Biocidal action

Hodges N.A. Hanlon G.W. (1991) Detection and measurement of combined biocide action. In Mechanisms of Action of Chemical Biocides (eds S.P. Denyer W.B. Hugo), Society for Applied Bacteriology Technical Series No. 27, pp. 297-310. Oxford Blackwell Scientific Publications. 

Formaldehyde, biocidal action, 34 (1997) 149 Free energy, biological action and linear, 10 (1974) 205... 

Zinc phosphide — a rodenticide — is relatively toxic when compared to elemental zinc or zinc oxide most of the biocidal action is attributed to the phosphide fraction. Acute oral LD50s for zinc... 

Low power ultrasound offers the possibility of enhancing the effects of chlorine. The results of a study of the combined effect of low power ultrasound and chlorination on the bacterial population of raw stream water are shown (Tab. 4.2). Neither chlorination alone nor sonication alone was able to completely destroy the bacteria present. When sonication is combined with chlorination however the biocidal action is significantly improved [10]. The effect can be ascribed partly to the break-up and dispersion of bacterial clumps and floes which render the individual bacteria more susceptible to chemical attack. In addition cavitation induced damage to bacterial cell walls will allow easier penetration of the biocide. 

The lipophilic nature of the organic ligands of copper 8-hydroxyquinolinate (21) helps to transport the copper atom into the cell. Once there, dissociation to the active species (27) is thought to occur (equation 9) the biocidal action may be due to the coordination of (27) with metal-binding sites of cell enzymes (B-69Mill500). 

An example of such a product is ioBio , marketed by Baltimore Aircoil Co. (BAC). It is proposed for small cooling systems. This system is, in effect, an in-line dispenser of prilled elemental iodine (U), with replaceable iodine canisters available. The equipment is placed in the makeup waterline to the tower, and in-line options include filters, water meters, and back-flow prevention devices. Claims made are that the biocidal action of the elemental iodine is not affected by changes in temperature, system load, or water chemistry. Also, the system is compatible with virtually all scale and corrosion inhibitors and does not contribute to the corrosion of metal surfaces. 

Apart from ready-to-use biocide formulations, there are also other chemicals that exhibit a degree of microbiological control, such as certain corrosion inhibitors that have a biostatic or biocidal action, for example, chromate. 

Sterilization by chemical methods. Biocidal action has been widely used for many years to control biofilm formation in closed systems, such as heat exchangers, cooling towers, and storage tanks.64, (Dexter)5... 

This group includes pharmaceuticals and pesticides, which have therapeutical and biocide action, respectively, on living organisms, along with a few compounds that improve plant germination. ... 

Acquired, non-plasmid-encoded resistance to biocides can result when bacteria are exposed to gradually increasing concentrations of a biocide. Examples are provided by highly QAC-resistant Serratia marcescens, and chlorhexidine-resistant Pr. mirabilis, Ps. aeruginosa and Ser. marcescens. However, in view of the multiple target sites associated with biocide action, it is unlikely that mutation plays a key role in resistance. 

With some biocide treatments there is a simple direct relationship between ATP and viable cell counts. However, where the mechanism of biocide action is related to influences on cell bioenergetics, or the concentration range employed is biostatic and affects cell metabolism, then ATP results may not follow the same pattern as microbial counts. Under these circumstances low ATP results at relatively high microbial levels might be expected but it is also possible that ATP levels increase over a period of time. 

The chemistry, distribution and biocidal action of these toxic allelochemicals Is discussed. 

The broad-spectrum biocidal action induced by phototoxic allelochemicals has been demonstrated toward a range of organisms including bacteria, fungi, nematodes, insects as well as non-photo-toxin-containing plants. Table III summarizes the organisms susceptible to photosensltlzatlon by alpha-terthienyl, a phototoxin characteristic of many Asteraceae species (4, 10-11). The toxicity of this thiophenic polyine toward plant pathogens (e.g.,... 

Investigations of bactericide activity and toxicity of synthesized homo- and copolymers showed that these preparations were very active and posses biocide action in relation to grampositive (St.Aureus) and gram-negative (E.coli) microorganisms and that a lot of samples had low toxicity (Table 1). 

Sodium azide and potassium azide have a broad range of biocidal action, possessing, besides herbicidal activity, fungicidal, bactericidal, nematocidal and insecticidal activity. 

The described mechanisms of detergency are put into practice by using synthetic micelle-forming surfactants, among which the mixtures of anionic and nonionic surfactants (particularly alkylsulfates and oxyethylenated alcohols) make 10 to 40 % of the total detergent formulation. Cationic surfactants (alkylamines) that are also included into synthetic detergent formulations may contribute up to 5% of the total amount of formulation. These substances reveal biocidal action and control micelle formation by forming mixed micelles. 

Because the chlorine can react with many organic substances found in water systems, there is a "chlorine demand" that will affect the biocidal activity of a particular dose. It is usually necessary to add excess chlorine in order to leave a free residual of chlorine in the system to ensure efficient biocidal action. Some comments on chlorine treatment programmes are contained in Table 14.11 [Betz Laboratories Inc. 1976]. 

Those products that have good biocidal action against these microorganisms can be considered effective. Yet, surprisingly, many manufacturers of over-the-counter (OTC) formulations do not have documented evidence of effectiveness from in vitro studies [time-kill and minimum inhibitory concentration (MIC)] to support their label claims for preoperative skin preps. In vivo studies performed on human volunteers are designed to assure that the products are anti-microbially effective within 10 minutes of application and are antimicrobially persistent for up to 6 hours postapplication. 

The use of cationic surfactants in chain lubricant formulations for biocidal action can be split... 

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