Prevalence and Intra-Family Phylogenetic Divergence of <i>Burkholderiaceae</i>-Related Endobacteria Associated with Species of <i>Mortierella</i>

Abstract

Endofungal bacteria are widespread within the phylum Mucoromycota, and these include Burkholderiaceae-related endobacteria (BRE). However, the prevalence of BRE in Mortierellomycotinan fungi and their phylogenetic divergence remain unclear. Therefore, we examined the prevalence of BRE in diverse species of Mortierella. We surveyed 238 isolates of Mortierella spp. mainly obtained in Japan that were phylogenetically classified into 59 species. BRE were found in 53 isolates consisting of 22 species of Mortierella. Among them, 20 species of Mortierella were newly reported as the fungal hosts of BRE. BRE in a Glomeribacter-Mycoavidus clade in the family Burkholderiaceae were separated phylogenetically into three groups. These groups consisted of a group containing Mycoavidus cysteinexigens, which is known to be associated with M. elongata, and two other newly distinguishable groups. Our results demonstrated that BRE were harbored by many species of Mortierella and those that associated with isolates of Mortierella spp. were more phylogenetically divergent than previously reported.

Aposymbiosis of a <i>Burkholderiaceae</i>-Related Endobacterium Impacts on Sexual Reproduction of Its Fungal Host

“…Template DNA was extracted from the six-to twelveday-old mycelia of each clonal line incubated on a sterilized cellophane sheet placed on 1/2 CMMY agar (8.5 g corn meal agar [Difco], 10 g malt extract [Difco], 1 g yeast extract [Difco], and 7.5 g Bacto agar [Difco] in 1 L distilled water) using Prepman TM Ultra sample reagent (Applied Biosystems) in accordance with Sato et al (2010). Diagnostic PCR was performed using the bacterial universal primers 10F and 1541R in accordance with Takashima et al (2018b). After PCR, amplification of the 16S rRNA gene was checked by agarose gel electrophoresis.…”

“…Young germlings of the sporangiospores of each clonal line immobilized by 2% low melting point agar were transferred to a 1.5-mL tube. FISH was performed using agar pieces containing sporangiospores in accordance with Takashima et al (2018b).…”

“…Among them, one isolate, M. sugadairana YTM39, did not form zygospores under zygospore-inducing conditions, whereas the other two did. The isolate, M. sugadairana YTM39, was different from the other two isolates because it harbored a BRE, which was phylogenetically clustered within MorBRE group C assigned by Takashima et al (2018b). Based on the differences observed in zygospore formation by the isolate, M. sugadairana YTM39 and the two other isolates as well as the presence of the bacterium, we hypothesized that the bacterium affects zygospore formation by this isolate.…”

“…Recent studies using molecular techniques revealed that bacterial endosymbionts inhabit early diverging fungal lineages, such as Mucoromycota (Spatafora et al, 2016;Bonfante and Desirò, 2017). These bacterial endosymbionts were known as endofungal or endohyphal bacteria and mostly related to the family Burkholderiaceae, and, thus, were termed Burkholderia-related endobacteria (Bonfante and Desirò, 2017) or Burkholderiaceae-related endobacteria (BRE) (Takashima et al, 2018b). BRE were generally found in hyphae and asexual spores (Lumini et al, 2007;Sato et al, 2010;Ohshima et al, 2016;Mondo et al, 2017;Takashima et al, 2018a) as well as in sexual spores (Mondo et al, 2017).…”

Cultivation Renaissance in the Post-Metagenomics Era: Combining the New and Old

“…Fungi-bacteria interactions ( e.g ., Rhizobium sp.-endophytic fungi, soil indigenous bacteria-pathogenic Fusarium sp., and Burkholderiaceae- related endobacteria and plant and soil fungi Mortierella spp.) related to plant growth and health were also investigated (8, 26, 44). Mourad et al .…”