bluuebunny/crossref_metadata_2025 huggingface dataset:
Rhizosphere Response as a Factor in Competition Among Three Serogroups of Indigenous
Rhizobium japonicum
for Nodulation of Field-Grown Soybeans
Authors: Moawad H. A. , Ellis W. R. , Schmidt E. L.
Published: January 2020

Rhizosphere response was studied as a factor in competition among indigenous
Rhizobium japonicum
serogroups for the nodulation of soybeans under field conditions.
R. japonicum
serogroups 110, 123, and 138 were found to coexist in a Waukegan field soil where they were determined to be the major nodulating rhizobia in soybean nodules. Competitive relationships among the three serogroups in that soil and in rhizospheres were examined during two growing seasons with several host cultivars with and without inoculation and with a nonlegume. Enumeration of each of the three competitors was carried out on inner rhizosphere and nonrhizosphere soil by immunofluorescence with serogroup-specific fluorescent antibodies. Rhizobia present in early- and late-season nodules were identified by fluorescent antibody analysis. Populations of each serogroup increased gradually in host rhizospheres, not exceeding 10
6
/g of rhizosphere soil during the first few weeks after planting, whereas numbers in fallow soil remained at initial levels (10
4
to 10
5
/g). The rhizosphere effects were minor in host plants during this period of nodule initiation and were about the same for all three serogroups. Although serogroup 123 gave no evidence of dominance in early host rhizospheres, it clearly dominated in nodule composition, occupying 60 to 100% of the nodules. High densities of all three serogroups were observed in host rhizospheres during flowering. Rhizosphere populations, especially of serogroup 123, were still high during pod fill and seed maturation. The rhizosphere responses of the
R. japonicum
serogroups were much greater with the soybean cultivars than with oats, but even in host rhizospheres the
R. japonicum
populations were greatly outnumbered by other bacteria. The success of serogroup 123 in achieving nodulation does not appear to be due to superior colonization of the host rhizosphere.
Adhesion of
Colletotrichum lindemuthianum
Spores to
Phaseolus vulgaris
Hypocotyls and to Polystyrene
Authors: Young David H. , Kauss Heinrich
Published: January 2020

Adhesion of
Colletotrichum lindemuthianum
spores to
Phaseolus vulgaris
hypocotyls and to polystyrene was inhibited by the respiratory inhibitors sodium azide and antimycin A, indicating a requirement for metabolic activity in adhesion. Various commercial proteins and Tween 80 also reduced adhesion to both surfaces. Binding was enhanced by the presence of salts: sodium, potassium, calcium, and magnesium chlorides were equally effective. The removal of surface wax from hypocotyls by chloroform treatment greatly reduced their subsequent ability to bind spores. The results suggest a similar mechanism for spore adhesion to the plant surface and to polystyrene, involving purely physical surface properties rather than group-specific binding sites.
7 alpha-Dehydroxylation of bile acids by resting cells of a Eubacterium lentum-like intestinal anaerobe, strain c-25
Authors: Masuda N , Oda H , Hirano S , Masuda M , Tanaka H
Published: January 2020

7 alpha-Dehydroxylation of cholic acid and chenodeoxycholic acid by whole cells of strain c-25, a Eubacterium lentum-like intestinal anaerobe, was studied. 7 alpha-Dehydroxylase activity was observed only in whole cells grown in the presence of the primary bile acid (cholic acid or chenodeoxycholic acid). Chenodeoxycholic acid was twice as effective as cholic acid as an inducer. Although cells grown in the presence of chenodeoxycholic acid had no significant substrate specificity for the two primary bile acids, cells grown in the presence of cholic acid showed two times greater activity against cholic acid than chenodeoxycholic acid. Exposure of cell suspensions to atmospheric oxygen resulted in little loss of the 7 alpha-dehydroxylase activity. The induced enzyme had an optimal pH range of 7.3 to 7.7. Although adding flavin mononucleotide to the growth medium significantly increased the 7 alpha-dehydroxylation of bile acids without an increase in cell growth, inhibition of the enzyme activity was observed in the resting cell system when flavin mononucleotide was included in the reaction mixture.
Use of Poisons in Determination of Microbial Manganese Binding Rates in Seawater
Authors: Rosson Reinhardt A. , Tebo Bradley M. , Nealson Kenneth H.
Published: January 2020

A method was developed to determine whether microorganisms mediate the precipitation of manganese(II) in the marine environment. Radioactive
54
Mn(II) was used as a tracer to measure the precipitation (binding and oxidation) of Mn(II) [i.e., the
54
Mn(II) trapped on 0.2-μm membrane filters] in the presence and absence of biological poisons. A variety of antibiotics, fixatives, and metabolic inhibitors were tested in laboratory control experiments to select poisons that did not interfere in the chemistry of manganese. The poisons were deemed suitable if (i) they did not complex Mn(II) more strongly than the ion-exchange resin Chelex 100, (ii) they did not interfere in the adsorption of
54
Mn(II) onto synthetic δMnO
2
(manganate), (iii) they did not cause desorption of
54
Mn(II) which had been preadsorbed onto synthetic manganate, and (iv) they did not solubilize synthetic
54
manganate. In addition, several known chelators, reducing agents, and buffers normally added to microbiological growth media or used in biochemical assays were tested. Most additions interfered to some extent with manganese chemistry. However, at least one inhibitor, sodium azide, or a mixture of sodium azide, penicillin, and tetracycline was shown to be appropriate for use in field studies of
54
Mn(II) binding. Formaldehyde could also be used in short incubations (1 to 3 h) but was not suitable for longer time course studies. The method was applied to studies of Mn(II) precipitation in Saanich Inlet, British Columbia, Canada. Bacteria were shown to significantly enhance the rate of Mn(II) removal from solution in the manganese-rich particulate layer which occurs just above the oxygen-hydrogen sulfide interface in the water column.
Distribution and effects of a defined six-member murine-derived microflora in gnotobiotic gerbils
Authors: Bartizal K F , Wostmann B S , Wagner M
Published: January 2020

The gnotobiotic gerbil was selected as a model with which to study the effects of colonization with a defined microflora on organ morphology, histology, and selected blood biochemical parameters. Gerbils were maintained germfree for 13 months but failed to reproduce, presumably because of the enlarged cecum. A colony of gnotobiotic gerbils that was associated with a bacterial flora consisting of Lactobacillus brevis, Streptococcus faecalis, Staphylococcus epidermidis, Bacteroides vulgatus, Enterobacter aerogenes, and a Fusobacterium sp. was established. These gnotobiotic gerbils had smaller ceca than germfree gerbils and proved capable of reproduction. Except for the presence of large numbers of Bacteroides organisms in the stomach and greater numbers of S. epidermidis in gnotobiotic gerbils, the number and location of gastrointestinal bacteria were similar in conventional and gnotobiotic gerbils. Bacteroides sp. was the second most predominant microorganism present in gnotobiotic gerbils, whereas clostridia were reported to be the second most predominant microorganism in conventional gerbils. Microscopic examination of direct-impression smears indicated that fusobacteria were present on mucosal surfaces. Intestines of gnotobiotic gerbils weighed twice as much as the intestines of conventional gerbils. Intestinal tissue water weight values from conventional and gnotobiotic gerbils were similar. Histological examination of gerbil intestinal tissue revealed no cellular hypertrophy and no evidence of inflammation in gnotobiotic gerbil intestines. Spleens of gnotobiotic gerbils showed no germinal center stimulation. Statistical differences in total serum glucose, serum protein, and hematocrit levels were found between conventional and gnotobiotic gerbils.
Methanogenesis in a Thermophilic (58°C) Anaerobic Digestor:
Methanothrix
sp. as an Important Aceticlastic Methanogen
Authors: Zinder S. H. , Cardwell S.C. , Anguish T. , Lee M. , Koch M.
Published: January 2020

Aceticlastic methanogens and other microbial groups were enumerated in a 58°C laboratory-scale (3 liter) anaerobic digestor which was fed air-classified municipal refuse, a lignocellulosic waste (loading rate = 1.8 to 2.7 g of volatile solids per liter per day; retention time = 10 days). Two weeks after start-up,
Methanosarcina
sp. was present in high numbers (10
5
to 10
6
CFU/ml) and autofluorescent
Methanosarcina
-like clumps were abundant in sludge examined by using epifluorescence microscopy. After about 4 months of digestor operation, numbers of
Methanosarcina
sp. dropped 2 to 3 orders of magnitude and large numbers (most probable number = 10
6
to 10
7
/ml) of a thermophilic aceticlastic methanogen morphologically resembing
Methanothrix
sp. were found.
Methanothrix
sp. had apparently displaced
Methanosarcina
sp. as the dominant aceticlastic methanogen in the digestor. During the period when
Methanothrix
sp. was apparently dominant, acetate concentrations varied between 0.3 and 1.5 μmol/ml during the daily feeding cycle, and acetate was the precursor of 63 to 66% of the methane produced during peak digestor methanogenesis. The apparent

K
m

value obtained for methanogenesis from acetate, 0.3 μmol/ml, indicated that the aceticlastic methanogens were nearly saturated for substrate during most of the digestor cycle. CO
2
-reducing methanogens were capable of methanogenesis at rates more than 12 times greater than those usually found in the digestor. Added propionate (4.5 μmol/ml) was metabolized slowly by the digestor populations and slightly inhibited methanogenesis. Added
n
-butyrate, isobutyrate, or
n
-valerate (4.5 μmol/ml each) were broken down within 24 h. Isobutyrate was oxidized to acetate, a novel reaction possibly involving isomerization to
n
-butyrate. The rapid growth rate and versatile metabolism of
Methanosarcina
sp. make it a likely organism to be involved in start-up, whereas the low

K
m

value of
Methanothrix
sp. for acetate may cause it to be favored in stable digestors operated with long retention times.
Laboratory Calibrations of the [
3
H]Adenine Technique for Measuring Rates of RNA and DNA Synthesis in Marine Microorganisms
Authors: Winn Christopher D. , Karl David M.
Published: January 2020

The nucleic acid synthesis rates of several marine phytoplankton and bacteria grown in chemostat and batch cultures were measured by using [
3
H]adenine. The [
3
H]adenine synthesis rates showed excellent agreement with the known rates of synthesis estimated from chemical RNA and DNA data. Under certain conditions, RNA turnover and ATP pool compartmentalization produce inaccuracies in synthesis measurements made with [
3
H]adenine. However, accurate measurements of the rates of microbial RNA and DNA synthesis can be made in any environmental situation provided a few simple precautions are observed. First, time course experiments are recommended. Second, experiments should be conducted for periods long enough to avoid problems arising from disequilibria of internal ATP pools. Finally, exogenous [
3
H]adenine should remain in the medium over the length of the time course.
Autotrophic Growth of Gas Vacuolate Strains of
Microcyclus aquaticus
on Methanol and Hydrogen
Authors: Konopka Allan , Szentes Mark
Published: January 2020

Seven strains of
Microcyclus aquaticus
were found to be capable of growth on methanol and hydrogen as energy sources. Carbon was incorporated as CO
2
via the Calvin cycle, as shown by the presence of ribulosebisphosphate carboxylase activity in methanol-grown cells and by the absence of key enzymes of the ribulose monophosphate and serine pathways. In addition, incoporation of [
14
C]methanol into cells was diminished when cultures were incubated in gas atmospheres enriched with carbon dioxide.
Antimicrobial Effects of Ionizing Radiation on Artificially and Naturally Contaminated Cacao Beans
Authors: Restaino L. , Myron J. J. J. , Lenovich L. M. , Bills S. , Tscherneff K.
Published: January 2020

With an initial microbial level of ca. 10
7
microorganisms per g of Ivory Coast cacao beans, 5 kGy of gamma radiation under an atmosphere of air reduced the microflora per g by 2.49 and 3.03 logs at temperatures of 35 and 50°C, respectively. Bahia cacao beans were artificially contaminated with dried spores of
Aspergillus flavus
and
Penicillium citrinum
, giving initial fungal levels of 1.9 × 10
4
and 1.4 × 10
3
spores per g of whole Bahia cacao beans, respectively. The average
D
10
values for
A. flavus
and
P. citrinum
spores on Bahia cacao beans were 0.66 and 0.88 kGy, respectively.
Comparison of methods to measure acute metal and organometal toxicity to natural aquatic microbial communities
Authors: Jonas R B , Gilmour C C , Stoner D L , Weir M M , Tuttle J H
Published: January 2020

Microbial communities in water from Baltimore Harbor and from the mainstem of Chesapeake Bay were examined for sensitivity to mercuric chloride, monomethyl mercury, stannic chloride, and tributyltin chloride. Acute toxicity was determined by measuring the effects of [3H]thymidine incorporation, [14C]glutamate incorporation and respiration, and viability as compared with those of controls. Minimum inhibitory concentrations were low for all metals (monomethyl mercury, less than 0.05 microgram liter-1; mercuric chloride, less than 1 microgram liter-1; tributyltin chloride, less than 5 micrograms liter-1) except stannic chloride (5 mg liter-1). In some cases, mercuric chloride and monomethyl mercury were equally toxic at comparable concentrations. The Chesapeake Bay community appeared to be slightly more sensitive to metal stress than the Baltimore Harbor community, but this was not true for all treatments or assays. For culturable bacteria the opposite result was found. Thymidine incorporation and glutamate metabolism were much more sensitive indicators of metal toxicity than was viability. To our knowledge, this is the first use of the thymidine incorporation method for ecotoxicology studies. We found it the easiest and fastest of the three methods; it is at least equal in sensitivity to metabolic measurements, and it likely measures the effects on greater portion of the natural community.
Observations on the Distinction Between Oligotrophic and Eutrophic Marine Bacteria
Authors: Martin Pierre , MacLeod Robert A.
Published: January 2020

The nutritional requirements of two marine bacteria designated as oligotrophic because they could grow on media containing 10 mg of C per liter supplied as peptone and two classified as eutrophic because they could grow only at higher concentrations of C supplied as peptone were examined. Each of the four organisms was found to have its own unique group of compounds which could serve either individually or in combination as sources of carbon and energy for growth. When the peptone in the medium was replaced by another appropriate source of carbon and energy, the difference in the capacity of the organisms examined to grow at 10 mg of C per liter disappeared, and all four organisms could be described as being oligotrophic. Some of the organisms required a low concentration of one specific carbon source but a higher concentration of another. One of the organisms was inhibited by high concentrations of one specific carbon source but not by another. The observations indicate that current methods of enumeration based on the capacity of cells to grow in the presence of high or low concentrations of complex mixtures of nutrients such as peptone do not distinguish between two broad classes of bacteria differing intrinsically in their ability to grow at high and low concentrations of nutrients. Whether two such broad classes exist seems extremely doubtful. Which organisms will multiply in a particular environment will depend on both the specific nutrients available and their concentrations.
Bacteria associated with crabs from cold waters with emphasis on the occurrence of potential human pathogens
Authors: Faghri M A , Pennington C L , Cronholm L S , Atlas R M
Published: January 2020

A diverse array of bacterial species, including several potential human pathogens, was isolated from edible crabs collected in cold waters. Crabs collected near Kodiak Island, Alaska, contained higher levels of bacteria than crabs collected away from regions of human habitation. The bacteria associated with the crabs collected near Kodiak included Yersinia enterocolitica, Klebsiella pneumoniae, and coagulase-negative Staphylococcus species; the pathogenicity of these isolates was demonstrated in mice. Although coliforms were not found, the bacterial species associated with the tissues of crabs collected near Kodiak indicate possible fecal contamination that may have occurred through contact with sewage. Compared with surrounding waters and sediments, the crab tissues contained much higher proportions of gram-positive cocci. As revealed by indirect plate counts and direct scanning electron microscopic observations, muscle and hemolymph tissues contained much lower levels of bacteria than shell and gill tissues. After the death of a crab, however, the numbers of bacteria associated with hemolymph and muscle tissues increased significantly. Microcosm studies showed that certain bacterial populations, e.g., Vibrio cholerae, can be bioaccumulated in crab gill tissues. The results of this study indicate the need for careful review of waste disposal practices where edible crabs may be contaminated with microorganisms that are potential human pathogens and the need for surveillance of shellfish for pathogenic microorganisms that naturally occur in marine ecosystems.
Bacteriological quality of crops irrigated with wastewater in the Xochimilco plots, Mexico City, Mexico
Authors: Rosas I , Báez A , Coutiño M
Published: January 2020

Xochimilco county plots (Mexico City), one of the most fertile agricultural areas in the Valley of Mexico, produce a large portion of the fresh vegetables consumed in the city. These plots are generally irrigated with domestic wastewater, and for this reason, it was deemed important to examine and evaluate the bacteriological quality of the water, soil, and vegetables from these plots that are harvested and marketed. The soils were also examined for the classical parameters such as nitrates, ammonia, etc., and organic matter and texture. The crops selected for this study were radishes, spinach, lettuce, parsley, and celery because they are usually consumed raw. The highest bacterial counts were encountered in leafy vegetables, i.e., spinach (8,700 for total coliform and 2,400 for fecal coliform) and lettuce (37,000 for total coliform and 3,600 for fecal coliform). Statistically significant differences in bacterial counts between rinsed and unrinsed edible portions of the crops were observed even in rinsed vegetables, and high densities of fecal coliform were detected, indicating that their consumption represents a potential health hazard. The total coliform values found in irrigation water ranged from 4 X 10(4) to 29 X 10(4), and for fecal coliform the values ranged from 5 X 10(2) to 30 X 10(2).
Toxic effects of fermented and unfermented sorghum meal diets naturally contaminated with mycotoxins
Authors: Kazanas N , Ely R W , Fields M L , Erdman J W
Published: January 2020

Male weanling rats fed diets containing fermented and unfermented tannin-free sorghum meals naturally contaminated with traces of ochratoxin A, zearalenone, and an unidentified toxic substance developed anorexia. Mean changes in body weight over a 28-day feeding period for rats fed fermented and unfermented sorghum meal and ANCR casein diets of 8% protein were -2.8, +13.8, and +100.5 g, respectively. Rats fed fermented sorghum meal developed alopecia; hematological findings showed a decreased mean corpuscular volume, hypochromic microcytosis, balanced leukopenia, and hypoproteinuria . Histological findings showed testicular hypoplasia of the germinal epithelium and no mature spermatozoa. Necrosis and mineralization in Henle's loop were also observed. No damage was apparent to the liver, cerebellum, cerebrum, spleen, or adrenal glands.
Biotyping and virulence factors in clinical and environmental isolates of Aeromonas species
Authors: Burke V , Robinson J , Cooper M , Beaman J , Partridge K , Peterson D , Gracey M
Published: January 2020

Biochemical characteristics and virulence factors were compared in 147 Aeromonas spp. isolated from patients with diarrhea and in 94 strains isolated from metropolitan water supplies in the same area during the same period. Fermentation of arabinose occurred with 58.5% of the environmental strains and 15% of the clinical isolates; 39.4% of the strains from water and 6.8% of the fecal isolates fermented salicin. The frequency of esculin hydrolysis was the same in both groups. Ninety-one percent of clinical isolates and 70.2% of environmental strains were enterotoxigenic and, except for four clinical isolates, all of these strains also produced hemolysins. Hemagglutination that was inhibited by fucose and mannose but not by galactose was found in 67% of the water isolates and 10.2% of the clinical strains. Although the distribution of several characteristics differs in clinical and environmental strains, many of the strains found in water have properties identical with those of the clinical isolates. We suggest that such strains may be potential enteric pathogens.
Detection of T-2 toxin in Fusarium sporotrichioides-infected corn by enzyme-linked immunosorbent assay
Authors: Gendloff E H , Pestka J J , Swanson S P , Hart L P
Published: January 2020

A competitive enzyme-linked immunosorbent assay was used to screen for T-2 toxin in Fusarium sporotrichioides -infected corn. The assay detected T-2 toxin in diluted methanol extracts of corn samples at concentrations of 0.05 ng/ml. In infected corn samples, enzyme-linked immunosorbent assay and gas-liquid chromatography estimations of T-2 toxin concentrations were similar.
Susceptibility of Saccharomyces spp. and Schwanniomyces spp. to the aminoglycoside antibiotic G418
Authors: Panchal C J , Whitney G K , Stewart G G
Published: January 2020

Industrially useful polyploid yeasts such as the brewing yeasts do not possess any auxotrophic genetic markers and hence are not easily amenable to plasmid-mediated DNA transformations. In an attempt to obtain genetic markers, a number of useful Saccharomyces sp. strains and some amylolytic Schwanniomyces sp. strains were tested for their susceptibility to the antibiotic Geneticin G418 , a 2-deoxystreptamine reported to be active against bacteria, yeasts, and plant and animal cells. All of the Saccharomyces sp. strains, including the brewing strains, were found to be susceptible to G418 in the concentration range of 150 to 500 micrograms/ml. Of the three Schwanniomyces species investigated, only Schwanniomyces castellii (strain 1402) was found to be resistant to G418 at concentrations up to 1 mg/ml. Resistance was exhibited both in liquid media and on glycerol-peptone-yeast extract agar plates. This finding is interesting in view of the possibility of using this strain as a DNA donor for transformations aimed at introducing the amylolytic capability into brewing yeasts.
Formation of trichothecenes by Fusarium solani var. coeruleum and Fusarium sambucinum in potatoes
Authors: el-Banna A A , Scott P M , Lau P Y , Sakuma T , Platt H W , Campbell V
Published: January 2020

Fusarium solani var. coeruleum can form deoxynivalenol in potato tubers and in liquid medium, although concentrations observed in the rot were highly variable; acetyldeoxynivalenol and HT-2 toxin were detected in 1 to 3 tubers only (of 57). Trichothecenes were also detected in a very few (3 of 20) cultures of Fusarium sambucinum in potato tubers.
Novel method for studying the public health significance of macroinvertebrates occurring in potable water
Authors: Levy R V , Cheetham R D , Davis J , Winer G , Hart F L
Published: January 2020

An experimental procedure was developed to study the association of selected bacteria and macroinvertebrates and their response to free available chlorine disinfection. The organisms selected for study were Escherichia coli ( LacZ545 ), Enterobacter cloacae (ATCC 23355), and the amphipod Hyalella azteca . E. coli was shown to bind tightly (1.6 X 10(4) CFU per amphipod ) to this macroinvertebrate and to resist repeated attempts to wash it off. E. cloacae was shown to bind much less tightly (1.4 X 10(3) CFU per amphipod ) to H. azteca and was less resistant to removal by washing. The extent of association is a function of macroinvertebrate size (surface area), but the procedure produces repeatable results usable for controlled experimentation. This method, together with the dual bacterial identification criteria (morphology and antibiotic resistance), was used to study the response of unassociated and associated E. coli and E. cloacae to disinfection with free available chlorine at 1.0 mg/liter. Unassociated E. coli populations decreased to less than 1% of their zero time controls within 1 min of contact time, whereas more than 2% of the associated E. coli populations remained viable after 60 min of contact at 1.0 mg of free available chlorine per liter. Unassociated E. cloacae populations decreased to less than 1% of their zero time controls within 1 min of contact time, whereas ca. 15% of the associated E. cloacae populations remained viable after 60 min of contact at 1.0 mg of free available chlorine per liter.(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of Temperature on Consecutive Denitrification Reactions in Brookston Clay and Fox Sandy Loam
Authors: McKenney D. J. , Johnson G. P. , Findlay W. I.
Published: January 2020

The kinetics of several steps in the microbial denitrification process in Brookston clay and Fox sandy loam, two soils common to Southwestern Ontario, were studied in the temperature range of 5 to 25°C. The extent of chemical denitrification was also determined in otherwise identical but sterilized soils at temperatures up to 80°C. A gas flow system was used in which soil gases were continuously removed from anaerobic soil columns by argon carrier gas. Net steady-state rates of NO and N
2
O production, rates of loss of NO
3
−
, and production and loss of NO
2
−
were measured over periods of up to 5 days. Arrhenius activation energies for the zero-order process NO
3
−
→ NO
2
−
were calculated to be 50 ± 9 kJ mol
−1
for Brookston clay and 55 ± 13 kJ mol
−1
for Fox sandy loam. The overall reaction, NO
2
−
→ NO (chemodenitrification), in both sterile soils was accurately first order with respect to NO
2
−
; the activation energy was 70 ± 2.8 kJ mol
−1
in Brookston clay and 79 ± 1.2 kJ mol
−1
in the sandy loam, and the preexponential factors were (2.3 ± 1.2) × 10
9
and (5.7 ± 1.2) × 10
9
min
−1
, respectively.
Improved system for floor cleaning in health care facilities
Authors: Schmidt E A , Coleman D L , Mallison G F
Published: January 2020

A new system has been developed for sanitizing floors in hospitals; this system replaces the traditional procedure of daily dusting and wet mopping with a disinfectant-detergent solution and periodic buffing . This new system relies on a sequence of procedures consisting of dust mopping using a chemically treated dust mop, machine buffing of a sprayed-on polymer treatment, and a second dust mopping . The effectiveness of the procedures was evaluated by means of surface sampling for bacterial contamination and air sampling for airborne bacteria and dust. The level of bacterial contamination on the floors was reduced by 93.6% by using the new system, compared with 79.8% by using the conventional process of dust mopping and wet mopping with a disinfectant solution. The levels of airborne bacteria during and after the individual procedures did not vary significantly from the initial level (123.6 CFU/per m3 of air). A survey of representative colonies from air samples revealed staphylococci, gram-positive bacilli, gram-positive diplococci, yeast cells, and infrequent gram-negative rods. The distribution at the conclusion of the sanitizing process was similar to that at the outset. Similarly, the levels of airborne dust measured during and after the individual procedures did not vary significantly from the initial level. When compared with the traditional method of cleaning by wet mopping , the new method was significantly more effective in removal of microbial contamination and required less labor.
Comparison of microporous filters for concentration of viruses from wastewater
Authors: Rose J B , Singh S N , Gerba C P , Kelley L M
Published: January 2020

The 1-MDS Virosorb filter and the 50S and 30S Zeta-plus filters, all with a net positive charge, were compared with the negatively charged Filterite filter for concentration of naturally occurring coliphages and animal viruses from sewage effluent. When Filterite filters were used, the effluent was adjusted to pH 3.5 and AlCl3 was added before filtration to facilitate virus adsorption. No adjustment was required with the positively charged filters. Sets of each filter type were eluted with 3% beef extract (pH 9.5) or eluted with 0.05 M glycine (pH 11.5). A maximum volume of 19 liters could be passed through 142-mm diameter Filterite filters before clogging, whereas only 11, 11, and 15 liters could be passed through the 1-MDS, 50S, and 30S filters, respectively. For equal volumes passed through the filters, coliphage recoveries were 14, 15, 18, and 37% in primary effluent and 40, 97, 50, and 46% in secondary effluent for the Filterite , 1-MDS, 50S, and 30S filters, respectively. No statistically significant difference was observed in the recovery of animal viruses among the filters from secondary effluent, whereas in the Filterite and 50S filters, higher numbers of viruses from primary effluent were recovered than in the 1-MDS and 30S filters in two of three collections. Glycine was found to be a less-efficient eluent than beef extract in the recovery of naturally occurring viruses.
Effect of Substrate Concentration and Organic and Inorganic Compounds on the Occurrence and Rate of Mineralization and Cometabolism
Authors: Wang Yei-Shung , Subba-Rao R. V. , Alexander Martin
Published: January 2020

Isopropyl
N
-phenylcarbamate (IPC) at 400 pg and 1 μg/ml was mineralized in samples of sewage, but only the lower concentration was mineralized in lake water samples in a 50-day period. IPC at 1 μg/ml disappeared from lake water, but it was converted to organic products. Mineralization of IPC at 400 pg/ml in lake water was enhanced by additions of inorganic nutrients or a mixture of nonchlorinated water pollutants but not by yeast extract or mixtures containing aromatic compounds or excretions of primary producers. The mineralization of 200 pg of 2,4-dichlorophenoxyacetate per ml of lake water was not affected by additions of low levels of yeast extract or compounds excreted by primary producers but was enhanced by low concentrations of mixtures of water pollutants. It is suggested that some chemicals that are found to be converted only to organic products, presumably by cometabolism, in tests using the concentrations commonly employed in laboratory evaluations may be mineralized at the lower concentrations prevailing in natural waters.
Bioconversion of alpha-[14C]zearalenol and beta-[14C]zearalenol into [14C]zearalenone by Fusarium roseum 'Gibbosum'
Authors: Richardson K E , Hagler W M , Hamilton P B
Published: January 2020

Cultures of Fusarium roseium 'Gibbosum' on rice were treated with [14C]zearalenone, alpha[14C]zearalenol, or beta-[14C]zearalenol to determine whether a precursor-product relationship exists among these closely related fungal metabolites. Culture extracts were purified by silica gel column chromatography and fractionated by high-pressure liquid chromatography, and the level of radioactivity was determined. Within 7 days, the beta-[14C]zearalenol was converted to zearalenone, and no residual beta-[14C]zearalenol was detectable. Most of the alpha-[14C]zearalenol added was also converted into zearalenone with 14 days. In cultures treated with [14C]zearalenone, no radioactivity was noted in any other components.
Synthesis of Extracellular Proteinase by
Pseudomonas fluorescens
Under Conditions of Limiting Carbon, Nitrogen, and Phosphate
Authors: McKellar R. C. , Cholette H.
Published: January 2020

The influence of carbon, nitrogen, and phosphate concentrations on growth and proteinase production by
Pseudomonas fluorescens
32A was examined. In mineral salts medium containing dialyzed skim milk supernatant as an inducer, maximum growth was obtained at 1.0 and 2.5 mM orthophosphate at 20 and 5°C, respectively. At both temperatures, 5 mM orthophosphate was required for maximum proteinase production, whereas significant inhibition was found at 10 mM. Orthophosphate was the only phosphate compound able to support growth. With sodium pyruvate as the carbon source, maximum enzyme synthesis was at 100 mM carbon at both temperatures. At both 20 and 5°C maximum growth and enzyme production was found with 10 mM NH
4
Cl. A bioassay for available phosphate based on the growth of
P. fluorescens
32A in phosphate-limited mineral salts medium showed that skim milk and skim milk supernatant contained 50 and 10 mM orthophosphate, respectively. Proteinase production in skim milk was 2.6- and 12-fold greater than that in optimal mineral salts medium at 20 and 5°C, respectively. These results suggest that proteinase production in milk does not occur as a result of nutrient limitation and may be regulated in part by milk phosphates.
Protection of
Bacillus larvae
from Oxygen Toxicity with Emphasis on the Role of Catalase
Authors: Dingman D. W. , Stahly Donald P.
Published: January 2020

Sporulation of
Bacillus larvae
NRRL B-3650 occurred only at aeration rates lower than those used for cultivation of most
Bacillus
species. One possible explanation for the requirement for a low level of aeration in
B. larvae
is that toxic forms of oxygen such as H
2
O
2
and superoxide are involved. The superoxide dismutase levels of strain B-3650 were similar to those of
Bacillus subtilis
168 during sporulation, and no NADH peroxidase was present. Catalase activity was absent during exponential growth and first appeared near the start of the stationary phase. The catalase activity was 2,700 times less than that in
B. subtilis
168 at the same stage of development. Therefore, the relative deficiency of catalase (and NADH peroxidase) might be the cause of the apparent O
2
toxicity. It was postulated that
B. larvae
might accumulate H
2
O
2
in the medium and exhibit more than normal sensitivity to H
2
O
2
. Experimental results did not verify either postulate, but the possibilities of intracellular accumulation of H
2
O
2
and unusual sensitivity to endogenous H
2
O
2
were not excluded. The catalase present in early-stationary-phase cells was soluble, heat labile, and inhibited by cyanide, azide, and hydroxylamine. An increase in catalase activity also occurred at the time of appearance of refractile spores in both
B. larvae
NRRL B-3650 and
B. subtilis
168. The level of catalase activity in strain B-3650 was 5,400 times less than that in
B. subtilis
168 at this stage. In
B. larvae
, this second increase occurred primarily within the developing endospore. The activity in spore extracts was particulate, heat stable, and inhibited by hydroxylamine but not by azide or cyanide. Synthesis of catalase in
B. larvae
was unaffected by H
2
O
2
, O
2
, or glucose.
Effectiveness of 1-bromo-3-chloro-5,5-dimethylhydantoin against Legionella pneumophila in a cooling tower
Authors: Fliermans C B , Harvey R S
Published: January 2020

Cooling towers are considered to be man-made amplifiers of Legionella spp. Thus, the proper maintenance and choice of biocides is important. The only biocidal measure that has thus far been shown to be effective in field tests is the judicious use of chlorination. Perturbation studies with 1-bromo-3-chloro-5, 5-dimethylhydantoin (Bromicide; Great Lakes Chemical Corp., West Lafayette, Ind.) (BCD) were conducted on an industrial cooling tower shown to contain Legionella pneumophila. At the concentrations recommended by the manufacturer, neither the density nor the activity of L. pneumophila was affected. At comcentrations greater than 2.0 ppm (2.0 micorgram/ml) free of residual, BCD was not effective in reducing L. pneumophila to source water concentrations, nor was it effective in reducing the 2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride activity of the bacterium in situ. The data indicate that at concentrations up to 2.0 ppm, BCD is not effective in these tower studies.
Factors affecting spore formation in a Candida albicans strain
Authors: Montazeri M , Hedrick H G
Published: January 2020

Growth and spore formation of Candida albicans Y-45 was enhanced by low oxygen tension. Mycelium and chlamydospores were abundantly found on rice infusion-Tween 80 agar within 48 to 96 h, and abundant chlamdospore production occurred most rapidly under reduced oxygen tension and incubation at 30 degrees C. Zn, Mg, Mn, anf Fe were tested for their ability to promote filamentation in C. albicans Y-45. Filamentation under conditions of low Mg and high Mn suggested that morphogenesis is possibly correlated with the presence of salts of these heavy metals.
Effect of restricted aeration on catabolism of cholic acid by two Pseudomonas species
Authors: Smith M G , Park R J
Published: January 2020

Examination of some previously isolated bile acid-utilizing Pseudomonas strains showed that Pseudomonas sp. ATCC 31752, together with other fluorescent strains, can be assigned to Pseudomonas putida biotype B, whereas Pseudomonas sp. ATCC 31753, like most other nonfluorescent strains, is an unrecognized phenotype. A study was made of the growth of these two species at 25 degrees C and pH 7.0 in a fermentor with 2.5 g of sodium cholate liter-1 as sole carbon source, and the catabolism of the cholate and its products was followed by high-pressure liquid chromatographic and thin-layer chromatographic examination. At aeration rates of either 150 or 5 ml min-1 liter-1, growth of each species followed the same catabolic pathway. 7 alpha, 12 beta-Dihydroxy-1,4-androstadiene-3,17-dione was the major catabolite formed, with 0.3 g liter-1 being the maximum concentration that accumulated at the higher aeration rate, whereas 1.4 g liter-1 accumulated at the lower aeration rate, irrespective of the species used. The latter yield is sufficiently high to be of potential commercial value if such a catabolite were found to be economically useful for steroid drug manufacture. It is postulated that the rate-limiting step in cholic acid catabolism by these species at the lower aeration rate is 9 alpha-hydroxylation, a step requiring molecular oxygen, hence, the marked effect of oxygen limitation on catabolite accumulation. Another consequence of oxygen limitation is the production of a red pigment in the culture medium, which, however, does not affect catabolite recovery.
Propagation of
Rhizopus javanicus
Biosorbent
Authors: Treen-Sears Margaret E. , Martin Stanley M. , Volesky Bohumil
Published: January 2020

After propagation of
Rhizopus javanicus
in defined media containing glucose, urea, and mineral salts in deionized distilled water, the ability of the nonliving biomass to sequester cupric ion was assayed. Growth, uptake capacity (saturation uptake at >1 mM Cu
2+
concentration in solution), and biosorptive yield (biomass concentration × uptake capacity) were increased by augmentation of the growth medium with mineral salts once growth was under way. In the stationary phase, the uptake capacity of mycelia, which were normally a poor biosorbent, was improved within 4 h of trace metal addition to the growth medium. Growth of the culture was inhibited by excessive concentrations (0.04 to 40 μM) of metals in the medium in the following order: Cu > Co ≥ Ni > Mn > Mo; zinc was not inhibitory at 40 μM, and chromium was stimulatory at 0.53 μM but slightly inhibitory at higher levels. Iron and potassium phosphate stimulated growth at levels of 0.53 and 40 mM, respectively. When
R. javanicus
was propagated in a medium with a high salt concentration, exponential growth (0.23 h
−1
) to a biomass concentration of >3 g/liter and a biosorptive yield of >500 μmol/liter was achieved. It is evident that the powerful biosorbent characteristics of
Rhizopus
biomass led to depletion of available trace minerals in suspension culture, which in turn limited growth.
Rhizobia are attracted to localized sites on legume roots
Authors: Gulash M , Ames P , Larosiliere R C , Bergman K
Published: January 2020

Clouds of Rhizobium meliloti were attracted to localized sites on the surface of the infectible region of alfalfa roots. This behavior, which required active motility and chemotaxis, was not species specific. Correlation between the behavior of various mutants and their competitiveness for nodulation suggests that cloud formation has a role in the infection of host legume roots by rhizobia.
Diel Production and Microheterotrophic Utilization of Dissolved Free Amino Acids in Waters Off Southern California
Authors: Carlucci A. F. , Craven D. B. , Henrichs S. M.
Published: January 2020

Diel patterns of dissolved free amino acid (DFAA) concentration and microheterotrophic utilization were examined in the spring and fall of 1981 in euphotic waters from the base of the mixed layer off the southern California coast. The average depths of the isotherms sampled were 19.2 m for spring and 9.0 m for fall. Total DFAA levels were generally higher in the spring than in the fall, 18 to 66 nM and 14 to 20 nM, respectively. Two daily concentration maxima and minima were observed for total DFAAs as well as for most individual DFAAs. Maxima were usually measured in the mid-dark period and in the early afternoon; minima were typically observed in early morning and late afternoon. Bacterial cell numbers reached maximal values near midnight in both seasons. These increases coincided with one of the total DFAA maxima. The second total DFAA maximum occurred in early to midafternoon, during the time of maximum photosynthetic carbon production and rapid dissolved amino acid utilization. Microbial metabolism (incorporation plus respiration) of selected
3
H-amino acids was 2.7 to 4.1 times greater during the daylight hours. DFAA turnover times, based on these metabolic measurements, ranged between 11 and 36 h for the amino acids tested, and rates were 1.7 to 3.7 times faster in the daylight hours than at night. DFAA distributions were related to primary production and chlorophyll
a
concentrations. Amino acids were estimated to represent 9 to 45% of the total phytoplankton exudate. Microheterotrophic utilization or production of total protein amino acids was estimated as 3.6 μg of C liter
−1
day
−1
in spring and 1.9 μg of C liter
−1
day
−1
in the fall. Assimilation efficiency for dissolved amino acids averaged 65% for marine microheterotrophs.
Development of Rapidly Fermenting Strains of
Saccharomyces diastaticus
for Direct Conversion of Starch and Dextrins to Ethanol
Authors: Laluce Cecilia , Mattoon James R.
Published: January 2020

Alcoholic fermentation, growth, and glucoamylase production by 12 strains of
Saccharomyces diastaticus
were compared by using starch and dextrins as substrates. Haploid progeny produced from a rapidly fermenting strain, SD2, were used for hybridization with other
S. diastaticus
and
Saccharomyces cerevisiae
haploids. Alcoholic fermentation and enzyme production by hybrid diploids and their haploid parents were evaluated. Although the dosage of the
STA
or
DEX
(starch or dextrin fermentation) genes may enhance ethanol production, epistatic effects in certain strain combinations caused decreases in starch-fermenting activity. Both the nature of the starch or dextrin used and the fermentation medium pH had substantial effects on alcohol production. Commercial dextrin was not as good a substrate as dextrins prepared by digesting starch with α-amylase. Crude manioc starch digested by α-amylase was fermented directly by selected hybrids with almost 100% conversion efficiency. The manioc preparation contained adequate minerals and growth factors. This procedure should be suitable for direct commercial application in manioc-producing regions in Brazil and elsewhere. A rapidly fermenting haploid strain, SD2-A8, descended from strain SD2, contains two unlinked genes controlling formation of extracellular amylase. A convenient method for detecting these genes (
STA
genes) in replica plates containing large numbers of meiotic progeny was developed.
Ethanol Production by Thermophilic Bacteria: Physiological Comparison of Solvent Effects on Parent and Alcohol-Tolerant Strains of
Clostridium thermohydrosulfuricum
Authors: Lovitt R. W. , Longin R. , Zeikus J. G.
Published: January 2020

The effects of temperature, solvents, and cultural conditions on the fermentative physiology of an ethanol-tolerant (56 g/liter at 60°C) and parent strain of
Clostridium thermohydrosulfuricum
were compared. An ethanol-tolerant mutant was selected by successive transfer of the parent strain into media with progressively higher ethanol concentrations. Physiological differences noted in the mutant included enhanced growth, tolerance to various solvents, and alterations in the substrate range and the fermentation end product ratio. Ethanol tolerance was temperature dependent in the mutant but not in the parent strain. The mutant grew with ethanol concentrations up to 8.0% (wt/vol) at 45°C, but only up to 3.3% (wt/vol) at 68°C. Low ethanol concentration (0.2 to 1.6% [wt/vol]) progressively inhibited the parent strain to where glucose was not fermented at 2.0% (wt/vol) ethanol. Both strains grew and produced alcohols on glucose complex medium at 60°C in the presence of either 5% methanol or acetone, and these solvents when added at low concentration stimulated fermentative metabolism. The mutant produced ethanol at high concentrations and displayed an ethanol/glucose ratio (mole/mole) of 1.0 in media where initial ethanol concentrations were ≤4.0% (wt/vol), whereas when ethanol concentration was changed from 0.1% to 1.6% (wt/vol), the ethanol/glucose ratio for the parent strain changed from 1.6 to 0.6. These data indicate that
C. thermohydrosulfuricum
strains are tolerant of solvents and that low ethanol tolerance is not a result of disruption of membrane fluidity or glycolytic enzyme activity.
Selection of Galactose-Fermenting
Streptococcus thermophilus
in Lactose-Limited Chemostat Cultures
Authors: Thomas Terence D. , Crow Vaughan L.
Published: January 2020

Stock cultures of
Streptococcus thermophilus
are essentially galactose negative (Gal
−
). Although both galactose 1-phosphate uridyl transferase and uridine-5-diphospho-glucose 4-epimerase are present, suggesting that the genes for the Leloir pathway exist, cells cannot induce high levels of galactokinase. Therefore, galactose is largely excreted when cultures are grown on lactose, and most strains cannot be readily adapted to grow on free galactose. Gal
−
cultures were grown in a chemostat under lactose limitation in which high concentrations of residual galactose were present. Under this selection pressure, Gal
+
organisms eventually took over the culture with all four strains examined. Gal
+
cells had induced galactokinase, and three of the four strains grew on free galactose with doubling times of 40 to 50 min. When Gal
+
organisms were grown on lactose in batch culture, the galactose moiety was only partially utilized while lactose was still present. As lactose was exhausted, and catabolite repression was lifted, the Leloir pathway enzymes (especially galactokinase) were induced and the residual galactose fermented. Neither phospho-β-galactosidase activity nor the enzymes of the
d
-tagatose 6-phosphate pathway were detected in
S. thermophilus.
In contrast to
Streptococcus cremoris
and
Streptococcus lactis
, fermentation was homolactic with galactose in batch cultures and with lactose limitation in the chemostat. When mixed Gal
+
-Gal
−
cultures were repeatedly transferred in milk, the Gal
−
cells became the dominant cell type. The Gal
−
phenotype of stock cultures probably reflects their prolonged maintenance in milk.