bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequence representations and their utility for predicting protein-protein interactions
Authors: Kimothi Dhananjay , Biyani Pravesh , Hogan James M
Published: January 2020

Protein-Protein Interactions (PPIs) are a crucial mechanism underpinning the function of the cell. Predicting the likely relationship between a pair of proteins is thus an important problem in bioinformatics, and a wide range of machine-learning based methods have been proposed for this task. Their success is heavily dependent on the construction of the feature vectors, with most using a set of physico-chemical properties derived from the sequence. Few work directly with the sequence itself.

Recent works on embedding sequences in a low dimensional vector space has shown the utility of this approach for tasks such as protein classification and sequence search. In this paper, we extend these ideas to the PPI task, making inferences from the pair instead of for the individual sequences. We evaluate the method on human and yeast PPI datasets, benchmarking against the established methods. These results demonstrate that we can obtain sequence encodings for the PPI task which achieve similar levels of performance to existing methods without reliance on complex physico-chemical feature sets.
Production of germ-free mosquitoes via transient colonisation allows stage-specific investigation of host-microbiota interactions
Authors: Romoli Ottavia , Schönbeck Johan Claes , Hapfelmeier Siegfried , Gendrin Mathilde
Published: January 2020

The mosquito microbiota impacts the physiology of its host and is essential for normal larval development, thereby influencing transmission of vector-borne pathogens. Germ-free mosquitoes generated with current methods show larval stunting and developmental deficits. Therefore, functional studies of the mosquito microbiota have so far mostly been limited to antibiotic treatments of emerging adults. In this study, we developed a novel approach to produce germ-freeAedes aegyptimosquitoes. It is based on reversible colonisation with bacteria genetically modified to allow complete decolonisation at any developmental stage. We show that, unlike germ-free mosquitoes previously produced using sterile diets, reversibly colonised mosquitoes show no developmental retardation and reach the same size as control adults. This allowed us to uncouple the study of the microbiota in larvae and adults. In adults, we detected no impact of bacterial colonisation on mosquito fecundity or longevity. In larvae, we performed a transcriptome analysis and diet supplementation experiments following decolonisation during the third larval instar. Our data suggest that bacteria support larval development by contributing to folate biosynthesis and by enhancing energy storage. Our study establishes a novel tool to study the microbiota in insects and deepens our knowledge on the metabolic contribution of bacteria to mosquito development.
Dynamic multimodal interactions in navigating wood ants: What do path details tell us about cue integration?
Authors: Buehlmann Cornelia , Aussel Alexia , Graham Paul
Published: January 2020

Ants are expert navigators using multiple cues from multiple sensory modalities to navigate successfully. Here, we present the results of systematic studies of multimodal cue use in navigating wood ants,Formica rufa. Ants learnt to navigate to a feeder that was defined by an olfactory cue, visual cue and airflow presented together. When ants learnt to find a feeder that was placed in the centre of the visual cue, well-trained ants were not anymore able to accurately approach the feeder when either the olfactory or visual cue were removed in tests. This confirms that some form of cue binding has taken place. However, in a visually simpler task with the feeder located at the edge of the visual cue, ants still approached the feeder accurately when individual cue components were removed. Hence, cue binding is flexible and depends on the navigational context. In general, cues act additively in determining the ants’ paths accuracy, i.e. the use of multiple cues increased navigation performance. Moreover, across different training conditions, we saw different motor patterns in response to different sensory cues. For instance, ants had more sinuous paths with more turns when they followed an odour plume but did not have any visual cues. Having visual information with the odour enhanced performance and therefore positively impacted on plume following. Interestingly, paths characteristics of ants from the two multimodal groups with a different visual task were different, suggesting that the observed flexibility in cue binding may be a result of the ants’ movement characteristics.

Summary statement

We investigated the impact of multimodal information on navigating ants. Ants showed flexible response to multimodal information depending on the sensori-motor contingencies of the navigation task.
SMALL ALPHAHERPESVIRUS LATENCY-ASSOCIATED PROMOTERS DRIVE EFFICIENT AND LONG-TERM TRANSGENE EXPRESSION IN THE CENTRAL NERVOUS SYSTEM
Authors: Maturana Carola J. , Verpeut Jessica L. , Pisano Thomas J. , Dhanerawala Zahra M. , Esteves Andrew , Enquist Lynn W. , Engel Esteban A.
Published: January 2020

Recombinant adeno-associated viral vectors (rAAV) are used as gene therapy vectors to treat central nervous system (CNS) diseases. Despite their safety and broad tropism, important issues need to be corrected such as the limited payload capacity and the lack of small gene promoters providing long-term, pan-neuronal transgene expression in the CNS. Commonly used gene promoters are relatively large and can be repressed a few months after CNS transduction, risking the long-term performance of single-dose gene therapy applications. We used a whole-CNS screening approach based on systemic delivery of AAV-PHP.eB, iDisco+ tissue-clearing and light-sheet microscopy, to identify three small latency-associated promoters (LAP) from the herpesvirus pseudorabies virus (PRV). These promoters are LAP1 (404bp), LAP2 (498bp) and LAP1_2 (880bp). They drive chronic transcription of the virus encoded latency-associated transcript (LAT) during productive and latent phases of PRV infection. We observed stable, pan-neuronal transgene transcription and translation from AAV-LAP in the CNS for six months post AAV transduction. In several CNS areas, the number of cells expressing the transgene was higher for LAP2 than the large conventional EF1α promoter (1264bp). Our data suggests that the LAP are suitable candidates for viral vector-based CNS gene therapies requiring chronic transgene expression after one-time viral-vector administration.
poly(UG)-tailed RNAs in Genome Protection and Epigenetic Inheritance
Authors: Shukla Aditi , Yan Jenny , Pagano Daniel J. , Dodson Anne E. , Fei Yuhan , Gorham Josh , Seidman J.G. , Wickens Marvin , Kennedy Scott
Published: January 2020

Mobile genetic elements threaten genome integrity in all organisms. MUT-2/RDE-3 is a ribonucleotidyltransferase required for transposon silencing and RNA interference (RNAi) inC. elegans. When tethered to RNAs in heterologous expression systems, RDE-3 can add long stretches of alternating non-templated uridine (U) and guanosine (G) ribonucleotides to the 3’ termini of these RNAs (polyUG or pUG tails). Here, we show that, in its natural context inC. elegans, RDE-3 adds pUG tails to transposon RNAs, as well as to targets of RNAi. pUG tails with more than 16 perfectly alternating 3’ U and G nucleotides convert otherwise inert RNA fragments into agents of gene silencing. pUG tails promote gene silencing by recruiting RNA-dependent RNA Polymerases (RdRPs), which use pUG-tailed RNAs as templates to synthesize small interfering RNAs (siRNAs). Cycles of pUG RNA-templated siRNA synthesis and siRNA-directed mRNA pUGylation underlie dsRNA-directed transgenerational epigenetic inheritance in theC. elegansgermline. Our results show that pUG tails convert RNAs into transgenerational memories of past gene silencing events, which, we speculate, allow parents to inoculate progeny against the expression of unwanted or parasitic genetic elements.
Meat demand in China: to include or not to include meat away from home?
Authors: Bai Junfei , Seale James L. , Wahl Thomas I.
Published: January 2020

This study examines meat consumption in China, the world's largest meat consumer and producer, by considering both meat consumed at home and away from home based upon a diary‐based household survey. The results indicate that income growth leads to beef, poultry, other meat and pork away from home consumption to grow more than proportionally to total meat consumption. We also find that meats consumed away from home grow faster than at home counterparts due to higher income elasticities, suggesting that ignoring meat away from home could significantly underestimate current and future meat consumption.
Nucleolin promotes Ang II‐induced phenotypic transformation of vascular smooth muscle cells by regulating EGF and PDGF‐BB
Authors: Fang Li , Wang Kang‐Kai , Zhang Peng‐Fei , Li Tao , Xiao Zhi‐Lin , Yang Mei , Yu Zai‐Xin
Published: January 2020

RNA‐binding properties of nucleolin play a fundamental role in regulating cell growth and proliferation. We have previously shown that nucleolin plays an important regulatory role in the phenotypic transformation of vascular smooth muscle cells (VSMCs) induced by angiotensin II (Ang II). In the present study, we aimed to investigate the molecular mechanism of nucleolin‐mediated phenotypic transformation of VSMCs induced by Ang II. Epidermal growth factor (EGF) and platelet‐derived growth factor (PDGF) inhibitors were used to observe the effect of Ang II on phenotypic transformation of VSMCs. The regulatory role of nucleolin in the phenotypic transformation of VSMCs was identified by nucleolin gene mutation, gene overexpression and RNA interference technology. Moreover, we elucidated the molecular mechanism underlying the regulatory effect of nucleolin on phenotypic transformation of VSMCs. EGF and PDGF‐BB played an important role in the phenotypic transformation of VSMCs induced by Ang II. Nucleolin exerted a positive regulatory effect on the expression and secretion of EGF and PDGF‐BB. In addition, nucleolin could bind to the 5′ untranslated region (UTR) of EGF and PDGF‐BB mRNA, and such binding up‐regulated the stability and expression of EGF and PDGF‐BB mRNA, promoting Ang II‐induced phenotypic transformation of VSMCs.
Improved Procedure for Production of Cytochalasin E and Tremorgenic Mycotoxins by
Aspergillus clavatus
Authors: Demain A. L. , Hunt N. A. , Malik V. , Kobbe B. , Hawkins H. , Matsuo K. , Wogan G. N.
Published: January 2020

This report describes an improved procedure for production of cytochalasin E and tremorgens by solid substrate, agitated fermentation of
Aspergillus clavatus
on pearled barley.
Microtiter assay for interferon: microspectrophotometric quantitation of cytopathic effect
Authors: McManus N H
Published: January 2020

This report describes an accurate, reproducible, and efficient microassay for human interferon, using a dye-uptake method to quantitate cytopathogenicity. The antiviral activity was measured by using a Gilford 300-N microsepctrophotometer, with the automatic programmer, sampler, and data lister. Two hundred interferon samples, each in a final volume of 1.0 ml, may be analyzed and recorded in 45 min. The reproducibility of a laboratory reference interferon and the human international reference B 69/19 on two different cell lines, using the model Q Oxford sampler, was found to be excellent, with the standard error of the log10 geometric mean of both references +/- 0.04 to 0.06.
Inhibition of Clostridium perfringens by heated combinations of nitrite, sulfur, and ferrous or ferric ions
Authors: Asan T , Solberg M
Published: January 2020

Heating mixtures of sodium nitrite, cysteine, and either ferrous sulfate or ferric chloride at 121 C for 20 min at pH 6.5 or 6.3 produced a potent inhibitor of Clostridium perfringens vegetative cells and spores when added to previously heat-sterilized fluid thioglycolate medium. When the mixtures containing FeSO4 at pH 5.2 or FeCl3 at pH 2.7 were heated, the inhibitory effect was not produced. These responses seem to eliminate the possibility that cysteine nitrosothiol is the agent responsible for the heated-nitrite inhibition known as the Perigo effect. The variable pH responses also cast doubt upon the role of the black Roussin salt as the agent of the Perigo effect.
Further studies on a mycoparasitic basidiomycete species
Authors: Cerrato R F , de la Cruz R E , Hubbell D H
Published: January 2020

An unidentified basidiomycete was found capable of parasitizing 37 of 50 isolates of fungi tested as hosts. All phytopathogenic fungi tested, as well as most of the saprophytic fungi, were susceptible to this mycoparasite. In some cases, reproductive structures as well as hyphae were infected. High glucose-yeast extract ratios in the test medium favored parasitism. The mycoparasite was able to utilize 14 of 27 compounds tested as carbon sources.
Growth of Enterobacter aerogenes in a chemostat with double nutrient limitations
Authors: Cooney C L , Wang D I , Mateles R I
Published: January 2020

The behavior of Enterobacter aerogenes during growth in chemostats limited by single and double nutrient restrictions was examined. On the assumption that different essential nutrients act to limit growth in different ways, we selected pairs of nutrients likely to affect different aspects of metabolism. Results show that macromolecular cell composition can be controlled by using more than one nutrient restriction. The polysaccharide content of the cells is readily manipulated by the ratio of carbon to nitrogen in the inlet nutrients. Also, at low dilution rates, ratios of protein to ribonucleic acid are dependent on the ratio of phosphate to nitrogen in the input nutrients. An examination of both acetic acid and metabolite production (as measured by ultraviolet absorbance of culture filtrates) showed that accumulation of these products was dependent on both dilution rate and type of nutrient limitation(s). These results were examined in terms of the problems of translation of batch to continuous culture processes and the use of selected nutrient limitations to control noncellular product formation.
Effect of dissolved oxygen and Eh and Bacteroides fragilis during continuous culture
Authors: Onderdonk A B , Johnston J , Mayhew J W , Gorbach S L
Published: January 2020

Bacteroides fragilis subsp. fragilis was maintained in a chemostat modified for anaerobic conditions to test the effects of dissolved oxygen and Eh on growth. Using a defined medium containing glucose and a dilution rate of 0.16 h -1, a stable population of 3 X 10(9) colony-forming units/ml was present. At this steady state, the pH was 5.6, the Eh was -50 mV, and the dissolved oxygen concentration was 0% atmospheric saturation. The Eh was then adjusted to +300 mV by adding potassium ferricyanide while oxygen was excluded; in this system there were no demonstrable changes from the steady state in viable cells, pH, glucose concentration, or volatile fatty acid production. In other experiments oxygen was introduced into the original steady state at a dissolved oxygen concentration of 10% atmospheric saturation for a period of 6 to 8 h. During O2 exposure, the viable cell count decreased at a rate comparable to the theoretical washout rate for a static bacterial culture. Similar results were obtained with a dissolved oxygen concentration of 25 and 100%. Other effects of O2 exposure included an increase in Eh from -50 to +250 mV, a decrease in glucose consumption, and a decrease in volatile fatty acid production. These results suggest that dissolved oxygen has a bacteriostatic effect on B. fragilis in continuous culture, which may be independent of changes in Eh alone.
Measuring the potential activity of hydrocarbon-degrading bacteria
Authors: Walker J D , Colwell R R
Published: January 2020

[14C]hydrocarbons were utilized as a means of estimating the hydrocarbon-degrading potential of bacteria in estuarine and marine environments. Evaporation of the hydrocarbons must be considered in estimates of oxidation. Amount of mineralization of [14C]hexadecane can be equated with the total number of petroleum-degrading bacteria and the percentage of the total heterotrophic population, which they represent. Mineralization activity was found to be related to the activity of the bacterial populations during in situ incubation. Rates of mineralization were observed, as follows, for [14C]hexadecane greater than [14C]naphthalene greater than [14C]toluene greater than [14C]cyclohexane. Increased rates of uptake and mineralization were observed for bacteria in samples collected from an oil-polluted harbor compared with samples from a relatively unpolluted, shellfish-harvesting area, e.g., turnover times of 15 and 60 min for these areas, respectively, using [14C]hexadecane.
Enumeration of petroleum-degrading microorganisms
Authors: Walker J D , Colwell R R
Published: January 2020

A variety of factors, including concentration of oil, antibiotics, dyes, and inoculum washes, were examined to determine their effect on the total counts of microorganisms on oil-containing media. The media found to be best for enumerating petroleum-degrading microorganisms contained 0.5% (vol/vol) oil and 0.003% phenol red, with Fungizone added for isolating bacteria and streptomycin and tetracycline added for isolating yeasts and fungi. Washing the inoculum did not improve recovery of petroleum degraders. Specifically, silica gel-oil medium and a yeast medium are recommended for enumeration of petroleum-degrading bacteria and yeasts and fungi, respectively. It is suggested that counts of petroleum degraders be expressed as percentage of the total population rather than total numbers of petroleum degraders per se. Incubation temperature and presence of oil was found to influence the numbers of petroleum-degrading microorganisms at a given sampling site.
Starvation effects on Escherichia coli and aquatic bacterial responses to nutrient addition and secondary warming stresses
Authors: Wu S Y , Klein D A
Published: January 2020

A gram-negative polar flagellated rod, isolated from a Colorado mountain stream and considered to be an Aeromonas sp., a mixed aquatic microbial population, and a culture of Escherichia coli were starved to determine their responses to the short-term presence of nutrients and mild warming stress (49.5 C for 2 min) in relation to starvation time. At the beginning of the starvation period, the Aeromonas isolate was extremely sensitive to the secondary warming stress. This response was markedly diminished after a 3-week starvation period. The mixed aquatic microbial population showed a similar trend in becoming less sensitive to stress with increased starvation. E coli under similar conditions, became more sensitive to the secondary stress after exposure to glucose. Respiration measurements after glucose additions also indicated that E. coli responded in a different manner to starvation stress and glucose presence than the Aeromonas isolate. The increased sensitivity of E. coli to secondary stress and short-term nutrient availability after starvation may contribute to the exclusion of this organism from aquatic environments.
Byssotoxin A, a secondary metabolite of Byssochlamys fulva
Authors: Kramer R K , Davis N D , Diener U L
Published: January 2020

Byssochlamys fulva, isolated from corn, was grown on nutrient-amended shredded wheat medium for 14 days at 25 C. Crude solvent extract from these cultures was toxic to brine shrimp, chicken embryos, and rats. The extract was slightly inhibitory to the germination of of pea seeds, but was nontoxic to ten species of bacteria and one of yeast. One metabolite was isolated, given the trivial name byssotoxin A, and partially characterized chemically and physically.
New Type of Turbidostat with Intermittent Determination of Cell Density Outside the Culture Vessel
Authors: Sorgeloos P. , Van Outryve E. , Persoone G. , Cattoir-Reynaerts A.
Published: January 2020

An inexpensive turbidostat featuring intermittent determination of optical density in an interchangeable measuring tube and incorporating electronic circuits for the automated mechanics is described.
Survey of aflatoxicosis in farm animals
Authors: Smith R B , Griffin J M , Hamilton P B
Published: January 2020

Over a 22-month period, 278 submissions of farm animals were made to the North Carolina Diagnostic Laboratory for suspected aflatoxicosis, and 94 cases were confirmed on the basis of finding aflatoxin in the feed and the occurrence of bile ductule proliferation. There was an annual variation in the incidence of aflatoxicosis, as well as a seasonal variation: the peak incidence occurred in the winter, and the minimum incidence occurred during the summer. The annual increase coincided with the corn harvest. All confirmed cases occurred on farms that raised and stored their own corn, and 88% were in swine. The cases were geographically localized in the eastern section of North Carolina (94% of the total cases) where 82% of the swine and 79% of the corn are produced. Mean concentration of aflatoxin in feed samples from the confirmed cases was 3,890 mug/kg, and the mean value for corn used in making the feed was 5,180 mug/kg. Only aflatoxin B1 was found in the samples. These data were interpreted to mean that the incidence and severity of aflatoxicosis is greater than previously suspected, that poor on-farm storage of corn is a primary contributing factor, that aflatoxin formation continues during and after the milling process, and that mycotoxicoses other than aflatoxicosis may cause equal or greater problems.
Microbial Studies on Shelf Life of Cabbage and Coleslaw
Authors: King A. Douglas , Michener H. David , Bayne Henry G. , Mihara Keiko L.
Published: January 2020

The microbiology of a common commercial type of coleslaw was investigated with the objective of extending its shelf life at refrigerator temperature by delaying microbiological spoilage. Cabbage, its principal ingredient, had a total bacterial count of about 10
5
/g. Microbial growth in cabbage was prevented by storage at 1 C but not at 10 C or above. In coleslaw, the cabbage flora died and was replaced by the flora of the cultured sour cream contained in the dressing. At 14 C, the total count increased and the coleslaw deteriorated organoleptically. At 7 C, bacterial growth was suppressed but organoleptic deterioration occurred as rapidly as at 14 C. Thus, the deterioration was caused primarily by the physiological breakdown of plant tissue rather than by microorganisms, as was the original premise.
Effect of delayed evisceration on the microbial quality of meat
Authors: Gill C O , Penney N , Nottingham P M
Published: January 2020

The postomortem invasion of muscle and other tissues by bacteria from the intestinal tract was studied with the use of radioactive tracers. The injection of 14C-labeled bacteria or spores into the intestines of guinea pig carcasses within 24 h of death resulted in the rapid spread of 14C throughout carcasses. When live bacteria were injected along with the labeled cells, it was not possible to isolate viable organisms from the body tissues if the living animal had been exposed to the bacteria. It appears that animals are immune to their normal intestinal flora and that this immunity persists after death; thus passage of these bacteria into the lymphatic system does not necessarily result in the presence of live bacteria in carcass tissues. It therefore seems that a delay of up to 24 h before evisceration would not lead to deep tissue contamination of the carcass by organisms usually present in the intestines. Further evidence for this hypothesis was obtained by showing that muscle and lymph nodes from uneviscerated lamb carcasses hung for 24 h at 20 C remained sterile.
Delayed Release Nutrient Supplement for Mushroom Culture
Authors: Carroll A. D. , Schisler L. C.
Published: January 2020

The disadvantages associated with the supplementation of noncomposted nutrients to mushroom compost at spawning were largely overcome by encapsulating microdroplets of vegetable oil within a protein coat that was denatured with formaldehyde. Increases in mushroom yield of 60% were obtained. Delayed nutrient release was indicated by prolonged stimulation of yields beyond the first few flushes.
Substitute for agar in solid media for common usages in microbiology
Authors: Watson N , Apirion D
Published: January 2020

The potassium salt of carrageenan was found to be an adequate replacement for agar in solid bacteriological media. The common microbial genetic techniques, such as purifying colonies by streaking, replication tests, and titration of cultures, were carried out sucessfully with a number of mutant strains of Escherichia coli.
Ultrastructure of rumen bacterial attachment to forage cell walls
Authors: Akin D E
Published: January 2020

The degradation of forage cell walls by rumen bacteria was investigated with critical-point drying/scanning electron microscopy and ruthenium red staining/transmission electron microscopy. Differences were observed in the manner of attachment of different morphological types of rumen bacteria to plant cell walls during degradation. Cocci, constituting about 22% of the attached bacteria, appeared to be attached to degraded plant walls via capsule-like substances averaging 58 nm in width (range, 21 to 84 nm). Many bacilli appeared to adhere to forage substrates without distinct capsule-like material, although unattached bacteria with capsules were observed occasionally. Certain bacili appeared to be attached to degraded tissue via small amounts of extracellular material, but others apparently had no extracellular material. Bacilli with a distinct morphology due to an irregularly folded, electron-dense outer layer or layers (about 15 nm thick) and without fibrous extracellular material consituted about 37% of the attached bacteria and were observed to adhere so closely to degraded plant walls that the bacterial shape conformed to the shape of the degraded zone. In the rumen ecosystem, bacteria appeared to adhere to plant substrates during degradation by capsule-like material and by small amounts of extracellular material, as well as by the other means not observable by electron microscopy.
Selective isolation of Neisseria sicca from the human oral cavity on eosin methylene blue agar
Authors: Querido N B , De Araujo W C
Published: January 2020

Strains of Neisseria sicca and N. mucosa, but not N. perflava, N. subflava, N. flava, or N. flavescens were found to grow on eosin methylene blue agar. The distribution of N. sicca on the tongue dorsum, the gingival crevice area, and the coronal surfaces of teeth of humans was determined using this medium. N. sicca averaged about 5% of the total cultivable organisms of the tongues of 14 subjects examined, but it was present in only trace quantities in dental plaque on the coronal surfaces of teeth or in the gingival crevice area.
Dye Reduction Method for Estimating Bacterial Counts in Ground Beef
Authors: Emswiler B. S. , Kotula A. W. , Chesnut C. M. , Young E. P.
Published: January 2020

A dye reduction method was developed for estimating total aerobic and/or psychrotrophic bacterial counts in ground beef. The method is based on color changes in indicator disks placed on the meat surface.
Exopolymer production and flocculation by zoogloea mp6
Authors: Unz R F , Farrah S R
Published: January 2020

Flocculation by Zoogloea MP6 was accompanied by the production of a mucopolysaccharide exopolymer. Polymer formation was initiated in mid-logarithmic growth phase, and the quantity produced appeared to be influenced by the level of carbon and nitrogen in the culture medium.
Invalidity of the acetylene reduction assay in alkane-utilizing, nitrogen-fixing bacteria
Authors: De Bont J A , Mulder E G
Published: January 2020

The cause of the failure of the C2H2-C2H4 assay for nitrogen-fixing bacteria growing on lower alkanes was studied. Acetylene was a strong competitive inhibitor of methane oxidation for methane-utilizing bacteria, as well as for the oxidation of lower alkanes by other bacteria, so that energy and reducing power were no longer available for the reduction of acetylene by nitrogenase. Nitrogen-fixing bacteria grown on alkanes may reduce acetylene when intermediates of alkane-breakdown or other substrates oxidizable in the presence of acetylene are supplied. Ethylene co-oxidation is not responsible for the failure of the test, because acetylene also inhibits this co-oxidation along with methane oxidation.
Salmonella in horses: a source of contamination of horsemeat in a packing plant under federal inspection
Authors: Anderson G D , Lee D R
Published: January 2020

Cecal samples from 270 slaughter horses revealed that 41 samples (15.1%) contained Salmonella. Of 233 horsemeat samples tested, Salmonella was isolated from 62 samples, or 26.6%. Only 2 of 158 human stool specimens from the plant workers revealed Salmonella. Predominant serotypes isolated from the horsemeat were Salmonella enteritidis Good and Anatum, whereas the serotypes Agona and Derby predominated the horse cecal isolates. Preliminary data indicate that the high percentage of meat contamination is surface contamination due to poor slaughtering technique.
Evaluation of Pfizer selective enterococcus and KF media for recovery of fecal streptococci from water by membrane filtration
Authors: Brodsky M H , Schiemann D A
Published: January 2020

Pfizer selective enterococcus (PSE) and KF agars were compared for their recovery of fecal streptococci from sewage effluent on membrane filters. The results showed that PSE agar is highly selective for the enterococci. The tan color resulting from esculin hydrolysis, which was not always visible on the surfaces of the colonies, is not considered a necessary differential characteristic on PSE agar since more than 90% of all colonies recovered on membrane filters were confirmed as fecal streptococci and 86% were confirmed as enterococci. The detection of esculin hydrolysis on membrane filters was not improved by using the new Millipore type HC filter. KF agar recovered significantly greater numbers of organisms but was not as selective, with 83% of the typical colonies being confirmed as fecal streptococci and 54% as enterococci. An attempt to improve the selectivity of KF agar while retaining its inclusiveness by incubation at 45 C was not successful.
Microbial Degradation of Lignocellulose: the Lignin Component
Authors: Crawford Don L. , Crawford Ronald L.
Published: January 2020

A new procedure was developed for the study of lignin biodegradation by pure or mixed cultures of microorganisms. Natural lignocelluloses were prepared containing
14
C in primarily their lignin components by feeding plants
l
-[U-
14
C]phenylalanine through their cut stems. Lignin degradation was observed in numerous soils by monitoring evolution of
14
CO
2
from [
14
C]lignin-labeled oak (
Quercus albus
), maple (
Acer rubrum
), and cattail (
Typha latifola
). An organism (
Thermonospora fusca
ATCC 27730) that is known to degrade cellulose but not lignin was shown to grow on lignocellulose in the presence of [
14
C]lignocelluloses without evolution of
14
CO
2
. A known lignin degrader (a white-rot fungus,
Polyporus versicolor
) was shown to readily evolve
14
CO
2
from damp
14
C-labeled cattail and
14
C-labeled maple.
Activated sludge degradation of adipic acid esters
Authors: Saeger V W , Kalley R G , Hicks O , Tucker E S , Mieure J P
Published: January 2020

The biodegradability of three aliphatic adipic acid diesters and a 1,3-butylene glycol adipic acid polyester was determined in acclimated, activated sludge systems. Rapid primary biodegradation from 67 to 99+% was observed at 3- and 13-mg/liter feed levels for di-n-hexyl adipate, di(2-ethylhexyl) adipate, and di(heptyl, nonyl) adipate in 24 h. When acclimated, activated sludge microorganisms were employed as the seed for two carbon dioxide evolution procedures, greater than 75% of the theoretical carbon dioxide was evolved for the three diesters and the polyester in a 35-day test period. The essentially complete biodegradation observed in these studies suggests that these esters would not persist when exposed to similar mixed microbial populations in the environment.
Environmental factors influencing the rate of hydrocarbon oxidation in temperate lakes
Authors: Ward D M , Brock T D
Published: January 2020

Rates of hydrocarbon biodegradation were estimated by following oxygen uptake during mineral oil oxidation or oxidation of [1-14C]hexadecane to 14CO2, when these substrates were added to natural water samples from Wisconsin lakes. A lag phase preceded hydrocarbon oxidation, the length of which depended on population density or on factors influencing growth rate and on the presence of nonhydrocarbon organic compounds. Hydrocarbon oxidation was coincident with growth and presumably represented the development of indigenous hydrocarbon-degrading microorganisms in response to hydrocarbon additions. In detailed studies in Lake Mendota, it was found that, despite the continued presence of hydrocarbon-degrading microorganisms in water samples, seasonal variations in the rates of mineral oil and hexadecane oxidation occurred which correlated with seasonal changes in temperature and dissolved inorganic nitrogen and phosphorus. The temperature optimum for oil biodegradation remained at 20 to 25 C throughout the year, so that temperature was the main limiting factor during winter, spring, and fall. During summer, when temperatures were optimal, nutrient deficiencies limited oil biodegradation, and higher rates could be obtained by addition of nitrogen and phosphorus. The rates of hydrocarbon biodegradation were thus high only for about 1 month of the ice-free period, when temperature and nutrient supply were optimal. Nutrient limitation of oil biodegradation was also demonstrated in 25 nutrient-poor lakes of northern Wisconsin, although in almost every case oil-degrading bacteria were detected. Knowledge of temperature and nutrient limitations thus will help in predicting the fate of hydrocarbon pollutants in freshwater.
One-tube oxidation-fermentation methods: limitations posed by atypical fermentative reactions
Authors: Sivendra R
Published: January 2020

Atypical fermentation in the two-tube method of Hugh and Leifson (1953), whereby acid was produced in the sealed tube but not in the open tube, was determined to be the result of a preferential metabolism of peptone over the reactant carbohydrate. These atypical fermentations are only partially detected by one-tube oxidation-fermentation methods, and as such they constitute a source of limitation to the routine use of these abbreviated techniques for oxidative-fermentation determinations.
Lecithin agar for detection of microbial phospholipases
Authors: Chrisope G L , Fox C W , Marshall R T
Published: January 2020

Lecithin agar was developed on which phospholipase C produced turbid zones and phospholipase A produced clear zones. Reactions on lecithin agar agreed 74% of the time with reactions in egg yolk broth. On lecithin agar, interpretation was easier, phospholipase A was detectable, and opaque zones were visible 1 or 2 days earlier than on egg yolk agar. All constituents of the medium can be autoclaved.
Comparison of Enrichment Procedures for Fluorescent Antibody and Cultural Detection of Salmonellae in Raw Meat and Poultry
Authors: Thomason Berenice M. , Dodd David J.
Published: January 2020

No advantage was shown in preenriching raw meat samples for detecting salmonellae by fluorescent antibodies or culture. Trypticase soy-tryptose (Edwards and Ewing, 1972) was equal to or better than selenite-cystine as a postenrichment broth.
Toxicity of ammonia to algae in sewage oxidation ponds
Authors: Abeliovich A , Azov Y
Published: January 2020

Ammonia, at concentrations over 2.0 mM and at pH values over 8.0, inhibits photosynthesis and growth of Scenedesmus obliquus, a dominant species in high-rate sewage oxidation ponds. Photosynthesis of Chlorella pyrenoidosa, Anacystis nidulans, and Plectonema boryanum is also susceptible to ammonia inhibition. Dark respiration and cell morphology were unaffected by any combination of pH and ammonia concentrations tested, thus limiting the apparent effect to inhibition of the normal function of the chloroplasts. Methylamine had the same effect as ammonia, and its penetration into the cells was found to be pH dependent. Therefore, the dependence of toxicity of amines to algae on pH apparently results from the inability to penetrate the cell membrane in the ionized form. When operated at 120-h detention time of raw wastewater, the high-rate oxidation pond maintained a steady state with respect to algal growth and oxygen concentration, and the concentration of ammonia did not exceed 1.0 mM. Shifting the pond to 48-h detention time caused an increase in ammonia concentration in the pond water to 2.5 mM, and the pond gradually turned anaerobic. Photosynthesis, which usually elevates the pH of the pond water to 9.0 to 10.0, could not proceed beyond pH 7.9 because of the high concentration of ammonia, and the algal population was washed out and reduced to a concentration that could maintain a doubling time of 48 h without photosynthesis bringing the pH to inhibitory levels. Under these conditions, the pH of the bond becomes a factor that limits the operational efficiency of the oxidation pond.
Factors influencing the production of cellulases by Sporotrichum thermophile
Authors: Coutts A D , Smith R E
Published: January 2020

Cellulase production and growth of a strain of Sporotrichum thermophile were studied by using a mineral salts medium supplemented with yeast extract and insoluble cellulose. The effects of cultural conditions, such as pH, nitrogen source, substrate concentration, and temperature, were examined. Maximum production of C1 and CX cellulases occurred at 45 C in 2 to 4 days, in the presence of 1% Solka/Floc as substrate, when NaNO3 or urea used as sources of nitrogen. Under these conditions, cellulolytic activity of culture filtrates appeared to be similar to that reported for Trichoderma viride grown in a favorable environment. However, comparable yields of cellulase were produced by S. thermophile in less than one-quarter the time required by mesophilic fungi.
Production of antibody against ochratoxin A
Authors: Chu F S , Chang F C , Hinsdill R D
Published: January 2020

Antibody against ochratoxin A was obtained after repeated injection of different protein-ochratoxin A conjugates to rabbits. Among many protein-ochratoxin conjugates tested, bovine serum albumin-ochratoxin A was found to be the best antigen. The antibody is specific for ochratoxins A, C, and T, but is not specific for ochratoxins B, alpha, and other coumarin derivatives. The sensitivity for ochratoxin A detection using a binding assay is in the range of 0.5 to 10 ng/0.5-ml sample. Detailed methods for the preparation of protein-ochratoxin conjugates, preparation of immune serum, and methods for antibody titers are described.
Inactivation kinetics of some microorganisms subjected to a variety of stresses
Authors: Cox C S
Published: January 2020

Loss of viability in aerosols of Escherichia coli B, E. coli commune, E. coli Jepp (in nitrogen atmospheres), and Semliki forest virus (in air) was determined as a function of relative humidity at 26.5 C. The decay patterns could be accounted for accurately by means of an equation derived from a postulated mechanism involving population distributions and first-order denaturation kinetics. Analyses of published curves describing loss of viability (all of which were semiexponential, ie., J-shaped) for various microorganisms stressed by different techniques showed that the proposed mechanism also provided an explanation for effects of the following factors (in the absence of open air, oxygen, or radiation): (i) influence of relative humidity upon aerosol susvival; (ii) dissemination of aerosols from the wet and dry states; (iii) protecting additives; (iv) relative humidity change before reconstitution; (v) reconstituting fluids; (vi) water content of freeze-dried product; (vii) storage gas; and (viii) storage temperature. The date indicate that low temperatures and high pressures were likely to be conducive to the preservation of viable bacteria and viruses, provided that cold shock and decompression shock were absent.
Influence of certain indigenous gastrointestinal microorganisms on duodenal alkaline phosphatase in mice
Authors: Yolton D P , Savage D C
Published: January 2020

Alkaline phosphatase activity was assayed in duodenal homogenates or extracts from adult specific pathogen-free (SPF) and germfree mice and gnotobiotic mice monoassociated with a Lactobacillus sp., a Bacteroides sp., or a coliform strain indigenous to SPF mice. Activity levels of the enzyme were much higher in the preparations from germfree mice than in those from the SPF controls. In the gnotobiotes monoassociated either with a freshly isolated Lactobacillus sp. or a Bacteroides sp., the levels of alkaline phosphatase activity were intermediate between the values for germfree and SPF mice. By contrast, in the gnotobiotes monoassociated with a coliform strain, alkaline phosphatase activity remained at high germfree levels. Butanol extracts of duodenal tissue from SPF mice, germfree mice, and exgermfree mice associated with an indigenous microflora from SPF mice (conventionalized) were subjected to acrylamide gel electrophoresis. A stain for alkaline phosphatase activity revealed three major bands in the gels prepared with extracts from SPF and conventionalized mice, but only two in the gels prepared with extracts from germfree mice. All three bands may have been present in the latter gels. One of the bands (the middle one) may have been obscured, however, by high activity in the slowest moving band. As determined by densitometric scanning, the slowest moving band had much higher activity in the preparations from germfree animals than in those from SPF or conventionalized mice. These findings suggest that the indigenous microbial flora affects not only quantitatively, but also qualitatively, the activity of alkaline phosphatases in the mouse intestinal mucosa.
Inactivation of poliovirus in digested sludge
Authors: Ward R L , Ashley C S
Published: January 2020

The effect of anaerobically digested sludge on poliovirus during incubation at temperatures between 28 and 4 C was studied. Although virus was fully recoverable from sludge, its infectivity decreased in proportion to the time and temperature of incubation. The rate ranged from greater than 1 log per day at 28 C to about 1 log every 5 days at 4 C. The mechanism of inactivation was studied at the lower temperature where the sedimentation coefficients of most inactivated particles were not detectably modified. The ribonucleic acid (RNA) of these particles appeared to have been nicked and had an average sedimentation value about 70% that of RNA from infectious virus. Since the specific infectivity of RNA from particles recovered from sludge was directly proportional to that of the particles from which it was extracted, loss of infectivity was probably due to inactivation of RNA. Some breakdown was also found in the two largest viral proteins of inactivated particles. Thus, the mechanism of inactivation may be cleavage of viral proteins followed by nicking of encapsulated RNA. Because no virucidal activity was found in raw sludge, this component of digested sludge appears to be a product of the digestion process.
Production of a precursor to the pyrimidine moiety of thiamine
Authors: Rubin H E , Love S H
Published: January 2020

The supernatant fluid from cultures of Escherichia coli W-11, a pur E mutant, prevented the inhibition of growth of E. coli B in a medium containing adenine or adenosine. Adenine inhibition was prevented more readily than adenosine inhibition. More than 90% of the biological activity of the supernatant fluid was recovered in the anionic fraction after treatment with Dowex-50 (NH4+). The cationic fraction, containing large amounts of 5-aminoimidazole ribonucleoside (AIRS), did not prevent adenine inhibition. The W-11 supernatant fluid was shown by bioautography to contain only one compound that prevented adenine inhibition. Proliferating and non-proliferating cultures produced only one compound that prevented adenine inhibition. The compound was shown to be an intermediate (int-1) in the biosynthesis of the pyrimidine moiety of thiamine, Int-1 was stable during sterilization at 121 C for 15 min, during concentration by either flask evaporation or lyophilization, and after storage for several days at 4 C or at -- 20 C. Int-1 was distinguishable from other known derivatives or intermediates of the pyrimidine moiety. A scheme is presented that illustrates the proposed relationship between int-1 and the synthesis of thiamine.
Microbial transformation of 2,4,6-trinitrotoluene and other nitroaromatic compounds
Authors: McCormick N G , Feeherry F E , Levinson H S
Published: January 2020

A variety of nitroaromatic compounds, including 2,4,6-trinitrotoluene (TNT), were reduced by hydrogen in the presence of enzyme preparations from Veillonella alkalescens. Consistent with the proposed reduction pathway, R-NO2 H2 leads to R-NO H2 leads to R-NHOH H2 leads to R-NH2, 3 mol of H2 was utilized per mol of nitro group. The rates of reduction of 40 mono-, di-, and trinitroaromatic compounds by V. alkalescens extract were determined. The reactivity of the nitro groups depended on other substituents and on the position of the nitro groups relative to these substituents. In the case of the nitrotoluenes, the para-nitro group was the most readily reduced, the 4-nitro position of 2,4-dinitrotulene being reduced first. The pattern of reduction of TNT (disappearance of TNT and reduction products formed) depended on the type of preparation (cell-free extract, resting cells, or growing culture), on the species, and on the atmosphere (air or H2). The "nitro-reductase" activity of V. alkalescens extracts was associated with protein fractions, one having some ferredoxin-like properties and the other possessing hydrogenase activity. Efforts to eliminate hydrogenase from the reaction have thus far been unsuccessful. The question of whether ferredoxin acts as a nonspecific reductase for nitroaromatic compounds remains unresolved.
Liberation of sulfate from sulfate esters by soils
Authors: Houghton C , Rose R A
Published: January 2020

When incubated with acid, alkaline, and neutral soils, a variety of synthetic sulfate esters representing the various classes of these compounds was hydrolyzed by enzymes, probably of microbial origin. The appearance of sulfate in the soil water occurred immediately after introduction into the soils with some esters, whereas with others it occurred only after lag periods. Heat treatment destroyed the hydrolytic acitivity in the soils. The ester sulfate groups present in humic acid extracted from the soil appeared to be resistant to hydrolysis by a variety of sulfohydrolases extracted from bacteria and other organisms.
Hot-Loop Test for the Determination of Carbon Dioxide Production from Glucose by Lactic Acid Bacteria
Authors: Sperber William H. , Swan Janice
Published: January 2020

A hot-loop test was found to be more rapid, convenient, and reliable for the detection of carbon dioxide production than were conventional methods such as displacement of agar plugs and precipitation in barium hydroxide.
Isolation of
Pseudomonas aeruginosa
and Other Bacterial Species from Ornamental Aquarium Plants
Authors: Trust T. J. , Bartlett Karen H.
Published: January 2020

Ornamental aquarium plants were demonstrated to carry as many as 10
8
viable mesophilic bacteria per g. Gram-negative organisms predominated among the 19 genera of bacteria identified.
Pseudomonas aeruginosa
was readily isolated from 53% of the samples tested.