Microbiology of pollen and bee bread : taxonomy and enzymology of molds

Abstract

One-hundred and forty-eight molds were isolated from the following samples of almond, Prunus dulcis, pollen : floral pollen collected by hand; corbicular pollen from pollen traps placed on colonies of honey bees, Apis mellifera, in the almond orchard; and bee bread stored in comb cells for one, three, and six weeks. The majority of molds identified were Penicillia (32%), Mucorales (21%), and Aspergilli (17%). In general, the number of isolates decreased in pollen as it was collected and stored by the bees. Each type of pollen sample appeared to differ in regard to mold flora and dominant species. Aureobasidium pullulans, Penicillium corylophilum, Penicillium crustosum, and Rhizopus nigricans were among the molds that may have been introduced by bees during collection and storage of pollen. Mucor sp., the dominant mold in floral pollen, was not found in corbicular pollen and bee bread. Tests for 19 enzymes revealed that most of the molds produced caprylate esterase-lipase, leucine aminopeptidase, acid phosphatase, phosphoamidase, B-glucosidase, and Macetyl-B-glucosaminidase. Thus, enzymes involved in lipid, protein and carbohydrate metabolism were produced by pollen molds. Molds could also contribute organic acids, antibiotics and other metabolites.