A Water-Soluble Antibiotic in Rhubarb Stalk Shows an Unusual Pattern of Multiple Zones of Inhibition and Preferentially Kills Slow-Growing Bacteria.

Organic extract of Rhubarb () roots is known to have several medicinal uses. However, not much research has been done with the rhubarb stalk. The aim of this research is to evaluate the anti-bacterial and anti-proliferative effects of the aqueous extract from rhubarb stalks.

Maillard reaction products inhibit the periodontal pathogen Aggregatibacter actinomycetemcomitans by chelating iron.

Objective: To determine the mechanism of growth inhibition of Aggregatibacter actinomycetemcomitans by Maillard reaction products (MRP).

Design: Growth and cell viabilities in the presence or absence of MRP were measured for both the rough and smooth variants of the bacteria. Effects of addition of ferrous and ferric ions on the inhibition of the bacteria by MRP were determined.

Antibiotic in myrrh from preferentially kills nongrowing bacteria.

Aim: To demonstrate that myrrh oil preferentially kills nongrowing bacteria and causes no resistance development.

Method: Growth inhibition was determined on regular plates or plates without nutrients, which were later overlaid with soft agar containing nutrients to continue growth. Killing experiments were done in broth and in buffer without nutrients.

Increased Viability of Sugar Transport-Deficient Mutant of the Periodontal Pathogen, Aggregatibacter actinomycetemcomitans.

The periodontal pathogen, Aggregatibacter actinomycetemcomitans is extremely sensitive to even a mildly acidic pH resulting from metabolic acids secreted during growth, losing viability rapidly as the pH goes below 6.0. Cells grown at high glucose concentration grow fast but rapidly lose viability.

Does microwave sterilization of growth media involve any non-thermal effect?

Fast reactions mediated by microwaves are often attributed by many to non-thermal effect. We show here that rapid formation of Maillard reaction products during microwave sterilization of growth medium results from concentration effect and not any non-thermal effect. This leads to an improved method for microwave sterilization of growth media.

Sensitivity of the periodontal pathogen Aggregatibacter actinomycetemcomitans at mildly acidic pH.

Background: Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), a capnophilic facultative anaerobe, is associated with localized aggressive periodontitis and endocarditis. When grown in broth, the cells begin to die rapidly after overnight growth. The cells also often lose viability on plates within a few days.

Microwave sterilization of growth medium alleviates inhibition of Aggregatibacter actinomycetemcomitans by Maillard reaction products.

Aggregatibacter (Actinobacillus) actinomycetemcomitans is the causative agent of localized aggressive periodontitis and endocarditis. The bacteria grow slowly even in a rich medium and rapidly lose viability after about 19 h of growth. One of the reasons for the slow growth and for the decreased viability is the conventional method of making growth media by autoclaving.

Bacterial conjugation in the cytoplasm of mouse cells.

Intracellular pathogenic organisms such as salmonellae and shigellae are able to evade the effects of many antibiotics because the drugs are not able to penetrate the plasma membrane. In addition, these bacteria may be able to transfer genes within cells while protected from the action of drugs. The primary mode by which virulence and antibiotic resistance genes are spread is bacterial conjugation.

tfoX (sxy)-dependent transformation of Aggregatibacter (Actinobacillus) actinomycetemcomitans.

tfoX (sxy) is a regulatory gene needed to turn on competence genes. Aggregatibacter (Actinobacillus) actinomycetemcomitans has a tfoX gene that is important for transformation. We cloned this gene on an IncQ plasmid downstream of the inducible tac promoter.