bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Transformation of an
argB
Mutant of
Aspergillus oryzae
Authors: Hahm Young Tae , Batt Carl A.
Published: January 2020

An
argB
mutant of
Aspergillus oryzae
NRRL 492 has been genetically transformed with the
Aspergillus nidulans argB
gene. Protoplasts were generated with a combination of Novozyme 234 and β-glucuronidase and regenerated on sucrose-stabilized minimal medium without arginine as described for
A. nidulans.
A frequency of 5 to 10 transformants per μg of DNA was obtained; however, most transformants appeared abortive. The
A. nidulans argB
gene and vector sequences appeared to be integrated into the
A. oryzae
chromosome.
Mineralization of polycyclic aromatic hydrocarbons by a bacterium isolated from sediment below an oil field
Authors: Heitkamp M A , Cerniglia C E
Published: January 2020

Microbiological analyses of sediments chronically exposed to petrogenic hydrocarbons resulted in the isolation of a gram-positive, rod-shaped bacterium which mineralized naphthalene (59.5% of the original amount), phenanthrene (50.9%), fluoranthene (89.7%), pyrene (63.0%), 1-nitropyrene (12.3%), 3-methylcholanthrene (1.6%), and 6-nitrochrysene (2.0%) to carbon dioxide when grown for 2 weeks in pure culture with organic nutrients. The bacterium tolerated salt concentrations up to 4% and grew well at 24 to 30 degrees C. The use of this bacterium may be an attractive alternative to existing physicochemical methods for the remediation of polycyclic aromatic hydrocarbons in the environment.
Degradation of DNA in cells and extracts of the obligately anaerobic bacterium Roseburia cecicola upon exposure to air
Authors: Martin J H , Savage D C
Published: January 2020

High-molecular-weight chromosomal DNA from Roseburia cecicola, an oxygen-intolerant anaerobe, could be isolated only when the bacterial cells were kept under anaerobic conditions up to the time of cell lysis. When the cells were exposed to oxygen before lysis, the chromosomal DNA degraded. Likewise, linear but not covalently closed circular DNAs degraded in cell extracts of the organism that were exposed to atmospheres containing O2 but not in extracts that were maintained in a reduced state. Covalently closed circular DNAs were nicked but not degraded in the oxidized extracts.
A pH Control System Based on Malate Decarboxylation for the Cultivation of Lactic Acid Bacteria
Authors: Daeschel M. A.
Published: January 2020

Most species of lactic acid bacteria decarboxylate
l
-malate to lactate and CO
2
if an energy source such as glucose is present. A proton is taken up in the reaction, which prevents pH decreases in the growth medium caused by lactic acid production from glucose fermentation. MRS broth (pH 7.0) (Difco Laboratories) containing 10 mM glucose and various concentrations of
l
-malate (0, 25, 50, 75, and 100 mM) was used to cultivate
Lactobacillus plantarum
. After 72 h at 37°C, all malate was decarboxylated and all glucose was fermented, with resultant final pH values of 4.5, 6.3, 6.9, 7.3, and 7.5, respectively. When
d
-malate (which cannot be decarboxylated) was substituted for
l
-malate, the final pH values were 4.5, 5.2, 5.6, 5.8, and 5.9. By varying the ratios of glucose to
l
-malate in the growth medium, it was possible to obtain pH values which were lower, the same, or higher than the initial pH values. In contrast, buffers such as phosphate only retard decreases in pH.
l
-Malate, when compared with K
2
PO
4
on an equal molar basis, provided greater resistance to decreases in pH. Higher specific growth rates were observed for
L. plantarum
and
Leuconostoc mesenteroides
when
l
-malate rather than K
2
PO
4
was incorporated into the growth medium.
Effects of co-occurring aromatic hydrocarbons on degradation of individual polycyclic aromatic hydrocarbons in marine sediment slurries
Authors: Bauer J E , Capone D G
Published: January 2020

Rates of polycyclic aromatic hydrocarbon (PAH) degradation and mineralization were influenced by preexposure to alternate PAHs and a monoaromatic hydrocarbon at relatively high (100 ppm) concentrations in organic-rich aerobic marine sediments. Prior exposure to three PAHs and benzene resulted in enhanced [14C]naphthalene mineralization, while [14C]anthracene mineralization was stimulated only by benzene and anthracene preexposure. Preexposure of sediment slurries to phenanthrene stimulated the initial degradation of anthracene. Prior exposure to naphthalene stimulated the initial degradation of phenanthrene but had no effect on either the initial degradation or mineralization of anthracene. For those compounds which stimulated [14C]anthracene or [14C]naphthalene mineralization, longer preexposures (2 weeks) to alternative aromatic hydrocarbons resulted in an even greater stimulation response. Enrichment with individual PAHs followed by subsequent incubation with one or two PAHs showed no alteration in degradation patterns due to the simultaneous presence of PAHs. The evidence suggests that exposure of marine sediments to a particular PAH or benzene results in the enhanced ability of these sediments to subsequently degrade that PAH as well as certain other PAHs. The enhanced degradation of a particular PAH after sediments have been exposed to it may result from the selection and proliferation of specific microbial populations capable of degrading it. The enhanced degradation of other PAHs after exposure to a single PAH suggests that the populations selected have either broad specificity for PAHs, common pathways of PAH degradation, or both.
Effects of Glucose Concentrations on Cadmium, Copper, Mercury, and Zinc Toxicity to a
Klebsiella
sp
Authors: Brynhildsen Lena , Lundgren Bo V. , Allard Bert , Rosswall Thomas
Published: January 2020

The influence of glucose concentration on Cd, Cu, Hg, and Zn toxicity to a
Klebsiella
sp. was studied by following the degradation of
14
C-labeled glucose at pH 6.0. Uptake of
14
C into the cells was also determined. The carbon concentrations ranged from 0.01 to 40 mg liter
−1
, which are equivalent to soluble C concentrations in natural environments. The toxicity of Cu, Cd, and Zn to a
Klebsiella
sp. was affected considerably by the C concentration. Copper at 10
−5
M was toxic when the carbon concentration was 10 or 40 mg liter
−1
, while at 0.01 to 1.0 mg liter
−1
no toxicity was observed. Cadmium and zinc were toxic at 10
−2
M in media containing 0.01 to 1.0 mg of C liter
−1
. At C concentrations greater than 1.0 mg liter
−1
, the inhibition of glucose degradation and carbon assimilation was observed at 10
−3
M Cd and Zn. The toxicity of mercury seemed to be independent of the C concentration. Results of this study showed that the nutritional state of an organism may have a profound effect on its sensitivity to metals. Metals taken up by an energy-driven transport system may be less toxic under conditions of C starvation. The C concentration should be taken into account when evaluating results from toxicity studies, especially as most microorganisms in nature live under energy-limited conditions.
Oxidation of Ferrous Iron and Elemental Sulfur by
Thiobacillus ferrooxidans
Authors: Espejo Romilio T. , Escobar Blanca , Jedlicki Eugenia , Uribe Paulina , Badilla-Ohlbaum Ricardo
Published: January 2020

The oxidation of ferrous iron and elemental sulfur by
Thiobacillus ferrooxidans
that was absorbed and unabsorbed onto the surface of sulfur prills was studied. Unadsorbed sulfur-grown cells oxidized ferrous iron at a rate that was 3 to 7 times slower than that of ferrous iron-grown cells, but sulfur-grown cells were able to reach the oxidation rate of the ferrous iron-adapted cells after only 1.5 generations in a medium containing ferrous iron. Bacteria that were adsorbed to sulfur prills oxidized ferrous iron at a rate similar to that of unadsorbed sulfur-grown bacteria. They also showed the enhancement of ferrous iron oxidation activity in the presence of ferrous iron, even though sulfur continued to be available to the bacteria in this case. An increase in the level of rusticyanin together with the enhancement of the ferrous iron oxidation rate were observed in both sulfur-adsorbed and unadsorbed cells. On the other hand, sulfur oxidation by the adsorbed bacteria was not affected by the presence of ferrous iron in the medium. When bacteria that were adsorbed to sulfur prills were grown at a higher pH (ca. 2.5) in the presence of ferrous iron, they rapidly lost both ferrous iron and sulfur oxidation capacities and became inactive, apparently because of the deposition of a jarosite-like precipitate onto the surface to which they were attached.
Transduction of Escherichia coli by bacteriophage P1 in soil
Authors: Zeph L R , Onaga M A , Stotzky G
Published: January 2020

Transduction of Escherichia coli W3110(R702) and J53(RP4) (10(4) to 10(5) CFU/g of soil) by lysates of temperature-sensitive specialized transducing derivatives of bacteriophage P1 (10(4) to 10(5) PFU/g of soil) (P1 Cm cts, containing the resistance gene for chloramphenicol, or P1 Cm cts::Tn501, containing the resistance genes for chloramphenicol and mercury [Hg]) occurred in soil amended with montmorillonite or kaolinite and adjusted to a -33-kPa water tension. In nonsterile soil, survival of introduced E. coli and the numbers of E. coli transductants resistant to chloramphenicol or Hg were independent of the clay amendment. The numbers of added E. coli increased more when bacteria were added in Luria broth amended with Ca and Mg (LCB) than when they were added in saline, and E. coli transductants were approximately 1 order of magnitude higher in LCB; however, the same proportion of E. coli was transduced with both types of inoculum. In sterile soil, total and transduced E. coli and P1 increased by 3 to 4 logs, which was followed by a plateau when they were inoculated in LCB and a gradual decrease when they were inoculated in saline. Transduction appeared to occur primarily in the first few days after addition of P1 to soil. The transfer of Hg or chloramphenicol resistance from lysogenic to nonlysogenic E. coli by phage P1 occurred in both sterile and nonsterile soils. On the basis of heat-induced lysis and phenotype, as well as hybridization with a DNA probe in some studies, the transductants appeared to be the E. coli that was added. Transduction of indigenous soil bacteria was not unequivocally demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)
Nonspecific Factors Involved in Attachment of Entomopathogenic Deuteromycetes to Host Insect Cuticle
Authors: Boucias D. G. , Pendland J. C. , Latge J. P.
Published: January 2020

The attachment of the conidia of the insect-pathogenic fungi
Nomuraea rileyi, Beauveria bassiana
, and
Metarrhizium anisopliae
to insect cuticle was mediated by strong binding forces. The attachment was passive and nonspecific in that the conidia adhered readily to both host and nonhost cuticle preparations. The hydrophobicity of the conidial wall and the insect epicuticle appeared to mediate the adhesion process. Detergents, solvents, and high-molecular-weight proteins known to neutralize hydrophobicity reduced conidial binding when added to conidium-cuticle preparations. However, these chemicals did not remove the hydrophobic components from the epicuticle or from conidial preparations. The outer surface of the conidium consists of a resilient layer of well-organized fascicles of rodlets. Intact rodlets extracted from
B. bassiana
conidia bound to insect cuticle and exhibited the hydrophobicity expressed by intact conidia. Both electrostatic charges and various hemagglutinin activities were also present on the conidial surface. However, competitive-inhibition studies indicated that these forces played little, if any, role in the adhesion process.
Fumonisins--novel mycotoxins with cancer-promoting activity produced by Fusarium moniliforme
Authors: Gelderblom W C , Jaskiewicz K , Marasas W F , Thiel P G , Horak R M , Vleggaar R , Kriek N P
Published: January 2020

Cultures on corn of Fusarium moniliforme MRC 826 are known to cause leukoencephalomalacia in horses and to be toxic and hepatocarcinogenic in rats. Culture material of this F. moniliforme isolate has also been shown to exhibit cancer-promoting activity in a short-term cancer initiation-promotion bioassay with diethylnitrosamine-initiated rats and the induction of gamma-glutamyl-transpeptidase-positive (GGT+) foci as an endpoint after 4 weeks of promotion. This bioassay was used as a monitoring system to isolate cancer-promoting compounds from cultures of F. moniliforme MRC 826. Culture material was successively extracted with ethyl acetate and CH3OH-H2O (3:1). Most of the cancer-promoting activity was recovered in the CH3OH-H2O extract and remained in the aqueous phase following partitioning of this extract between CH3OH-H2O (1:3) and CHCl3. The CH3OH-H2O fraction was chromatographed on an Amberlite XAD-2 column, and the active fraction was eluted with CH3OH. This fraction was chromatographed on a silica gel column with CHCl3-CH3OH-CH3COOH (6:3:1) as eluent and further purified on a C18 reverse-phase column. Two pure compounds were isolated, and these have been chemically characterized and given the trivial names fumonisin B1 and B2. At least 2 g of the major compound fumonisin B1 was purified from 1 kg of culture material. Fumonisin B1 in the diet (0.1%) significantly (P less than 0.001) induced the formation of GGT+ foci in the livers of initiated as well as noninitiated rats.(ABSTRACT TRUNCATED AT 250 WORDS)
O-Methylation of Chlorinated
para
-Hydroquinones by
Rhodococcus chlorophenolicus
Authors: Häggblom Max M. , Apajalahti Juha H. A. , Salkinoja-Salonen Mirja S.
Published: January 2020

Rhodococcus chlorophenolicus
PCP-I, a degrader of polychlorinated phenols, guaiacols (2-methoxyphenols), and syringols (2,6-dimethoxyphenols), was shown to O-methylate the degradation intermediate, a chlorinated
para
-hydroquinone, into 4-methoxyphenol. O-methylation was constitutively expressed, whereas the degradation of chlorophenols and chlorohydroquinones was inducible in
R. chlorophenolicus.
The O-methylating reaction required two hydroxyl groups in positions
para
to each other.
R. chlorophenolicus
selectively methylated the hydroxyl group flanked by two chlorine substituents. Tetrachlorohydroquinone, trichlorohydroquinone, and 2,6-dichlorohydroquinone were methylated into tetrachloro-4-methoxyphenol, 2,3,5-trichloro-4-methoxyphenol, and 3,5-dichloro-4-methoxyphenol, respectively. Chlorohydroquinones with only one chlorine adjacent to a hydroxyl group were methylated only in trace amounts, and no metabolite was formed from hydroquinone. The degradation intermediates formed in hydroxylation of tetrachloroguaiacol and trichlorosyringol by
R. chlorophenolicus
were O-methylated into two isomeric trichlorodimethoxyphenols and two isomeric dichlorotrimethoxyphenols, respectively.
R. chlorophenolicus
also degraded the polychlorinated methylation products (tetrachlorinated and trichlorinated 4-methoxyphenols), but not mono- and dichlorinated 4-methoxyphenols.
Microbial degradation of xenobiotic, aromatic pollutants in humic water
Authors: Larsson P , Okla L , Tranvik L
Published: January 2020

The microbial degradation of a number of 14C-labeled, recalcitrant, aromatic pollutants, including trichloroguaiacol and di-, tri-, and pentachlorophenol, was investigated in aquatic model systems in the laboratory. Natural, mixed cultures of microorganisms in the water from a brown-water lake with a high content of humic compounds mineralized all of the tested substances to a higher degree than did microorganisms in the water from a clear-water lake. Dichlorophenol was the most rapidly degraded pollutant.
Phenolic Compound Utilization by the Soft Rot Fungus
Lecythophora hoffmannii
Authors: Bugos Robert C. , Sutherland John B. , Adler John H.
Published: January 2020

Nine phenolic compounds were metabolized by the soft rot fungus
Lecythophora hoffmannii
via protocatechuic acid and subsequently cleaved by protocatechuate 3,4-dioxygenase as determined by oxygen uptake, substrate depletion, and ring cleavage analysis. Catechol was metabolized by catechol 1,2-dioxygenase. Fungal utilization of these aromatic compounds may be important in the metabolism of wood decay products.
Phosphate starvation induces uptake of glyphosate by Pseudomonas sp. strain PG2982
Authors: Fitzgibbon J , Braymer H D
Published: January 2020

Pseudomonas sp. strain PG2982 has the ability to use the phosphonate herbicide, glyphosate, as a sole phosphorus source (J. K. Moore, H. D. Braymer, and A. D. Larson, Appl. Environ. Microbiol. 46:316-320, 1983). Glyphosate uptake is maximal in the late log phase of growth and is induced by phosphate starvation. Uptake is inhibited by phosphate and arsenate, but not by the amino acids glycine and sarcosine. The Km and Vmax for glyphosate uptake were calculated to be 23 microM and 0.97 nmol/mg (dry weight) per min, respectively. A phosphate transport system with a broad substrate specificity may be responsible for glyphosate uptake.
Metabolic processes involved in repair of Escherichia coli cells damaged by exposure to acid mine water
Authors: Wortman A T , Bissonnette G K
Published: January 2020

Escherichia coli was stressed by exposure to filter-sterilized acid mine water. Synthetic processes required for repair of sublethally injured survivors were studied by the addition of specific metabolic inhibitors to a resuscitation broth. Inhibitors of protein, RNA, DNA, lipid, and peptidoglycan synthesis as well as uncouplers and inhibitors of electron transport and ATPase activity were used. Acid mine water injury was severe, causing damage to the outer and cytoplasmic membranes. Repair of sublethally injured cells required protein, RNA, and lipid synthesis as well as a proton motive force.
Role of starch as a substrate for Bacteroides vulgatus growing in the human colon
Authors: McCarthy R E , Pajeau M , Salyers A A
Published: January 2020

Bacteroides vulgatus is the numerically predominant Bacteroides species in the human colonic microflora. Unlike other colonic Bacteroides species, B. vulgatus is not a versatile utilizer of polysaccharides. The only types of polysaccharide that support rapid growth and high growth yields by all strains are the starches amylose and amylopectin. Amylase and alpha-glucosidase activities are among the highest found in a bacterial fraction obtained from human feces. This observation raised the question of whether B. vulgatus was the source of the fecal enzymes. Both alpha-glucosidase and amylase were produced at 20- to 40-fold-higher levels when B. vulgatus was grown on maltose, amylose, or amylopectin than when B. vulgatus was grown on glucose or other monosaccharides. Both enzymes had the same pI (4.6 to 5.0) and undenatured molecular weight (150,000). The pIs and molecular weights of the B. vulgatus amylase and alpha-glucosidase were the same as those of the fecal enzymes. To determine whether the B. vulgatus alpha-glucosidase was identical to the fecal alpha-glucosidase, we partially purified the B. vulgatus enzyme and raised an antiserum against it. Using this antiserum, we showed that all strains of B. vulgatus produced the same enzyme. The antiserum did not detect the B. vulgatus alpha-glucosidase in the bacterial fraction from human feces, even when a partially purified preparation of the fecal enzyme was used. Thus the alpha-glucosidase activity in the bacterial fraction from human feces is not the B. vulgatus enzyme.
Mycotoxins and Fusarium spp. associated with infected ears of corn in Minnesota
Authors: Abbas H K , Mirocha C J , Meronuck R A , Pokorny J D , Gould S L , Kommedahl T
Published: January 2020

Five Fusarium species were isolated from the grain of dent corn (Zea mays) selected from 20 of 32 damaged fields in 10 counties in Minnesota on the basis of hyphal growth visible on kernels in the field. Three mycotoxins were identified in the infected ears: zearalenone, deoxynivalenol, and 15-acetyl-deoxynivalenol. This is the first report of the presence of 15-acetyl-deoxynivalenol on corn ears in the field prior to harvest and in combination with deoxynivalenol and zearalenone. Ninety-nine cultures were selected from colonies growing from kernels on an agar medium; 30% of the cultures were F. graminearum, 23% were F. subglutinans, 20% were F. moniliforme, 14% were F. oxysporum, and 12% were F. proliferatum.
Polyethylene glycol precipitation for recovery of pathogenic viruses, including hepatitis A virus and human rotavirus, from oyster, water, and sediment samples
Authors: Lewis G D , Metcalf T G
Published: January 2020

Polyethylene glycol 6000 precipitation was found to be an effective concentration method that enhanced the chances for detecting human virus pathogens in environmental samples. Percent recoveries from eluates of fresh and estuarine waters with 8% polyethylene glycol 6000 averaged 86 for hepatitis A virus, 77 for human rotavirus Wa, 87 for simian rotavirus SA11, and 68 for poliovirus. Percent recoveries of 97, 40, 97 and 105, respectively, for the same viruses were obtained from oyster eluates by the same procedure. Percent recoveries of 97 for hepatitis A virus and 78 for human rotavirus Wa were obtained from sediment eluates containing 2 M NaNO3 with a final concentration of 15% polyethylene glycol 6000. The polyethylene glycol method was shown to be more effective than the organic flocculation method for recovery of hepatitis A virus and rotaviruses Wa and SA11, but not of poliovirus 1 in laboratory studies. In field trials, hepatitis A virus or rotavirus or both were recovered from 12 of 18 eluates by polyethylene glycol, compared with recovery from 9 of 18 eluates by organic flocculation from fresh and estuarine waters subject to pollution.
Effect of Benzoic Acid on Growth Yield of Yeasts Differing in Their Resistance to Preservatives
Authors: Warth Alan D.
Published: January 2020

Yeasts grown in the presence of benzoic acid tolerated 40 to 100% higher benzoic acid concentrations than did those grown in the absence of weak-acid-type preservatives. They also accumulated less benzoate in the presence of glucose. In chemostat cultures, benzoic acid reduced growth yield and the rate of cell production but increased specific fermentation rates. Benzoate contents were lower than those required for equilibrium when cells were impermeable to benzoate anion. Intracellular pHs were maintained near neutrality. Between species, stimulation of fermentation was inversely related to preservation resistance but was unrelated to the maximum rate of fermentation. The results show that a major effect of benzoic acid on yeasts in the presence of an energy source is the energy requirement for the reduction in cytoplasmic benzoate concentration and maintenance of pH. This energy source is unavailable for growth, resulting in lower growth yields and rates. Resistant species may be less permeable to undissociated benzoic acid.
Mineralization of Carbofuran by a Soil Bacterium
Authors: Ramanand K. , Sharmila M. , Sethunathan N.
Published: January 2020

A bacterium, tentatively identified as an
Arthrobacter
sp., was isolated from flooded soil that was incubated at 35°C and repeatedly treated with carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl
N
-methylcarbamate). This bacterium exhibited an exceptional capacity to completely mineralize the ring-labeled
14
C in carbofuran to
14
CO
2
within 72 to 120 h in a mineral salts medium as a sole source of carbon and nitrogen under aerobic conditions. Mineralization was more rapid at 35°C than at 20°C. No degradation of carbofuran occurred even after prolonged incubation under anaerobic conditions. The predicted metabolites of carbofuran, 7-phenol (2,3-dihydro-2,2-dimethyl-7-benzofuranol) and 3-hydroxycarbofuran, were also metabolized rapidly. 7-Phenol, although formed during carbofuran degradation, never accumulated in large amounts, evidently because of its further metabolism through ring cleavage. The bacterium readily hydrolyzed carbaryl (1-naphthyl
N
-methylcarbamate), but its hydrolysis product, 1-naphthol, resisted further degradation by this bacterium.
Formation of fusarenone X, nivalenol, zearalenone, alpha-trans-zearalenol, beta-trans-zearalenol, and fusarin C by Fusarium crookwellense
Authors: Golinski P , Vesonder R F , Latus-Zietkiewicz D , Perkowski J
Published: January 2020

Fusarium crookwellense KF748 (NRRL A-28100) (isolated from dry rotted potato tubers in Central Poland) produced six mycotoxins on both rice and corn substrates at 25 degrees C. The metabolites detected were zearalenone, alpha-trans-zearalenol, beta-trans-zearalenol, fusarin C, and the trichothecenes fusarenone X and nivalenol. This is the first report of formation of alpha-trans-zearalenol, beta-trans-zearalenol, fusarenone X, and nivalenol by F. crookwellense.
Improved Method for Determining Bacterial Filtration Rates in Zooplankton
Authors: Marvalin Olivier , Lazarek Stanislaw
Published: January 2020

Filtration rates were determined for a natural population of zooplankton grazers (
Bosmina longirostris
[Müll.],
Cyclops vicinus vicinus
[Ulianine],
Acanthodiaptomus denticornis
[Wierz.], and
Daphnia longispina
[Müll.]) by using
3
H-labeled bacteria as food for these organisms. There was a relationship between filtration rates of the major zooplankton grazers and the prevailing algal and bacterial composition in the lake water. Low filtration rates were obtained in the presence of colonial and filamentous cyanobacteria. The rapid process of bacterial adhesion to the external organs of grazers can result in an overestimation of filtration rates. By using the simple method presented here, filtration rates, with simultaneous correction for bacterial adhesion, can be quickly determined.
Induction and Catabolite Repression of β-Glucosidase Synthesis in
Myceliophthora thermophila
D-14 (= ATCC 48104)
Authors: Roy Samir K. , Raha Syamal K. , Dey Susanta K. , Chakrabarty S. L.
Published: January 2020

β-Glucosidase activity in
Myceliophthora thermophila
D-14 (= ATCC 48104) was inducible and was produced in culture filtrate during growth with various inducers, of which PNPG (
p
-nitrophenyl-β-
d
-glucoside) was the most efficient. Induction of β-glucosidase also occurred when the organism was grown in medium supplemented with different carbon sources. Carboxymethyl cellulose, cellobiose, and Solka-Floc were found effective for induction of enzyme biosynthesis. The addition of glucose to the culture medium severely repressed β-glucosidase synthesis, which could not be reversed by exogenous cyclic AMP or dibutyryl cyclic AMP.
Enumeration of anaerobic bacterial microflora of the equine gastrointestinal tract
Authors: Mackie R I , Wilkins C A
Published: January 2020

Samples from the duodenum, jejunum, and ileum, as well as from the cecum and colon, were obtained from 11 mature grass-fed horses. Viable counts of total culturable and proteolytic bacteria were made on habitat-simulating media containing 40% clarified ruminal fluid. The mean pHs in the duodenum, jejunum, and ileum were 6.32, 7.10, and 7.47, respectively; the mean pH decreased to 6.7 in the hindgut. The acetate concentration increased along the length of the small intestine and was the only volatile fatty acid present in this gut segment. Molar proportions of acetate, propionate, and butyrate in the hindgut were 85:10:3. Differences in bacterial counts on habitat-simulating media containing equine cecal fluid or clarified ruminal fluid were negligible. Bacterial counts showed a substantial population in the duodenum (ca. 2.9 x 10(6) per g [wet weight] of sample), and this increased to 29.0 x 10(6) in the jejunum and 38.4 x 10(6) in the ileum. Proteolytic bacteria formed a high proportion of the total culturable bacteria, especially in duodenal samples. Counts of proteolytic bacteria per gram (wet weight) of sample were 3.0 x 10(6), 15.6 x 10(6), and 22.0 x 10(6) in the duodenum, jejunum, and ileum, respectively. There was a close relationship between lumenal and mucosal bacterial counts, although actual values were lower in mucosal samples. The mucosal bacterial population in the duodenum was high relative to the lumenal population. Although the comparison of bacterial populations in the hindgut of the horse and white rhino was limited to a single animal, the results were of interest. Counts were higher in the cecum than in the colon for both the horse and the white rhino.(ABSTRACT TRUNCATED AT 250 WORDS)
Chlorella viruses isolated in China
Authors: Zhang Y P , Burbank D E , Van Etten J L
Published: January 2020

Plaque-forming viruses of the unicellular, eucaryotic, exsymbiotic, Chlorella-like green algae strain NC64A, which are common in the United States, were also present in fresh water collected in the People's Republic of China. Seven of the Chinese viruses were examined in detail and compared with the Chlorella viruses previously isolated in the United States. Like the American viruses, the Chinese viruses were large polyhedra and sensitive to chloroform. They contained numerous structural proteins and large double-stranded DNA genomes of at least 300 kilobase pairs. Each of the DNAs from the Chinese viruses contained 5-methyldeoxycytosine, which varied from 12.6 to 46.7% of the deoxycytosine, and N6-methyldeoxyadenosine, which varied from 2.2 to 28.3% of the deoxyadenosine. Four of the Chinese virus DNAs hybridized extensively with DNA from the American virus PBCV-1, and three hybridized poorly.
Demethylation of Dimethylsulfoniopropionate and Production of Thiols in Anoxic Marine Sediments
Authors: Kiene Ronald P. , Taylor Barrie F.
Published: January 2020

Dimethylsulfoniopropionate (DMSP) is a natural product of algae and aquatic plants, particularly those from saline environments. We investigated whether DMSP could serve as a precursor of thiols in anoxic coastal marine sediments. The addition of 10 or 60 μM DMSP to anoxic sediment slurries caused the concentrations of 3-mercaptopropionate (3-MPA) and methanethiol (MSH) to increase. Antibiotics prevented the appearance of these thiols, indicating biological formation. Dimethyl sulfide (DMS) and acrylate also accumulated after the addition of DMSP, but these compounds were rapidly metabolized by microbes and did not reach high levels. Acrylate and DMS were probably generated by the enzymatic cleavage of DMSP. MSH arose from the microbial metabolism of DMS, since the direct addition of DMS greatly increased MSH production. Additions of 3-methiolpropionate gave rise to 3-MPA at rates similar to those with DMSP, suggesting that sequential demethylation of DMSP leads to 3-MPA formation. Only small amounts of MSH were liberated from 3-methiolpropionate, indicating that demethiolation was not a major transformation for 3-methiolpropionate. We conclude that DMSP was degraded in anoxic sediments by two different pathways. One involved the well-known enzymatic cleavage to acrylate and DMS, with DMS subsequently serving as a precursor of MSH. In the other pathway, successive demethylations of the sulfur atom proceeded via 3-methiolpropionate to 3-MPA.
Production by
Streptomyces viridosporus
T7A of an Enzyme Which Cleaves Aromatic Acids from Lignocellulose
Authors: Donnelly Paula K. , Crawford Don L.
Published: January 2020

The lignocellulose-degrading actinomycete
Streptomyces viridosporus
T7A produced an extracellular esterase when grown in a mineral salts-yeast extract medium. Extracellular esterase activity was first detected during the late stationary phase and typically followed the appearance of intracellular activity. When the organism was grown in lignocellulose-supplemented medium, esterase activity was not increased, but lignocellulose-esterified
p
-coumaric acid and vanillic acid were released into the medium. Polyacrylamide gels showed that several extracellular esterases differing in substrate specificity were produced. Ultrafiltration was used to concentrate the esterase prior to purification. Activity was recovered mostly in the molecular weight fraction between 10,000 and 100,000. Concentrated esterase was further purified by DEAE-Sepharose anion-exchange chromatography to a specific activity 11.82 times greater than that in the original supernatant. There were seven detectable esterase active proteins in the partially purified enzyme solution. Three were similar esterases that may be isoenzymes. The partially purified esterase had a pH optimum for activity of 9.0, a temperature optimum of 45 to 50°C, and a
K

m

and
V
max
of 0.030 mM and 0.097 μmol/min per ml, respectively, when
p
-nitrophenyl butyrate was the substrate. The enzyme was unstable above 40°C but retained activity when stored at 4 or −20°C. It lost some activity (20%) when lyophilized. Substrate specificity assays showed that it hydrolyzed ester linkages of
p
-nitrophenyl butyrate, α-naphthyl acetate, α-naphthyl butyrate, and lignocellulose. Vanillic and
p
-coumaric acids were identified as products released from lignocellulose. The enzyme is thought to be a component of the lignocellulose-degrading enzyme system of
S. viridosporus
.
Host Ranges of the IncN Group Plasmid pCU1 and Its Minireplicon in Gram-Negative Purple Bacteria
Authors: Krishnan B. Rajendra , Iyer V. N.
Published: January 2020

The bacterial host ranges of the conjugatively self-transmissible IncN group plasmid pCU1 and its mobilizable miniderivative, pCU785, were examined. Species of the gram-negative purple bacteria were chosen for this study. Conjugative mobilization of pCU785 into a wide variety of bacteria was facilitated by the presence of
oriT
of the broad-host-range plasmid RK2 in pCU785. Although the host range of the IncN
tra
system of pCU1 is broad, the host range of its replicon is limited. However, the pCU1 replicon can be maintained in
Agrobacterium, Bradyrhizobium
, and
Rhizobium
species under conditions that select for plasmid maintenance. It is lost efficiently from these populations on release of selection.
Possible mechanisms responsible for the reduced intestinal flora in hibernating leopard frogs (Rana pipiens)
Authors: Banas J A , Loesche W J , Nace G W
Published: January 2020

Mechanisms and factors that normally control the large intestinal flora were investigated to determine whether changes in these parameters could account for the decreased bacterial concentration and facultative nature of the flora found in hibernating frogs. It appeared that low temperatures and limited nutrients were the main factors responsible for the decrease in the bacterial concentration and may also have been responsible for the increase in the proportions of facultative organisms, since no change in the redox potential was seen. The hibernating frogs were extremely sluggish in the removal of India ink particles from the circulatory system by the Kupffer cells of the liver compared with nonhibernating frogs. They were unable to mount an antibody response to bovine serum albumin, but their serum did exhibit killing of Pseudomonas paucimobilis, suggesting opsonization by preformed antibody and complement. The role of these host factors in protecting the hibernating frog against this indigenous flora is discussed.
Determination of Poly-β-Hydroxybutyrate and Poly-β-Hydroxyvalerate in Activated Sludge by Gas-Liquid Chromatography
Authors: Comeau Yves , Hall Kenneth J. , Oldham William K.
Published: January 2020

A convenient gas-liquid chromatography procedure to quantify poly-β-hydroxybutyrate and poly-β-hydroxyvalerate in activated sludge was developed by combining lyophilization of the samples, purification of the chloroform phase by water reextraction, and the use of capillary columns. With a flame ionization detector the sensitivity was estimated at 10
−5
g/liter.
Ruminal cellulolytic bacteria and protozoa from bison, cattle-bison hybrids, and cattle fed three alfalfa-corn diets
Authors: Varel V H , Dehority B A
Published: January 2020

Ruminal cellulolytic bacteria and protozoa and in vitro digestibility of alfalfa fiber fractions were compared among bison, bison hybrids, and crossbed cattle (five each) when they were fed alfalfa and corn in a ratio of 100:0, 75:25, and 50:50, respectively. The total number of viable bacteria (2.16 x 10(9) to 5.44 x 10(9)/ml of ruminal fluid) and the number of cellulolytic bacteria (3.74 x 10(7) to 10.9 x 10(7)/ml) were not different among groups of animals fed each diet. The genera of protozoa in all of the animal groups were similar; however, when either the 100:0 or 50:50 diet was used the percentage of Entodinium sp. was lower and the percentage of Diplodiniinae was higher (P less than 0.05) in bison than in bison hybrids or cattle. Bacteroides succinogenes made up the largest number of cellulolytic isolates from bison (58 and 36%, respectively, on the 100:0 and 75:25 diets), which were more numerous (P less than 0.05) than those from bison hybrids (36 and 12%) and cattle (33 and 18%). This was offset by a lower number of cellulolytic Butyrivibrio isolates. The numbers of Ruminococcus albus and R. flavefaciens isolates, in general, were similar among the bovid species, although R. flavefaciens generally made up less than 10% of the cellulolytic isolates. In vitro digestibility coefficients were greater (P less than 0.05) for the bison when the 75:25 diet was used and similar for the other two diets. The concentration of ruminal volatile fatty acids was larger (P less than 0.05) in bison than in bison hybrids and cattle when the 50:50 diet was used.(ABSTRACT TRUNCATED AT 250 WORDS)
Biodegradation of polycyclic hydrocarbons by Phanerochaete chrysosporium
Authors: Bumpus J A
Published: January 2020

The ability of the white rot fungus Phanerochaete chrysosporium to degrade polycyclic aromatic hydrocarbons (PAHs) that are present in anthracene oil (a distillation product obtained from coal tar) was demonstrated. Analysis by capillary gas chromatography and high-performance liquid chromatography showed that at least 22 PAHs, including all of the most abundant PAH components present in anthracene oil, underwent 70 to 100% disappearance during 27 days of incubation with nutrient nitrogen-limited cultures of this fungus. Because phenanthrene is the most abundant PAH present in anthracene oil, this PAH was selected for further study. In experiments in which [14C]phenanthrene was incubated with cultures of P. chrysosporium containing anthracene oil for 27 days, it was shown that 7.7% of the recovered radiolabeled carbon originally present in [14C]phenanthrene was metabolized to 14CO2 and 25.2% was recovered from the aqueous fraction, while 56.1 and 11.0% were recovered from the methylene chloride and particulate fractions, respectively. High-performance liquid chromatography of the 14C-labeled material present in the methylene chloride fraction revealed that most (91.9%) of this material was composed of polar metabolites of [14C]phenanthrene. These results suggest that this microorganism may be useful for the decontamination of sites in the environment contaminated with PAHs.
Acetate-Activating Enzymes of
Bradyrhizobium japonicum
Bacteroids
Authors: Preston Glenn G. , Zeiher Carolyn , Wall Judy D. , Emerich David W.
Published: January 2020

Acetyl coenzyme A (acetyl-CoA) synthetase and acetate kinase were localized within the soluble portion of
Bradyrhizobium japonicum
bacteroids, and no appreciable activity was found elsewhere in the nodule. The presence of each acetate-activating enzyme was confirmed by separation of the two enzyme activities on a hydroxylapatite column, by substrate dependence of each enzyme in both the forward and reverse directions, by substrate specificity, by inhibition patterns, and also by identification of the reaction products by C
18
reverse-phase high-pressure liquid chromatography. Phosphotransacetylase activity, found in the soluble portion of the bacteroid, was dependent on the presence of potassium and was inhibited by added sodium. The greatest acetyl-CoA hydrolase activity was found in the root nodule cytosol, although appreciable activity also was found within the bacteroids. The combined specific activities of acetyl-CoA synthetase and acetate kinase-phosphotransacetylase were approximate to that of the pyruvate dehydrogenase complex, thus providing
B. japonicum
with sufficient capacity to generate acetyl-CoA.
Purification and Characterization of an Endo-(1,3)-β-
d
-Glucanase from
Trichoderma longibrachiatum
Authors: Tangarone B. , Royer J. C. , Nakas J. P.
Published: January 2020

A laminarinase [endo-(1,3)-β-
d
-glucanase] has been purified from
Trichoderma longibrachiatum
cultivated with
d
-glucose as the growth substrate. The enzyme was found to hydrolyze laminarin to oligosaccharides varying in size from glucose to pentaose and to lesser amounts of larger oligosaccharides. The enzyme was unable to cleave laminaribiose but hydrolyzed triose to laminaribiose and glucose. The enzyme cleaved laminaritetraose, yielding laminaritriose, laminaribiose, and glucose, and similarly cleaved laminaripentaose, yielding laminaritetraose, laminaritriose, laminaribiose, and glucose. The enzyme cleaved only glucans containing β-1,3 linkages. The pH and temperature optima were 4.8 and 55°C, respectively. Stability in the absence of a substrate was observed at temperatures up to 50°C and at pH values between 4.9 and 9.3. The molecular mass was determined to be 70 kilodaltons by sodium dodecyl sulfate-12.5% polyacrylamide gel electrophoresis, and the pI was 7.2. Enzyme activity was significantly inhibited in the presence of HgCl
2
, MnCl
2
, KMnO
4
, and
N
-bromosuccinimide. The

K
m

of the enzyme on laminarin was 0.0016%, and the
V
max
on laminarin was 3,170 μmol of glucose equivalents per mg of the pure enzyme per min.
Sugar Utilization and Acid Production by Free and Entrapped Cells of
Streptococcus salivarius
subsp.
thermophilus, Lactobacillus delbrueckii
subsp.
bulgaricus,
and
Lactococcus lactis
subsp.
lactis
in a Whey Permeate Medium
Authors: Audet Pascal , Paquin Celine , Lacroix Christophe
Published: January 2020

Cells of
Streptococcus salivarius
subsp.
thermophilus
and
Lactococcus lactis
subsp.
lactis
entrapped in
k
-carrageenan-locust bean gum gel performed similarly to free cells in the conversion of lactose to lactic acid. Bead diameter influenced the fermentation rate. Cells entrapped in smaller beads (0.5 to 1.0 mm) showed higher release rates, higher lactose, glucose, and formic acid utilization, higher galactose accumulation, and higher lactic acid production than did cells entrapped in larger beads (1.0 to 2.0 mm). Values for smaller beads were comparable with those for free cells. Immobilization affected the fermentation rate of lactic acid bacteria, especially
Lactobacillus delbrueckii
subsp.
bulgaricus.
Entrapped cells of
L. delbrueckii
subsp.
bulgaricus
demonstrated a lower lactic acid production than did free cells in batch fermentation. The kinetics of the production of formic and pyruvic acids by
L. lactis
subsp.
lactis
and
S. salivarius
subsp.
thermophilus
are presented.
Biotransformation and detoxification of T-2 toxin by soil and freshwater bacteria
Authors: Beeton S , Bull A T
Published: January 2020

Bacterial communities isolated from 17 of 20 samples of soils and waters with widely diverse geographical origins utilized T-2 toxin as a sole source of carbon and energy for growth. These isolates readily detoxified T-2 toxin as assessed by a Rhodotorula rubra bioassay. The major degradation pathway of T-2 toxin in the majority of isolates involved side chain cleavage of acetyl moieties to produce HT-2 toxin and T-2 triol. A minor degradation pathway of T-2 toxin that involved conversion to neosolaniol and thence to 4-deacetyl neosolaniol was also detected. Some bacterial communities had the capacity to further degrade the T-2 triol or 4-deacetyl neosolaniol to T-2 tetraol. Two communities, TS4 and KS10, degraded the trichothecene nucleus within 24 to 48 h. These bacterial communities comprised 9 distinct species each. Community KS10 contained 3 primary transformers which were able to cleave acetate from T-2 toxin but which could not assimilate the side chain products, whereas community TS4 contained 3 primary transformers which were able to grow on the cleavage products, acetate and isovalerate. A third community, AS1, was much simpler in structure and contained only two bacterial species, one of which transformed T-2 toxin to T-2 triol in monoculture. In all cases, the complete communities were more active against T-2 toxin in terms of rates of degradation than any single bacterial component. Cometabolic interactions between species is suggested as a significant factor in T-2 toxin degradation.
Enhanced Cellulose Fermentation by an Asporogenous and Ethanol-Tolerant Mutant of
Clostridium thermocellum
Authors: Tailliez P. , Girard H. , Millet J. , Beguin P.
Published: January 2020

A mutant of
Clostridium thermocellum
isolated after UV mutagenesis and selection for resistance to fluoropyruvate was found to be asporogenous and ethanol tolerant. The mutant was also an ethanol hyperproducer, able to ferment 63 g of cellulose into 14.5 g of ethanol per liter of medium. The ratio of ethanol to total organic acids produced by the mutant was increased, and H
2
production was decreased. Culture conditions were optimized for ethanol production by the new strain.
Mycotoxin production by Fusarium oxysporum and Fusarium sporotrichioides isolated from Baccharis spp. from Brazil
Authors: Mirocha C J , Abbas H K , Kommedahl T , Jarvis B B
Published: January 2020

Fusarium oxysporum isolated from roots of and soil around Baccharis species from Brazil produced the trichothecenes T-2 toxin, HT-2 toxin, diacetoxyscirpenol, and 3'-OH T-2 (TC-1), whereas Fusarium sporotrichioides from the same source produced T-2 toxin, HT-2 toxin, acetyl T-2, neosolaniol, TC-1, 3'-OH HT-2 (TC-3), iso-T-2, T-2 triol, T-2 tetraol, and the nontrichothecenes moniliformin and fusarin C. Several unknown toxins were found but not identified. Not found were macrocyclic trichothecenes, zearalenone, wortmannin, and fusarochromanone (TDP-1).
Cytokinins in
Azotobacter vinelandii
Culture Medium
Authors: Taller Barbara J. , Wong Tit-Yee
Published: January 2020

Azotobacter vinelandii
OP was grown to stationary phase in defined medium. The cell-free culture medium was analyzed for cytokinin content by XAD-2 and Sephadex LH-20 chromatography, thin-layer chromatography, tobacco callus bioassay, and enzyme immunoassay. Three cytokinin-active fractions were detected and tentatively identified as
trans
-zeatin, isopentenyladenosine, and isopentenyladenine. The total cytokinin activity was equivalent to 0.75 μg of kinetin per liter.
Acute Copper and Cupric Ion Toxicity in an Estuarine Microbial Community
Authors: Jonas Robert B.
Published: January 2020

Copper was acutely toxic to the estuarine microbial community of Middle Marshes, N.C. Under ambient water quality conditions, 10 μg of added total copper [Cu(II)] liter
−1
reduced the CFU bacterial abundance by up to 60% and inhibited the amino acid turnover rate (AATR) by as much as 30%. Copper toxicity, however, was a quantitative function of free cupric ion (Cu
2+
) activity that was not directly related to Cu(II) or ligand-bound copper. By using a nitrilotriacetic acid-cupric ion buffer to control pCu (−log Cu
2+
activity), it was found that an in situ pCu of 10.1 was bactericidal, reducing the CFU by 60%, but inhibited the AATR by only about 10%. A bacterial bioassay that was used to estimate the pCu in Cu(II)-treated Middle Marshes samples indicated that less than 0.5% of added Cu(II) was in the free cupric ion form. CFU was a more sensitive indicator of low-level copper stress than was AATR. When tested at different times, native microbial community responses to acute cupric ion stress were quantitatively quite similar even when there were large differences in bacterial abundances and in situ metabolic rates. Variations were observed in response to Cu(II) treatments at different times, but these were likely due to differences in water quality, which would quantitatively influence the distribution of copper complexes that were present. Asymptotic response curves suggest that some degree of copper resistance exists in this community. At a pCu of 8, more than 2 orders of magnitude above the minimum inhibitory level, the CFU was still 5 to 10% and the AATR was about 3% of the control values.