Diversity of bacteria in slovak and foreign honey, with assessment of its physico-chemical quality and counts of cultivable microorganisms

from apiaries and commercial trade in Slovakia and foreign countries (Latvia, Switzerland, India, Japan and Tanzania) as well as to
indicate their physico-chemical and basic microbiological quality. Study of each sample consisted of physico-chemical analysis (water
content, pH, free acidity and electrical conductivity), basic microbiological analysis performed by dilution plating method (total plate
count, sporulating aerobic microorganisms, bacteria from Enterobacteriaceae family, preliminary lactic acid bacteria and microscopic
fungi) and metagenomic analysis for bacterial diversity evaluation. Seven samples did not meet with legislative limits of physico-chemical
parameters. Average values of cultivable microbial groups ranged at level 1-2 log CFU.g-1
, while bacteria from Enterobacteriaceae family
were not detected in any samples. Sporulating microorganisms occurred most often, in 77% of samples and yeasts were proven in 60% of
samples. Bacterial diversity, determined by metagenomic analysis, was varied. We distinguished 2 groups – group A and group B. Group
A contained mainly fresh (produced in 2018) Slovak and Swiss honey and we found mainly genus Lactobacillus followed by genus
Bombella in them. Group B contained mainly older Slovak honey (produced in 2017) and commercial foreign samples, in which
production year is difficult to know. Group B samples were interesting because of human bacteria presence with genus Prevotella
dominance. Redundancy analysis showed significant connection of the electric conductivity and microbial assemblage, that indicates
important influence of botanical origin to microbial representation in honey.