天山乌鲁木齐河源1号冰川不同海拔可培养空气源酵母菌系统发育及多样性研究

为了了解天山乌鲁木齐河源1号冰川（简称乌源1号冰川）空气及气溶胶中可培养酵母菌的多样性、系统发育、空间分布及其与冰川生境酵母菌的关系,在乌源1号冰川西支3个海拔梯度位点收集空气气溶胶,采用4种培养基分离空气源酵母菌,根据菌落形态和显微镜镜检细胞形态初步分组,采用MSP-PCR指纹分型和rRNA基因间隔序列（ITS）确定酵母菌菌株的系统发育和分类地位,并分析了空气源酵母菌群落的多样性及空间分布特征。研究表明：从乌源1号冰川的表面空气共分离414株酵母菌,全部隶属于担子菌门（Basidiomycota）,MSP-PCR指纹分型划分为53个基因型,代表菌株ITS基因测序结果显示隶属于9属28种,其中24种为伞菌亚门（Agariomycotina）成员,4种属于柄锈菌亚门（Pucciniomycotina）,其中Holtermanniella、Vishniacozyma、Filobasidium、Dioszegia为优势酵母菌属。有6株酵母菌最适生长温度为16~18 ℃,为嗜冷菌,其余24株为耐冷菌,最适生长温度为22~25 ℃。Holtermanniella festucosa与Vishniacozyma victoriae为冰川空气广布的优势酵母菌种（22.22%、16.91%）,其他大多为来自周边生境的耐冷酵母菌,在冰川生境均有分布。此外,在小幅度的海拔梯度上,3个海拔高度的空气酵母菌群落结构有所不同,但多样性指数没有显著差异。冰川生境酵母菌来源与其周边空气酵母菌密切相关,但以Holtermanniella属为代表的空气源优势酵母在冰川生境不能分离,说明冰川的严酷条件对外源微生物具有明显的选择作用。     

Intraspecific diversity of Aureobasidium pullulans strains from different marine environments

Totally more than 500 yeast strains were isolated from seawater, sea sediments, mud of sea salterns, marine fish guts and marine algae. The results of routine and molecular biology identification methods show that nine strains among these marine yeasts belong to Aureobasidium pullulans, although the morphologies of their colonies are very different. The marine yeasts isolated from different marine environments indicate that A. pullulans is widely distributed in different environmental conditions. These Aureobasidium pullulans strains include A. pullulans 4#2, A. pullulans N13d, A. pullulans HN3-11, A. pullulans HN2-3, A. pullulans JHSc, A. pullulans HN4.7, A. pullulans HN5.3, A. pullulans HN6.2 and A. pullulans W13a. A. pullulans 4#2 could produce cellulase and single cell protein. A. pullulans N13d could produce protease, lipase, amylase and cellulase. Both A. pullulans HN3-11 and A. pullulans HN2-3 were able to produce protease, lipase and cellulase. A. pullulans JHSc could secrete cellulase and killer toxin. Both A. pullulans HN4.7 and A. pullulans HN5.3 could yield lipase and cellulase. A. pullulans W13a was able to secrete extracellular amylase and cellulase while A. pullulans HN4.7 and A. pullulans N13d could produce siderophores. This means that different A. pullulans strains from different marine environments have different physiological characteristics, which may be applied in many different biotechnological industries.     

Screening of protease-producing marine yeasts for production of the bioactive peptides

Over 400 yeast strains from seawater and sediments were obtained, but only five strains named HN2 -3, N13d, N13C, Mb5 and HN3 - 2 among them could form clear zones around their colonies on the double plates with 2.0% casein. Peptides in the hydrolysate produced by the proteases from strains HN2 -3 and N13d had higher angiotensin I-converting-enzyme （ACE）-inhibitory activity. The two marine yeast strains were identified to be Aureobasidium pullulans according to the results of routine yeast identification and molecular methods. After purification of the proteases from the two marine yeast strains, it was found that the optimal pH for them was both 9.0, both of them were serine alkaline protease. However, the optimal temperature for the protease from the strain HN2 -3 was 52℃ while that from strain N13d was 48℃. ACE-inhibitory activity of the peptides in the hydrolysate of shrimp protein produced by the purified protease from the strain HN2 -3 was the highest while antioxidant activity in the hydrolysate of spirulina protein produced by the purified protease from the strain N13d was the highest.     

Occurrence and diversity of <Emphasis Type="Italic">Pichia</Emphasis> spp. in marine environments

A total of 328 yeast strains from seawater, sediments, mud of salterns, the guts of marine fish and marine algae were obtained. The results of routine identification and molecular methods show that five yeast strains obtained in this study belonged to Pichia spp., including Pichia guilliermondii 1uv-small, Pichia ohmeri YF04d, Pichia fermentans YF12b, Pichia burtonii YF11A and Pichia anomala YF07b. Further studies revealed that Pichia anomala YF07b could produce killer toxin against pathogenic yeasts in crabs while Pichia guilliermondii 1uv-small could produce high activity of extracellular inulinase. It is advisable to test if Pichia ohmeri YF04d obtained in this study is related to central-venous-catheter-associated infection.     

Enhanced Carotenoid Production by a Mutant of the Marine Yeast Rhodotorula sp. hidai

1 Introduction In recent years, carotenoids have received increasing attention as they have extensive use in medicine, cosmetic, chemistry, food industry and feed industry. In industry, carotenoid and astaxanthin can be used as the additives of food or feeds. Carotenoids can also serve as the precursor of vitamin A in mammals. In recent years, many types of carotenoid have aroused extensive interest because of their many beneficial effects on human health. For in-stance, lycopene and astaxant…     

Occurrence and diversity of marine yeasts in Antarctica environments

A total of 28 yeast strains were obtained from the sea sediment of Antarctica.According to the results of routine identi-fication and molecular characterization,the strains belonged to species of Yarrowia lipolytica,Debaryomyces hansenii,Rhodotorula slooffiae,Rhodotorula mucilaginosa,Sporidiobolus salmonicolor,Aureobasidium pullulans,Mrakia frigida and Guehomyces pullu-lans,respectively.The Antarctica yeasts have wide potential applications in biotechnology,for some of them can produce b-galactosidase and killer toxins.     

Occurrence and Diversity of Pichia spp. in Marine Environments

A total of 328 yeast strains from seawater, sediments, mud of saltems, the guts of marine fish and marine algae were obtained. The results of routine identification and molecular methods show that five yeast strains obtained in this study belonged to Pichia spp., including Pichia guilliermondii luv-small, Pichia ohmeri YF04d, Pichiafermentans YF12b, Pichia burtonii YF11A and Pichia anomala YF07b. Further studies revealed that Pichia anomala YF07b could produce killer toxin against pathogenic yeasts in crabs while Pichia guilliermondii luv-small could produce high activity of extracellular inulinase. It is advisable to test if Pichia ohmeri YF04d obtained in this study is related to central-venous-catheter-associated infection.     

Alkaline Protease Production by a Strain of Marine Yeasts

Yeast strain 10 with high yield of protease was isolated from sediments of saltern near Qingdao, China. The protease had the highest activity at pH 9.0 and 45℃. The optimal medium for the maximum alkaline protease production of strain 10 was 2.5 g soluble starch and 2.0 g NaNO3 in 100 mL seawater with initial pH6.0. The optimal cultivation conditions for the maximum protease production were temperature 24.5 ℃, aeration rate 8.0 L min^- 1 and agitation speed 150 r min^-1 . Under the optimal conditions, 623.1 Umg^-1 protein of alkaline protease was reached in the culture within 30 h of fermentation.     

Enhanced carotenoid production by a mutant of the marine yeast Rhodotorula sp. hidai

After a serial of UV, EMS and NTG mutagenesis, a mutant named MM of the red marine yeast strain Rhodotorula sp. hidai was obtained. The mutant MM could produce 603.93 μg g⁻¹ of carotenoid within 5 days in the medium containing 4.0 g sucrose, 1.5 g yeast extract, 0.1 g MgSO₄, and 100 mL of sea water, with pH 6.0 and at 30 °C, while only 213.18 μg g⁻¹ of carotenoid was produced by the wild type under the same conditions.