Testudinimyces gracilis gen. nov, sp. nov. and Astrotestudinimyces divisus gen. nov, sp. nov., two novel, deep-branching anaerobic gut fungal genera from tortoise faeces
Testudinimyces gracilis gen. nov, sp. nov. and Astrotestudinimyces divisus gen. nov, sp. nov., two novel, deep-branching anaerobic gut fungal genera from tortoise faeces
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细小睾丸菌属
DOI：
10.1099/ijsem.0.005921
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发表时间：
2023
影响因子：
2.8
通讯作者：
Elshahed, Mostafa S.
中科院分区：
文献类型：
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作者：
Pratt, Carrie J.;Chandler, Emily E.;Youssef, Noha H.;Elshahed, Mostafa S.
厌氧肠道真菌(AGF，Neocallimastigmycota)是真菌王国中的一个基本游动孢子门。目前已描述了20个属，所有这些属都是从哺乳动物食草动物的消化道中分离出来的。在这里，我们报告了从龟的粪便样本中分离和鉴定新的AGF分类群。从7个不同的龟种中分离到29个真菌菌株。利用LSU rRNA基因的D1/D2区、核糖体内转录间隔区1和RNA聚合酶II大亚基的系统发育分析，将所有分离物分成两个不同的深分支分支(分支T和B)，与它们最近的培养亲缘关系(Khoyollomyces Ramosus)有很高的序列差异。从分离株转录本预测的多肽计算的平均氨基酸同一性值在60.80-66.21 %(分支T)和61.24-64.83 %(分支B)之间，与所有其他AGF分类单元相比，该值显著低于最近推荐的新寄生孢子菌门的属(85%)和科(75%)的分界值。这两个分支的生长温度范围都较宽(20-45 °C，T分支最适30 °C，B分支30-42 °C，最适39 °C)。显微镜分析表明，两个分支的菌株都产生了丝状菌丝、多中心根状生长模式和单鞭毛游动孢子。T分支菌株的特征是产生不分枝的、主要是狭窄的菌丝和小的游动孢子，而B分支菌株的特征是产生多个孢子囊和孢子囊，这些孢子囊起源于单一的中心肿胀，导致大的多孢子囊结构。基于它们独特的系统发育位置、AAI值和表型特征，我们建议将它们归入两个新属(Testudinimyces和AstroteStudinimyce)和种(T.gracilisandA.Divisus)。模式种为T130AT(T.gracilis)和B1.1T(A.divisus)。
The anaerobic gut fungi (AGF,Neocallimastigomycota) represent a basal zoosporic phylum within the kingdomFungi. Twenty genera are currently described, all of which were isolated from the digestive tracts of mammalian herbivores. Here, we report on the isolation and characterization of novel AGF taxa from faecal samples of tortoises. Twenty-nine fungal isolates were obtained from seven different tortoise species. Phylogenetic analysis using the D1/D2 region of the LSU rRNA gene, ribosomal internal transcribed spacer 1, and RNA polymerase II large subunit grouped all isolates into two distinct, deep-branching clades (clades T and B), with a high level of sequence divergence to their closest cultured relative (Khoyollomyces ramosus). Average amino acid identity values calculated using predicted peptides from the isolates’ transcriptomes ranged between 60.80–66.21 % (clade T), and 61.24–64.83 % (clade B) when compared to all other AGF taxa; values that are significantly below recently recommended thresholds for genus (85%) and family (75%) delineation in theNeocallimastigomycota. Both clades displayed a broader temperature growth range (20–45 °C, optimal 30 °C for clade T, and 30–42 °C, optimal 39 °C for clade B) compared to all other AGF taxa. Microscopic analysis demonstrated that strains from both clades produced filamentous hyphae, polycentric rhizoidal growth patterns, and monoflagellated zoospores. Isolates in clade T were characterized by the production of unbranched, predominantly narrow hyphae, and small zoospores, while isolates in clade B were characterized by the production of multiple sporangiophores and sporangia originating from a single central swelling resulting in large multi-sporangiated structures. Based on the unique phylogenetic positions, AAI values, and phenotypic characteristics, we propose to accommodate these isolates into two novel genera (TestudinimycesandAstrotestudinimyces), and species (T. gracilisandA. divisus) within the orderNeocallimastigales. The type species are strains T130AT(T. gracilis) and B1.1T(A. divisus).