Two new species of the industrially relevant genus Absidia (Mucorales) from soil of the Brazilian Atlantic Forest

ABSTRACT

During a survey of Mucorales in soil from an upland forest area in Pernambuco, Brazil, two specimens were isolated and characterized based on their morphological, physiological, and molecular data (ITS and LSU rDNA). Phylogenetic analyses of the isolates revealed that the strains URM 8209 and URM 8210 are closely related to species of Absidia. URM 8209 forms conical, subglobose, and strawberry-shaped columellae and the sporangiospores are cylindrical and ellipsoid. URM 8210 produces hemispheric, subglobose, and strawberry-shaped columellae and the sporangiospores are globose, subglobose, ellipsoid, and short cylindrical. Based on evidence obtained through analysis of datasets (LSU and ITS rDNA regions), A. saloaensis sp. nov. (URM 8209) and A. multispora sp. nov. (URM 8210) are proposed here as novel species of Absidia. A table with morphological characteristics of Neotropical Absidia spp. is provided.

Keywords:
Cunninghamellaceae; Mucoromyceta; rDNA; soil; taxonomy

Introduction

The genus Absidia is composed of cosmopolitan fungal species commonly isolated from soil, herbivorous dung and decaying substrates (van Tieghem 1878). Species of this genus commonly produce sporangiophores in whorls, arising from stolons that bear apophysate and pyriform sporangia with a deliquescent wall. Rhizoids are never opposed to sporangiophores (Benny 2001), and columellae may be conical, subglobose, or aplanate, frequently showing an apical projection (van Tieghem 1878; Hoffmann et al. 2007). Absidia species reproduce asexually by the formation of sporangiospores and sexually through the formation of zygospores within zygosporangia supported by opposite suspensory cells that have appendages (Hoffmann et al. 2007; Hoffmann 2010).

Among mucoralean species of Absidia that have been studied for their industrial importance, A. coerulea specimens are capable of transforming saponins that show high yield and regioselectivity to 20 (S)-protopanaxatriol (Chen et al. 2007). Absidia glauca performs biotransformation of 3-Oxo-Oleanolic acid resulting in hydroxylated metabolites and both species mentioned above are excellent chitosan producers used in food processing, antimicrobial production and biotransformation of steroid products (Abdel-Fattah et al.1984; Smith et al. 1989; Muzzarelli et al.1994; Brzezowska et al. 1996; Huszcza & Gladysz 2003 Rungsardthong et al.2006;Dai et al.2009). Absidia griseola has biotransformation capacity, carrying out microbial hydroxylation of progesterone resulting in 14α-hydroxyprogesterone and 6β, 11α-dihydroxyprogesterone (Habibi et al. 2012). Absidia fusca and A. cylindrospora are used in bioremediation processes due to their ability to degrade polycyclic aromatic compounds, such as hydrocarbons (Guiraud et al.2008). Specimens of A. cylindrospora have also been used for biosorption of Cadmiun, Copper and Lead metals under experimental conditions (Albert et al. 2018).

Hesseltine & Ellis (1964; 1966) and Ellis & Hesseltine (1965) monographed the genus Absidia and grouped its species based on the shape of sporangiospores. Later, in a molecular-physiology and micromorphology study of Absidia, Hoffmann et al. (2007) showed that the species of this genus basically consisted of three groups separated according to the growth temperatures: (1) mesophilic species, with ideal growth between 25 and 34 °C (includes all currently accepted Absidia s.s species), (2) mycoparasite species of other mucoralean fungi, with optimal growth between 14 and 25 ºC (species after being transferred to Lentamyces), and (3) thermotolerant species, with optimal growth between 37 and 45 °C [species after being transferred to Lichtheimia by Hoffmann et al. (2009)]. In the last 10 years, six new Absidia species have been reported worldwide: A. caatinguensis, A. jindoensis, A. koreana, A. panacisoli, A. stercoraria, and A. terrestris (Ariyawansa et al. 2015; Li et al. 2016; Crows et al. 2018; Wanasinghe et al. 2018; Zhang et al. 2018).

During a survey on the diversity of mucoralean fungi in soils of upland forest fragments in the semiarid area of Brazil, two specimens of Absidia that varied morphologically and genetically in comparison with the other species of the same genus were isolated. Based on morphological, physiological, and molecular analyses (LSU and ITS rDNA regions), two new species of Absidia are being proposed here.

Materials and methods

Sampling sites

Soil samples were collected from the Brejo Nature Reserve (09º00.418´ S 036º46.898´ W) located in Saloá municipality, Pernambuco State, Brazil. The average annual temperature in this region is 20 ºC, with the rainy season beginning in January/February and ending in September/October and precipitation ranging between 0 to 50 mm in the driest months and 50 to 100 mm in the wettest months. The vegetation is a predominant trait of the species of the Atlantic ombrophilous and semi-deciduous forests, being found in the herbaceous areas composed of litter, shrubby vegetation, grasses, and shrubs. The soil has a podzolic characteristic, with areas ranging from being clayey to containing granite blocks (Silva-Júnior et al. 2012).

Isolation and purification of Absidia spp.

Five milligrams of soil were inoculated directly into Petri dishes containing wheat germ agar culture medium (Benny 2008) plus chloramphenicol (80 mg.L^-1), in triplicate. Growth was observed for seven days at room temperature (28 °C) under alternating light and dark conditions. Fragments of mycelium were removed directly from the Petri dishes under a Leica EZ4 stereomicroscope and transferred to malt extract agar plates (MEA) (Benny 2008). Slides corresponding to the holotypes of A. saloaensis sp. nov. (URM 94180) and A. multispora sp. nov. (URM 94181) where deposited in the Herbarium URM of the Universidade Federal de Pernambuco. Ex-type living cultures of A. saloaensis sp. nov. (URM 8209) and A. multispora sp. nov. (URM 8210) where deposited in the culture collection Micoteca URM of the Universidade Federal de Pernambuco. Pure cultures were also deposited in the culture collection (CNUFC) of the Environmental Microbiology Laboratory Fungarium, Chonnam National University, Gwangju, Korea (A. saloaensis sp. nov. CNUFC B190012 and A. multispora sp. nov. CNUFC B190013).

Growth experiments

Pure cultures were grown in triplicates in MEA and potato dextrose agar (PDA) and incubated at 15, 20, 25, 28, 30, and 35 °C for 15 days. For morphological identification, fragments were removed from the cultures and observed under a stereomicroscope (Carl Zeiss Axioscope 40) and light microscope (Leica DM500). The color designation of the colonies was performed according to previous literature (Maerz & Paul 1950).

Molecular analysis (DNA extraction, amplification, cloning and sequencing)

Genomic DNA was extracted from fresh fungal mycelia that were grown on cellophane at 25 °C for four days using the SolgTM Genomic DNA Preparation Kit (Solgent Co. Ltd., Daejeon, Korea) according to the manufacturer's instructions with a few modifications. The modifications included the DNA precipitated overnight at -20 ^oC using an equal volume of ice-cold 100 % isopropanol and the DNA pellet was washed twice using 500 μL of ice-cold 70 % ethanol. The rDNA ITS region was amplified using the ITS1 and ITS4 primers (White et al. 1990), and LROR and LR3 were used to amplify the large subunit (LSU) rDNA (Vilgalys & Hester 1990; Rehner & Samuels 1995). The PCR products were purified using an Accuprep PCR Purification Kit (Bioneer Corp.). PCR products of the LSU region were used for direct sequencing on the ABI PRISM 3730XL Genetic Analyzer (Applied Biosystems, California, USA) (Macrogen, Daejeon, Korea).

Since direct sequencing of the ITS region from PCR products was unsuccessful, PCR products were cloned using the pGEM-T Easy Vector System (Promega) cloning kit, following the manufacturer’s instructions. These clones were sequenced using primers M13F forward (5’- GTAAAACGACGGCCAGT-3’) and M13R-pUC reverse (5’-CAGGAAACAGCTATGAC-3’) by ABI PRISM 3730XL Genetic Analyzer.

Sequence alignment and phylogenetic analyses

Raw sequences were assembled and edited (edges trimmed) using BioEdit (Hall 1999). All sequence data used in this study were obtained from GenBank (https://www. ncbi.nlm.nih.gov). Sequences were aligned using MAFFT 7 (https://mafft.cbrc.jp/alignment/server) (Katoh et al. 2019) and then manually refined in MEGA7 (Kumar et al. 2016). Bayesian inference (two runs over 3 × 10⁶ generations with a burn-in of 2500) and maximum likelihood (with support estimated by bootstrap analysis with 1000 replicates) analyses were performed with Mrbayes 3.2.2 (Ronquist et al. 2012) and PhyML 3.0 (Guindon et al. 2010), respectively. The best-fit model of nucleotide substitution for each data set was obtained using jModelTest v.2.1.10 software (Guindon & Gascuel 2003; Darriba et al. 2012)

Sequence data were compared with those of similar sequences available in the National Center for Biotechnology Information GenBank database using BLASTn. The newly obtained sequences were deposited in the GenBank database: A. saloaensis sp. nov.: ITS (MN953781), LSU (MN953783), and A. multispora sp. nov: ITS (MN953780), LSU (MN953782) (Tab. 1).

Table 1
Accession numbers in collection cultures and voucher numbers of sequences used for the phylogenetic analysis

Species name	Collection No.	GenBank accession No.
		ITS	LSU
Absidia anomala Hesselt. & J.J. Ellis	1CBS 125.68T5FSU5798	JN205815 EF030523	JN206593 -
Absidia caatinguensis D.X. Lima & A.L. Santiago	6URM7156T	KT308168	KT308170
Absidia californica J.J. Ellis & Hesselt.	1CBS 314.78	JN205816	JN206582
Absidia coerulea Bainier	1CBS 102.28 1CBS 104.08	JN205821 JN205811	JN206584 HM849703
Absidia cuneospora G.F. Orr & Plunkett	1CBS 101.59T1CBS 102.59	- JN205819	JN206580 JN206579
Absidia cylindrospora var. cylindrospora Hagem	1CBS 100.08	JN205822	JN206588
Absidia cylindrospora var. nigra Hesselt. & J.J. Ellis	1CBS 127.68T	-	JN206589
Absidia cylindrospora var. rhizomorpha Hesselt. & J.J. Ellis	1CBS 153.63T	-	JN206594
Absidia fusca Linnem.	1CBS 102.35T1CBS 346.97	JN205814 JN205817	HM849707 -
Absidia glauca Hagem	1CBS 101.08 1CBS 100. 48	JN205810 JN205820	HM849705 JN206581
Absidia heterospora Y. Ling	1CBS101.29T	-	JN206595
Absidia jindoensis Hyang B. Lee & T.T.T. Nguyen	2CNUFC-PTI1-1T	MF926622	MF926616
Absidia koreana Hyang B. Lee, Hye W. Lee & T.T. Nguyen	3EML-IFS45-1T3EML-IFS45-2	KR030062 KR030063	KR030056 KR030057
Absidia macrospora Váňová	5FSU4746 1CBS 697.68T	AY944882 -	EU736303 HM849704
Absidia multispora sp. nov. T.R.L. Cordeiro, D.X. Lima, Hyang B. Lee & A.L. Santiago	6 URM 8210 T	MN953780	MN953782
Absidia pseudocylindrospora Hesselt. & J.J. Ellis	1CBS 100.62T	NR_145276	JN206591
Absidia psychrophilia Hesselt. & J.J. Ellis	1CBS 17268T	-	JN206587
Absidia repens Tiegh.	1CBS 115583	JN205813	HM849706
Absidia saloaensis sp. nov. T.R.L. Cordeiro, D.X. Lima, Hyang B. Lee & A.L. Santiago	6 URM 8209 T	MN953781	MN953783
Absidia spinosa var. spinosa Lendn.	1CBS 106.08	JN205809	JN206590
Absidia terrestris Rosas de Paz, Dania García, Guarro, Cano & Stchigel	4FMR 14989T	LT795003	LT95005
Chlamydoabsidia padenii Hesselt. & J.J. Ellis	1CBS 172.67T	-	JN206586
Cunninghamella phaeospora Boedijn	1CBS 692.68NT	JN205864	HM849697
Cunninghamella vesiculosa P.C. Misra	1CBS 989.96T	JN205897	HM849693
Halteromyces radiatus Shipton & Schipper	1CBS 162.75T	-	JN206596

• ¹
  CBS culture collection of the Westerdijk Fungal Biodiversity Institute, The Netherlands; ² CNUFC: Chonnam National University Fungal Collection,Gwangju, South Korea; ³ EML: Environmental Microbiology Laboratory (Fungarium, Chonnam National University), Gwangju, South Korea; ⁴ FMR: Universitat Rovira i Virgili (URV), Tarragona, Spain; ⁵ FSU: Friedrich Schiller University, Jena, Germany; ⁶ URM Micoteca and URM herbarium: Universidade Federal de Pernambuco, Recife, Brazil ; ^T and ^NT = ex-type and ex-neotype strains.

Results

Phylogenetic analyses

The phylogenetic relationship of two novel species and related species was determined by analysis of concatenated sequences datasets of two loci (ITS and LSU) (Fig.1). The concatenated alignment consisted of 1516 characters (including alignment gaps) with 816 and 700 characters used in the ITS and LSU, respectively. TIM2+I+G was found to be the most suitable model for the analysis of the concatenated ITS-LSU sequences. Absidia multispora URM 8210 was closely related to A. anomala CBS 125.68. The BLASTn search revealed that the ITS and LSU sequences of URM 8210 strain were 92.7 % and 97.7 % identical with A. anomala (GenBank accession numbers: EF030523 and JN982937), respectively. Absidia saloaensis URM 8209 was clustered together with A. koreana EML-IFS45-1 in the concatenated ITS-LSU tree. In addition, the BLASTn search showed that ITS and LSU sequences of URM 8209 were 83.14 % and 93.9 % homologous with A. koreana (GenBank accession numbers: KR030062 and KR030056), respectively.

Figure 1
Phylogenetic tree of Absidia multispora URM 8210 and Absidia saloaensis URM 8209 and related species based on maximum likelihood (ML) analysis of a combined DNA data set of ITS and LSU sequences. Bootstrap values for Bayesian posterior probabilities (BYPP) over 0.95 and maximum likelihood greater than 70 % are placed above the branches. Bootstrap values lower than 0.95 and 70 % are marked with “*”, and absent are marked with “-”. The bar indicates the number of substitutions per position. Cunninghamella phaeospora CBS 692.68 and Cunninghamella vesiculosa CBS 989.96 were used as outgroups. The new species are in blue and the type species are indicated with ^T (ex-type) or ^NT (neotype).

Taxonomy

Absidia multispora T.R.L. Cordeiro, D.X. Lima, Hyang B. Lee & A.L. Santiago sp. nov. (Fig. 2A-I).

Figure 2
Absidia multispora (URM 8210). A. Surface of colony on PDA at 28°C; B, C. Branched sporangiophore with fertile sporangia and an abortive sporangium; D. Branched sporangiophore with fertile sporangia; E. Unbranched sporangiophore with sporangium; F, G. Unbranched sporangiophore with a columella with one projection on its surface; H. Rhizoids; I. Sporangiospores. Bars: B, C, D, E, F, G, I = 10 µm; H = 20 µm.

Etymology: multispora. Reference to variable-shaped sporangiospores that are produced.

Diagnosis: Differs from other species of Absidia by the combination of the following characters: globose, subglobose, ellipsoid, cylindrical, short-cylindrical, and irregular sporangiospores. Sporangia subglobose and pyriform and columellae which are hemispheric, subglobose and strawberry-shaped, some of them with a projection on their surface.

Type: Brazil, Pernambuco: Saloá, Fazenda Brejo Nature Reserve (09º00.418´ S 036º46.898´ W) isolated from soil samples, 10 Nov 2018, T.R.L. Cordeiro (Holotype: URM 94181, Herbarium URM; Ex-type: URM 8210, Micoteca URM). Index Fungorum number: IF557224. GenBank accession numbers: MN953780 and MN953782 (ITS and LSU, respectively).

Description: Colony brownish gray turning dark gray (MP21 A1, gray-drab), zoned, colonizing the entire Petri dish (9 cm in diam) within five days at 28 °C; light gray reverse (MP20 A1, minera-grey). Odor absent. Rhizoids present, short or long, branched or unbranched. Stolons light gray, with slightly encrusted wall. Sporangiophores slightly brownish-gray, arising from stolons, usually unbranched, single or in whorls of 2 (4), occasionally with aging, up to 270 µm in length and 5 µm in width, some with one swelling, thick-walled; successive branches may originate from abortive sporangia; one septum was observed near the apophysis, two septa were rarely present. Sporangia brownish-gray, apophysate, subglobose, and pyriform, up to 30 µm in diam, multisporated, and smooth-walled. Columellae hyaline, hemispheric, subglobose, and strawberry-shaped, (7-) 10-16 × (-7) 10-15 (-20) µm, smooth-walled. Projection on columellae present or absent; when present, mostly conical, short or thin, elongated, needle-like, up to 5 × 2.5 µm. Collar usually evident. Sporangiospores brownish-gray, globose, subglobose (2.5-) 5-7.5 (-9), ellipsoid, short cylindrical, broadly-ellipsoidal, irregular, 5-9.5 (-12) × (3.5) 5-7.5 (-9) µm, smooth, and thick-walled. Chlamydospores absent. Zygospores not observed.

Absidia saloaensis T.R.L. Cordeiro, D.X. Lima, Hyang B. Lee & A.L. Santiago sp. nov. (Fig. 3A-I).

Figure 3
Absidia saloaensis (URM 8209). A. Surface of colony on PDA at 28°C; B. Two sporangiophores in a whorl with sporangia and rhizoids; C, D, E, F, G. Unbranched sporangiophore with a columella with one projection on its surface; H. Rhizoids; I. Sporangiospores. Bars: B = 50 µm; C, D, E, F, G, I = 10 µm; H = 100 µm.

Etymology: saloaensis. Reference to the city (Saloá) from where the species was first isolated.

Diagnosis: Differs from other species of Absidia by the combination of the following characters: strawberry-shaped columellae, and cylindrical and elliptical sporangiospores.

Type: Brazil, Pernambuco: Saloá, Fazenda Brejo Nature Reserve, 09º00.418´ S 036º46.898´ W, isolated from soil samples, 10 Nov 2018, T.R.L. Cordeiro (Holotype: URM 94180, Herbarium URM; Ex-type: URM 8209, Micoteca URM). Index Fungorum number: IF557227. GenBank accession: MN953781 and MN953783 (ITS and LSU, respectively).

Description: Colony grayish-brown (MP22 C1, dusty-gr.) colonizing the entire Petri dish (9 cm in diam) within five days at 28 °C; reverse grayish-white zoned (MP21 B2, olive-gray). Odor absent. Rhizoids present, weakly branched. Stolons hyaline, smooth-walled. Sporangiophores hyaline, long and short, growing along the stolons and terminally, up to 280 µm in length and 6 µm in width, erect, slightly encrusted walled, with one septum near the apophysis, and occasionally with one swelling; solitary or more often in whorls of 5 (6); sporangia hyaline, pyriform (15-) 20-35 µm in diam, multisporate, deliquescent, smooth-walled, apophysate. When the sporangium wall liquefies, some sporangiospores may remain attached to the columellae. Columellae hyaline, conical to subglobose and strawberry-shaped, (4.5-) 7-22 × (5-) 8.5-20 (-25) µm, smooth-walled; collar visible. Projection on the columella generally elliptical, conical, or needle-shaped, up to 5 × 3.5 µm, occasionally short, almost inconspicuous. Sporangiospores hyaline, mostly cylindrical and elliptical, (3.5-) 5-7 (9.5) × 2.5-3.5 (-5) µm, some slightly constricted in the center, smooth-walled. Chlamydospores absent. Zygospores not observed.

Discussion

Morphologically, A. saloaensis sp. nov. and A. multispora sp. nov. present characteristics of the Absidia sensu stricto group, such as apophysate sporangiophores arising from stolons, rhizoids never opposed to sporangiophores, and pyriform sporangia (Benny 2001). For the Neotropical region, only nine species had been reported (Tab. 2).

Table 2
Morphological characteristics of Absidia species from Neotropics plus A. koreana.

Species	Colony color	Whorls	Sporangiophores	Sporangia	Columellae	Projection	Sporangiospores
A. anomala 3	Gray to light violet.	Up to 2.	40-105 × 3-9 µm.	Pyriform, 12-26 µm in diam.	Hemispherical, 6.5-20 µm in diam.	Up to 2 µm in length.	Cylindrical to somewhat constricted in the center to short oval, 3-4 × 2.2 µm.
A. californica 4	Light gray to grayish olive.	Not formed.	150-250 × 7-11 µm.	Globose to oval, 10-30 µm in diam.	Hemispherical, some hemielliptical, 14.5-26.5 µm in diam.	Up to 4.5 × 5.5 µm.	Globose, 3.5-4 µm in diam.
A. cuneospora 1	Light gray to pearl gray.	Up to 3.	30-150 × 2-4 µm.	Globose, 13-32 μm in diam.	Hemispherical to nearly globose, 9-19.5 μm in diam.	Swollen at apex, 6-7 × 2.5-3 μm.	Lacrimoid to wedge-shaped, 4.5-6.5 µm in length.
A. cylindrospora 3	Pale olive-buff.	Up to 4.	36-300 × 2-7 µm.	Pyriform, 10-35 μm diam.	Hemispherical, 8.5-26 µm diam.	Rounded and often bulbous, up to 4.5 µm in length.	Cylindrical to slightly broader at one end, 3.3-5.5 × 2.2-3.5 µm.
A. caatinguensis 6	Brownish gray.	Up to 6 (7).	40-150 × 2.5-5 µm.	Pyriform 17.5-27.5 μm diam.	Mostly hemispherical, some subglobose, 10-20 μm diam.	Bulbous at distal end up to 5.75 × 2.5 μm.	Cylindrical, slightly constricted at the central portion, 5-7.5 × 2.5-3.7 μm.
A. koreana 6	Grayish with or smoky gray.	Up to 6.	3.84-4.6 μm in width, variable in length.	Globose to slightly elliptical, 19.33-23.64 × 21.06-26.3 μm.	Globose, 10.9-16.96 × 11.46-18.89 μm.	Not informed.	Short-cylindrical or cylindrical, 3.54-4.48 × 2.15-2.35 μm.
A. multispora sp. nov.8	Brownish gray, turning dark gray.	Up to 2 (4).	Up to 270 × 5 µm.	Pyriform and subglobose, up to 30 µm in diam.	Hemispherical, subglobose, or strawberry-shaped, 10-16 × 10-15 µm in diam.	Mostly conical, or elongated, needle-like, up to 5 × 2.5 µm.	Globose, subglobose 5-7.5 diam, ellipsoid, short cylindrical, broadly-ellipsoidal, irregular, 5-9.5 × 5-7.5 µm.
A. pseudocylindrospora 2,3	Pale to dark olive-gray	Up to 5-7 (11).	45-172 × 3-6 µm.	Pyriform, 15-35 µm in diam.	Globose to nearly hemispherical, 9-26 µm in diam.	Globose to hemispherical, up to 6 µm in length.	Cylindrical or nearly so, up to 3.5-5 × 2.4 µm.
A. repens 5	Light grayish olive to olive gray.	Not formed.	140-250 × 2.5-6 µm; short sporangiophores 12-78 × 2.2-4.5 µm.	Oval to elliptical, 15-36 × 7-15 µm, turning globose, 19-26.5 µm in diam.	Hemispherical, 5-25 µm in diam.	With a bulbous swelling at end, up to 9 µm in length.	Short oval to irregular oval, 2.8-5.5 × 2-3 µm, few globose up to 6.5 µm in diam,
A. saloaensis sp. nov.8	Grayish brown.	Up to 5 (6).	Up to 280 × 6 µm.	Pyriform, 20-35 µm in diam.	Conical to subglobose and strawberry-shaped, 7-22 × 8.5-20 µm.	Elliptical, conical, or needle-shaped, up to 5 × 3.5 µm.	Cylindrical and elliptical, 5-7 × 2.5-3.5 µm, some slightly constricted in the center.
A. spinosa 3	Smoke gray to drab.	Up to 1-4 (8).	100-250 × 5-10.5 µm.	Pyriform, up to 12-30 µm in diam.	Hemispherical, 8-21 µm in diam.	Cylindrical to rounded, up to 1.5-4.5 × 0.5-1 µm.	Short cylindrical with rounded ends, up to 5 × 5.5 µm.
A. terrestris 7	Grayish brown.	Not formed.	25-215 × 2.5-5 µm.	Pyriform, 17.5-27.5 × 17.5-22.5 µm.	Globose, 5-7.5 µm diam.	Up to 5-7.5 µm.	Cylindrical, 4-5 × 2-4 µm.

• ¹
  Orr & Plunkett (1959); ²Hesseltine & Ellis (1961); ³Hesseltine & Ellis (1964); ⁴Ellis & Hesseltine (1965); ⁵Hesseltine & Ellis (1966); ⁶et al.); ⁷et al.); ⁸ This article.

Absidia multispora sp. nov. is phylogenetically closely related to A. anomala (Fig. 1). However, morphologically, the former differs from A. anomala in the size and shape of sporangiospores and columellae. Absidia anomala produces cylindrical sporangiospores with 3-4 × 2.2 µm, differing from A. multispora sp. nov. that produces sporangiospores globose, subglobose (2.5-) 5-7.5 (-9) µm, ellipsoidal, short cylindrical, broadly-ellipsoidal, and irregular with 5-9.5 (-12) × (3.5) 5-7.5 (-9) µm. Additionally, the columellae of A. multispora are hemispherical, subglobose, and strawberry-shaped, unlike the ones of A. anomala that are hemispherical only (Hesseltine & Ellis 1964).

Absidia saloaensis sp. nov. is phylogenetically related to A. koreana (Fig. 1), but morphologically both species are different. A. saloaensis produces bigger columellae and sporangiospores than those observed in A. koreana. Furthermore, A. saloaensis produces strawberry-shaped columellae, while A. koreana has globose columellae. The sporangiospores of A. koreana are cylindrical with 2.07-4.28 × 1.73-1.98 µm (Ariyawansa et al. 2015), unlike A. saloaensis sp. nov. sporangiospores that are cylindrical and elliptical with (3.5-) 5-7 (9.5) × 2.5-3.5 (-5) µm.

In conclusion, our molecular analyses (ITS and LSU rDNA) show that A. multispora sp. nov. and A. saloaensis sp. nov. are genetically different from other Absidia species. Additionally, both novel isolates exhibit a combination of morphological traits that are not yet described for other Absidia species. In addition to their bioremediation capacity, Absidia species present great potential as chitosan producers and biotransformers of saponins, organic acids, and steroids. Therefore, future experiments to elucidate whether A. saloaensis and A. multispora exhibit industrial potential should be highly encouraged.

Acknowledgements

The authors express their gratitude to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the scholarships provided to authors and for the research grant awarded to A.L. Santiago. This manuscript was financed by the project ‘Diversity of Mucoromycotina in the different ecosystems of the Atlantic Rainforest of Pernambuco’ (FACEPE- APQ - 0842-2.12/14) and was supported in part by the Graduate Program for the Undiscovered Taxa of Korea funded by NIBR of the Ministry of Environment (MOE) of Korea.

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Publication Dates

• Publication in this collection
  02 Oct 2020
• Date of issue
  Jul-Sep 2020

History

• Received
  11 Feb 2020
• Accepted
  12 June 2020