Assessing the bacterial community associated with Rafflesia Kerri Meijer related to pollinator activity

Rafflesia kerri Meijer is a parasitic flowering plant from the family of Rafflesiaceae and is found in the tropical rainforest of the main range of northern part of Peninsular Malaysia up to southern part of Thailand. The species emits foul smell, believed to be mimicking rotten carcass decomposed by bacteria, thus attracting the carrion flies from the family of Calliphoridae to visit the flower and indirectly pollinate them. In order to bridge the research gaps in Rafflesia’s pollination biology, metagenomic approach was used to assess the composition of bacteria in order to understand their functional diversity as inhabitant on Rafflesia. Taxonomical classification revealed that an abundance of bacteria inhabit Rafflesia. The result shows 99.94 % and 99.69 % of bacteria were identified from pool female (PF) and pool male (PM) samples respectively. In phylum classification, a total of 19 and 26 phyla were identified from the PF and PM samples, respectively. Of the identified phyla, the top five most abundant bacteria for both samples were from Proteobacteria (PF – 99.33 %; PM – 86.32 %), followed by Firmicutes (PF - 0.26 %; PM – 6.66 %), Bacteroidetes (PF – 0.02 %; PM – 6.46 %), Actinobacteria (PF and PM – 0.3 %), and Cyanobacteria (PF – 0.02 %; PM – 0.05%). The majority of the identified bacteria were the common bacteria found associated with blow flies and human gut. The Clusters of Orthologous Groups (COG) analysis indicated that the protein with metabolism functions constituted the higher percentage (PF – 52.08 % and PM – 48.28 %) of the whole metagenome followed by cellular processes and signalling (PF – 17.15 % and PM – 19.06 %). The metabolism process contributing to chemical constituents of volatile compounds acts as chemical cues to attract the pollinator. The in-depth SEED subsystem classification reveals about 10.51 % (PF) and 10.02 % (PM) sequences of the whole metagenome were related to genes coding for amino acid and derivatives. The sub-classification shows the enzymes were involved in the degradation of amino acids and derivatives synthesized volatile organic compounds; sulphur-containing compounds (methanethiol, DMS, DMDS, DMTS), indole, skatole, putrescine, isobutyl amines and phenyl acetic acid. These compounds are the common attractant in attracting the Calliphoridae to the source. Therefore, the study reveals that the bacteria community associated with Rafflesia play a role as contributors in scent emission enticing pollinator to visit and pollinate the flower.