scholarly journals Growth of Escherichia coli Coexpressing Phosphotriesterase and Glycerophosphodiester Phosphodiesterase, Using Paraoxon as the Sole Phosphorus Source

2004 ◽  
Vol 70 (1) ◽  
pp. 404-412 ◽  
Author(s):  
Sean Yu McLoughlin ◽  
Colin Jackson ◽  
Jian-Wei Liu ◽  
David L. Ollis
Keyword(s):  
Escherichia Coli ◽  
Enterobacter Aerogenes ◽  
Sole Source ◽  
Limiting Factor ◽  
E Coli ◽  
Dimethyl Phosphate ◽  
Genes Encoding ◽  
Phosphorus Source ◽  
Hydrolysis Of ◽  
Methyl Phosphate

ABSTRACT Phosphotriesterases catalyze the hydrolytic detoxification of phosphotriester pesticides and chemical warfare nerve agents with various efficiencies. The directed evolution of phosphotriesterases to enhance the breakdown of poor substrates is desirable for the purposes of bioremediation. A limiting factor in the identification of phosphotriesterase mutants with increased activity is the ability to effectively screen large mutant libraries. To this end, we have investigated the possibility of coupling phosphotriesterase activity to cell growth by using methyl paraoxon as the sole phosphorus source. The catabolism of paraoxon to phosphate would occur via the stepwise enzymatic hydrolysis of paraoxon to dimethyl phosphate, methyl phosphate, and then phosphate. The Escherichia coli strain DH10B expressing the phosphotriesterase from Agrobacterium radiobacter P230 (OpdA) is unable to grow when paraoxon is used as the sole phosphorus source. Enterobacter aerogenes is an organism capable of growing when dimethyl phosphate is the sole phosphorus source. The enzyme responsible for hydrolyzing dimethyl phosphate has been previously characterized as a nonspecific phosphohydrolase. We isolated and characterized the genes encoding the phosphohydrolase operon. The operon was identified from a shotgun clone that enabled E. coli to grow when dimethyl phosphate is the sole phosphorus source. E. coli coexpressing the phosphohydrolase and OpdA grew when paraoxon was the sole phosphorus source. By constructing a short degradative pathway, we have enabled E. coli to use phosphotriesters as a sole source of phosphorus.

scholarly journals The Escherichia coli Protein YfeX Functions as a Porphyrinogen Oxidase, Not a Heme Dechelatase

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
Harry A. Dailey ◽  
Alecia N. Septer ◽  
Lauren Daugherty ◽  
Daniel Thames ◽  
Svetlana Gerdes ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Iron Removal ◽  
Anaerobic Growth ◽  
Limiting Factor ◽  
Alizarin Red ◽  
Content Type ◽  
E Coli ◽  
Genes Encoding

ABSTRACT The protein YfeX from Escherichia coli has been proposed to be essential for the process of iron removal from heme by carrying out a dechelation of heme without cleavage of the porphyrin macrocycle. Since this proposed reaction is unique and would represent the first instance of the biological dechelation of heme, we undertook to characterize YfeX. Our data reveal that YfeX effectively decolorizes the dyes alizarin red and Cibacron blue F3GA and has peroxidase activity with pyrogallal but not guiacol. YfeX oxidizes protoporphyrinogen to protoporphyrin in vitro. However, we were unable to detect any dechelation of heme to free porphyrin with purified YfeX or in cellular extracts of E. coli overexpressing YfeX. Additionally, Vibrio fischeri, an organism that can utilize heme as an iron source when grown under iron limitation, is able to grow with heme as the sole source of iron when its YfeX homolog is absent. Plasmid-driven expression of YfeX in V. fischeri grown with heme did not result in accumulation of protoporphyrin. We propose that YfeX is a typical dye-decolorizing peroxidase (or DyP) and not a dechelatase. The protoporphyrin reported to accumulate when YfeX is overexpressed in E. coli likely arises from the intracellular oxidation of endogenously synthesized protoporphyrinogen and not from dechelation of exogenously supplied heme. Bioinformatic analysis of bacterial YfeX homologs does not identify any connection with iron acquisition but does suggest links to anaerobic-growth-related respiratory pathways. Additionally, some genes encoding homologs of YfeX have tight association with genes encoding a bacterial cytoplasmic encapsulating protein. IMPORTANCE Acquisition of iron from the host during infection is a limiting factor for growth and survival of pathogens. Host heme is the major source of iron in infections, and pathogenic bacteria have evolved complex mechanisms to acquire heme and abstract the iron from heme. Recently Létoffé et al. (Proc. Natl. Acad. Sci. U. S. A. 106:11719–11724, 2009) reported that the protein YfeX from E. coli is able to dechelate heme to remove iron and leave an intact tetrapyrrole. This is totally unlike any other described biological system for iron removal from heme and, thus, would represent a dramatically new feature with potentially profound implications for our understanding of bacterial pathogenesis. Given that this reaction has no precedent in biological systems, we characterized YfeX and a related protein. Our data clearly demonstrate that YfeX is not a dechelatase as reported but is a peroxidase that oxidizes endogenous porphyrinogens to porphyrins.

Антимікробна резистентність провідних збудників інфекцій сечових шляхів у Києві (Україна)

2017 ◽  
Vol 1 (2) ◽  
pp. 48-60
Author(s):  
A.G. Salmanov ◽  
A.V. Rudenko
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Klebsiella Pneumoniae ◽  
Staphylococcus Epidermidis ◽  
Klebsiella Oxytoca ◽  
Enterobacter Aerogenes ◽  
Enterobacter Cloacae ◽  
Proteus Vulgaris ◽  
Providencia Rettgeri ◽  
E Coli

Мета роботи — вивчити резистентність до антибіотиків бактеріальних збудників інфекцій сечових шляхів (ІСШ), виділених у пацієнтів урологічного стаціонару в м. Києві. Матеріали і методи. Досліджено 1612 штамів бактерій, виділених із сечі хворих з ІСШ (цистит, уретрит, пієлонефрит), госпіталізованих в урологічне відділення ДУ «Інститут урології НАМН України» у м. Києві протягом 2016 р. Серед пацієнтів переважали жінки — 1201 (74,5 %). Вік хворих становив від 17 до 74 років. Для збору даних використано медичну документацію лікарні. Мікробіологічні дослідження виконано у лабораторії мікробіології ДУ «Інститут урології НАМН України». Аналізували результати культурального дослідження зразків сечі, зібраних за наявності клінічних ознак ІСШ. Дослідження клінічного матеріалу та інтерпретацію отриманих результатів проводили загальноприйнятими методами. Вивчено чутливість уропатогенів до 31 антибіотика дискодифузійним методом відповідно до рекомендацій Інституту клінічних та лабораторних стандартів США (Clinical and Laboratory Standards Institute (CLSI)). Результати та обговорення. Аналіз мікробного спектра сечі виявив домінування серед уропатогенів штамів Escherichia coli (32,0 %), Enterococcus faecalis (19,5 %), Klebsiella pneumoniae (10,9 %), Staphylococcus epidermidis (8,9 %), S. haemolyticus (6,5 %) та Pseudomonas aeruginosa (6,4 %). Частка Enterococcus faecium, Enterobacter aerogenes і Streptococcus viridans становила відповідно 2,5, 2,2 і 1,6 %, Enterobacter cloacae, Klebsiella oxytoca, Acinetobacter baumannii, Proteus vulgaris та Providencia rettgeri — менше 1,0 %. У більшості випадків (69,7 %) мікроорганізми виділено у монокультурі, у решті випадків — у мікробних асоціа- ціях. Високу резистентність до тестованих антибіотиків виявили штами E. aerogenes (45,1 %), E. cloacae (45,7 %), E. faecium (40,9 %), E. faecalis (40,7 %), E. coli (39,9 %), P. aeruginosa (34,0 %), K. pneumoniae (28,6 %). Найбільш активними до уропатогенів були іміпенем (E. coli — 87,6 %, P. aeruginosa — 75,7 %, E. cloacae — 67,3 %, E. aerogenes — 72,6 %, K. pneumoniae — 93,2 %), меропенем (E. coli — 89,1 %, P. aeruginosa — 76,7 %, K. pneumoniae — 82,6 %), лефлоцин (E. coli — 74,5 %, ентерококи — 78,7 %, P. aeruginosa — 76,7 %, E. cloacae — 73,9 %, E. aerogenes — 80,4 %, K. pneumoniae — 83,5 %), амоксицилін/клавуланат (ентерококи — 84,6 %), фурагін (ентерококи — 82,6 %), цефоперазон (K. pneumoniae — 89,2 %, P. aeruginosa — 73,8 %), цефтріаксон (K. pneumoniae — 80,1 %). Висновки. Антибіотикорезистентність збудників ІСШ — важлива терапевтична проблема. Найбільшою активністю до уропатогенів характеризуються іміпенем, меропенем, лефлоцин, амоксицилін/ клавуланат, фурагін, цефоперазон, цефтріаксон, які можна розглядати як препарат вибору для призначення стартової терапії ІСШ. Необхідно здійснювати постійний моніторинг за резистентністю до дії антибіотиків. Політику використання антибіотиків у кожному стаціонарі слід визначати залежно від локальних даних щодо резистентності до протимікробних препаратів.

Fate of Escherichia coli O157:H7 and Other Coliforms in Commercial Mayonnaise and Refrigerated Salad Dressing

1995 ◽  
Vol 58 (1) ◽  
pp. 13-18 ◽  
Author(s):  
ERROL V. RAGHUBEER ◽  
JIM S. KE ◽  
MICHAEL L. CAMPBELL ◽  
RICHARD S. MEYER
Keyword(s):  
Escherichia Coli ◽  
Storage Temperature ◽  
Enterobacter Aerogenes ◽  
Antimicrobial Effect ◽  
Coliform Bacteria ◽  
Escherichia Coli O157 ◽  
Salad Dressing ◽  
E Coli ◽  
Survival Pattern ◽  
High Level

Commercial mayonnaise and refrigerated ranch salad dressing were inoculated at two levels with two strains of Escherichia coli O157:H7, a non-pathogenic E. coli, and the non-fecal coliform Enterobacter aerogenes. Results showed that at the high inoculation level (>106 colony forming units [CFU]/g) in mayonnaise stored at room temperature (ca. 22°C) both strains of O157:H7 were undetected at 96 h. At the high inoculation level, all strains of coliform bacteria tested survived longer in salad dressing stored at 4°C than in mayonnaise stored at 22°C. The O157:H7 strains were still present at low levels after 17 days. The survival time in the low-level inoculum (104CFU/g) study decreased, but the survival pattern in the two products was similar to that observed in the high-level inoculum study. Slight differences in survival among strains were observed. The greater antimicrobial effect of mayonnaise may be attributable to differences in pH, water activity (aw), nutrients, storage temperature, and the presence of lysozyme in the whole eggs used in the production of commercial mayonnaise. Coliform bacteria survived longer in refrigerated salad dressing than in mayonnaise particularly at the high-level inoculum. Both mayonnaise (pH 3.91) and salad dressing (pH 4.51) did not support the growth of any of the microorganisms even though survival was observed.

scholarly journals Ferric uptake regulator (Fur) reversibly binds a [2Fe-2S] cluster to sense intracellular iron homeostasis in Escherichia coli

2020 ◽  
Vol 295 (46) ◽  
pp. 15454-15463 ◽  
Author(s):  
Chelsey R. Fontenot ◽  
Homyra Tasnim ◽  
Kathryn A. Valdes ◽  
Codrina V. Popescu ◽  
Huangen Ding
Keyword(s):  
Escherichia Coli ◽  
Iron Content ◽  
Iron Homeostasis ◽  
Ferric Uptake Regulator ◽  
Intracellular Iron ◽  
Free Iron ◽  
E Coli ◽  
Genes Encoding ◽  
Fur Protein ◽  
Mutant Cells

The ferric uptake regulator (Fur) is a global transcription factor that regulates intracellular iron homeostasis in bacteria. The current hypothesis states that when the intracellular “free” iron concentration is elevated, Fur binds ferrous iron, and the iron-bound Fur represses the genes encoding for iron uptake systems and stimulates the genes encoding for iron storage proteins. However, the “iron-bound” Fur has never been isolated from any bacteria. Here we report that the Escherichia coli Fur has a bright red color when expressed in E. coli mutant cells containing an elevated intracellular free iron content because of deletion of the iron–sulfur cluster assembly proteins IscA and SufA. The acid-labile iron and sulfide content analyses in conjunction with the EPR and Mössbauer spectroscopy measurements and the site-directed mutagenesis studies show that the red Fur protein binds a [2Fe-2S] cluster via conserved cysteine residues. The occupancy of the [2Fe-2S] cluster in Fur protein is ∼31% in the E. coli iscA/sufA mutant cells and is decreased to ∼4% in WT E. coli cells. Depletion of the intracellular free iron content using the membrane-permeable iron chelator 2,2´-dipyridyl effectively removes the [2Fe-2S] cluster from Fur in E. coli cells, suggesting that Fur senses the intracellular free iron content via reversible binding of a [2Fe-2S] cluster. The binding of the [2Fe-2S] cluster in Fur appears to be highly conserved, because the Fur homolog from Hemophilus influenzae expressed in E. coli cells also reversibly binds a [2Fe-2S] cluster to sense intracellular iron homeostasis.

scholarly journals Detection and Quantification of Superoxide Formed within the Periplasm of Escherichia coli

2006 ◽  
Vol 188 (17) ◽  
pp. 6326-6334 ◽  
Author(s):  
Sergei Korshunov ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Phagocytic Cells ◽  
Free Living ◽  
E Coli ◽  
Superoxide Formation ◽  
Genes Encoding ◽  
Copper Zinc ◽  
Primary Substrate

ABSTRACT Many gram-negative bacteria harbor a copper/zinc-containing superoxide dismutase (CuZnSOD) in their periplasms. In pathogenic bacteria, one role of this enzyme may be to protect periplasmic biomolecules from superoxide that is released by host phagocytic cells. However, the enzyme is also present in many nonpathogens and/or free-living bacteria, including Escherichia coli. In this study we were able to detect superoxide being released into the medium from growing cultures of E. coli. Exponential-phase cells do not normally synthesize CuZnSOD, which is specifically induced in stationary phase. However, the engineered expression of CuZnSOD in growing cells eliminated superoxide release, confirming that this superoxide was formed within the periplasm. The rate of periplasmic superoxide production was surprisingly high and approximated the estimated rate of cytoplasmic superoxide formation when both were normalized to the volume of the compartment. The rate increased in proportion to oxygen concentration, suggesting that the superoxide is generated by the adventitious oxidation of an electron carrier. Mutations that eliminated menaquinone synthesis eradicated the superoxide formation, while mutations in genes encoding respiratory complexes affected it only insofar as they are likely to affect the redox state of menaquinone. We infer that the adventitious autoxidation of dihydromenaquinone in the cytoplasmic membrane releases a steady flux of superoxide into the periplasm of E. coli. This endogenous superoxide may create oxidative stress in that compartment and be a primary substrate of CuZnSOD.

scholarly journals Escherichia coli Mutants Lacking All Possible Combinations of Eight Penicillin Binding Proteins: Viability, Characteristics, and Implications for Peptidoglycan Synthesis

1999 ◽  
Vol 181 (13) ◽  
pp. 3981-3993 ◽  
Author(s):  
Sylvia A. Denome ◽  
Pamela K. Elf ◽  
Thomas A. Henderson ◽  
David E. Nelson ◽  
Kevin D. Young
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Binding Proteins ◽  
Kanamycin Resistance ◽  
Open Reading Frames ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Peptidoglycan Biosynthesis ◽  
Kanamycin Resistance Cassette ◽  
Genes Encoding

ABSTRACT The penicillin binding proteins (PBPs) synthesize and remodel peptidoglycan, the structural component of the bacterial cell wall. Much is known about the biochemistry of these proteins, but little is known about their biological roles. To better understand the contributions these proteins make to the physiology ofEscherichia coli, we constructed 192 mutants from which eight PBP genes were deleted in every possible combination. The genes encoding PBPs 1a, 1b, 4, 5, 6, and 7, AmpC, and AmpH were cloned, and from each gene an internal coding sequence was removed and replaced with a kanamycin resistance cassette flanked by two ressites from plasmid RP4. Deletion of individual genes was accomplished by transferring each interrupted gene onto the chromosome of E. coli via λ phage transduction and selecting for kanamycin-resistant recombinants. Afterwards, the kanamycin resistance cassette was removed from each mutant strain by supplying ParA resolvase in trans, yielding a strain in which a long segment of the original PBP gene was deleted and replaced by an 8-bpres site. These kanamycin-sensitive mutants were used as recipients in further rounds of replacement mutagenesis, resulting in a set of strains lacking from one to seven PBPs. In addition, thedacD gene was deleted from two septuple mutants, creating strains lacking eight genes. The only deletion combinations not produced were those lacking both PBPs 1a and 1b because such a combination is lethal. Surprisingly, all other deletion mutants were viable even though, at the extreme, 8 of the 12 known PBPs had been eliminated. Furthermore, when both PBPs 2 and 3 were inactivated by the β-lactams mecillinam and aztreonam, respectively, several mutants did not lyse but continued to grow as enlarged spheres, so that one mutant synthesized osmotically resistant peptidoglycan when only 2 of 12 PBPs (PBPs 1b and 1c) remained active. These results have important implications for current models of peptidoglycan biosynthesis, for understanding the evolution of the bacterial sacculus, and for interpreting results derived by mutating unknown open reading frames in genome projects. In addition, members of the set of PBP mutants will provide excellent starting points for answering fundamental questions about other aspects of cell wall metabolism.

scholarly journals Escherichia coli Competence Gene Homologs Are Essential for Competitive Fitness and the Use of DNA as a Nutrient

2006 ◽  
Vol 188 (11) ◽  
pp. 3902-3910 ◽  
Author(s):  
Vyacheslav Palchevskiy ◽  
Steven E. Finkel
Keyword(s):  
Escherichia Coli ◽  
Sole Source ◽  
Extracellular Dna ◽  
Nutrient Source ◽  
Genetic Competence ◽  
Exogenous Dna ◽  
Competitive Fitness ◽  
E Coli ◽  
Widespread Phenomenon

ABSTRACT Natural genetic competence is the ability of cells to take up extracellular DNA and is an important mechanism for horizontal gene transfer. Another potential benefit of natural competence is that exogenous DNA can serve as a nutrient source for starving bacteria because the ability to “eat” DNA is necessary for competitive survival in environments containing limited nutrients. We show here that eight Escherichia coli genes, identified as homologs of com genes in Haemophilus influenzae and Neisseria gonorrhoeae, are necessary for the use of extracellular DNA as the sole source of carbon and energy. These genes also confer a competitive advantage to E. coli during long-term stationary-phase incubation. We also show that homologs of these genes are found throughout the proteobacteria, suggesting that the use of DNA as a nutrient may be a widespread phenomenon.

scholarly journals 1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Julieta Cabrera ◽  
Dwight Acosta ◽  
Alcides López ◽  
Roberto J. Candal ◽  
Claudia Marchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Photocatalytic Activity ◽  
Bactericidal Activity ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
E Coli ◽  
1D Nanostructures ◽  
Sol Gel Synthesis ◽  
Hydrolysis Of ◽  
Tio2 Nanostructures

TiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis). The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. The photocatalytic activity of 1D nanostructures was evaluated by measuring the deactivation of E. coli in stirred water in the dark and under UV-A/B irradiation. Results show that in addition to the bactericidal activity of TiO2 under UV-A illumination, under dark conditions, the decrease in bacteria viability is ascribed to mechanical stress due to stirring.

Inhibition of Escherichia coli O157:H7 in Ripening Dry Fermented Sausage by Ground Yellow Mustard

2008 ◽  
Vol 71 (3) ◽  
pp. 486-493 ◽  
Author(s):  
GARY H. GRAUMANN ◽  
RICHARD A. HOLLEY
Keyword(s):  
Escherichia Coli ◽  
Starter Culture ◽  
Escherichia Coli O157 ◽  
Fermented Sausage ◽  
Yellow Mustard ◽  
E Coli ◽  
Dry Fermented Sausage ◽  
Hydrolysis Of ◽  
Antimicrobial Effectiveness ◽  
Dry Sausage

Compounds generated by the enzymatic hydrolysis of glucosinolates naturally present in mustard powder are potently bactericidal against Escherichia coli O157:H7. Because E. coli O157:H7 can survive the dry fermented sausage manufacturing process, 2, 4, and 6% (wt/wt) nondeheated (hot) mustard powder or 6% (wt/wt) deheated (cold) mustard powder were added to dry sausage batter inoculated with E. coli O157:H7 at about 7 log CFU/g to evaluate the antimicrobial effectiveness of the powders. Reductions in E. coli O157:H7 populations, changes in pH and water activity (aw), effects on starter culture (Pediococcus pentosaceus and Staphylococcus carnosus) populations, and effects of mustard powder on sausage texture (shear) were monitored during ripening. Nondeheated mustard powder at 2, 4, and 6% in dry sausage (0.90 aw) resulted in significant reductions in E. coli O157:H7 (P < 0.05) of 3.4, 4.4, and 6.9 log CFU/g, respectively, within 30 days of drying. During fermentation and drying, mustard powder did not affect P. pentosaceus and S. carnosus activity in any of the treatments. Extension of drying to 36 and 48 days reduced E. coli O157:H7 by >5 log CFU/g in the 4 and 2% mustard powder treatments, respectively. The 6% deheated mustard powder treatment provided the most rapid reductions of E. coli O157:H7 (yielding <0.20 log CFU/g after 24 days) by an unknown mechanism and was the least detrimental (P < 0.05) to sausage texture.

Shellac Formulations To Reduce Epiphytic Survival of Coliform Bacteria on Citrus Fruit Postharvest†

2001 ◽  
Vol 64 (11) ◽  
pp. 1756-1760 ◽  
Author(s):  
RAYMOND G. McGUIRE ◽  
ROBERT D. HAGENMAIER
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Limit Of Detection ◽  
Citrus Fruit ◽  
Enterobacter Aerogenes ◽  
Coliform Bacteria ◽  
Undetectable Level ◽  
Neutral Solution ◽  
E Coli ◽  
Epiphytic Survival

Survival of the coliform bacteria Enterobacter aerogenes and Escherichia coli was monitored in a neutral carboxyme-thylcellulose formulation and in shellac formulations with various pH and concentrations of ethanol and the preservative paraben; populations were subsequently measured from the surface of citrus fruit coated with these formulations. Numbers of the two bacteria increased over 24 h from 106 CFU/ml to approximately 108 CFU/ml in the carboxymethylcellulose solution, but over this time numbers remained little changed in the neutral solution of shellac. The Enterobacter was more tolerant of alcohol over a 3-h period; although its numbers in a shellac solution with 10% ethanol dropped from more than 106 CFU/ml to just over 103 CFU/ml, E. coli and a third species, Klebsiella pneumoniae, declined toward the limit of detection (5 CFU/ml) during this time. The addition of morpholine to increase the formulation pH to 9.0 caused numbers of bacteria to plummet to an undetectable level within 30 to 60 min. On Ruby Red grapefruit and Valencia oranges in storage at 13°C numbers of E. aerogenes and E. coli declined over 2 weeks from 105 CFU/cm2 to less than 2.5 × 101, but most of the loss in numbers occurred within 1 day. Numbers remained significantly less on shellacked fruit compared with those applied in the carboxymethylcellulose coating, and a shellac coating prepared from a pH 9 solution was more toxic to these species than one in which 12% ethanol had been added to the neutral formulation. The addition of the preservative paraben in the basic shellac was further inhibitory.

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