Honeybee glucose oxidase—its expression in honeybee workers and comparative analyses of its content and H2O2-mediated antibacterial activity in natural honeys

Abstract

Antibacterial properties of honey largely depend on the accumulation of hydrogen peroxide (H2O2), which is generated by glucose oxidase (GOX)-mediated conversion of glucose in diluted honey. However, honeys exhibit considerable variation in their antibacterial activity. Therefore, the aim of the study was to identify the mechanism behind the variation in this activity and in the H2O2 content in honeys associated with the role of GOX in this process. Immunoblots and in situ hybridization analyses demonstrated that gox is solely expressed in the hypopharyngeal glands of worker bees performing various tasks and not in other glands or tissues. Real-time PCR with reference genes selected for worker heads shows that the gox expression progressively increases with ageing of the youngest bees and nurses and reached the highest values in processor bees. Immunoblot analysis of honey samples revealed that GOX is a regular honey component but its content significantly varied among honeys. Neither botanical source nor geographical origin of honeys affected the level of GOX suggesting that some other factors such as honeybee nutrition and/or genetic/epigenetic factors may take part in the observed variation. A strong correlation was found between the content of GOX and the level of generated H2O2 in honeys except honeydew honeys. Total antibacterial activity of most honey samples against Pseudomonas aeruginosa isolate significantly correlated with the H2O2 content. These results demonstrate that the level of GOX can significantly affect the total antibacterial activity of honey. They also support an idea that breeding of novel honeybee lines expressing higher amounts of GOX could help to increase the antibacterial efficacy of the hypopharyngeal gland secretion that could have positive influence on a resistance of colonies against bacterial pathogens.

Glucose oxidase activity and hydrogen peroxide accumulation in Croatian honeys

“…According to our knowledge, there are no available literature reports that correlate evolved H 2 O 2 concentration with the glucose oxidase activity in honey. The only correlation reported is those by Bucekova et al (2014), who found that the amount of H 2 O 2 produced in honey solution could be correlated with the GOX levels. However, in this research authors examined the GOX levels in honey by immunobloting technique using a polyclonal antibody against the GOX, while hydrogen peroxide content in honeys diluted to 40 % of volume to volume ratio was determined after four hours of incubation at 37 °C.…”

Honey-sensitive Pseudomonas aeruginosa mutants are impaired in catalase A

“…Hydrogen peroxide is mainly produced during glucose oxidation catalysed by the bee enzyme glucose oxidase (GOX), which is introduced during nectar harvesting by bees (White et al, 1963). GOX is a regular honey component but its content varies significantly amongst different honeys (Bucekova et al, 2014). Furthermore, there is a positive correlation between the level of GOX in honey and the level of hydrogen peroxide in diluted honey.…”

Quantification of bee-derived peptide defensin-1 in honey by competitive enzyme-linked immunosorbent assay, a new approach in honey quality control

“…We showed previously that the levels of another bee-derived protein, GOX, varied significantly among samples (Bucekova et al 2014). The variation in …”

“…The antibacterial efficacy of various honey samples was evaluated by the minimum inhibitory concentration (MIC) assay according to Bucekova et al (2014). Determination of MIC was conducted according to the recommendations of the Clinical and Laboratory Standards Institute (2003).…”