gene codes for the malolactic enzyme which catalyzes the conversion of
l
-malate to
l
-lactate. A genetically engineered yeast strain with this enzymatic capability would be of considerable value to winemakers.
L. delbrueckii
DNA was cloned in
E. coli
on the plasmid pBR322, and two
E. coll
clones able to convert
l
-malate to
l
-lactate were selected. Both clones contained the same 5-kilobase segment of
L. delbrueckii
DNA. The DNA segment was transferred to
E. coli
-yeast shuttle vectors, and gene expression was analyzed in both hosts by using enzymatic assays for
l
-lactate and
l
-malate. When grown nonaerobically for 5 days,
E. coli
cells harboring the malolactic gene converted about 10% of the
l
-malate in the medium to
l
-lactate. The best expression in
S. cerevisiae
was attained by transfer of the gene to a shuttle vector containing both a yeast 2-μm plasmid and yeast chromosomal origin of DNA replication. When yeast cells harboring this plasmid were grown nonaerobically for 5 days, ca. 1.0% of the
l
-malate present in the medium was converted to
l
-lactate. The
L. delbrueckii
controls grown under these same conditions converted about 25%. A laboratory yeast strain containing the cloned malolactic gene was used to make wine in a trial fermentation, and about 1.5% of the
l
-malate in the grape must was converted to
l
-lactate. Increased expression of the malolactic gene in wine yeast will be required for its use in winemaking. This will require an increased understanding of the factors governing the expression of this gene in yeasts.
Elucidation of Growth Inhibition and Acetic Acid Production by
Clostridium thermoaceticum
Authors: Wang George , Wang Daniel I. C.
Published: January 2020

The production of acetic acid by
Clostridium thermoaceticum
was studied by using batch fermentations. In a pH-controlled fermentation with sodium hydroxide (pH 6.9), this organism was able to produce 56 g of acetic acid per liter. On the other hand, when the pH was not controlled and was decreased during fermentation to 5.4, the maximum attainable acetic acid concentration was only 15.3 g/liter. To obtain a better understanding of the end product inhibition, various salts were tested to determine their effect on the growth rate of
C. thermoaceticum
. An inverse linear relationship between the growth rate and the final cell concentration to the sodium acetate concentration was found. By using different concentrations of externally added sodium salts, the relative growth inhibition caused by the anion was found to be in the order of acetate > chloride > sulfate. Various externally added cations of acetate were also examined with respect to their inhibitory effects on growth. The relative magnitude of inhibition on the growth rate was found to be ammonium > potassium > sodium. The combined results have shown that the undissociated acetic acid was much more inhibitory than the ionized acetate ion. Complete growth inhibition resulted when the undissociated acetic acid concentration was between 0.04 and 0.05 M and when the ionized acetate concentration was 0.8 M. Therefore, at low pH (below 6.0), undissociated acetic acid is responsible for growth inhibition, and at high pH (above 6.0), ionized acetate ion is responsible for growth inhibition.
Salt Stress Control of Intracellular Solutes in Streptomycetes Indigenous to Saline Soils
Authors: Killham K. , Firestone M. K.
Published: January 2020

Actinomycetes were isolated from a number of saline and saline-sodic California soils. From these isolates, two species of
Streptomyces
(
S. griseus
and
S. californicus
) were selected to assess their physiological response to salinity. NaCl was more inhibitory to growth rates and specific growth yields than were equivalent concentrations of KCl. Intracellular concentrations of the free amino acid pool increased in response to salt stress. Whereas the neutral free amino acids proline, glutamine, and alanine accumulated as salinity increased, concentrations of the acidic free amino acids glutamate and aspartate were reduced. Accumulation of free amino acids by streptomycetes under salt stress suggests a response typical of procaryotes, although the specific amino acids involved differ from those associated with other gram-positive bacteria. Above a salinity threshold of about 0.75 M (−3.8 MPa), there was little further intracellular accumulation of free amino acids, whereas accumulation of K
+
salts sharply increased.