Function Of RNA Helicase Gene From The Antarctic Ice Algae Chlamydomonas Sp.ICE-L And Biodiversity Analysis Of Carrageenan Producing Seaweeds From Indonesia

Antarctica is a cold environment which experiences high salinity and temperaturefluctuations, the specific geographic and climatic characteristics made it a distinctiveecosystem. Antarctic microorganisms have developed particular adaptation mechanismsthat successfully enable them to thrive in this harsh environment. This provides researchmaterials for the study of biological resistance to low temperature and high salt stress.The object of this study is the Antarctic ice alga Chlamydomonas sp. ICE-L.DEAD-box helicase not only mediated NTP-dependent double-stranded RNA helix,but also plays an important role in the process of plant adaptation to various abioticstresses. A DEAD-box RNA helicase CiDDX5gene was identified from the EST libraryof the Antarctic ice algae, Chlamydomonas sp. ICE-L. The full-length ofChlamydomonas sp. ICE-L CiDDX5gene contained an open reading frame of2,077bpencoding a nitrate reductase of513amino acids. Phylogenetic analysis showed that thegene was homologous to the known green algae RNA helicase genes with identities of65%,64%and63%to C. reinhardtii, Volvox carteri and Chlorella vulgaris respectively.According to the analysis of expressed sequence tags cDNA Library of Antarctic icealgae of ICE-L (ESTs), CiDDX5gene sequence was obtained; we used Primer Primer5.0software required to design specific primer and chosed GAPDH and RLP19as thereference gene. Through real-time quantitative technique, mede the one growing in thenormal temperature at7℃cultured respectively0h and12h as control, others wereplaced at-20℃for0.5h,1H,3h,6h and12h as well as3times salinity of seawatertreatmented respectively for0.5h,1h,3h,6h and12h, with normal salinity cultured0hand12h as the control, with the calculation method of2-ΔΔCt, we got the ICE-LCiDDX5gene variation of Antarctic Chlamydomonas that-20℃treatment and3timesthe salinity of different treatment.The expressions of CiDDX5gene were up-regulated under both the lowtemperature and high salinity stress conditions, which indicated the role of CiDDX5gene in the regulation of abiotic stress adaptation of Antarctic ice alga Chlamydomonassp. ICE-L.Forty strains of carrageenan producing algae were collected form Lembongan andNusa Penida islands of Indonesia. Genomic DNA from the samples was extracted, andmitochondrial Cox2-3genes were cloned and sequenced. The classifications of thesamples were determined by constructing a phylogentic tree. The result indicated that all the samples were divided into two different species: Eucheuma denticulatum andKappaphycus striatum. This study adds to our knowledge of biodiversity of thecarrageenan producing seaweeds from Indonesia.This thesis was separated from the red alga of κ-carrageenan enzyme producingstrains, and the fermentation conditions of strain and culture medium optimization.After screening and rescreening10high-yield strains, the highest enzyme activity was1.18U/mL. By optimizing the culture conditions for enzyme activity of single factortest and orthogonal test. Test to determine the best culture conditions for enzymeproduction strains: liquid volume in flask fermentation liquid, in the75mL inoculationwas7%, pH8, culture temperature30℃; the composition of culture medium: g/L κ-carrageenan3, yeast extract for2g/L, NaCl for20g/L. Significant results showed thatthe effect of NaCl on enzyme activity was the highest.