Analyse pollinique, propriétés physico-chimiques et action antibactérienne des miels d'abeilles africanisées Apis mellifera et de Méliponinés du Brésil

Abstract - Pollen analysis, physico-chemical properties and antibacterial action of Brazilian honeys from Africanized honeybees (Apis mellifera L) and stingless bees
Two groups of Brazilian honeys were analyzed : - from Africanized honeybees (20 samples; = G₁); - from stingless bees (14 samples; = G₂). In the palynological studies, the pollen grains were identified by comparing them with a reference catalogue at the University of São Paulo bee laboratory of the USP. The acetolysis method was used to facilitate observations. In G₁ the most active honeys against bacteria were those where Mimosa and Eucalyptus pollen was predominant. In G₂, a honey produced by Plebeia sp with Borreria/Mimosa pollen and another by Melipona subnitida with Mimosa bimucronata pollen, were found to be most active against bacteria. There was less moisture and free acidity in the Apis honeys whereas the pH was lower in the honeys from stingless bees. Moisture was the characteristic which best differentiated the two groups (table IV). In colour, both ranged between amber and light-amber. All honeys were assayed against 7 strains of bacteria (tables V et VI). The honey was mixed in a concentration of 5-25% with agar and put on a plate; drops of bacterium culture were then spread inside this solid culture. After 24 h at 37°C a 1-5 grading was given to the honey tested, depending on the bacterial growth. Honeys from stingless bees had a stronger inhibition capacity than Apis honeys but this varied according to the species of stingless bee. The honeys from Apis showed inhibition with an average concentration of 15%, whereas in honeys from stingless bees the average inhibitory concentration was 11%. The minimum concentrations were 12.5% and 5.5% respectively. For both groups the least resistant bacterium was Bacillus stearothermophilus (Bst) and the most resistant Escherichia coli (Ec) (fig 2). Both groups of honeys were mainly bacteriostatic, ie in spite of sometimes damaging the bacteria they inhibited but did not kill them (Gram test). Honeys from the tribe Trigonini were found to be better antibacterial agents than those from Meliponini.