Please join us on for our next meeting to be held on Sunday 17 November 2024 from 1—2 pm AEST (Qld time) or 3pm AEDT (NSW, Vic time).

This will be an in person meeting only. Unfortunately we're unable to Zoom this presentation.

Microorganisms of Australian stingless bees 

By Dr Flavia Massaro

Summary

Australian stingless bees store their honey and pollen in pots made of propolis, a resin-beeswax mixture used as a construction material in the nest. Tetragonula bees collect many plant resins including from fruit capsules of Corymbia torelliana “cadaghi” trees, then stock such resins inside their nests to make propolis when needed. Stingless bees raise their brood in pots where the larvae are mass-provisioned, potentially involving microorganisms. The nest materials can contain chemicals with antimicrobial properties, and also volatiles that may originate from microbial fermentation, so some nest microorganisms may be beneficial to the colony. Gut microbiota and nest microorganisms with novel species have been recently discovered.

My talk will describe the yeasts, fungi and bacteria found in healthy Australian Meliponini nests. Three stingless bee species were kept in hives and allowed to visit the same flora near Brisbane. Genetic molecular techniques and advanced chemical analyses identified the nest microbial species and also their chemical abilities to inhibit yeast and fungal growth.

We found that the yeast Starmerella meliponinorum was highly associated with Tetragonula nests but not with nests of Austroplebeia australis. This yeast thrives in high osmotic concentrations, such as in high sugar substrates including fructose. S. meliponinorum grows at pH 4.0, can produce ethanol up to 2.3% and several volatiles, but it is sensitive to a potentially toxic compound named 2-PE. The full genome of the isolated CBS 9117 strain is under investigation to understand its biochemical potential.

Australian stingless bee nests harbour diverse bacterial communities. In Tetragonula nests, fermentative lactobacilli colonized the whole brood cells made of propolis and larval food. However, S. meliponinorum yeasts was found only in the propolis walls, not in the provisions. Further studies will unravel the interplay of the symbiotic Starmerella and lactobacilli in Tetragonula brood development.

Biography

Flavia graduated from the University of the Sunshine coast by investigating the chemical composition and bioactivities of propolis and honey from Tetragonula carbonaria bees, propolis from Apis mellifera hives in South-East Australia. Flavia showed that the resins collected by Tetragonula bees, including from fruit capsules of Corymbia torelliana “cadaghi” trees showed antimicrobial activity against human pathogenic bacteria. As a Postdoc, Flavia joined the Invertebrate Microbiology Group led by A/Prof Caroline Hauxwell at Queensland University of Technology where this work about stingless bee nest microorganisms was generously supported by the Faculty of Science.

To attend in person, come to the Bulimba Community Centre, 1 Barramul St, Bulimba, Brisbane. Free for members, $5 for non-members.