Patterns of yeast diversity distribution and its drivers in rhizosphere soil of Hami melon orchards in different regions of Xinjiang

Background The unique climatic conditions of the Xinjiang region nurture rich melon and fruit resources, the melon and fruit sugar sources provide sufficient nutrients for the survival of yeast, and the diverse habitats accompanied by extreme climatic conditions promote the production of yeast diversity and strain resources. However, the relationship between yeast species and their relationship with environmental factors in the soil of Xinjiang specialty cash crop Hami melon is not clear. Here, we aimed to characterize the diversity, community structure, and relationship between yeast species and environmental factors in Hami melon orchards soils in different regions of Xinjiang, China. Results Based on Illumina MiSeq high-throughput sequencing analysis of the D1 domain of the LSU rRNA genes, the community richness of yeast in the soil of Northern Xinjiang was higher than in the Southern and Eastern Xinjiang, but the community diversity was significantly lower in the Northern Xinjiang than in the Southern and Eastern Xinjiang. A total of 86 OTUs were classified into 59 genera and 86 species. Most OTUs (90.4%) belonged to the Basidiomycota; only a few (9.6%) belonged to Ascomycota. The most dominant species in the Southern, Eastern and Northern Xinjiang were Filobasidium magnum (17.90%), Solicoccozyma aeria (35.83%) and Filobasidium magnum (75.36%), respectively. Principal coordinates analysis (PCoA) showed that the yeast community composition in the soils of the three regions were obviously different, with the Southern and Eastern Xinjiang having more similar yeast community. Redundancy analysis (RDA) showed that soil factors such as conductivity (CO), total phosphorus (TP) and Total potassium (TK) and climate factors such as average annual precipitation (PRCP), relative humidity (RH) and net solar radiation intensity (SWGNT) were significantly correlated with yeast communities (P < 0.05). Conclusion There are abundant yeast resources in the rhizosphere soil of Hami melon orchard in Xinjiang, and there are obvious differences in the diversity and community structure of yeast in the three regions of Xinjiang. Differences in climatic factors related to precipitation, humidity and solar radiation intensity and soil factors related to conductivity, total phosphorus and total potassium are key factors driving yeast diversity and community structure.

Global Patterns in Culturable Soil Yeast Diversity

Yeasts, broadly defined as unicellular fungi, fulfill essential roles in soil ecosystems as decomposers and nutrition sources for fellow soil-dwellers. Broad-scale investigations of soil yeasts pose a methodological challenge as metagenomics are of limited use on this group of fungi. Here we characterize global soil yeast diversity using fungal DNA barcoding on 1473 yeasts cultured from 3826 soil samples obtained from nine countries in six continents. We identify mean annual precipitation and international air travel as two significant predictors of soil yeast community structure and composition worldwide. Anthropogenic influences on soil yeast communities, directly via travel and indirectly via altered rainfall patterns resulting from climate change, are concerning as we found common infectious yeasts frequently distributed in soil in several countries. Our discovery of 41 putative novel species highlights the need to revise the current estimate of ~1500 recognized yeast species. Our findings demonstrate the continued need for culture-based studies to advance our knowledge of environmental yeast diversity.

Metagenomic-based Approach for the Analysis of Yeast Diversity Associated with Amylase Production in Lai (Durio Kutejensis)

This study reported the application of a next generation sequencing (NGS) analysis of yeast diversity in native Indonesian fruit, Durio Kutejensis, collected from Borneo, Central Kalimantan. The analysis was designed to observe the microbial consortium associated with solid state fermentation (SSF) for amylase production. Together with the additional data from culture-dependent analysis, we observed the morphological features, molecular characteristics, and amylase concentration produced by each isolate. We performed Solid State Fermentation (SSF) for amylase production and the enzyme activity was then determined using UV-Vis spectrophotometer at 540 nm. Result obtained from metagenomic approach consist of 4 group that fungal species included in the Ascomycota identified as Botryosphaeria dothidea (1.35%), Lasiodiplodia crassispora (17.62%), Aureobasidium pullulans (55.02%), Paraphoma chrysanthemicola (11.38%), Preussia funiculate (1.90%), Sporormiella intermedia (0.82%), Myrothecium gramineum (1.35%), Fusarium oxysporum (6.24%), Fusarium proliferatum (3.25%) and Phialemoniopsis curvata (1.08%). The results of isolation using culturable medium in the form of YMA obtained 40 yeast isolates. A total of 40 representative isolates from durian fruit were screened, two positive amylase isolates based on clear zones formed were DU 4.2 (Candida sorboxylosa) and DU4.22 (Cyberlindnera fabianii) isolates with amylolytic index of DU 4.2 isolates at 0.24 and DU 4.22 at 0.72 with an incubation time of 48 h. The highest amylase enzyme activity was found in isolate DU 4.2 of 31.21 U / mL.

Patterns of Yeast Diversity Distribution and its Drivers in Rhizosphere Soil of Hami Melon Orchards in Different Regions of Xinjiang

Background: Yeast is an essential type of microscopic fungus found in the soil. It is vital to develop the resources of yeast to gain a better understanding of its role and potential in maintaining soil ecological balance and providing microbial resources. A special ecological environment is required for the evolution of yeast species. Xinjiang in China has unique climatic conditions with abundant melon and fruit resources. Here, we aimed to evaluate the diversity, community structure, and relationship between yeast species and environmental factors in Hami melon orchards in different regions of Xinjiang, China.Results: We used Illumina MiSeq high-throughput sequencing analysis to cluster 29,090 yeast sequences into 87 operational taxonomic units (OTUs) with 97% sequence similarity and 47 genera and 73 species. Most sequences (93.16%) belonged to the Basidiomycota; only a few (6.84%) belonged to Ascomycota. We detected 10 dominant genera and 11 dominant species with relative abundances > 1% in all sample sequences. We found that the yeast communities were significantly more diverse in the eastern Xinjiang region than in the southern and northern Xinjiang regions. The most dominant genera in the southern, eastern, and northern Xinjiang regions were Pseudozyma (54.77%), Solicoccozyma (28.6%), and Filobasidium (88.08%), respectively. Redundancy analysis (RDA) results indicated that the main factors influencing the structure of yeast in the study sites were CO, total phosphorus (TP), and total potassium (TK) of the soil.Conclusion: Our results suggest the presence of diversity and structural differences in yeast species among the southern, eastern, and northern Xinjiang regions. Eastern Xinjiang had the highest community diversity with a more even distribution of species. Differences in the geographical environment and the physicochemical properties of soils were probably the key factors driving yeast diversity and community structure.

Yeasts in different types of cheese

<abstract> <p>Yeasts constitute an important part of cheeses, and especially the artisanal ones. The current study reviews the occurrence of yeasts in different cheese varieties and the role of yeasts in cheesemaking process. The use of molecular methods for identification and strain typing has extended the knowledge for yeast diversity in cheeses. For the study of the occurrence of yeasts in different cheese types, seven categories are used, that is: 1) hard, 2) semi-hard, 3) soft, which includes soft pasta-filata and whey cheeses, 4) white brined cheeses, 5) mould surface ripened, 6) bacterial surface ripened cheeses, and 7) blue cheeses. For some cheese types, yeasts are the main microbial group, at least for some part of their ripening process, while for some other types, yeasts are absent. Differences between industrially manufactured cheeses and artisanal cheeses have specified. Artisanal cheeses possess a diverse assortment of yeast species, mainly belonging to the genera <italic>Candida</italic>, <italic>Clavisporalus</italic>, <italic>Cryptococcus</italic>, <italic>Debaryomyces</italic>, <italic>Geotrichum</italic>, <italic>Issatchenkia</italic>, <italic>Kazachstania</italic>, <italic>Kluyveromyces</italic>, <italic>Kodemaea</italic>, <italic>Pichia</italic>, <italic>Rhodotorula</italic>, <italic>Saccharomyces</italic>, <italic>Saturnispora</italic>, <italic>Torulaspora</italic>, <italic>Trichosporon</italic>, <italic>Yarrowia</italic> and <italic>ZygoSaccharomyces</italic>. The role of the yeasts for selected cheeses from the seven cheese categories is discussed.</p> </abstract>

Salt concentration effect on yeast diversity of the Ivorian traditional fermented fish adjuevan

This study aimed to investigate the yeast diversity in adjuevan fermented at the laboratory scale according to salt concentration following both traditional fermentation methods. Thus, the fish species Galeoides decadactylus was fermented with salt added at 10 %, 15 %, 20 %, 25 % and 30 % (w/w) for five days. Yeast identification using PCR-DDGE method reveled seven species which were Pichia fermentans, Candida zeylanoides, Candida sp, Hanseniaspora osmophila, Kluyveromyces sp; Torulaspora delbrueckii and Kluyveromyces marxianus. These species varied according to fermentation method used and salt concentration added with Pichia fermentans and Hanseniaspora osmophila as dominant strains. These results showed also that Kluyveromyces marxianus and Torulaspora delbrueckii were more tolerant to sodium chloride than the others. This work confirmed that yeasts were involved and participated in adjuevan production. Therefore, these yeasts should be tested for their functionality during the fermentation, and some might be useful as starter culture to produce better quality fermented fish adjuevan.