Phyllosphere eukaryotic microalgal communities in rainforests:Drivers and diversity

Phyllosphere algae are common in tropical rainforests,forming visible biofilms or spots on plant leaf surfaces.However,knowledge of phyllosphere algal diversity and the environmental factors that drive that diversity is limited.The aim of this study is to identify the environmental factors that drive phyllosphere algal community composition and diversity in rainforests.For this purpose,we used single molecule real-time sequencing of full-length 18S rDNA to characterize the composition of phyllosphere microalgal communities growing on four host tree species(Ficus tikoua,Caryota mitis,Arenga pinnata,and Musa acuminata) common to three types of forest over four months at the Xishuangbanna Tropical Botanical Garden,Yunnan Province,China.Environmental 18S rDNA sequences revealed that the green algae orders Watanabeales and Trentepohliales were dominant in almost all algal communities and that phyllosphere algal species richness and biomass were lower in planted forest than in primeval and reserve rainforest.In addition,algal community composition differed significantly between planted forest and primeval rainforest.We also found that algal communities were affected by soluble reactive phosphorous,total nitrogen,and ammonium contents.Our findings indicate that algal community structure is significantly related to forest type and host tree species.Furthermore,this study is the first to identify environmental factors that affect phyllosphere algal communities,significantly contributing to future taxonomic research,especially for the green algae orders Watanabeales and Trentepohliales.This research also serves as an important reference for molecular diversity analysis of algae in other specific habitats,such as epiphytic algae and soil algae.

Mrakia psychrophila sp.nov.,a new species isolated from Antarctic soil

The yeast strain （Y18） was isolated from a soil sample collected from Fildes Peninsula, Antarctica. The strain is a psychrophilic yeast with optimum and maximum growth temperatures of 10 ℃ and 18 ℃, respectively. Teliospores were formed after 7 d on malt agar, when the germination of teliospores was observed. Both inositol and D-glucuronate were assimilated. Positive results of the DBB （diazonium blue B） color reaction, urease test, and starch formation were observed. The major CoQ is Qs. All results indicated that Y18 belongs to the genes of Mrakia. The 18S rDNA sequence analyses showed that Y18 is closely related to Mrakiafrigida. DNA-DNA relatedness study, and some biochemistry characteristics indicated that Y18 represents a new species for which Mrakia psychrophila sp. nov. is proposed.

Screening and performance of L-14, a novel, highly efficient and low temperature-resistant cellulose-degrading strain

In view of the low bioconversion efficiency of agricultural biomass waste in low-temperature environments in winter,a low-temperature-resistant cellulose-degrading strain,L-14,was successfully screened by restrictive cultures from humus-rich soil in the Daqing Zhalong wetland region.According to morphological observations and 18S rDNA sequence analysis,the cellulose-degrading strain L-14 was identified as a Neurospora sp,belonging to fungus.Different parameters,such as temperature,initial pH,carbon,nitrogen and lecithin,were optimized using a single-factor experiment and a response surface methodology(RSM).When the temperature was 16°C,the optimal conditions for enzyme production were an initial pH 8.20,10.45 g/L of bran,5.28 g/L of yeast powder,and 4.25 g/L of lecithin.The carboxymethyl cellulase(CMCase)activity of strain L-14 was 63.598 IU/mL.Strain L-14 had a high level of cellulose degradation activity,excellent resistance to low temperatures and environmental adaptability,indicating its good application prospects in substrates pretreatment of biogas engineering.