Effect of antimicrobial compounds on the number of bacteria in stems of cut rose flowers

Abstract

1990. Efect of antimicrobial compounds on the number of bacteria in stems of cut rosepowers. Journal of Applied Bacteriology 68, 117-122.The presence of chlorine in solution (bleach), a slow release chlorine (DICA), a quaternary ammonium compound (benzalkonium chloride), a hydroxyquinoline compound (HQC), or aluminium sulphate in the vase water decreased the number of bacteria in stems of cut 'Sonia' roses, with respect to untreated controls. However, when the concentration of the antimicrobial compound was high enough to reduce the number of bacteria in stems (measured after 7 d of vase life) to below the detection limit, the roses showed severe leaf chlorosis and leaf abscission. Benzalkonium chloride resulted in damage at a concentration just enough to reduce the number of bacteria in stems. Effects of HQC, aluminium sulphate, and silver nitrate on the number of bacteria were variable. In experiments in which HQC was relatively ineffective, only one bacterial strain was found in the stem. This strain grew on HQC concentrations as high as 400 mgjl, and was identified as Pseudomonas Juorescens.

Effect of different vase solutions on postharvest longevity of cut foliage <i>Ophiopogon</i> <i>japonicus</i>

“…Among many chemical preservatives, sucrose is the most commonly used vase solution ingredient as it improves the water balance and osmotic potential of cut flowers (Lal et al, 1990). Incorporation of antimicrobial agents into vase solution can decrease the bacterial population (van Doorn et al, 1990). Cytokinins have proven to increase the vase life of cut foliage by maintaining the integrity of the tonoplast membrane and preventing leakage of proteases which hydrolyses the soluble proteins including those in the chloroplast and mitochondrial membranes (Subhashini et al, 2011).…”

When is a Vase Solution Biocide not, or not only, Antimicrobial?

“…Physan-20, a commercial mixture of 50% n-alkyl (C 12 -C 18 ) dimethylbenzylammonium chlorides and 50% n-alkyl (C 12 -C 14 ) dimethylethylbenzylammonium chlorides (Van Doorn and Reid, 1992), 2-hydroxy-3-ionene chloride polymer (HICP) (Ueyama and Ichimura, 1998), and benzalkonium chloride (Knee, 2000) are QACs proven to extend the vase life of cut flowers and foliage (Table 2). Benzalkonium chloride at 50, 100, 500, 1000, and 2000 mg·L −1 has been used in vase solutions of cut Rosa hybrida 'Sonia' (Van Doorn et al, 1990). At higher concentrations of 500, 1000, and 2000 mg·L −1 it reduced bacterial numbers in the stem to 3.4 × 10 6 , 2.0 × 10 5 , and < 2.7 × 10 2 cfu/g FW, respectively, as compared to the water control (3.6 × 10 8 and 2.5 × 10 7 cfu/g FW in repeat experiments); however, the tested treatment concentrations resulted in leaf discolouration to lighter green and also leaf abscission.…”

“…A given definition for a biocide is "a substance that kills all living organisms (commonly used with reference to microorganisms), pathogenic or non-pathogenic" (Block, 1991b). In the context of handling cut stems of ornamental plant species in preservative (Joyce, 1998), pulsing (Joyce, 1993) and vase solutions (Knee, 2000), biocides are considered important to achieve the full postharvest longevity inherent in cut flowers and foliage (Van Doorn, 1997); that is, provision of antimicrobial biocides in vase solutions prolongs their vase life Ketsa et al, 1995;Knee, 2000;Pompodakis et al, 2004;Put et al, 1992;Van Doorn et al, 1990, 1991a. The dictionary definition of an antimicrobial is "active against microorganisms" (Pearsall, 1998).…”

“…The dictionary definition of an antimicrobial is "active against microorganisms" (Pearsall, 1998). Among the principle antimicrobial compounds that have been used to extend the vase life of cut flowers are: (i) chlorine and bromine compounds, such as sodium dichloroisocyanuric acid (Na-DICA) Knee, 2000;Van Doorn et al, 1990;Xie et al, 2007) and sodium hypochlorite (NaOCl) (Van Doorn et al, 1990); (ii) hydroxyquinoline (HQ) compounds, such as 8-hydroxyquinoline citrate (HQC) (Knee, 2000;Marousky, 1969;Van Doorn et al, 1990) and 8-hydroxyquinoline sulphate (HQS) (Hussein, 1994); (iii) quaternary ammonium compounds, such as benzalkonium chloride (n-alkyl dimethylbenzyl ammonium chloride) where the alkyl group may vary from C 8 H 17 to C 18 H 37 (Knee, 2000;Van Doorn et al, 1990); the proprietary compound Physan-20 (n-alkyl (C 12 and C 14 ) dimethyl ethylbenzyl ammonium chloride) (Doi and Reid, 1995); Isocil or Legend MK, where 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (CMI/MI) are the active ingredients (Ichimura et al, 2006;Knee, 2000); Dantogard…”

“…Further, Van Doorn et al (1990) compared HQC, benzalkonium chloride, DICA, NaOCl, Al 2 (SO 4 ) 3 , and AgNO 3 with regard to both the inhibition of bacterial multiplication in rose stems and their phytotoxic effects on the foliage. The authors concluded that none of the compounds tested with cut rose 'Sonia' had "a consistent and high antibacterial effect at concentrations which were not phytotoxic".…”