A set of four strains representing a novel basidiomycetous yeast species
Rhodotorula sampaioana
f. a., sp. nov. were isolated from two different habitats, subsurface waters of Lake Negra in ...Argentina, and the gut of a xylophagous termite in India. Phylogenetic analyses of LSU and ITS sequences showed that they belonged to the genus
Rhodotorula
of the order Sporidiobolales (subphylum Pucciniomycotina) and the closest known relative being
R. kratochvilovae
. The new species differed from
R. kratochvilovae
CBS 7436 (AF071436, AF444520) by nine nucleotide substitutions and one deletion (1.7 % sequence variation) in a 593 bp D1/D2 region, and by five nucleotide substitutions and three deletions (1.3 %) in a 592 bp ITS region, respectively. Several morphological and physiological differences were also observed between
R. kratochvilovae
and the strains obtained during this study. These data support the proposal of
Rhodotorula sampaioana
as a novel species, with CRUB 1124 as the holotype, CBS 10798 as ex-type, and NFCCI 4872 as an additional strain. The GenBank accession numbers of the LSU and ITS sequences of
Rhodotorula sampaioana
f. a., sp. nov. are EF595748 and MW879331. The MycoBank number is MB 838533.
Three strains, SMT1.3, SMT1.10, and SMT2.2, representing a novel asexual ascomycetous yeast species, were isolated from the gut of a termite
Odontotermes horni
in Maharashtra, India. Phylogenetic ...analyses of the LSU, ITS, and SSU sequences revealed that they belonged to the genus
Nakazawaea
, with
N. siamensis
as the closest relative. The new species differed from the type strain of
N. siamensis
(DMKU-RK467
T
) by 11 substitutions in the D1/D2 region of the large subunit (LSU) rRNA gene and by 8 substitutions and one gap in the small subunit (SSU) rRNA gene. Notable biochemical and physiological differences were also observed between
N. siamensis
and the new species. Hence, the species
Nakazawaea odontotermitis
f.a., sp. nov. is proposed. The type strain is SMT1.3
T
(MTCC 13,105 = NFCCI 5011 = PYCC 9153). GenBank accession numbers of the LSU, ITS and SSU sequences of
Nakazawaea odontotermitis
f.a., sp. nov. are MZ234240, MZ234239, and OK384663. The MycoBank number is MB 841926.
Many plant pathogenic filamentous fungi undergo fusion of conidia through conidial anastomosis tubes (CATs), which is believed to facilitate horizontal gene transfer between species. We discovered a ...remarkable inter-specific CAT fusion between two important plant fungal pathogens Colletotrichum gloeosporioides and C. siamense. In an invitro assay, under no selection pressure, the inter-specific CAT fusion was preferred with higher frequency (25% ± 5%) than intra-specific CAT fusion (11% ± 3.6%). Different stages of CAT fusion viz. CAT induction, homing, and fusion were observed during this inter-specific CAT fusion. The CAT fusion was found to be higher in absence of nutrients and under physiological stresses. This CAT fusion involved a quorum sensing phenomenon, wherein the CAT induction was dependent on conidial density and the putative quorum sensing molecule was extractable in chloroform. Movement of nuclei, mitochondria, and lipid droplets were observed during the CAT fusion. Post CAT fusion, the resulting conidia gave rise to putative heterokaryotic progenies with variable colony characteristics as compared to their parental strains. Few heterokaryons showed variable AFLP banding pattern compared to their parental strains, thereby suggesting a possible genetic exchange between the two species through CAT fusion. The heterokaryotic progenies exhibited varied fitness under different stress conditions. Our study illustrated a possible role of inter-specific CAT fusion in generation of genetic and phenotypic diversity in these fungal pathogens.
Bollo
is a traditional Goan fermented food in which coarse wheat/wheat and finger millet is leavened with
toddy
. We here isolated 42 yeast strains from
Bollo
batter. Initial screening of the ...isolates with probiotic properties yielded four yeast isolates (DABRP1, DABRP2, DABRP5 and DABRP12). These isolates exhibited tolerance to high bile salt concentration and acidic pH and resistance to various antibiotics, which indicated their probiotic nature. All these yeast isolates were identified as
Saccharomyces cerevisiae
through D1D2-LSU-rDNA sequencing. These yeast isolates also showed higher percent hydrophobicity towards chloroform followed by n-hexadecane and o-xylene indicating their mucosal surface-adhesive property. To evaluate the safety of the isolates for them to be called as generally recognized as safe, the pathogenic behavior of the isolates determined through the in vitro hemolysis assay and evaluation of DNase and gelatinase activities. None of the isolates exhibited hemolysis or produced DNase or gelatinase and thus were considered potentially safe. In terms of beneficial effects, the most potent isolate
S. cerevisiae
DABRP5 showed antibacterial activity against the test pathogens. It also showed excellent antioxidant activity with DPPH free radical scavenging activity of 68.85 ± 0.69%, anti-inflammatory activity with 60.39 ± 0.34% inhibition of protein denaturation, and antidiabetic activity with 71.75 ± 0.45% inhibition of α-amylase activity. The isolate produced α-amylase, lipase, and β-galactosidase. The probiotic potential of the isolate
S. cerevisiae
DABRP5 was similar to that of the reference strain (
Saccharomyces boulardii
CNCM I-745) used in this study. The results thus indicate that yeast isolates from
Bollo
batter have probiotic potential.
Floral nectar is colonised by microbes, especially yeasts which alter the scent, temperature, and chemical composition of nectar, thereby playing an essential role in pollination. The yeast ...communities inhabiting the nectar of tropical flowers of India are not well explored. We isolated 48 yeast strains from seven different tropical flowering plants. Post MSP-PCR-based screening, 23 yeast isolates and two yeast-like fungi were identified, which belonged to 16 species of 12 genera viz.
Candida
(2 species),
Aureobasidium
(2 species),
Metschnikowia
(2 species),
Meyerozyma
(1 species),
Saitozyma
(1 species),
Wickerhamomyces
(1 species),
Kodamaea
(2 species),
Pseudozyma
(1 species),
Starmerella
(1 species),
Hanseniaspora
(1 species),
Rhodosporidiobolus
(1 species),
Moesziomyces
(1 species), and two putative novel species. All yeast strains were assessed for their osmotolerance abilities in high salt and sugar concentration. Among all the isolates,
C. nivariensis
(SRA2.2, SRA1.1 and SRA2.1),
M. caribbica
(SRA4.8 and SRA4.6),
S. flava
SRA4.2, and
M. reukaufii
SRA3.2 showed significant growth in high concentrations of sugar (40–50% glucose), as well as salt (12–15% NaCl). All 25 strains were also screened for their ability to utilise xylose to produce xylitol.
Meyerozyma caribbica
was the most efficient xylitol producer, wherein three strains of this species (SRA4.6, SRA4.1, and SRA4.8) generated 18.61 to 21.56 g l
−1
of xylitol, with 0.465–0.539 g g
−1
yields. Through this study, we draw attention towards the tropical floral nectar as a potential niche for the isolation of diverse, osmotolerant, and xylitol-producing yeasts. Such osmotolerant yeasts have potential applications in food industries and biofuel production.
Itajahya rosea was found growing in association with Leucaena leucocephala plants at Savitribai Phule Pune University campus in India. The species identity was confirmed by phylogenetic analysis ...based on ITS and LSU regions of rDNA, wherein, our fugus was placed along with I. rosea in phylogenetic tree. It represents first record of I. rosea from India. Frequent visitation by Drosophila species on I. rosea fruiting body particularly on gleba was observed. The Drosophila got attracted to the detached gleba under the laboratory conditions and even sometimes, they prefer to sit over the gleba as compare to their food banana. It suggested that I. rosea gleba or pseudostipe produces some compounds for attraction and feeding behavior of Drosophila species. Therefore, we characterized the volatile attractants produced by gleba and pseudostipe of I. rosea by GC-MS analysis. Nineteen compounds were identified from gleba while nine compounds were recovered from the pseudostipe. Out of them, blends of three abundant odor producing volatile compounds were reported namely, Hexadecane, Pentadecane and Nonadecane, which are responsible for attraction of Drosophila toward the gleba. Three fatty acids namely 9,12-octadecadienoic acid (Z,Z), hexadecanoic acid and benzoic acid ethyl ester produced are served as an appetitive signal through olfactory response of Drosophila, so the flies were feed on the gleba. Two pheromones' compounds, heneicosane and (+)-(5S,9S)-5,9-dimethylpentadecane, were also reported in pseudostipe and gleba, respectively, which play a role in Drosophila for breeding. Our study highlights an intriguing chemical ecology of fungus-Drosophila interaction.
The conidia of a hemibiotrophic fungus, Colletotrichum gloeosporioides, can conventionally form a germ tube (GT) and develop into a fungal colony. Under certain conditions, they tend to get connected ...through a conidial anastomosis tube (CAT) to share the nutrients. CAT fusion is believed to be responsible for the generation of genetic variations in few asexual fungi, which appears problematic for effective fungal disease management. The physiological and molecular requirements underlying the GT formation versus CAT fusion remained underexplored. In the present study, we have deciphered the physiological prerequisites for GT formation versus CAT fusion in C. gloeosporioides. GT formation occurred at a high frequency in the presence of nutrients, while CAT fusion was found to be higher in the absence of nutrients. Younger conidia were found to form GT efficiently, while older conidia preferentially formed CAT. Whole transcriptome analysis of GT and CAT revealed highly differential gene expression profiles, wherein 11,050 and 9786 genes were differentially expressed during GT formation and CAT fusion, respectively. A total of 1567 effector candidates were identified; out of them, 102 and 100 were uniquely expressed during GT formation and CAT fusion, respectively. Genes coding for cell wall degrading enzymes, germination, hyphal growth, host-fungus interaction, and virulence were highly upregulated during GT formation. Meanwhile, genes involved in stress response, cell wall remodeling, membrane transport, cytoskeleton, cell cycle, and cell rescue were highly upregulated during CAT fusion. To conclude, the GT formation and CAT fusion were found to be mutually exclusive processes, requiring differential physiological conditions and sets of DEGs in C. gloeosporioides. This study will help in understanding the basic CAT biology in emerging fungal model species of the genus Colletotrichum.
Itajahya rosea was found growing in association with Leucaena leucocephala plants at Savitribai Phule Pune University campus in India. The species identity was confirmed by phylogenetic analysis ...based on ITS and LSU regions of rDNA, wherein, our fugus was placed along with I. rosea in phylogenetic tree. It represents first record of I. rosea from India. Frequent visitation by Drosophila species on I. rosea fruiting body particularly on gleba was observed. The Drosophila got attracted to the detached gleba under the laboratory conditions and even sometimes, they prefer to sit over the gleba as compare to their food banana. It suggested that I. rosea gleba or pseudostipe produces some compounds for attraction and feeding behavior of Drosophila species. Therefore, we characterized the volatile attractants produced by gleba and pseudostipe of I. rosea by GC-MS analysis. Nineteen compounds were identified from gleba while nine compounds were recovered from the pseudostipe. Out of them, blends of three abundant odor producing volatile compounds were reported namely, Hexadecane, Pentadecane and Nonadecane, which are responsible for attraction of Drosophila toward the gleba. Three fatty acids namely 9,12-octadecadienoic acid (Z,Z), hexadecanoic acid and benzoic acid ethyl ester produced are served as an appetitive signal through olfactory response of Drosophila, so the flies were feed on the gleba. Two pheromones’ compounds, heneicosane and (þ)-(5S,9S)-5,9-dimethylpentadecane, were also reported in pseudostipe and gleba, respectively, which play a role in Drosophila for breeding. Our study highlights an intriguing chemical ecology of fungus-Drosophila interaction.
Xylophagous termites are capable of degrading lignocellulose by symbiotic gut microorganisms along with the host's indigenous enzymes. Therefore, the termite gut might be a potential niche to obtain ...natural yeasts with celluloytic, xylanolytic and ethanologenic traits required for bioethanol production from lignocellulosic biomass. In this study, we cultured 79 yeasts from three different termites viz. Coptotermes heimi, Odontotermes javanicus and Odontotermes obesus. After suitable screening methods, we identified 53 yeasts, which belonged to 10 genera and 16 different species of both ascomycetous and basidiomycetous yeasts. Most yeasts in the present study represent their first-ever isolation from the termite gut. Representative strains of identified yeasts were evaluated for their cellulolytic, xylanolytic, and ethanologenic abilities. None of the isolates showed cellulase activity; 22 showed xylanolytic activity, while six produced substantial quantities of ethanol. Among xylanolytic cultures, Pseudozyma hubeiensis STAG 1.7 and Hannaella pagnoccae STAG 1.14 produced 1.31 and 1.17 IU of xylanase. Among ethanologenic yeasts, the strains belonging to genera Candida and Kodamaea produced high amount of ethanol. Overall, highest ethanol level of 4.42 g/L was produced by Candida tropicalis TS32 using 1% glucose, which increased up to 22.92 g/L at 35 °C, pH 4.5 with 5% glucose. Fermentation of rice straw hydrolysate gave 8.95 g/l of ethanol with a yield of 0.42 g/g using the strain TS32. Our study highlights the gut of wood-feeding termites as a potential source of diverse yeasts that would be useful in the production of xylanase and bioethanol.
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