Phenolic Compounds Contained in Little-known Wild Fruits as Antiadhesive Agents Against the Beverage-Spoiling Bacteria Asaia spp

Abstract

The aim of the study was to evaluate antioxidant activity and total phenolic content of juice from three different types of fruits: elderberry (Sambucusnigra), lingonberry (Vacciniumvitis-idaea) and cornelian cherry (Cornusmas), and their action against adhesion of bacterial strains of Asaialannensis and Asaiabogorensis isolated from spoiled soft drinks. The antioxidant profiles were determined by total antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl, DPPH), and ferric-reducing antioxidant power (FRAP). Additionally, total polyphenol content (TPC) was investigated. Chemical compositions of juices were tested using the chromatographic techniques: high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Adhesion properties of Asaia spp. cells to various abiotic materials were evaluated by luminometry, plate count and fluorescence microscopy. Antioxidant activity of fruit juices expressed as inhibitory concentration (IC₅₀) ranged from 0.042 ± 0.001 (cornelian cherry) to 0.021 ± 0.001 g/mL (elderberry). TPC ranged from 8.02 ± 0.027 (elderberry) to 2.33 ± 0.013 mg/mL (cornelian cherry). Cyanidin-3-sambubioside-5-glucoside, cyanidin-3-glucoside, and cyanidin-3-sambubioside were detected as the major anthocyanins and caffeic, cinnamic, gallic, protocatechuic, and p-coumaric acids as the major phenolic acids. A significant linear correlation was noted between TPC and antioxidant capacity. In the presence of fruit juices a significant decrease of bacterial adhesion from 74% (elderberry) to 67% (lingonberry) was observed. The high phenolic content indicated that these compounds may contribute to the reduction of Asaia spp. adhesion.

Keywords: Asaia spp.; anti-adhesion; berry juices; fruit juices; polyphenols.

Figure 1

Principal component analysis (PCA) of chemical components identified using HPLC and LC-MS methods. The compounds characteristic for elderberry are marked in purple, lingonberry in red, and cornelian cherry in green. Blue markers correspond to compounds that are common to tested juices.

Figure 2

Adhesion of Asaia strains (Asaia lannensis and Asaia bogorensis) to glass, polystyrene and polyethylene terephthalate (PET) in minimal medium with addition of 10% elderberry, lingonberry and cornelian cherry. Results are expressed as relative adhesion coefficient A(%). Values are means of three determinations ± standard deviation. Values with the different letters are statistically different (p < 0.05). a—p ≥ 0.05; b—0.005 < p < 0.05; c—p < 0.005; The results were compared to those received for a control medium.

Figure 3

Adhesion of Asaia strains to glass, polystyrene and PET in minimal medium with addition of 10% elderberry, lingonberry and cornelian cherry. Results are expressed in relative light units (RLU)/cm². Values are means of three determinations ± standard deviation. Values with the different letters are statistically different (p < 0.05). a—p ≥ 0.05; b—0.005 < p < 0.05; c—p < 0.005; The results were compared to those received for a control medium.

Figure 4

Microscopic observation of the biofilms formed in: (A) control (minimal medium); (B) medium with cornelian cherry juice; (C) medium with lingonberry juice; (D) medium with elderberry juice.