A Preliminary Investigation of Marine Yeast Biodiversity in New Zealand Waters

<p>This is the first known investigation of marine yeast biodiversity from waters surrounding New Zealand’s main Islands. Marine yeasts were cultured onto agar plates from algae sampled at three locations in the Wellington Region. DNA extractions and PCR amplifications of the internal transcribed spacer (ITS) regions were conducted, and resultant sequence data were used for isolate identification and phylogenetic analysis. Yeasts isolated during this investigation were not unique; seventy-four isolates were identified from a range of genera that are frequently detected in marine and terrestrial environments worldwide. Furthermore, high ITS sequence similarity was observed between yeasts isolated during this investigation and those from geographically distant locations. These findings may indicate that marine yeasts are ubiquitous at a global level, although evidence is insufficient as to whether yeasts also demonstrate biogeographic distribution patterns. Yeasts isolated during this investigation may have ecological implications in New Zealand’s marine environment; marine yeasts are likely to play a general saprophytic role and certain genera are pathogenic. Isolates were also identified from genera that have previously demonstrated beneficial properties and applications, including the production of useful compounds and highly nutritious yeast biomass, biocontrol potential against the postharvest decay of produce, and degradation abilities that may enable bioremediation of polluted marine environments.</p>

A Preliminary Investigation of Marine Yeast Biodiversity in New Zealand Waters

<p>This is the first known investigation of marine yeast biodiversity from waters surrounding New Zealand’s main Islands. Marine yeasts were cultured onto agar plates from algae sampled at three locations in the Wellington Region. DNA extractions and PCR amplifications of the internal transcribed spacer (ITS) regions were conducted, and resultant sequence data were used for isolate identification and phylogenetic analysis. Yeasts isolated during this investigation were not unique; seventy-four isolates were identified from a range of genera that are frequently detected in marine and terrestrial environments worldwide. Furthermore, high ITS sequence similarity was observed between yeasts isolated during this investigation and those from geographically distant locations. These findings may indicate that marine yeasts are ubiquitous at a global level, although evidence is insufficient as to whether yeasts also demonstrate biogeographic distribution patterns. Yeasts isolated during this investigation may have ecological implications in New Zealand’s marine environment; marine yeasts are likely to play a general saprophytic role and certain genera are pathogenic. Isolates were also identified from genera that have previously demonstrated beneficial properties and applications, including the production of useful compounds and highly nutritious yeast biomass, biocontrol potential against the postharvest decay of produce, and degradation abilities that may enable bioremediation of polluted marine environments.</p>

Introducing a Marine Biorefinery System for the Integrated Production of Biofuels, High-Value-Chemicals, and Co-Products: A Path Forward to a Sustainable Future

Biofuels have many environmental and practical benefits as a transportation fuel. They are among the best alternatives to fossil fuels- thanks to their capacity for negative carbon emissions, which is vital for archiving the global ambition of a net-zero economy. However, conventional biofuel production takes place on inland sites and relies on freshwater and edible crops (or land suitable for edible crop production), which has led to the food versus fuel debate. It also suffers technical and economical barriers owing to the energy balance and the cost of production compared with fossil fuels. Establishing a coastal integrated marine biorefinery (CIMB) system for the simultaneous production of biofuels, high-value chemicals, and other co-products could be the ultimate solution. The proposed system is based on coastal sites and relies entirely on marine resources including seawater, marine biomass (seaweed), and marine microorganisms (marine yeasts and marine microalgae). The system does not require the use of arable land and freshwater in any part of the production chain and should be linked to offshore renewable energy sources to increase its economic feasibility and environmental value. This article aims to introduce the CIMB system as a potential vehicle for addressing the global warming issue and speeding the global effort on climate change mitigation as well as supporting the world’s water, food and energy security. I hope these perspectives serve to draw attention into research funding for this approach.

Introducing a Marine Biorefinery System for the Integrated Production of Biofuels, High-Value-Chemicals and Co-products: A Path Forward to a Sustainable Future

Biofuels have many environmental and practical benefits as a transportation fuel. They are among the best alternatives to fossil fuels due to their capacity for negative carbon emissions, which is vital for archiving the global ambition of a Net-Zero Economy. However, conventional biofuel production takes place on inland sites and relies on freshwater and edible crops (or land suitable for edible crop production), which has led to the food vs fuel debate. It also suffers technical and economical barriers due to the energy balance and the cost of production compared to fossil fuels. Establishing a coastal integrated marine biorefinery (CIMB) system for the simultaneous production of biofuels, high-value chemicals, and other co-products could be the ultimate solution. The proposed system is based on coastal sites and relies on marine resources including seawater, marine biomass (seaweed) and marine microorganisms (marine yeasts and marine microalgae). The system will not require the use of arable land and freshwater in any part of the production chain and will be linked to offshore renewable energy sources to increase its economic and environmental value. This article aims to introduce the CIMB system as a potential vehicle for addressing global warming and speeding the global effort on climate change mitigation as well as increasing global water, food and energy security. I hope this perspective may serve to draw attention into research funding for this approach.

Adapting an Ergosterol Extraction Method with Marine Yeasts for the Quantification of Oceanic Fungal Biomass

Ergosterol has traditionally been used as a proxy to estimate fungal biomass as it is almost exclusively found in fungal lipid membranes. Ergosterol determination has been mostly used for fungal samples from terrestrial, freshwater, salt marsh- and mangrove-dominated environments or to describe fungal degradation of plant matter. In the open ocean, however, the expected concentrations of ergosterol are orders of magnitude lower than in terrestrial or macrophyte-dominated coastal systems. Consequently, the fungal biomass in the open ocean remains largely unknown. Recent evidence based on microscopy and -omics techniques suggests, however, that fungi contribute substantially to the microbial biomass in the oceanic water column, highlighting the need to accurately determine fungal biomass in the open ocean. We performed ergosterol extractions of an oceanic fungal isolate (Rhodotorula sphaerocarpa) with biomass concentrations varying over nine orders of magnitude. While after the initial chloroform-methanol extraction ~87% of the ergosterol was recovered, a second extraction recovered an additional ~10%. Testing this extraction method on samples collected from the open Atlantic Ocean, we successfully determined ergosterol concentrations as low as 0.12 pM. Thus, this highly sensitive method is well suited for measuring fungal biomass from open ocean waters, including deep-sea environments.

Effects of Rhodotorula mucilaginosa on the Immune Function and Gut Microbiota of Mice

As a dominant species among marine yeasts, Rhodotorula benthica accounts for ~50% of all marine yeasts. Rhodotorula is rich in a variety of bioactive substances and commonly used in the production of carotenoids by microbial fermentation and is worth developing. Therefore, the present study used a strain of Rhodotorula mucilaginosa isolated from the coastal waters of the South China Sea as the target yeast to investigate its impact on the immune function and gut microbiota of mice. A total of 200 mice were randomly divided into gavage groups and control group and garaged for 30 consecutive days at different concentration. Samples were collected on day 15 and day 30 of gavage administration. The results showed that R. mucilaginosa ZTHY2 could increase the thymus and spleen indices of mice, and its effect on the thymus index was more significant after long-term gavage administration. Short-term (15 days) gavage administration of R. mucilaginosa suspension enhanced delayed hypersensitivity in mice, increased serum IgG, IgA, and IL-2. Long-term (30 days) gavage administration of R. mucilaginosa suspension significantly enhanced the phagocytosis of macrophages in mice and significantly increased serum TNF-α and INF-γ. R. mucilaginosa ZTHY2 altered the structure of the gut microbiota of mice at the phylum and genus levels, leading to an increased relative abundance of Firmicutes and Lactobacillus and a decreased relative abundance of Bacteroidetes. This strain increased the beneficial intestinal bacteria and reduced the harmful intestinal bacteria in mice. This study provides experimental evidence and lays the foundation for the future development and application of this strain as a microecological source of carotenoids.

Protector effect of beta-glucans from shrimp pond-related yeasts in Penaeus vannamei rearing under white spot syndrome virus presence

This research study tested the protective effect of prolonged exposure of shrimp food supplemented with glucans from shrimp-pond related yeasts on shrimp Penaeus vannamei reared under the presence of the white spot syndrome virus (WSSV). The glucans extracted and purified from isolated marine yeasts identified as Debaryomyces hansenii, Candida tropicalis, Candida humilis, Candida glabrata, Pichia kudriavzevyi, Wickerhamomyces anomalus and the terrestrial Saccharomyces cerevisiae yeast were characterized by the Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The treatments were prepared with food enriched with the yeast beta-glucans and the control groups without beta-glucans. Shrimp were fed thrice a day and challenged orally with WSSV on days 31, 54, 66 and muscularly at day 70. The animals were assessed for the protective effect in terms of post-infection total hemocyte counts, and survival rate. The results indicated that marine yeasts possessed ß-1,3/1,6-glucans, and that D. hansenii was an excellent source yielding 30% of its dry biomass of pure glucans. For the positive control group where no glucans were added, WSSV challenges showed 100% survival when the virus was provided orally, and 40% when the virus was injected. These results also indicated that the shrimp line selected for this study was a resistant line for WSSV. Shrimp groups fed with glucans of the marine yeasts D. hansenii and C. humillis showed a significant protection, allowing shrimp survival of 66% while terrestrial yeast showed 57.14%. These results indicated that marine yeasts growing in the shrimp pond were an excellent source of beta-glucans that allowed extra protection against the mortality caused by this pathogenic virus.

Yeast the Present and Future Cell Facture

Yeasts are eukaryotic microorganisms that are existing in a wide range of habitats, thanks to their ability to adapt even in extreme locations and conditions. Moreover, the unicellular nature of yeasts makes them better suited for deep liquid substrates or moist and uneven surfaces. Till now, about 1500 species of yeasts are described, and the genus Saccharomyces is the well-studied genus of all the yeasts in terms of physiology and genetics. In this review, we elucidate the role of yeasts as biotechnological tool and their current and potential applications. We also highlighted the features, and industrial application of some marine yeasts. Furthermore, describing rarely basidiomycetous yeast involved in different applications. Contributions of yeasts and their enzymes in food, industrial, and pharmaceuticals fields were also discussed. Finally, employment of yeasts in biotransformation process was show.

Halotolerant Yeasts: Biodiversity and Potential Application

Halotolerant yeasts represent a heterogeneous group of unicellular fungi able to survive and thrive under hypersaline conditions. This review examines the biodiversity of halotolerant yeasts in various habitats with high salt content and the potential practical applications of this group of microorganisms in industry and agriculture. Halotolerant yeasts are found in various habitats with elevated salt content, including seawater, hypersaline ponds and salterns, saline soils and wastewaters, salt-containing foods. Habitats with moderate salinity, e.g. seawater, food products, olive fermentation wastewaters can boast a comparatively large biodiversity of yeasts both ascomycetes and basidiomycetes. Hypersaline niches are mostly inhabited by pigmented and melanized yeasts and yeast-like fungi. The adaptability and robustness of halotolerant yeasts could be exploited in several biotechnological fields, mainly the food industry and bioremediation. Yeasts isolated from food products with elevated salt content are studied as potential starter cultures in the corresponding fermenting products due to their enzymatic and antimicrobial activity and probiotic characteristics. Marine yeasts are of an increasing interest due to their production of various hydrolytic enzymes, biofuel production using seawater, bioremediation of saline wastewaters and the probiotic potential in aquaculture. Halotolerant yeasts found in various saline wastewaters could be used in bioremediation of wastewaters with high salinity containing various organic pollutants. However more research is required to achieve practical utilization of this group of microorganisms.