bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of para-substituents on the oxidative metabolism of o-nitrophenols by Pseudomonas putida B2
Authors: Zeyer J , Kocher H P , Timmis K N
Published: January 2020

Pseudomonas putida B2 is able to grow on o-nitrophenol (ONP) as the sole source of carbon and nitrogen. ONP was converted by a nitrophenol oxygenase to nitrite and catechol. Catechol was then attacked by a catechol 1,2-dioxygenase and further degraded through an ortho-cleavage pathway. ONP derivatives which were para-substituted with a methyl-, chloro-, carboxy-, formyl- or nitro-group failed to support growth of strain B2. Relevant catabolic enzymes were characterized to analyze why these derivatives were not mineralized. Nitrophenol oxygenase of strain B2 is a soluble, NADPH-dependent enzyme that is stimulated by magnesium, manganese, and calcium ions. It is active toward ONP, 4-methyl-, 4-chloro-, and to a lesser extent, 4-formyl-ONP but not toward 4-carboxy- or 4-nitro-ONP. In addition, 4-formyl-, 4-carboxy-, and 4-nitro-ONP failed to induce the formation of nitrophenol oxygenase. Catechol 1,2-dioxygenase of strain B2 is active toward catechol and 4-methyl-catechol but only poorly active toward chlorinated catechols. 4-Methyl-catechol is likely to be degraded to methyl-lactones, which are often dead-end metabolites in bacteria. Thus, of the compounds tested, only unsubstituted ONP acts as an inducer and substrate for all of the enzymes of a productive catabolic pathway.
Transfer of Plasmids to an Antibiotic-Sensitive Mutant of
Zymomonas mobilis
Authors: Buchholz Steven E. , Eveleigh Douglas E.
Published: January 2020

Wild-type strains of
Zymomonas mobilis
exhibit multiple antibiotic resistance and thus restrict the use of many broad-host-range plasmids in them as cloning vehicles. Antibiotic-sensitive mutants of
Z. mobilis
were isolated and used as hosts for the conjugal transfer of broad-host-range plasmids from
Escherichia coli
. Such antibiotic-sensitive strains can facilitate the application of broad-host-range plasmids to the study of
Z. mobilis
.
Evaluation of a tangential-flow multiple-filter technique for detection of Giardia lamblia cysts in water
Authors: Isaac-Renton J L , Fung C P , Lochan A
Published: January 2020

A system of tangential-flow filtration was evaluated for use in the detection of Giardia cysts in drinking water. This method was more sensitive in recovering cysts than a frequently used wound-orlon system of through-filtration.
Practical direct plaque assay for coliphages in 100-ml samples of drinking water
Authors: Grabow W O , Coubrough P
Published: January 2020

A practical single-agar-layer plaque assay for the direct detection of coliphages in 100-ml samples of water was designed and evaluated. With this assay a 100-ml sample of water, an agar medium containing divalent cations, and the host Escherichia coli C (ATCC 13706) were mixed in a single container, and the mixture was plated on 10 14-cm-diameter petri dishes. It was more sensitive, reliable, and accurate than various other methods and proved rapid, simple, and economic.
Variability of the Influence of Physicochemical Factors Affecting Bacterial Adhesion to Polystyrene Substrata
Authors: McEldowney Sharron , Fletcher Madilyn
Published: January 2020

The role of electrostatic and hydrophobic interactions and solid and liquid surface tensions in the adhesion of four bacterial species (
Pseudomonas fluorescens, Enterobacter cloacae, Chromobacterium
sp., and
Flexibacter
sp.) to hydrophobic polystyrene petri dishes and to more hydrophilic polystyrene tissue culture dishes was investigated. The effect of electrostatic interactions was investigated by determining the effects of different electrolyte solutions on attachment to and of different electrolyte and pH solutions on detachment from the polystyrene substrate. The significance of solid and liquid surface tensions and hydrophobic interactions was investigated by measuring the effects of different surfactants (including a concentration series of dimethyl sulfoxide) on adhesion and detachment. Adhesion varied with bacterial species, substratum, and electrolyte type and concentration, with no apparent correlation between adhesion and electrolyte valence or concentration. The influence of different pH and detergent solutions on bacterial detachment also varied with species, substratum, pH, and detergent type; however, the greatest degree of detachment of all strains from the surfaces was produced by detergent treatment. The results suggest that adhesion cannot be attributed to any one type of adhesive interaction. There was some evidence for both electrostatic and hydrophobic interactions, but neither interaction could wholly account for the data.
Alginate Production by Plant-Pathogenic Pseudomonads
Authors: Fett William F. , Osman Stanley F. , Fishman Marshall L. , Siebles T. S.
Published: January 2020

Eighteen plant-pathogenic and three non-plant-pathogenic pseudomonads were tested for the ability to produce alginic acid as an exopolysaccharide in vitro. Alginate production was demonstrated for 10 of 13 fluorescent plant-pathogenic pseudomonads tested with glucose or gluconate as the carbon source, but not for all 5 nonfluorescent plant pathogens and all 3 non-plant pathogens tested. With sucrose as the carbon source, some strains produced alginate while others produced both polyfructan (levan) and alginate. Alginates ranged from <1 to 28% guluronic acid, were acetylated, and had number-average molecular weights of 11.3 × 10
3
to 47.1 × 10
3
. Polyfructans and alginates were not elicitors of the soybean phytoalexin glyceollin when applied to wounded cotyledon surfaces and did not induce prolonged water soaking of soybean leaf tissues. All or most pseudomonads in rRNA-DNA homology group I may be capable of synthesizing alginate as an exopolysaccharide.
Development of a method for concentration of rotavirus and its application to recovery of rotaviruses from estuarine waters
Authors: Rao V C , Metcalf T G , Melnick J L
Published: January 2020

As part of our studies on the ecology of human enteric viruses, an improved method for detection of rotaviruses in water was developed, and their presence in Galveston Bay was monitored. Samples (378 liters) of estuarine water adjusted to pH 3.5 and a final AlCl3 molarity of 0.001 were filtered through 25-cm pleated cartridge-type filters (Filterite Corp., Timonium, Md.) of 3.0- and 0.45-micron porosity. Adsorbed virus was eluted with 1 liter of 10% tryptose phosphate broth, pH 9.5. Primary eluates were reconcentrated to a final volume of 10 to 20 ml by a simple and rapid magnetic iron oxide adsorption and elution procedure. Two percent casein at pH 8.5 effectively eluted rotavirus from iron oxide. A total of 21 of 72 samples of water, suspended solids, fluffy sediments, and compact sediments collected in different seasons in Galveston Bay yielded rotaviruses. Recovery of rotaviruses varied from 119 to 1,000 PFU/378 liters of water, 1,200 PFU/1,000 g of compact sediment, 800 to 3,800 PFU/378 liters of fluffy sediment, and 1,800 to 4,980 PFU from suspended solids derived from 378 liters of water based on immunofluorescent foci counts on cover slip cultures of fetal monkey kidney cells.
Decomposition Studies in Two Central Ontario Lakes Having Surficial pHs of 4.6 and 6.6
Authors: Hoeniger Judith F. M.
Published: January 2020

The rates of cellulose breakdown, composition of detrital microflora, and density of bacterial populations were determined in the epilimnetic sediments and water columns of two poorly buffered, oligotrophic, Canadian Shield lakes having mean surficial pHs of 4.6 (Bat Lake) and 6.6 (Harp Lake). The decomposition rate was significantly lower in oxic sediment of the acidified lake than of the circumneutral lake, but water column rates were almost identical in the two lakes. These results are explained in terms of the groups of cellulolytic microorganisms which were observed by phase-contrast microscopy as being active at the different sites: fungi in Bat Lake water and
Cytophaga
-like bacteria in the water and sediment of Harp Lake.
Cytophaga
-like bacteria were also the main decomposers in Bat Lake sediment, but their activity was restricted at porewater pHs of <5.0. Acridine orange direct counts of bacteria in the top centimeter of sediment ranged from 3.7 × 10
8
to 1.0 × 10
9
per g, and counts in planktonic water samples ranged from 4.9 × 10
5
to 1.2 × 10
6
per ml. Bacterial densities at most sites decreased significantly (
P
< 0.001) from August to late October, but did not show a consistent pattern of differences related to pH.
Degradation of Dead Microbial Biomass in a Marine Sediment
Authors: Novitsky James A.
Published: January 2020

The availability of dead microbial biomass in a marine beach sand to degradation and mineralization was examined. Microbial sand populations were labeled with [
14
C]glutamic acid, [
3
H]adenine, or [
3
H]thymidine and killed with chloroform. Live sand or seawater (or both) was added to the sterile labeled sand, and biochemical components of the populations were monitored for 10 days. Labeled RNA was degraded more quickly than labeled DNA, but both nucleic acids were degraded to approximately the same extent (60 to 70%).
3
H
2
O was a major acid-soluble breakdown product. RNA (and possibly DNA) breakdown products were reincorporated into DNA (and possibly RNA) during the incubation period. In addition to metabolite salvage, 32% of the total macromolecular
14
C was respired in the 10-day period regardless of whether sand or seawater was used as the inoculum. Respiration was essentially complete in 3 days, whereas nucleic acid degradation continued throughout the 10-day incubation. The results indicate that dead microbial biomass is a labile component of the sediment ecosystem.
Close Association of
Azospirillum
and Diazotrophic Rods with Different Root Zones of Kallar Grass
Authors: Reinhold Barbara , Hurek Thomas , Niemann Ernst-Georg , Fendrik Istvan
Published: January 2020

The populations of diazotrophic and nondiazotrophic bacteria were estimated in the endorhizosphere and on the rhizoplane of Kallar grass (
Leptochloa fusca
) and in nonrhizosphere soil. Microaerophilic diazotrophs were counted by the most-probable-number method, using two semisolid malate media, one of them adapted to the saline-sodic Kallar grass soil. Plate counts of aerobic heterotrophic bacteria were done on nutrient agar. The dominating N
2
-fixing bacteria were differentiated by morphological, serological, and physiological criteria. Isolates, which could not be assigned to a known species, were shown to fix nitrogen unequivocally by
15
N
2
incorporation. On the rhizoplane we found 2.0 × 10
7
diazotrophs per g (dry weight) of root, which consisted in equal numbers of
Azospirillum lipoferum
and
Azospirillum
-like bacteria showing characteristics different from those of known
Azospirillum
species. Surface sterilization by NaOCI treatment effectively reduced the rhizoplane population, so that bacteria released by homogenization of roots could be regarded as endorhizosphere bacteria.
Azospirillum
spp. were not detected in the endorhizosphere, but diazotrophic, motile, straight rods producing a yellow pigment occurred with 7.3 × 10
7
cells per g (dry weight) of root in the root interior. In nonrhizosphere soil we found 3.1 × 10
4
nitrogen-fixing bacteria per g. Diazotrophs were preferentially enriched in the Kallar grass rhizosphere. In nonrhizosphere soil they made up 0.2% of the total aerobic heterotrophic microflora, on the rhizoplane they made up 7.1%, and in the endorhizosphere they made up 85%. Owing to high numbers in and on roots and their preferential enrichment, we concluded that diazotrophs are in close association with Kallar grass. They formed entirely different populations on the rhizoplane and in the endorhizosphere.
Defined medium for Moraxella (Branhamella) catarrhalis
Authors: Juni E , Heym G A , Avery M
Published: January 2020

A defined medium for growth of 24 strains of Moraxella (Branhamella) catarrhalis was devised. This medium (medium B4) contains sodium lactate as a partial carbon source, proline as both a partial carbon source and a partial nitrogen source, aspartate as a partial nitrogen source, and the growth factors arginine, glycine, and methionine. Either aspartate, glutamate, or proline could serve as sole nitrogen source, but growth occurred at a significantly better rate if proline was present together with either aspartate or glutamate, or with both aspartate and glutamate. With the exception of strain ATCC 23246, all the strains had an absolute requirement for arginine and either a partial or absolute requirement for glycine. The concentration of glycine required for optimal growth was found to be relatively high for an amino acid growth factor. Heart infusion broth was found to be growth inhibitory for spontaneous mutants of one strain able to grow in the absence of arginine, and such mutants reverted readily to arginine dependence accompanied by the ability to grow faster on the complex medium. Growth rates in the defined medium B4 were enhanced by the simultaneous addition of asparagine, glutamate, glutamine, leucine, lysine, histidine, and phenylalanine.
Humic acid interference with virus recovery by electropositive microporous filters
Authors: Guttman-Bass N , Catalano-Sherman J
Published: January 2020

The effects of humic acid on poliovirus type 1 recovery from water by Zeta Plus 60S filters were investigated. The humic acid interfered by preventing virus adsorption to the filters, and the interference increased as a function of the amount of humic acid filtered. Humic acid decreased virus adsorption when filtered before the virus, but did not elute virus which had adsorbed to the filters. The effects on virus recovery were not due to alterations in virus titer or neutralizability. The addition of AlCl3, which improved virus recovery by electronegative filters in the presence of humic acid, did not aid in overall virus recovery by the Zeta Plus filters in the presence or absence of humic acid. However, the salt and humic acid in combination improved virus adsorption and concurrently reduced virus elution efficiency. The addition of NaH2PO4 had no direct effect on virus recovery and did not alter the effect of humic acid. In an attempt to identify the components of humic acid responsible for the interference, humic materials were fractionated by size by using Sephadex gel chromatography and dialysis, and the fractions were tested for interfering activity. Interference was not associated with specific size fractions of the humic materials.
Effect of organotins on fecal pollution indicator organisms
Authors: Pettibone G W , Cooney J J
Published: January 2020

Pure cultures of Escherichia coli and Streptococcus faecalis and environmental water samples were examined for the possibility that pollution involving organotin compounds could decrease the values for indicator organisms when standard methods were applied to the analysis of water samples. (CH3)2SnCl2 and (CH3)3SnCl decreased viable counts at about 10 to 100 mg of Sn liter-1 (8.4 X 10(-5) to 8.4 X 10(-4) mol of Sn liter-1), and tributyltin chloride was effective at about 0.1 to 1.0 mg of Sn liter-1 (8.4 X 10(-7) to 8.4 X 10(-6) mol of Sn liter-1. These concentrations, particularly for the methyltin compounds, are greater than the concentrations reported to date for these compounds in aquatic ecosystems. Thus, organotin compounds alone would not be likely to cause reductions in counts of indicator organisms measured by standard methods. However, it is suggested that, when combined with other environmental stressors or upon long exposure, organotins such as butyltins may contribute to the injury of indicator organisms.
Conjugal plasmid transfer (pAM beta 1) in Lactobacillus plantarum
Authors: Shrago A W , Chassy B M , Dobrogosz W J
Published: January 2020

The streptococcal plasmid pAM beta 1 (erythromycin resistance) was transferred via conjugation from Streptococcus faecalis to Lactobacillus plantarum and was transferred among L. plantarum strains. Streptococcus sanguis Challis was transformed with pAM beta 1 isolated from these transconjugants, and transformants harboring intact pAM beta 1 could conjugate the plasmid back to L. plantarum.
Effects of monovalent and divalent salts on the phospholipid and fatty acid compositions of a halotolerant Planococcus sp
Authors: Miller K J
Published: January 2020

The phospholipid headgroup and fatty acid compositions of a halotolerant Planococcus sp. (strain A4a) were examined when cells were grown in the presence of high concentrations of a variety of salts. The fatty acid composition of Planococcus sp. strain A4a was altered primarily as a function of the osmolality of the growth medium. The phospholipid headgroup composition was influenced by both the osmolality of the growth medium and the nature of the cation species present. An increase in the cardiolipin/phosphatidylglycerol molar ratio was detected when cells were grown in the presence of high concentrations of monovalent cations.
Fluorescence microscopy procedure for quantitation of yeasts in beverages
Authors: Koch H A , Bandler R , Gibson R R
Published: January 2020

Existing methods for quantitating yeasts in beverages include time-consuming plate counts that detect only living cells and hemacytometer counts that are reliable only at very high concentrations (e.g., 10(6) to 20 X 10(6) cells per ml). The new method described here involves the use of fluorescence microscopy with the fluorescent stain aniline blue to differentiate yeasts (and other fungi) from backgrounds for easy counting and also may be used in conjunction with membrane filtration to concentrate yeasts from liquids before cell enumeration. Recoveries averaged 91.5% for beverages spiked with levels of 500 to 600,000 organisms per ml. The correlation coefficient of count to spike level was 0.996.
Direct Acridine Orange Counting of Bacteria Preserved with Acidified Lugol Iodine
Authors: Nishino Shirley F.
Published: January 2020

Acidified and nonacidified Lugol iodine solution was tested under several storage temperatures and at several times as a preservative for marine bacteria. Direct counts with acridine orange showed no significant difference between glutaraldehyde- and Lugol iodine solution-preserved samples under any storage temperature when samples were counted within 1 week of collection. Specimens in long-term (up to 6 months) storage required refrigeration and treatment with acidified Lugol iodine solution for adequate preservation. Lugol iodine solution-preserved bacteria appeared intact under scanning electron microscopy. Lugol iodine solution did not preserve chlorophyll autofluorescence in phytoplankton.
Acetate Synthesis from H
2
plus CO
2
by Termite Gut Microbes
Authors: Breznak John A. , Switzer Jodi M.
Published: January 2020

Gut microbiota from
Reticulitermes flavipes
termites catalyzed an H
2
-dependent total synthesis of acetate from CO
2
. Rates of H
2
-CO
2
acetogenesis in vitro were 1.11 ± 0.37 μmol of acetate g (fresh weight)
−1
h
−1
(equivalent to 4.44 ± 1.47 nmol termite
−1
h
−1
) and could account for approximately 1/3 of all the acetate produced during the hindgut fermentation. Formate was also produced from H
2
+ CO
2
, as were small amounts of propionate, butyrate, and lactate-succinate. However, H
2
-CO
2
formicogenesis seemed largely unrelated to acetogenesis and was believed not to be a significant reaction in situ. Little or no CH
4
was formed from H
2
+ CO
2
or from acetate. H
2
-CO
2
acetogenesis was inhibited by O
2
, KCN, CHCl
3
, and iodopropane and could be abolished by prefeeding
R. flavipes
with antibacterial drugs. By contrast, prefeeding
R. flavipes
with starch resulted in almost complete defaunation but had little effect on H
2
-CO
2
acetogenesis, suggesting that bacteria were the acetogenic agents in the gut. H
2
-CO
2
acetogenesis was also observed with gut microbiota from
Prorhinotermes simplex, Zootermopsis angusticollis, Nasutitermes costalis
, and
N. nigriceps
; from the wood-eating cockroach
Cryptocercus punctulatus
; and from the American cockroach
Periplaneta americana.
Pure cultures of H
2
-CO
2
-acetogenic bacteria were isolated from
N. nigriceps
, and a preliminary account of their morphological and physiological properties is presented. Results indicate that in termites, CO
2
reduction to acetate, rather than to CH
4
, represents the main electron sink reaction of the hindgut fermentation and can provide the insects with a significant fraction (ca. 1/3) of their principal oxidizable energy source, acetate.
Analysis of mosquito larvicidal potential exhibited by vegetative cells of Bacillus thuringiensis subsp. israelensis
Authors: Walther C J , Couche G A , Pfannenstiel M A , Egan S E , Bivin L A , Nickerson K W
Published: January 2020

Vegetative Bacillus thuringiensis subsp. israelensis cells (6 X 10(5)/ml) achieved 100% mortality of Aedes aegypti larvae within 24 h. This larvicidal potential was localized within the cells; the cell-free supernatants did not kill mosquito larvae. However, they did contain a heat-labile hemolysin which was immunologically distinct from the general cytolytic (hemolytic) factor released during solubilization of B. thuringiensis subsp. israelensis crystals. The larvicidal potential of the vegetative cells was not due to poly-beta-hydroxybutyrate. Instead, it correlated with the ability of vegetative cells to sporulate during the bioassays. No toxicity was observed when bioassays were conducted in the presence of chloramphenicol or streptomycin. It is unlikely that the vegetative cells sporulate in the alkaline (pH 9.5 to 10.5) larval guts after ingestion. B. thuringiensis subsp. israelensis is not an alkalophile; we have been unable to grow it in culture at pH values of greater than or equal to 9.5. Moreover, we have been unable to demonstrate formation of a protective capsule. However, bacteria may replicate in the gut fluids of dead or dying mosquito larvae because their alkaline gut pH values drop markedly after exposure to the B. thuringiensis subsp. israelensis crystal toxins.
Comparative Study of the Ability of Three
Xanthobacter
Species To Metabolize Cycloalkanes
Authors: Magor Ann M. , Warburton Jean , Trower Michael K. , Griffin Martin
Published: January 2020

The ability of three species of
Xanthobacter
to metabolize cyclohexane and its derivatives has been compared.
Xanthobacter flavus
was unable to utilize any of the cycloalkanes under investigation.
X. autotrophicus
was unable to utilize cyclohexane but was able to grow with a limited range of substituted cycloalkanes, including cyclohexanol and cyclohexanone. Comparison of a previously isolated cyclohexane growing
Xanthobacter
sp. with
X. flavus
and
X. autotrophicus
indicated it to be closely related to
X. autotrophicus.
Studies with cell-free extracts have indicated that the route of metabolism for cyclohexanol by
X. autotrophicus
is the same as that shown for the cyclohexane growing
Xanthobacter
sp., proceeding via cyclohexanol→cyclohexanone→ ε-caprolactone→→ adipic acid. A comparison of the cyclohexanol dehydrogenase found in
X. autotrophicus
with that found in the cyclohexane-growing
Xanthobacter
sp. indicated these enzymes to be distinctly different from one another on the basis of substrate specificity, molecular weight, and pH optima. The cyclohexanone monooxygenase enzymes found in the two bacteria were also found to be different when the pH optima and cofactor specificity of the two enzymes were compared. Preliminary genetic studies on the cyclohexane-growing
Xanthobacter
sp. have indicated that there are no plasmids present in this bacterium. The presence of RP4 in the
Xanthobacter
sp. can be detected following its conjugation with an RP4-carrying
Escherichia coli
strain.
Extrapolation of biodegradation results to groundwater aquifers: reductive dehalogenation of aromatic compounds
Authors: Gibson S A , Suflita J M
Published: January 2020

The reductive biodegradation of a variety of haloaromatic substrates was monitored in samples from two sites within a shallow anoxic aquifer and was compared with freshwater sediment and sewage sludge. The metabolic capacity existing in methane-producing aquifer material was very similar to that in sediment in that three of four chlorobenzoates, five of seven chlorophenols, and one of two chlorophenoxyacetate herbicides were reductively dehalogenated in both types of incubations. The 2,4-dichlorophenoxyacetate was first converted to a dichlorophenol before dehalogenation occurred. Sewage sludge microorganisms dehalogenated four of seven chlorophenols tested and degraded both phenoxyacetate herbicides by first converting them to the corresponding chlorophenols, but the microorganisms did not transform the chlorobenzoates. In general, the same suite of initial metabolites were produced from a test substrate in all types of samples, as confirmed by cochromatography of the intermediates with authentic material. Aquifer microbiota from a sulfate-reducing site was unable to significantly degrade any of the haloaromatic substrates tested. Biological removal of the sulfate in samples from this site permitted dehalogenation of a model substrate, while stimulation of methanogenesis without removal of sulfate did not. These results demonstrate that dehalogenating microorganisms were present at this site but that their activity was at least partially inhibited by the high sulfate levels.
Denitrification by
Chromobacterium violaceum
Authors: Bazylinski Dennis A. , Palome Elaine , Blakemore Nancy A. , Blakemore Richard P.
Published: January 2020

One host (
Rana catesbiana
)-associated and two free-living mesophilic strains of bacteria with violet pigmentation and biochemical characteristics of
Chromobacterium violaceum
were isolated from freshwater habitats. Cells of each freshly isolated strain and of strain ATCC 12472 (the neotype strain) grew anaerobically with glucose as the sole carbon and energy source. The major fermentation products of cells grown in Trypticase soy broth (BBL Microbiology Systems, Cockeysville, Md.) supplemented with glucose included acetate, small amounts of propionate, lactate, and pyruvate. The final cell yield and culture growth rate of each strain cultured anaerobically in this medium increased approximately twofold with the addition of 2 mM NaNO
3
. Final growth yields increased in direct proportion to the quantity of added NaNO
3
over the range of 0.5 to 5 mM. Each strain reduced NO
3
−
, producing NO
2
−
, NO, and N
2
O. NO
2
−
accumulated transiently. With 2 mM NaNO
3
in the medium, N
2
O made up 85 to 98% of the N product recovered with each strain. N-oxides were recovered in the same quantity and distribution whether 0.01 atm (ca. 1 kPa) of C
2
H
2
(added to block N
2
O reduction) was present or not. Neither N
2
production nor gas accumulation was detected during NO
3
−
reduction by growing cells. Cell growth in media containing 0.5 to 5 mM NaNO
2
in lieu of NaNO
3
was delayed, and although N
2
O was produced by the end of growth, NO
2
−
-containing media did not support growth to an extent greater than did medium lacking NO
3
−
or NO
2
−
. The data indicate that
C. violaceum
cells ferment glucose or denitrify, terminating denitrification with the production of N
2
O, and that NO
2
−
reduction to N
2
O is not coupled to growth but may serve as a detoxification mechanism. No strain detectably fixed N
2
(reduced C
2
H
2
).
Selective partitioning of conidia of some Penicillium and Aspergillus species in aqueous two-phase systems
Authors: Ström G B , Blomquist G K
Published: January 2020

Conidia of Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Penicillium brevi-compactum, Penicillium frequentans, Penicillium spinulosum, and Penicillium verrucosum var. cyclopium were subjected to partition at varying pH values in an aqueous two-phase system containing charged polyethylene glycol. In the system, the partition behavior of the conidia of the Penicillium species varied when the pH was raised, while the conidia of the Aspergillus species seemed unaffected. P. brevi-compactum was separated from P. verrucosum var. cyclopium after only 10 transfers when subjected to stepwise partitioning. In the same way, 10 transfers were needed to separate P. verrucosum var. cyclopium from a mixture of conidia of three Aspergillus species. The partition behavior was influenced by the culture media used.
Assessment of in vivo revival, growth, and pathogenicity of Escherichia coli strains after copper- and chlorine-induced injury
Authors: Singh A , Yeager R , McFeters G A
Published: January 2020

Cells of one enteroinvasive and three enterotoxigenic strains of Escherichia coli were exposed to sublethal concentrations of copper and chlorine to produce 85 to 94% injury. Injured cells were intraluminally inoculated into ligated ileal loops of anesthetized mice, and injury was assessed at timed intervals. Substantial recovery (72-84%) of copper- and chlorine-injured cells was observed in the inoculated loops at 4 and 3 h, respectively. No appreciable increase in total numbers was observed during these time intervals. In vitro revival of copper-injured cells in phosphate-buffered saline alone after incubation at 35 degrees C for 4 h was not observed. However, a 60 to 70% revival occurred when 200 micrograms of protein per ml of mouse intestinal mucosal homogenate was incorporated into saline cell suspensions. The enterotoxigenic activity of copper-injured cells in rabbit ileal loops was somewhat reduced compared with that of chlorine-injured or uninjured cells. These results show that injured pathogenic E. coli cells can revive in the small intestine and appear to retain their enterotoxigenic activity.
Comparative study of expression of hemagglutinins, hemolysins, and enterotoxins by clinical and environmental isolates of non-O1 Vibrio cholerae in relation to their enteropathogenicity
Authors: Datta-Roy K , Banerjee K , De S P , Ghose A C
Published: January 2020

A comparative study was undertaken of clinical and environmental isolates of non-O1 Vibrio cholerae with respect to their hemagglutinating, hemolytic, enterotoxigenic, and enteropathogenic activities. Cell-associated hemagglutinin titers of the clinical and environmental isolates did not differ much, although the clinical isolates displayed higher cell-free hemagglutinin titers compared with those of environmental isolates. Culture supernatants of 61.5% (24 of 39) of clinical isolates showed hemolytic activity (greater than or equal to 10% lysis of rabbit erythrocytes), while only 33.3% (10 to 30) of the environmental group had such activity. Furthermore, hemolytic activities of the clinical isolates showed a good correlation with their cell-associated hemagglutinin titers which was not true for the environmental group. Culture supernatants of 45.8% (11 of 25) of the clinical and 20% (2 of 10) of the environmental isolates exhibited enterotoxigenic activity in the rabbit ileal loop assay. Such activity was mediated mainly by cholera toxin-like substances, although some of the isolates produced fluid-accumulating factors unrelated to cholera toxin. Experimental animal studies demonstrated that the enteropathogenic potential of the environmental isolates was significantly lower than that of the clinical group. Further analysis of our data showed that phenotypic expression of cholera toxin-like products by the non-O1 V. cholerae isolates was accompanied by their enteropathogenicity. The latter effect was also noted with some of the cholera toxin-negative isolates, particularly in those having high hemagglutinating and hemolytic titers.
Plasmid Involvement in Linalool Metabolism by
Pseudomonas fluorescens
Authors: Vandenbergh Peter A. , Cole Ronald L.
Published: January 2020

A bacterial strain was isolated from a wastewater lagoon and identified as
Pseudomonas fluorescens.
This isolate was able to utilize linalool as a sole carbon and energy source. The ability was found to be encoded on a 60-megadalton transmissible plasmid, pSRQ60. The plasmid was also mated into a commercial waste treatment strain, which expanded its ability to utilize other isoprenoid compounds.
Comparison of Bacterial Lipopolysaccharides by High-Performance Liquid Chromatography
Authors: Sutherland Ian W. , Kennedy Andrew F. D.
Published: January 2020

A comparison of lipid-free polysaccharides from gram-negative bacteria was rapidly accomplished by using high-performance liquid chromatography of underivatized hydrolysates. Examination of a number of such products revealed that, contrary to earlier reports,
Xanthomonas campestris
lipopolysaccharide contained heptose, together with rhamnose and galactose, but not mannose. The polymers from the methanotrophs “
Methylomonas albus
” and “
Methylosinus trichosporium
” contained heptose and glucose, and that from a “
Klebsiella aerogenes
” strain contained heptose, glucose, and galactose. The absence of heptose from the lipopolysaccharide of
Myxococcus xanthus
was confirmed.
Dinitrogen Production from Nitrite by a
Nitrosomonas
Isolate
Authors: Poth Mark
Published: January 2020

A chemolithotrophic ammonium-oxidizing bacterium that was able to reduce
15
NO
2
−
to
15
N
2
(
m/z
30) while oxidizing ammonium under conditions of oxygen stress was isolated from stream sediments. Energy was derived from ammonium oxidation, as evidence by growth, with CO
2
serving as the sole C source. The organism was a gram-negative, motile, short rod that failed to grow either aerobically or anaerobically in heterotroph media. The organism was identified as a
Nitrosomonas
sp.
Effects of Inoculum Size on Solid-Phase Fermentation of Fodder Beets for Fuel Ethanol Production
Authors: Gibbons William R. , Westby Carl A.
Published: January 2020

This fuel ethanol study examined the effects of
Saccharomyces cerevisiae
inoculum size on solid-phase fermentation of fodder beet pulp. A 5% inoculum (wt/wt) resulted in rapid yeast and ethanol (9.1% [vol/vol]) production. Higher inocula showed no advantages. Lower inocula resulted in lowered final yeast populations and increased fermentation times.
Color Variants of
Aureobasidium pullulans
Overproduce Xylanase with Extremely High Specific Activity
Authors: Leathers Timothy D.
Published: January 2020

Xylanase activity from naturally occurring color variants of
Aureobasidium pullulans
was associated with extracellular monomeric proteins of 20 to 21 kilodaltons. Xylanase represented nearly half the total extracellular protein, with a yield of up to 0.3 g of xylanase per liter. The specific activity of partially purified xylanase exceeded 2,000 IU/mg. Xylanase from typically pigmented strains appeared similar to that from color variants with respect to molecular weight, pH and temperature optima, and specific activity of purified (but not crude) enzyme. However, xylanase from typical strains made up only about 1.0% of total extracellular protein. Xylanase from strains of
Cryptococcus albidus
was associated with abundant proteins of about 43 kilodaltons and showed much lower specific activity.
Rhizobium trifolii
0403 Is Capable of Growth in the Absence of Combined Nitrogen
Authors: Urban James E. , Davis Lawrence C. , Brown Susan J.
Published: January 2020

Rhizobium trifolii
0403 was treated with 16.6 mM succinate and other nutrients and thereby induced to grow in nitrogen-free medium. The organism grew microaerophilically on either semisolid or liquid medium, fixing atmospheric nitrogen to meet metabolic needs. Nitrogen fixation was measured via
15
N incorporation (18%
15
N enrichment in 1.5 doublings) and acetylene reduction. Nitrogen-fixing cells had a

K
m

for acetylene of 0.07 atm (ca. 7.09 kPa), required about 3% oxygen for optimum growth in liquid medium, and showed a maximal specific activity of 5 nmol of acetylene reduced per min per mg of protein at 0.04 atm (ca. 4.05 kPa) of acetylene. The doubling time on N-free liquid medium ranged from 1 to 5 days, depending on oxygen tension, with an optimum temperature for growth of about 30°C. Nodulation of white clover by the cultures showing in vitro nitrogenase activity indicates that at least part of the population maintained identity with wild-type strain 0403.
Production and Characteristics of Raw-Starch-Digesting α-Amylase from a Protease-Negative
Aspergillus ficum
Mutant
Authors: Hayashida Shinsaku , Teramoto Yuji
Published: January 2020

Mutational experiments were carried out to decrease the protease productivity of
Aspergillus ficum
IFO 4320 by using
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. A protease-negative mutant, M-33, exhibited higher α-amylaseactivity than the parent strain under submerged culture at 30°C for 24 h. About 70% of the total α-amylase activity in the M-33 culture filtrate was adsorbed onto starch granules. The electrophoretically homogeneous preparation of raw-starch-adsorbable α-amylase (molecular weight, 88,000), acid stable at pH 2, showed intensive raw-starch-digesting activity, dissolving corn starch granules completely. The preparation also exhibited a high synergistic effect with glucoamylase I. A mutant, M-72, with higher protease activity produced a raw cornstarch-unadsorbable α-amylase. The purified enzyme (molecular weight, 54,000), acid unstable, showed no digesting activity on raw corn starch and a lower synergistic effect with glucoamylase I in the hydrolysis of raw corn starch. The fungal α-amylase was therefore divided into two types, a novel type of raw-starch-digesting enzyme and a conventional type of raw-starch-nondigesting enzyme.
Isolation and Characterization of Bacterial Strains with Inulinase Activity
Authors: Allais Jean-Jacques , Kammoun Sadok , Blanc Philippe , Girard Christel , Baratti Jacques C.
Published: January 2020

Thirty-two bacterial strains growing on inulin as the sole carbon and energy source were isolated from soil samples by enrichment culture on a mineral medium. Twenty of the strains were identified as
Flavobacterium multivorum.
All the bacteria contained a β-fructosidase that was active on both inulin and sucrose. The enzyme activity was cell bound and was produced at the end of the growth phase. These enzymes have potential uses in the preparation of fructose syrups from inulin and invert sugar from sucrose.
Production, Purification, and Characterization of α-Galactosidase from
Monascus pilosus
Authors: Wong Hin-Chung , Hu Chien-An , Yeh Hsi-Lien , Su Wanchuang , Lu Hsueh-Chih , Lin Chin-Fu
Published: January 2020

A
Monascus pilosus
strain was selected for production of intracellular α-galactosidase. Optimum conditions for mycelial growth and enzyme induction were determined. Galactose was one of the best enzyme inducers. The enzyme was purified by ammonium sulfate precipitation, gel filtration, and ion exchange chromatography and was demonstrated to be homogeneous by slab gel electrophoresis. The molecular weight of this enzyme, estimated by gel filtration, was about 150,000. The optimum conditions for the enzyme reaction was pH 4.5 to 5.0 at 55°C. The purified enzyme was stable at 55°C or below and in buffer at pH 3 to 8. The activity was inhibited by mercury, silver, and copper ions. The kinetics of this enzyme, with
p
-nitrophenyl-α-
d
-galactoside as substrate, was determined:
K

m

was about 0.8 mM, and
V
max
was 39 μmol/min per mg of protein. Enzymatic hydrolysis of melibiose, raffinose, and stachyose was analyzed by thin-layer chromatography.
Microbial Iron Reduction by Enrichment Cultures Isolated from Estuarine Sediments
Authors: Tugel Joyce B. , Hines Mark E. , Jones Galen E.
Published: January 2020

Microbial Fe reduction in acetate- and succinate-containing enrichment cultures initiated with an estuarine sediment inoculum was studied. Fe reduction was unaffected when SO
4
2−
reduction was inhibited by MoO
4
2−
, indicating that both processes could occur independently. Bacterially produced sulfide precipitated as FeS but was not completely responsible for Fe reduction. The separation of oxidized Fe particles from bacteria by dialysis tubing demonstrated that direct bacterial contact was necessary for Fe reduction. Fe reduction in cultures amended with NO
3
−
was delayed until NO
3
−
and NO
2
−
were removed. However, bacterial attachment to oxidized Fe particles in NO
3
−
-amended cultures occurred early during growth in a manner similar to NO
3
−
-free cultures. During late stages of growth, bacteria not attached to Fe particles became pale and swollen, while attached cells remained bright blue when examined by 4′,6-diamidine-2-phenylindole epifluo-rescence microscopy. The presence of added oxidized Mn had no effect on Fe reduction. The results suggested that enzymatic Fe reduction was responsible for reducing Fe in these cultures even in the presence of sulfide and that cells incapable of Fe reduction became unhealthy when Fe(III) was the only available electron acceptor.
Isolation of Pathogenic
Bacillus circulans
from Callus Cultures and Healthy Offshoots of Date Palm (
Phoenix dactylifera
L.)
Authors: Leary John V. , Nelson Nels , Tisserat Brent , Allingham Elizabeth A.
Published: January 2020

Pure cultures of a gram-negative, rod-shaped bacterium, which produced endospores after 3 to 5 days on solid medium, were isolated exclusively from tissue cultures of the date palm
Phoenix dactylifera
L. Electron microscopic examination of thin sections of the bacteria revealed the bilayer membrane typical of gramnegative bacteria and confirmed the nature of the spores as true endospores. Biochemical and physiological tests indicated that the bacteria were
Bacillus circulans. B. circulans
was consistently isolated from the internal tissues, including the meristem, of apparently healthy offshoots of date palm. When meristem and embryo callus tissue culture samples were injected with
B. circulans
isolated from similar tissue culture samples and from offshoots, the majority of the isolates produced a rapid, destructive soft rot of the tissues.
DNA hybridization probe for the Pseudomonas fluorescens group
Authors: Festl H , Ludwig W , Schleifer K H
Published: January 2020

Plasmid pHF360 was constructed from cloned rRNA genes (rDNA) of Pseudomonas aeruginosa and used as hybridization probe for the Pseudomonas fluorescens group. The probe was tested by dot and in situ colony hybridizations to chromosomal DNAs from a wide variety of organisms. pHF360 DNA hybridized exclusively to chromosomal DNAs from bacteria representing the P. fluorescens group and separated them clearly from all other bacteria tested in the present study. Determination of the nucleotide sequence of the cloned DNA showed that it is a fragment from a 23S rRNA gene of P. aeruginosa. It was compared with the published 23S RNA sequence from Escherichia coli.
Bioluminescence in a strain of the human pathogenic bacterium Vibrio vulnificus
Authors: Oliver J D , Roberts D M , White V K , Dry M A , Simpson L M
Published: January 2020

We report the existence of a bioluminescent strain of the human pathogen Vibrio vulnificus. The isolate was obtained from blood following a fatal wound infection and thus represents the first description of an infection caused by a luminescent bacterium.
Demonstration of a plasmid-borne gene encoding a thermostable direct hemolysin in Vibrio cholerae non-O1 strains
Authors: Honda T , Nishibuchi M , Miwatani T , Kaper J B
Published: January 2020

Of 15 Vibrio cholerae non-O1 strains, 2 produced a hemolysin termed NAG-rTDH, which is very similar to the thermostable direct hemolysin of V. parahaemolyticus. These two strains contained DNA sequences which are homologous to a DNA probe for the V. parahaemolyticus thermostable direct hemolysin gene. A probe-positive 9-kilobase HindIII fragment was cloned from a plasmid of a V. cholerae non-O1 strain into plasmid pBR322, and the resulting Escherichia coli clones produced intracellular NAG-rTDH.
Lysozyme-Sensitive Bioemulsifier for Immiscible Organophosphorus Pesticides
Authors: Patel Mukul N. , Gopinathan Karumathil P.
Published: January 2020

Two
Bacillus
strains capable of emulsifying immiscible organophosphorus pesticides were isolated by enrichment methods. The emulsifying factor produced by
Bacillus
strain FE-2 has a high molecular weight, is Iysozyme sensitive and thermostable, and can be precipitated with trichloroacetic acid or ammonium sulfate; it may be a glycolipopeptide. It is specific for immiscible organophosphorus pesticides and is secreted during growth in the presence of such pesticides.
Isolation and Characterization of a Fast-Growing, Thermophilic
Methanobacterium
Species
Authors: Zhao Yizhang , Zhang Hui , Boone David R. , Mah Robert A.
Published: January 2020

A thermophilic, autotrophic methanogen (strain CB12, DSM 3664) was isolated from a mesophilic biogas digestor. This bacterium used H
2
-CO
2
or formate as a substrate and grew as short rods, sometimes in pairs and in crooked filaments. Motility was not observed. Its optimum temperature (56°C) was lower than that of other thermophilic members of the genus
Methanobacterium
. The maximum observed specific growth rate was 0.564 h
−1
(74-min doubling time).
Heat resistance of bacterial spores correlated with protoplast dehydration, mineralization, and thermal adaptation
Authors: Beaman T C , Gerhardt P
Published: January 2020

Twenty-eight types of lysozyme-sensitive spores among seven Bacillus species representative of thermophiles, mesophiles, and psychrophiles were obtained spanning a 3,000-fold range in moist-heat resistance. The resistance within species was altered by demineralization of the native spores to protonated spores and remineralization of the protonated spores to calcified spores and by thermal adaptation at maximum, optimum, and minimum sporulation temperatures. Protoplast wet densities, and thereby protoplast water contents, were obtained by buoyant density sedimentation in Nycodenz gradients (Nyegaard and Co., Oslo, Norway). Increases in mineralization and thermal adaptation caused reductions in protoplast water content between limits of ca. 57 and 28% (wet weight basis), and thereby correlated with increases in sporal heat resistance. Above and below these limits, however, increases in mineralization and thermal adaptation correlated with increases in sporal resistance independently of unchanged protoplast water contents. All three factors evidently contributed to and were necessary for heat resistance of the spores, but dehydration predominated.
Effect of Temperature on Growth, Respiration, and Nutrient Regeneration by an Omnivorous Microflagellate
Authors: Caron David A. , Goldman Joel C. , Dennett Mark R.
Published: January 2020

The effect of temperature on the rates and extent of carbon and nitrogen cycling by the heterotrophic microflagellate
Paraphysomonas imperforata
(diameter, 7 to 12 μm) fed with the diatom
Phaeodactylum tricornutum
was investigated over an ecologically pertinent temperature range (14 to 26°C). All physiological rates investigated increased with increasing temperature.
Q
10
values were similar for all rate changes and were comparable to those which have been reported for other protozoa. In contrast to all rates, microflagellate gross growth efficiency and cell volume were unaffected by temperature. Decreases in the concentrations of particulate carbon and particulate nitrogen from grazed diatom cultures also were similar when summed over the entire growth phase of the microflagellate population. Therefore, the proportions of ingested carbon and nitrogen which were incorporated or remineralized by the microflagellate were independent of temperature between 14 and 26°C. At temperatures above 18°C, growth rates of
P. imperforata
were greater than the maximum growth rates reported for most phytoplankton. We conclude that the impact of
P. imperforata
on natural phytoplankton communities is not controlled by temperature above 18°C but may be affected by the rate at which zooplankton or microzooplankton prey on the microflagellate, as well as the inability of the microflagellate to graze efficiently when phytoplankton are present at low cell densities.