The Antibacterial Activity of Chitosan Products Blended with Monoterpenes and Their Biofilms against Plant Pathogenic Bacteria

Abstract

This study focuses on the biological activities of eleven chitosan products with a viscosity-average molecular weight ranging from 22 to 846 kDa in combination with the most active monoterpenes (geraniol and thymol), out of 10 tested, against four plant pathogenic bacteria, Agrobacterium tumefaciens, Erwinia carotovora, Corynebacterium fascians, and Pseudomonas solanacearum. The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC) that was found to be dependent on the type of the microorganism tested. The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5%) and the films were also evaluated against the tested bacteria. The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.

Effective Postharvest Preservation of Kiwifruit and Romaine Lettuce with a Chitosan Hydrochloride Coating

“…On B. cinerea, chitosan has also shown to inhibit the spore germination and this is an additional positive function that this organic material can express with respect to this dangerous pathogen [42]. Chitosan applications, in combination with essential oils, were also recently tested with respect to different bacterial plant pathogens and so our study assumes a particular relevance to improve sustainable strategies able to reduce the negative impact of different plant pathogens during postharvest phases [43]. The obtained results contribute to the idea and need of novel greener strategies and approaches for food quality and safety preservation.…”

“…Chitosan hydrochloride was dissolved at 1% (w/v) concentration in sterile distilled water under magnetic stirring for 2 h at RT. Then, 100 mL of the solution was added to 1 L of nutrient agar (NA) medium immediately before it was poured into the Petri dishes at a temperature of [40][41][42][43][44][45] • C, to obtain a final concentration of 1 g/L in the medium. Parallel controls were maintained with corresponding amounts of sterile distilled water mixed with NA medium.…”

Assessment of biological activities of chitosan Schiff base tagged with medicinal plants

“…The chitosan solution was prepared by dissolving chitosan in 1% aqueous acetic acid solution . The mixture of chitosan and water was stirred at room temperature for 30 minutes to get a clear chitosan solution.…”

In Vitro Antimicrobial and Antioxidant Activities of Monoterpenes against some Food-Borne Pathogens

“…The contents of each well were mixed on a microplate shaker at 200 rpm for 1 min prior to incubation for 24 h at 37°C. To indicate respiratory activity the presence of color was determined after adding 25 L/well of triphenyltetrazolium chloride (TTC, Sigma) dissolved in water (0.25%, w/v) as a chromogenic marker and incubated under appropriate cultivation conditions for 30 min in the dark (Badawy et al 2016). The absorbance was measured at 492 nm in an Ultra Microplate Reader (Robonik, PVT, LTD).…”

“…The free radical scavenging activity as antioxidant of the monoterpenes was evaluated using the stable radical N,N-dimethyl-1,4-phenylenediamine (DMPD) with concentrated 100 mM DMPD solution (Asghar et al 2007;Badawy et al 2016;Fogliano et al 1999). Standard solution of ascorbic acid (50-1000 mM) was prepared in deionized water.…”