A new method for the detection of microbial proteolytic enzymes in milk

1982 ◽  
Vol 49 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Allan J. Cliffe ◽  
Barry A. Law
Keyword(s):  
Proteolytic Enzymes ◽  
New Method ◽  
Gram Negative Bacteria ◽  
Optimum Conditions ◽  
Sample Processing ◽  
Gram Negative ◽  
Alternative Method ◽  
Simple Alternative ◽  
Extracellular Proteinases

SUMMARYOptimum conditions have been determined for the use of Hide Powder Azure (HPA) to estimate extracellular proteinases produced by psychrotrophic Gram-negative bacteria. This assay is quicker, more precise and 3·2 times more sensitive than assays of soluble N released from casein. It provides a simple alternative method for monitoring proteinase purification schemes. With the modification described it is now possible to determine proteinase activities directly in milk. In its simplest form the HPA assay is sufficiently sensitive to detect proteinases produced by as few as 1·5 x 106 c.f.u. ml-1 psychrobtrophs without the necessity for any sample processing.

scholarly journals Evaluation of antimicrobial activity of the endophytic actinomycete R18(6) against multiresistant Gram-negative bacteria

2016 ◽  
Vol 88 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Tiele Carvalho ◽  
Sueli Van Der Sand
Keyword(s):  
Antimicrobial Activity ◽  
Inhibitory Concentration ◽  
Proteolytic Enzymes ◽  
Gram Negative Bacteria ◽  
Bacteriostatic Activity ◽  
Submerged Cultures ◽  
Gram Negative ◽  
Endophytic Actinomycete ◽  
Endophytic Actinomycetes ◽  
Antimicrobial Substances

Endophytic actinomycetes are promising sources of antimicrobial substances. This study evaluates the activity of metabolites produced by the endophytic actinomycete R18(6) against Gram-negative bacteria multiresistant to antimicrobials. R18(6) isolate was grown in submerged cultures under different conditions: carbon source, temperature, pH and incubation time to optimize antimicrobials production. The actinomycete grown in base medium supplemented with 1% glucose, pH 6.5 and incubation at 30 ºC for 96 h with shaking at 100 rpm, exhibited the highest activity against the used Gram-negative bacteria. Minimum inhibitory concentration (MIC) of the crude extract produced by the microorganism varied between 1/32 and 1/256. It had bactericide or bacteriostatic activity, depending on the Gram-negative organism. The active extract was stable at high temperatures, and unstable in medium containing proteolytic enzymes. Micromorphology of R18(6) was investigated by optical and scan microscopy, revealing that it was morphologically similar to the genusStreptomyces.

Confirmation and Identification of Salmonella spp., Cronobacter spp., and Other Gram-Negative Organisms by the Bruker MALDI Biotyper Method: Collaborative Study, First Action 2017.09

2018 ◽  
Vol 101 (5) ◽  
pp. 1593-1609 ◽  
Author(s):  
Benjamin Bastin ◽  
Patrick Bird ◽  
M Joseph Benzinger ◽  
Erin Crowley ◽  
James Agin ◽  
...  
Keyword(s):  
United States ◽  
Collaborative Study ◽  
The United States ◽  
Gram Negative Bacteria ◽  
Salmonella Spp ◽  
Gram Negative ◽  
Genus Level ◽  
Alternative Method ◽  
Maldi Biotyper ◽  
Gram Negative Organisms

Abstract The Bruker MALDI Biotyper® method utilizes matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS for the rapid and accurate identification and confirmation of Gram-negative bacteria from select media types. The alternative method was evaluated using nonselective and selective agars to identify Cronobacter spp., Salmonella spp., and select Gram-negative bacteria. Results obtained by the Bruker MALDI Biotyper were compared to the traditional biochemical methods as prescribed in the appropriate reference methods. Two collaborative studies were organized, one in the United States focusing on Cronobacter spp. and other Gram-negative bacteria, and one in Europe focusing on Salmonella spp. and other Gram-negative bacteria. Fourteen collaborators from seven laboratories located within the United States participated in the first collaborative study for Cronobacter spp. Fifteen collaborators from 15 service laboratories located within Europe participated in the second collaborative study for Salmonella spp. For each target organism (either Salmonella spp. or Cronobacter spp.), a total of 24 blind-coded isolates were evaluated. In each set of 24 organisms, there were 16 inclusivity organisms (Cronobacter spp. or Salmonella spp.) and 8 exclusivity organisms (closely related non-Cronobacter spp. and non-Salmonella spp. Gram-negative organisms). After testing was completed, the total percentage of correct identifications from each agar type for each strain was determined at a percentage of 100.0% to the genus level for the Cronobacter study and a percentage of 100.0% to the genus level for the Salmonella study. For both non-Cronobacter and non-Salmonella organisms, a percentage of 100.0% was correctly identified. The results indicated that the alternative method produced equivalent results when compared to the confirmatory procedures specified by each reference method.

scholarly journals Applicability of Escherichia Coli As an Indicator for Assessing Quality of Disinfectants and Antiseptic During the COVID-19 Pandemic

2021 ◽  
Author(s):  
Reza Ali Fallahzadeh ◽  
Fariborz Omidi ◽  
Davoud Ghadirian ◽  
Azimeh Fallahzadeh ◽  
Mohammad Reza Nafisi
Keyword(s):  
Test Tube ◽  
Laboratory Method ◽  
Gram Negative Bacteria ◽  
Optimum Conditions ◽  
Gram Negative ◽  
E Coli ◽  
Different Types ◽  
Micro Organisms ◽  
Required Quality

Introduction: The application of disinfectant agents is a common way to fight against micro-organisms. Although there are different types of disinfectant agents to fight COVID-19, many of them do not have the required quality and efficiency. The present work was aimed to evaluate the quality of the available disinfectant agents using gram-negative E. coli bacteria. Materials and Methods: In the laboratory phase of the research, the gram-negative E. coli bacteria were used to evaluate the quality of disinfectants. According to the proposed laboratory method, microbial kit was prepared and used to evaluate the performance of disinfectants. Results: Based on the obtained results, 1.0 mL of microbial suspension in the test tube, as microbial kit, is used for quality assessment of the disinfectants. Also, based on the results and considering the optimum conditions, in case of growth of microorganisms, the quality of disinfectant is evaluated as unfavorable, and in the absence of growth of microorganisms, the quality of disinfectant is considered appropriate in terms of its effect on gram-negative bacteria and weaker microorganisms. Conclusion: Based on the obtained results, E. coli can be used as a reliable indicator for assessing the quality of the disinfectant agents used against COVID 19.

Fine Structure and Radiation Resistance in Acinetobacter: Studies on a Resistant Strain

1968 ◽  
Vol 3 (2) ◽  
pp. 273-294
Author(s):  
MARGARET J. THORNLEY ◽  
AUDREY M. GLAUERT
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Radiation Resistance ◽  
Cell Walls ◽  
Proteolytic Enzymes ◽  
Gram Negative Bacteria ◽  
Intact Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Isolated Cell

An electron-microscope study of thin sections and negatively stained preparations of intact cells and isolated cell walls of a bacterium which is moderately resistant to ionizing radiation, Acinetobacter strain 199A, showed that it is similar to other Gram-negative bacteria except for its mode of division and for the fine structure of some of the surface layers. During division the cells form a fairly thick septum similar to those observed in Gram-positive bacteria. An examination of the appearance and chemical composition of isolated cell walls before and after treatment with enzymes, detergents and lipid solvents revealed that three layers, each with a characteristic fine structure, are present in the cell wall: (1) an outer membrane with an array of peg-like subunits; (2) a layer of wrinkled material which is digested by proteolytic enzymes; and (3) a smooth, rigid layer, which contains the mucopeptide components of the cell wall. These observations are compared with the results of other workers for various Gram-negative bacteria. From comparisons with the structure of more radiation-sensitive strains of Acinetobacter, it appears that layer (2) may be associated with the radiation resistance of the organism.

Postantibiotic effect of aminoglycosides on Gram-negative bacteria evaluated by a new method

1988 ◽  
Vol 22 (1) ◽  
pp. 23-33 ◽  
Author(s):  
Barbro Isaksson ◽  
Lennart Nilsson ◽  
Rolf Maller ◽  
Lars Sör´n
Keyword(s):  
New Method ◽  
Gram Negative Bacteria ◽  
Postantibiotic Effect ◽  
Gram Negative

scholarly journals Whole-Genome Sequences of Two Pseudoalteromonas piscicida Strains, DE1-A and DE2-A, with Strong Antibacterial Activity against Vibrio vulnificus

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Gary P. Richards ◽  
David S. Needleman ◽  
Michael A. Watson ◽  
Shawn W. Polson
Keyword(s):  
Antibacterial Activity ◽  
Vibrio Vulnificus ◽  
Proteolytic Enzymes ◽  
Antibacterial Properties ◽  
Whole Genome ◽  
Gram Negative Bacteria ◽  
Genome Sequences ◽  
Gram Negative ◽  
Content Type ◽  
Bactericidal Properties

Highly vesiculated Pseudoalteromonas piscicida strains DE1-A and DE2-A were isolated from seawater and show bactericidal properties toward Vibrio vulnificus and other Gram-positive and Gram-negative bacteria. Here, we report the complete genome sequences of these two P. piscicida strains and identify proteolytic enzymes potentially involved in their antibacterial properties.

scholarly journals EFFECT OF PURIFIED ENZYMES ON VIRUSES AND GRAM-NEGATIVE BACTERIA

1936 ◽  
Vol 64 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Malcolm H. Merrill
Keyword(s):  
Proteolytic Enzymes ◽  
The Other ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Other Hand

Evidence is presented that some viruses behave like proteins in that they are inactivated by proteolytic enzymes, whereas others prove more or less resistant. Ten strains of living Gram-negative bacteria resisted the action of purified trypsin and chymotrypsin, while the killed organisms were rapidly digested. Gram-positive bacteria, on the other hand, were resistant whether living or dead. The findings are discussed.

ANTIBACTERIAL SUBSTANCES FROM STAPHYLOCOCCI

1967 ◽  
Vol 13 (8) ◽  
pp. 947-955 ◽  
Author(s):  
Chun-Yang Hsu ◽  
G. M. Wiseman
Keyword(s):  
Staphylococcus Aureus ◽  
Proteolytic Enzymes ◽  
Indicator Strain ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Solid Media ◽  
Ph Range

It was found that 4.9% of 1065 coagulase-positive and 8.5% of 387 coagulase-negative strains of Staphylococcus produced antibiotics inhibiting growth of the indicator strain, Staphylococcus aureus Oxford 209P.Zones of inhibition on solid media ranged from slight to 6 mm. Antibiotics produced by several of the most active strains were investigated in detail. With one or two exceptions, these substances inhibited the growth of Gram-positive rather than Gram-negative bacteria. Most staphylococcal strains were found to be more sensitive to antibiotics produced by coagulase-negative than positive strains selected. At the concentration used, these antibiotics did not kill all cells of the indicator strain, S. aureus 209P.The activity of the antibiotics was not totally destroyed by autoclaving or proteolytic enzymes, and was unaffected over the pH range 2.0–11.0. The antibiotics were dialyzable and their activity was inhibited by 10−3 M concentrations of EDTA but not by citrate.

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