Acetic Acid Bacteria, Newly Emerging Symbionts of Insects

Abstract

8Recent research in microbe-insect symbiosis has shown that acetic acid bacteria (AAB) establish symbiotic relationships with several insects of the orders Diptera, Hymenoptera, Hemiptera, and Homoptera, all relying on sugar-based diets, such as nectars, fruit sugars, or phloem sap. To date, the fruit flies Drosophila melanogaster and Bactrocera oleae, mosquitoes of the genera Anopheles and Aedes, the honey bee Apis mellifera, the leafhopper Scaphoideus titanus, and the mealybug Saccharicoccus sacchari have been found to be associated with the bacterial genera Acetobacter, Gluconacetobacter, Gluconobacter, Asaia, and Saccharibacter and the novel genus Commensalibacter. AAB establish symbiotic associations with the insect midgut, a niche characterized by the availability of diet-derived carbohydrates and oxygen and by an acidic pH, selective factors that support AAB growth. AAB have been shown to actively colonize different insect tissues and organs, such as the epithelia of male and female reproductive organs, the Malpighian tubules, and the salivary glands. This complex topology of the symbiosis indicates that AAB possess the keys for passing through body barriers, allowing them to migrate to different organs of the host. Recently, AAB involvement in the regulation of innate immune system homeostasis of Drosophila has been shown, indicating a functional role in host survival. All of these lines of evidence indicate that AAB can play different roles in insect biology, not being restricted to the feeding habit of the host. The close association of AAB and their insect hosts has been confirmed by the demonstration of multiple modes of transmission between individuals and to their progeny that include vertical and horizontal transmission routes, comprising a venereal one. Taken together, the data indicate that AAB represent novel secondary symbionts of insects.

Isolation, Characterization and Identification of Probiotic Lactic Acid Bacteria (LAB) from Honey Bees

“…Acetobacteraceae includes acetic acid bacteria (AAB), a large group of obligate aerobic gram-negative bacteria, well adapted to sugary and alcoholised fluid such as vinegar, fruit juice, sap water, alcoholic beverages and flowers. AAB of the genera Gluconobacter, Acetobacter, Gluconacetobacter and Saccharibacter have been reported as symbionts of bees that may also regulate the innate immune system homeostasis in insects (Crotti et al, 2010). The sugar-loving and flower-associated Gluconobacters are among the predominant bacterial groups in bees (Hamdi et al, 2011).…”

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

“…Further, Gluconobacter is a member of the acetic acid bacteria, many of which frequently occur in nectar (e.g. Acinetobacter, Asaia) [17,18, electronic supplementary material, table S1] and cause similar chemical changes in solutions analogous to nectar [43,46]. In addition, microbial species richness is generally low within individual flowers, which often contain only one or a few species [23,26,47], perhaps due to strong competition and priority effects [22].…”

High genetic diversity and variability of bacterial communities associated with the sandhopper Talitrus saltator (Montagu) (Crustacea, Amphipoda)

“…Moreover, despite several studies concerning the microflora of particular organs (e.g. gut or reproductive organs) (Crotti et al, 2010;Hamdi et al, 2011), as well as the presence and effect of Wolbachia infections (Ben Nasr et al, 2010;Cordaux et al, 2012), no data were reported about the variation of microbial communities among single individuals, nor about possible population-specific microbial communities.…”