Marine Yeast Research Articles

Checklist of Marine Fungi and Yeasts Associated with Holothuria (Mertensiothuria) leucospilota from Pangkor Island

Marine microorganisms such as fungi and yeasts can adapt to extreme marine environment conditions and play different roles especially in the nutrient cycling and as bioindicator of ocean change. This study was carried out to isolate and identify fungi and yeasts associated with Holothuria (Mertensiothuria) leucospilota from Pangkor Island, Perak, Malaysia in order to determine their species richness. Two specimens of H. leucospilota were collected from Giam Island and Teluk Nipah Beach of Pangkor Island. Nine samples of fungi and ten samples of yeasts were isolated from the internal and external parts of the H. leucospilota specimens such as cuticle, tentacle, coelomic fluid, cloaca, cuvierian tubules, and surrounding sediment and seawater. Polymerase Chain Reaction (PCR) and DNA sequencing of the Internal Transcribed Spacer (ITS) region were applied for species identification of the microorganisms. Sequence analyses of the ITS region resulted in the identification of five genera of fungi i.e. Cladosporium, Curvularia, Polyporaceae, Acremonium, and Penicillium; and four genera of yeasts i.e. Sterigmatomyces, Pichia, Debaryomyces, and Candida with some of them could be identified up to the species level. The findings have significantly contributed to the recentinformation on the checklist of fungi and yeasts isolated from the H. leucospilota specimens from Pangkor Island.

The utilization of seawater for the hydrolysis of macroalgae and subsequent bioethanol fermentation

A novel seawater-based pretreatment process was developed to improve the hydrolysis yield of brown (Laminaria digitata), green (Ulva linza) and red (Porphyra umbilicalis) macroalgae. Pre-treated with 5% sulphuric acid at 121 °C, 15 minutes, L. digitata, U. linza and P. umbilicalis liberated 64.63 ± 0.30%, 69.19 ± 0.11% and 63.03 ± 0.04% sugar in seawater compared with 52.82 ± 0.16%, 45.93 ± 0.37% and 48.60 ± 0.07% in reverse-osmosis water, respectively. Low hydrolysis yields (2.6–11.7%) were observed in alkali and hydrothermal pretreatment of macroalgae, although seawater led to relatively higher yields. SEM images of hydrolyzed macroalgae showed that reverse-osmosis water caused contortions in the remaining cell walls following acid and hydrothermal pre-treatments in the L. digitata and U. linza samples. Fed-batch fermentations using concentrated green seaweed hydrolysates and seawater with marine yeast Wickerhamomyces anomalus M15 produced 48.24 ± 0.01 g/L ethanol with an overall yield of 0.329 g/g available sugars. Overall, using seawater in hydrolysis of seaweed increased sugar hydrolysis yield and subsequent bioethanol production.

Improving the productivity of bioethanol production using marine yeast and seawater-based media

Water consumption has become a serious concern in renewable fuel production as demand for biofuels increases to address environmental issues associated with the use of fossil fuels. In recent years, several research groups have suggested seawater (SW) as a promising alternative to fresh water (FW) for the production of biofuels. However, the use of seawater rather than fresh water in the fermentation process is still a relatively unexplored area of research. In this paper, the tolerance of the marine yeast S. cerevisiae AZ65 to the presence of salts in seawater was investigated. The results indicated that S. cerevisiae AZ65 grew well in media containing up to 10.5% (w/v) sea salts and 20% (w/v) glucose compared with an industrial distiller's strain, S. cerevisiae NCYC2592. A multi-stage batch fermentation process was also investigated to increase ethanol productivity. Two different seawater based media were used: SW-YPD medium and SW-molasses medium. S. cerevisiae AZ65 achieved an ethanol concentration of 113.52 gL-1 with a productivity of 4.15 g L−1h−1 using SW-YPD medium and an ethanol concentration of 50.32 gL-1 with a productivity of 2.46 g L−1h−1 using SW-molasses medium. These results confirmed the potential of seawater and marine yeasts for implementation in the bioethanol industry using a multi-stage fermentation process.

Waste-grown heterotrophic microorganisms improve the production of Apocyclops dengizicus

Copepods are one of the essential live feeds in aquaculture and are commonly raised on algal diets. However, sustainable copepod productions in captivity are still unachievable due to lack of cost-effective feed and reliable culture protocols. Hence, this study investigated the effects of palm oil mill effluent (POME) grown marine microheterotrophs (bacteria, yeasts and protists) on the survival, population growth and F2 nauplii production of brackish water copepod, Apocyclops dengizicus, at laboratory scale. For each feeding experiment, an initial stocking density of fifty copepod nauplii (stage I) with triplicates of each treatment was cultured for the duration of twelve days. Copepods fed with POME-grown marine yeast, Meyerozyma guilliermondii (POME-MG), had significantly (p < .05) higher survival, population growth and F2 nauplii production as compared to copepods fed on other POME-grown microheterotrophs tested i.e. POME-grown: Shewanella algae (POME-SA), Rhodovulum sulfidophilum (POME-RS), Rhodotorula mucilaginosa (POME-RM), Aurantiochytrium limacinum (POME-AL), a mixed diet of POME-MG and POME-AL and an instant microalgae diet of Nannochloropsis oculata (N). In contrast, the survival, population growth and F2 nauplii production of copepods fed on either POME-MG or POME were not significantly different (p > .05). POME-MG and POME had comparable amounts of protein of 41.8% and 38.8% (on a dry weight basis), polyunsaturated fatty acids of 8.0% and 9.2% of total fatty acids and essential amino acids of 47.2% and 46.6% of total amino acids, respectively. However, the former diet had significantly higher amount of carbohydrate (24.8%) but lower content of lipids (11.0%) than the latter diet which contained 6.1% carbohydrate and 27.1% lipids. Our findings show that waste-based diets in particular POME-MG is suitable for mass culturing A. dengizicus because it enhances survival, population growth and nauplii production. Most importantly, such production method is scalable and economically viable as it requires a minimal production cost to achieve high copepod densities in the shortest time.

Characterization of Amylolytic Activity by a Marine-Derived Yeast Sporidiobolus pararoseus PH-Gra1

Marine yeasts have tremendous potential in industrial applications but have received less attention than terrestrial yeasts and marine filamentous fungi. In this study, we have screened marine yeasts for amylolytic activity and identified an amylase-producing strain PH-Gra1 isolated from sea algae. PH-Gra1 formed as a coral-red colony on yeast–peptone–dextrose (YPD) agar; the maximum radial growth was observed at 22 °C, pH 6.5 without addition of NaCl to the media. Based on the morphology and phylogenetic analyses derived from sequences of internal transcribed spacer (ITS) and a D1/D2 domain of large subunit of ribosomal DNA, PH-Gra1 was designated Sporidiobolus pararoseus. S. pararoseus is frequently isolated from marine environments and known to produce lipids, carotenoids, and several enzymes. However, its amylolytic activity, particularly the optimum conditions for enzyme activity and stability, has not been previously characterized in detail. The extracellular crude enzyme of PH-Gra1 displayed its maximum amylolytic activity at 55 °C, pH 6.5, and 0%–3.0% (w/v) NaCl under the tested conditions, and the activity increased with time over the 180-min incubation period. In addition, the crude enzyme hydrolyzed potato starch more actively than corn and wheat starch, and was stable at temperatures ranging from 15 °C to 45 °C for 2 h. This report provides a basis for additional studies of marine yeasts that will facilitate industrial applications.

Polyunsaturated fatty acids-enriched lipid from reduced sugar alcohol mannitol by marine yeast Rhodosporidiobolus fluvialis Y2

Brown macroalgae is a promising marine biomass for the production of bioethanol and biodiesel fuels. Here we investigate the biochemical processes used by marine oleaginous yeast for assimilating the major carbohydrate found in brown macroalgae. Briefly, yeast Rhodosporidiobolus fluvialis strain Y2 was isolated from seawater and grown in minimal medium containing reduced sugar alcohol mannitol as the sole carbon source with a salinity comparable to seawater. Conditions limiting nitrogen were used to facilitate lipid synthesis. R. fluvialis Y2 yielded 55.1% (w/w) and 39.1% (w/w) of lipids, per dry cell weight, from mannitol in the absence and presence of salinity, respectively. Furthermore, mannitol, as a sugar source, led to an increase in the composition of polyunsaturated fatty acids, linoleic acid (C18:2) and linolenic acid (C18:3), compared to glucose. This suggests that oxidation of mannitol leads to the activation of NADH-dependent fatty acid desaturases in R. fluvialis Y2. Such fatty acid composition may contribute to the cold-flow properties of biodiesel fuels. Our results identified a salt-tolerant oleaginous yeast species with unique metabolic traits, demonstrating a key role as a decomposer in the global carbon cycle through marine ecosystems. This is the first study on mannitol-induced synthesis of lipids enriched with polyunsaturated fatty acids by marine yeast.

Assessment of Diversity of Culturable Marine Yeasts Associated with Corals and Zoanthids in the Gulf of Thailand, South China Sea

Marine yeasts can occur in a wide range of habitats, including in marine invertebrates, in which they may play important roles; however, investigation of marine yeasts in marine invertebrates is scarce. Therefore, this study aims to explore the diversity of yeasts associated with corals and zoanthids in the Gulf of Thailand. Thirty-three coral and seven zoanthid samples were collected at two sampling sites near Mu and Khram islands. Fifty yeast strains were able to be isolated from 25 of the 40 samples collected. Identification based on sequence analyses of the D1/D2 domain of the large subunit rRNA gene revealed a higher number of strains in the phylum Basidiomycota (68%) than in the phylum Ascomycota. The ascomycetous yeasts comprised nine known species from four genera (Candida, Meyerozyma, Kodamaea, and Wickerhamomyces), whereas the basidiomycetous yeasts comprised 10 known species from eight genera (Vishniacozyma, Filobasidium, Naganishia, Papiliotrema, Sterigmatomyces, Cystobasidium, Rhodotorula, and Rhodosporidiobolus) and one potentially new species. The species with the highest occurrence was Rhodotorula mucilaginosa. Using principal coordinate analysis (PCoA) ordination, no marked differences were found in the yeast communities from the two sampling sites. The estimation of the expected richness of species was higher than the actual richness of species observed.

Efficiency of Marine Bacteria and Yeasts on the Biocontrol Activity of Pythium ultimum in Ancho-Type Pepper Seedlings

Ancho-type pepper (Capsicum annuum L.) is a crop susceptible to Pythium ultimum, which has already been controlled with synthetic fungicide applications; however, marine antagonist microorganisms could be an alternative source of control. The efficiency in vitro and in vivo of marine bacteria and yeasts was determined against P. ultimum. The inhibition of the radial growth of P. ultimum was quantified in vitro by the bacteria Stenotrophomonas rhizophila KM01 and KM02; Bacillus subtilis RBM01 and RBM02, B. amyloliquefaciens 2RLBF and 3R4CF; and Pseudomonas spp. 2R6BF and 2RE9CF, as well as the yeasts Debaryomyces hansenii 1R11AB, 1R11CB, and LL01 and Cryptococcus laurentii 2R3BF and 2R1CB. The β-1,3-glucanase activity of the marine microorganisms was quantified in the presence of the phytopathogen. The disease index (DI), growth parameters, and colony forming units (CFU) were determined in ancho-type pepper plants inoculated with marine bacteria, yeasts, and P. ultimum. The radial zone of the phytopathogen was inhibited by 80% and 75% by S. rhizophila KM01 and C. laurentii 2R1CB, respectively. D. hansenii LL01 and S. rhizophila KM02 showed the highest activity of β-1,3-glucanase, with 6060 U/mL and 47 U/mL, respectively. B. subtilis RBM02 protected 100% of the plants from the oomycete, and an increase was quantified in all the growth parameters and CFU. The use of these marine bacteria and yeasts are, therefore, an option for P. ultimum biocontrol in ancho-type pepper plants, thereby minimizing the application of synthetic fungicides.

β-D-glucan from marine yeast Debaryomyces hansenii BCS004 enhanced intestinal health and glucan-expressed receptor genes in Pacific red snapper Lutjanus peru

Previous studies have shown that marine yeast Debaryomyces hansenii BCS004 (also known as Dh004) has a potential biotechnological application. The aim of this study was to investigate the structural characterization, antioxidant properties and possible health inductor of dietary β-D-glucan BCS004. In this study, a glucan BCS004 was obtained containing (1–6)-branched (1–3)-β-D-glucan with low molecular weight and a high purity of 90 and 91.7% for one and 4 h, respectively. β-D-glucan BCS004 showed higher antioxidant activity, including DPPH radical and superoxide anion scavenging, β-carotene bleaching inhibition, and iron chelation activity. An in vitro study showed that β-D-glucan BCS004 was safe for peripheral blood leukocytes inducing proliferative effects. Moreover, in an in vivo study using β-D-glucan BCS004 no histopathological damages or intestinal inflammation were observed in fish. The gene expression analysis highlighted that dietary β-D-glucan BCS004 could also up-regulate glucan and macrophage receptor genes in intestine, such as C-type lectin (CTL) and macrophage mannose receptors (MMR). Overall, the results demonstrated that β-D-glucan from D. hansenii BCS004 could be an immunostimulant with antioxidant properties and beneficial effects on intestinal health in fish.

Reducing stress by improving performance of hatchery-reared Catarina scallop (Argopecten ventricosus) spat with different genera of beneficial microorganisms: A biochemical and molecular analysis

This study investigated the probiotic effects of one lactobacillus, one marine yeast, mix of three bacilli and mix of all probiotic strains on the growth, survival, antioxidant response (superoxide dismutase = SOD, catalase = CAT, gluthatione peroxidase = GPX) and immune response (lysozyme = LYZ, heat shock protein =HSP70) of hatchery-reared Catarina scallop Argopecten ventricosus early spat. The spat was exposed every three days for 28 days to a single dose of 1 × 106 CFU mL–1 of one of five treatments used in triplicate: (1) Lactobacillus plantarum (C3); (2) Candida cretensis (S10); (3) Mix of Bacillus cereus, Bacillus flexus, and Bacillus firmus (BMix); (4) Mix of 1 + 2+3 (LLBMix); (5) Group of spat without probiotics as control. Survival was 100 % in all probiotic treatments and the control group. The spat treated with the yeast (S10) and lactobacillus (C3) significantly increased absolute growth and growth rate compared to the control. The antioxidant activity and gene expression was significantly lower in all spat treated with probiotics than in the control group, particularly with the BMix, LLBMix (SOD), C3 (CAT, GPX), and BMix (CAT) strains. The immune activity and gene expression was also significantly lower in spat treated with probiotics, particularly BMix, LLBMix (LYZ), C3, BMix, and S10 (HSP70) strains, compared to the control group. The use of a single dose of probiotic or mix of different strains reduced activation of antioxidant and immune response and improved overall performance of hatchery-reared A. ventricosus spat.

In vitro Antioxidant activity of extracellular L-glutaminase enzyme isolated from marine yeast Rhodotorula sp. DAMB1

Yeasts from marine ecosystem have been recognized as producers of several bioactive compounds and also for various enzyme productions. The present study mainly focuses on the extracellular production, medium optimization and in vitro antioxidant activity of L-glutaminase enzyme from marine yeasts isolated from marine water samples of the backwaters of Andaman-Nicobar islands, India. A total of 26 marine yeast isolates were recovered using yeast malt agar (YMA) medium. After primary screening using minimal glutamine agar, 4 marine yeast isolates DAMB1, DAMB2, DAMB3 and DAMB4 showed positive enzyme activity. Zones of hydrolysis for DAMB1 and DAMB3 were 40mm and 30mm respectively. Further, secondary screening was done for the two potential yeast isolates at pH 7.6 along with nesslerization for quantitative analysis. Yeast isolate DAMB1 showed highest L-glutaminase enzyme activity of 67%. This was followed by medium optimization for better production of L-glutaminase enzyme. The optimum temperature and pH was 37°C and pH 8 respectively. Optimum carbon source was arabinose and optimum nitrogen source was found to be casein. The potential yeast isolates showed good antioxidant activity too. DAMB1 showed highest DPPH activity of 62% and DAMB2 showed DPPH activity of 47%. The potential yeast isolate was identified as Rhodotorula sp. DAMB1 (Acc. No. MK968443) using 18s rRNA sequencing method.

Kinetic models application on glycerol production from glucose by the marine yeast Candida orthopsilosis

This study aims to investigate the kinetic parameters of carbon source effect on biomass and glycerol production by Candida orthopsilosis HH52 isolated from marine sediment. The yeast isolate HH52 was selected among five tested marine isolates as the most efficient producer of glycerol (64.42 gl-1). Based on the phenotypic and genotypic identification, this isolate was identified as Candida orthopsilosis and was deposited in the GenBank database under the accession number MK156301. The maximum specific glycerol production rate (vmax) was 0.101 gg-1 (glycerol /biomass) at 225 gl-1glucose, whereas the maximum specific growth rate (μmax) was 0.211 hr-1 at 150 gl-1 glucose. The glycerol (YP/S) and biomass (YX/S) yield coefficients were 0.3576 and 0.1128 gg-1, respectively. These findings suggest the possibility of using Candida orthopsilosis HH52 as a promising source for glycerol production.

Macrocystis pyrifera: substrate for the production of bioactive compounds

In recent decades products of marine origin have been the subject of intense investigation; new substances with pharmacological and nutraceutical properties have been discovered. On the other hand, processes more economical and friendly to the environment to produce biocompounds are needed. One alternative is biorefinery for the production of diverse bioproducts starting from one raw material. Our research group studied Macrocystis pyrifera as source of carbohydrates and phlorotannins, and the conditions for their extraction have been determined. The production of carotenoids from algal carbohydrates and the use of phlorotannins from the brown seaweed as antioxidant and antibacterial compounds were evaluated. The extraction yield of carbohydrate and phlorotannins were 81.02 ± 8.9 and 1.62 ± 0.13%, respectively. Carbohydrates were used for the growth and production of carotenoids by a marine yeast Rhodotorula mucilaginosa. The carotenoid content of the yeast biomass was 427 mg g−1 of dry biomass. Main carotenoids were lycopene (38.4 ± 9.4%), β-carotene (21.8 ± 1.5%), and astaxanthin (1.8 ± 0.3%). The residual fraction was used as fertilizer for the hydroponic cultivation of lettuce obtaining an increase of 28 ± 2.8% in dry weight. Here, we have demonstrated that M. pyrifera can be used to obtain antioxidants/antimicrobials, as nutrient source for the biotechnological production of carotenoids; moreover, the residue can be used as fertilizer.

Enhancement of glycerol production by UV-mutagenesis of the marine yeast Wickerhamomyces anomalus HH16: kinetics and optimization of the fermentation process.

The current study aims to enhance glycerol production using UV-mutagenesis of the marine yeast Wickerhamomyces anomalus HH16 isolated from marine sediment collected from South Sinai Governorate, Egypt. Besides optimization of the culture conditions and analyzing the kinetic parameters of growth and glycerol biosynthesis by the mutant strain were studied. The marine yeast isolate HH16 was selected as the front runner glycerol-producer among all tested isolates, with glycerol yield recorded as 66.55gl-1. The isolate was identified based on the phenotypic and genotypic characteristics of W. anomalus. The genotypic characterization based on the internal transcribed spacer (ITS) sequence was deposited in the GenBank database with the accession number MK182824. UV-mutagenesis of W. anomalus HH16 by its exposure to UV radiation (254nm, 200 mWcm-2) for 5min; increased its capability in the glycerol production rate with 16.97% (80.15gl-1). Based on the kinetic and Monod equations, the maximum specific growth rate (μ max) and maximum specific glycerol production rate (v max) by the mutant strain W. anomalus HH16MU5 were 0.21h-1 and 0.103gg-1, respectively. Optimization of the fermentation parameters such as nitrogen source, salinity and pH has been achieved. The maximum glycerol production 86.55gl-1 has been attained in a fermentation medium composed of 200gl-1 glucose, 1gl-1 peptone, 3gl-1 yeast extract, and 58.44gl-1 NaCl, this medium was adjusted at pH 8 and incubated for 3days at 30°C. Moreover, results indicated the ability of this yeast to produce glycerol (73.33gl-1) using a seawater based medium. These findings suggest the applicability of using the yeast isolate W. anomalus HH16MU5 as a potential producer of glycerol for industrial purposes.

Impact of uranium exposure on marine yeast, Yarrowia lipolytica: Insights into the yeast strategies to withstand uranium stress

A marine yeast, Yarrowia lipolytica, was evaluated for morphological, physiological and biochemical responses towards uranium (U) exposure at pH 7.5. The yeast revealed biphasic U binding - a rapid biosorption resulting in ∼35% U binding within 15–30 min followed by a slow biomineralization process, binding up to ∼45.5% U by 24 h on exposure to 50 μM of uranyl carbonate. Scanning electron microscopy coupled with Energy Dispersive X-ray spectroscopy analysis of 24 h U challenged cells revealed the deposition of uranyl precipitates due to biomineralization. The loss of intracellular structures together with surface and subcellular localization of uranyl precipitates in 24 h U exposed cells were visualized by transmission electron microscopy. Cells treated with 50 μM U exhibited membrane permeabilization which was higher at 200 μM U. Enhanced reactive oxygen species (ROS) accumulation and lipid peroxidation, transient RNA degradation and protein oxidation were observed in U exposed cells. High superoxide dismutase levels coupled with uranium binding and bioprecipitation possibly helped in counteracting U stress in 50 μM U treated cells. Resistance to U toxicity apparently developed under prolonged uranyl (50 μM) incubations. However, cells could not cope up with toxicity at 200 μM U due to impairment of resistance mechanisms.

Macrocystis pyrifera source of nutrients for the production of carotenoids by a marine yeast Rhodotorula mucilaginosa.

To evaluate an aqueous extract of Macrocystis pyrifera as a nutrient source for the production of carotenoids by a marine Rhodotorula mucilaginosa isolated from seaweed samples. The effect of different culture conditions on the concentration of biomass and total pigments was evaluated using a Box-Behnken experimental design. The seaweed extract contained 15% ww-1 of protein and 20% ww-1 of carbohydrate; the main sugar in this fraction was trehalose (78%). The culture conditions that maximize the total pigment concentration (1·84±0·03mgl-1 ) were initial pH equal to 7, yeast extract as nitrogen source at a concentration of 4gl-1 , seaweed extract concentration at 25% v v-1 , incubation performed at 25°C and 150revmin-1 during 6days. Under optimal growth conditions, three carotenoids were identified among the pigments produced by R. mucilaginosa, lycopene (38·4±9·4%), β-carotene (21·8±1·5%) and astaxanthin (1·8±0·3%). Carotenoids of commercial interest (lycopene, β-carotene and astaxanthin) can be produced using a marine R. mucilaginosa cultivated with an aqueous extract of M. pyrifera as nutrient source. The total pigment concentration in the culture ranged between 0·82 and 1·84mgl-1 , and was significantly affected by the concentration of the seaweed extract, and yeast extract. This work demonstrates that M. pyrifera can be used as a nutrient source for the production of carotenoids by the marine yeast.

Species disparity response to mutagenesis of marine yeasts for the potential production of biodiesel

BackgroundAmong the third-generation biodiesel feed stock, oleaginous marine yeasts are the least studied microorganisms for such purpose.ResultsWild strains yeasts were isolated from various Tunisian marine sources including fish waste (Candida tenuis CtTun15, Debaryomyces hansenii DhTun2015, Trichosporon asahii TaTun15 and Yarrowia lipolytica YlTun15) and seawater (Rhodotorula mucilaginosa RmTun15). Following incubation with ethyl methanesulfonate (EMS: 75 mM) for various periods of time (T15, T30, T45, T60 min), the cell viability of these strains responded differentially according to yeast species. For instance, mutated CtTun15 did not survive after 30 min of EMS treatment; higher resistances were observed in DhTun2015 (45 min), in YlTun15, RmTun15 and in TaTun15 (60 min) but with significant decreased cell viabilities (survival rate: 6.02, 3.16, 11.22, 11.58, 7.70%, respectively). For all surviving mutated strains, the optima of biomass and lipid yields were detected after 96 h in YPD culture; but derived from strains submitted to different period of EMS incubation. In most mutated strains, the maximum biomass (BP) and lipid (LP) productivities coincided and were observed after 30 min of EMS incubation. Only CtTun15 showed different optima of BP and LP (after 30 min and 15 min, respectively). The fatty acids (FA) compositions considered essential in the prediction of biodiesel criteria; were highly affected by EMS mutagenesis. Essentially, 30- and 45-min EMS incubation induced the highest levels of PUFA and MUFA in YlTun15, RmTun15 and TaTun15 with non-significant differences in the different times. However, CtTun15 and DhTun2015 mutant strains responded differently, with the highest levels of MUFA observed following 15 and 45 min; and that of PUFA after 30 and 45 min, respectively.ConclusionThe methyl-esterification of FA from the three mutated yeast strains (30 min—YlTun15, RmTun15 and TaTun15) yielded biodiesel with physical proprieties consistent with the International Standard System. However, investigations are needed for up-scaling biodiesel production.

Occurrence and biodiversity of marine yeast in mangrove ecosystem of Shabi Creek, Gwadar- Pakistan

Abstract Shabi Creek receives saline water from the west bay of Gwadar and fresh water from Ankara River and its associated watershed. In Shabi Creek only Avicennia Marina is found out of three reported species of mangrove in Pakistan. Although Pakistan’s mangroves are widespread, and harbors very diverse biota has received less attention in terms of their microbial diversity particularly yeast. Marine yeasts are considered as a food source for some marine invertebrates and zooplankton and have been reported to produce useful compounds of human concern. In this study, we investigated the yeast diversity along the mangrove ecosystem of Shabi Creek, Gwadar. Yeast strains were extracted from different sections of mangrove plant such as root, stem, bark, branches, flowers, leaves, seawater, sediments, associated organisms and plants. Total 605 colonies were isolated which were further identified by their morphology and biochemical analysis and 17 distinct colonies were picked and were further analyzed by 26S rDNA gene amplicon. Sequence analysis was carried out with the help of CLC sequence viewer and the phylogenetic tree was constructed. In total 05 species of yeast were identified belonging to 04 genera i.e. Candida, Debaryomyces, Saccharomyces and Schizosaccharomyces. The identified species were Candida parapsilosis, Debaryomyces hansenii, Debaryomyces fabryii, Saccharomyces cerevisiae, Saccharomyces bayanus, Shizosaccharomyces pombe. The most dynamic growth of yeasts was observed in marine sediments among all samples. To the best of our knowledge, this is the first ever study conducted to investigate the biodiversity of mangrove ecosystem of Makran coast Gwadar, Pakistan. Keywords: Gwadar; Mangrove ecosystem; Marine yeast diversity; Shabi Creek http://dx.doi.org/10.19045/bspab.2019.80008

Potential and Enzymatic Characterizations of Marine Yeast for Pufas from Balai Taman Nasional Karimunjawa

Potential of huge mangrove ecosystem in Indonesia, especially in Balai Taman Nasional Karimunjawa, for exploration of potential microorganism. One of them were yeast. PUFA is beneficial as a source of food for low and high-level organisms. The aim of this study is to explored the potential of yeast by enzymatic methods, differences of culture media and molecular identification in Balai Taman Nasional Karimunjawa. The research flow included isolation of yeast from several mangrove ecosystem located in Karimunjawa by purposive sampling methods. The pine pollen used to bait, identification colony morphology, Protease, amylolytic, cellulolytic, Lipase Enzymatic Test, mass culture used a variety of different media, molecular identification used 18S rDNA. The results of the studied obtained 4 isolates with the code (T2, KM1, KM2, KM3) which have the potential on the lipase and protease enzyme. Molecular identification used 18S rDNA analysis showed that all isolates were the yeast. Differences in the use of media also produce various yeast biomass.

Enhanced biocontrol of fruit rot on muskmelon by combination treatment with marine Debaryomyces hansenii and Stenotrophomonas rhizophila and their potential modes of action

Separately and in combination a marine yeast Debaryomyces hansenii and a marine bacterium Stenotrophomonas rhizophila were evaluated for their biocontrol potential against Fusarium proliferatum on muskmelon fruit. The results show that the mixture of yeast and bacterium in vitro reduced the growth of F. proliferatum, possibly due to either by direct parasitism, nutrient competition, lytic enzymes, biosurfactants and/or volatile organic compounds (VOCs). Disease incidence and lesion diameter caused by F. proliferatum on muskmelon was reduced significantly, especially when fruit was inoculated with the mixture of D. hansenii + S. rhizophila. These results indicated that D. hansenii, S. rhizophila and their combination treatments were effective for the postharvest biocontrol of fruit rot on muskmelon.