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Search Results: 1 - 10 of 445 matches for " YULIN LESTARI "
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Purification and Characterization of Streptomyces sp. SKK1-8 xylanase
Anja Meryandini,Yulin Lestari,Nunuk Widhyastuti
Makara Seri Sains , 2008,
Abstract: Streptomyces sp. SKK1-8 is a xylanase produced bacteria. Purified xylanase has an optimum condition at pH 4.5 and 50oC. The molecular mass of purified xylanase were determined to be 14.4 kDa and 13.4 kDa. The xylanase was capable of hydrolysing p-NP-α-L-arabinofuranoside, p-NP-β-D-xylanopiranoside, p-NP-β-D-glucopiranoside, p-NP-α-D-galactopiranoside. The Km and Vmax values at 50oC measured on Birchwood xylan were 0.101 mg/ml and 0.1796 μmoles/minute/ml.
Potential Pseudomonas Isolated from Soybean Rhizosphere as Biocontrol against Soilborne Phytopathogenic Fungi
HAYATI Journal of Biosciences , 2011,
Abstract: Plants are liable to be attacked by soilborne fungal pathogens which are responsible to reduce plant growth and losses in yield. In Indonesia, indigenous soybeans’ rhizobacteria such as antifungal producing Pseudomonas sp. have not many been reported yet. Therefore, the potential of the Pseudomonas sp. as biocontrol agent should be deeply explored. The aim of this study was to screen the indigenous soybeans’ rhizobacteria Pseudomonas sp. that possessing biocontrol characters against soilborne mainly i.e. Sclerotium rolfsii, Fusarium oxysporum, and Rhizoctonia solani, in vitro and in planta. Eleven isolates identified Pseudomonas sp. CRB numbered by CRB-3, CRB-16, CRB-17, CRB-31, CRB-44, CRB-75, CRB-80, CRB-86, CRB-102, CRB-109, and CRB-112 were affirmed to be candidates of biocontrol agents toward the soilborne fungal pathogens. Pseudomonas sp. CRB inhibited growth of the pathogenic fungi approximately 11.1-60.0% in vitro. Among of them, 7 isolates were also produced siderophore, 2 isolates produced chitinase, and 4 isolates produced hydrogen cyanide. Seed coating with the Pseudomonas sp. CRB accomplished disease suppression in planta about 14.3-100% in sterile soil condition and 5.2-52.6% in non sterile soil condition. Consistency in high performance more than 30% of disease suppression in non sterile soil condition suggested that 5 isolates i.e. CRB-16, CRB-44, CRB-86, CRB-102, and CRB-109 isolates have great promising to be developed as biocontrol agents of soilborne pathogenic fungi.
Characterization of Xylanase Streptomyces spp. SKK1-8
HAYATI Journal of Biosciences , 2006,
Abstract: Streptomyces spp. SKK1-8 producing xylanase was isolated from soil sample from Sukabumi West Java. The xylanase have an optimum condition at pH 6 and 50 oC. Addition of 5 mM Cu2+ decreased the xylanase activity up to about 77%, whereas not by other cations. The xylanase was stable at 3 oC for 48 hours, and the enzyme half lifetime was 1 hour 45 minute at 50 oC. This xylanase showed the highest activity on oatspelt xylan, and their molecular masses were estimated approximately 16.80, 15.21, and 13.86 kDa. HPLC analysis showed that xylosa and arabinosa were the main hydrolytic product of birchwood xylan.
Endophytic Streptomyces spp. as Biocontrol Agents of Rice Bacterial Leaf Blight Pathogen (Xanthomonas oryzae pv. oryzae)
HAYATI Journal of Biosciences , 2012,
Abstract: Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of bacterial leaf blight (BLB), is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD) with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants inoculated with only Streptomyces spp. Plants inoculated with Xoo and sprayed with a chemical bactericide, and plants inoculated with only Xoo served as positive controls, whereas plants not inoculated with either Streptomyces spp. or Xoo were used as negative controls. The results showed that the effect of endophytic Streptomyces spp. on BLB disease expressed as area under disease progress curve (AUDPC) was not significantly different to that on control plants (P > 0.05). However, plants inoculated with endophytic Streptomyces spp. were significantly taller and produced higher tiller number than control plants (P < 0.05). Streptomyces spp. isolate AB131-1 gave the highest plant height. In vitro studies on biocontrol mechanisms of selected Streptomyces spp. isolates showed that isolate LBR02 gave the highest inhibition activity on Xoo growth, followed by AB131-1 and AB131-2. Two isolates (AB131-1 and LBR02) were able to produce chitinase, phosphatase, and siderophore which included biocontrol characteristics. Morphological and colonization studies under SEM and light microscopy confirmed that the three isolates were endophytic Streptomyces spp. from different species. These studies found that the paddy plant which was inoculated with endophytic Streptomyces spp. AB131-1 and infected by Xoo could increase the height of plant and number of tillers.
Bacterial communities associated with white shrimp (Litopenaeus vannamei) larvae at early developmental stages
Biodiversitas , 2010,
Abstract: Bacterial communities associated with white shrimp (Litopenaeus vannamei) larvae at early developmental stages. Biodiversitas 11 (2): 65-68.Terminal Restriction Fragment Length Polymorphism (T-RFLP) was used to monitor the dynamics of the bacterial communities associated with early developmental stages of white shrimp (Litopenaeus vannamei) larvae. Samples for analysis were egg, hatching nauplii, 24 hours old nauplii, and 48 hours old nauplii which were collected from one cycle of production at commercial hatchery. T-RFLP results indicated that the bacterial community associated with early stages of shrimp development might be transferred vertically from broodstock via egg. There was no significant difference between bacterial communities investigated, except the bacterial community of 48 hours old nauplii. Diversity analyses showed that the bacterial community of egg had the highest diversity and evenness, meanwhile the bacterial community of 48 hours old nauplii had the lowest diversity. Nine phylotypes were found at all stages with high abundance. Those TRFs were identified as γ- proteobacteria, α-proteobacteria, and bacteroidetes group.
Genetic Diversity of Antifungi-Producing Rhizobacteria of Pseudomonas sp. Isolated from Rhizosphere of Soybean Plant
Microbiology Indonesia , 2010, DOI: 10.5454/mi.4.1.7
Abstract: Antifungi-producing rhizobacteria have been recognized playing an important role in plant disease suppression. In our laboratory, 13 indigenous soybeans' rhizobacteria Pseudomonas sp. that showed strong growth inhibition of root pathogenic fungi, Rhizoctonia solani, Fusarium oxysporum and Sclerotium rolfsii, have been isolated from rhizosphere of soybean plant. For further understanding, the genetic diversity of the antifungi-producing Pseudomonas sp. was investigated using Amplified 16S rDNA Restriction Analysis (ARDRA) and 16S rRNA gene sequences analysis. 16S rDNA were amplified by PCR technique and digested with restriction endonuclease HaeIII, RsaI and AluI. Sequences of 16S rRNA gene were analyzed using the BLAST program for similarity searches on sequence databases. ARDRA based dendrogram analysis was carried out by neighbor-joining of TREECON 1.3b software package. ARDRA indicated the variability of Pseudomonas sp. based on the digestion sites. Dendrogram clustering analysis based on the restriction enzymes profile of the amplified rDNA distinguished Pseudomonas sp. into 7 ribotype groups. The sequences of 16S rRNA gene confirmed that the isolates belonging to Pseudomonas sp. and the phylogenetic tree formed 4 clusters. There was a quite overlap among ARDRA groups and 16S rRNA sequence clusters. This finding suggested that antifungal producing Pseudomonas sp. were present in the rhizosphere of soybean plant and the level of genetic diversity exist within these species. Sequence analysis of the 16S rRNA gene of the Pseudomonas sp. with an identical ARDRA pattern confirmed that members of an ARDRA group were closely related to each other.
Oversea Background Executive, Risk-Taking and Corporate Performance  [PDF]
Yulin Guo
Modern Economy (ME) , 2018, DOI: 10.4236/me.2018.912139
Abstract: Overseas background executives are becoming more and more important to enterprises. By analyzing the data of A-share listed companies in China from 2011 to 2017, this paper finds that the existence of overseas background executives is conducive to the improvement of corporate performance. And senior managers with overseas working experience and core managers with overseas experience in enterprises can play a more important role. At the same time, the study shows that risk-taking plays a mediating role in the impact of overseas executives on corporate performance. And only when the external institutional environment is good, can overseas executives play their role.
Effect of Heavy Metals Pollution to Seawater Quality and Fishery Resources (Case Study on Fish Death in Jakarta Bay)
Makara Seri Sains , 2004,
Abstract: Observation on heavy metals content in sea water were carried out in Jakarta Bay waters in May 2004. Heavy metals observed were Hg, Pb, Cd, Cu, Zn and Ni. This observation is conducted with fishes total death in this waters. Observation is done in Ancol beach 1 (3 stations), Ancol beach 2 (4 stations), Cilincing (3 stations), and Dadap River estuary (4 Station). The results showed that the average concentration of Hg, Cd and Cu in Ancol beach 1 were <0.001 ppm respectively, Pb is 0.001 ppm, Zn is 0.004 ppm, and Ni is 0.001 ppm. In Ancol beach 2 the average concentration of Hg, Cd, and Zn were <0.001 ppm, Pb is 0.002 ppm, Cu is 0.001 ppm and Ni 0.0017 ppm. In Cilincing the average concentration of Hg, Cd, and Zn were <0.001 ppm respectively, Pb and Cu were 0.002 ppm, and Ni was 0.0045 ppm. In Dadap River Estuary the average concentration of Hg and Cd were 0.001 ppm, Pb and Zn were 0.0027 ppm, Cu was 0.001 ppm, and Ni between 0.0012 ppm. The concentration of that sixth heavy metals in Ancol beach 1, 2, Cilincing, and Dadap River estuary still lower compared to the Threshold Value (TV) stated by The Office of State Ministry for Life Environment (2004) for sea biota namely 0.001 ppm for Hg and Cd, 0.008 ppm for Pb and Cd, 0.05 ppm for Zn and Ni. That way the concentration of Hg, Pb, Cd, Cu, Zn, and Ni in Ancol beach 1, 2, Clilincing and Dadap estuary not danger for sea biota, while in Ancol beach 3, the average concentration of Hg, Pb, and Cd has danger for sea biota. Thereby total death of fishes in this waters not caused by heavy metals, but by others factors, one of that factors is blooming toxic phytoplankton which produced toxin where sea water change to be red, and this phenomena known as red tide.
Lestari Handayani
Media of Health Research and Development , 2012,
Abstract: Foshu (Food for Specific Health Use) is processed by the ingredients of some functions in a well balanced body. The effectiveness and safety of each item is scientifically tested on human and animal. The Ministry of Health and Welfare of Japan has the authority to approve Foshu and monitor them strictly to make sure that the consumer get highest quality product. Foshu's purpose is to maintain and improve health in such way i.e. adjusting constipation, lowering cholesterol level, permit greater absorption of mineral, lowering blood pressure, prevent tooth decay and adjust the blood sugar level. Up to April 1998, 100 approval items have been already sold in the Japan market.
A MAC Scheme with QoS Guarantee for MANETs  [PDF]
Yanbin YANG, Yulin WEI
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.28088
Abstract: IEEE 802.11 distributed coordination function (DCF) can alleviate the collision and hidden station problem, but it doesn’t differentiate traffic categories (TC). Therefore, it can’t provide sufficient QoS support for different traffic categories. Recently, a new contention-based enhanced distributed channel access (EDCA) scheme was proposed which provides a probabilistic QoS support. In this paper, an adaptive EDCA scheme with QoS guarantee for mobile ad hoc networks (MANETs) is proposed. In this scheme, the EDCA scheme and the token bucket algorithm (TBA) are combined to adjust the contention window (CW). Our scheme provides the traffic differentiation.
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