*Author for Correspondence.
Institute of Biological Sciences, Faculty of Science,
University of Malaya,
50603 Kuala Lumpur, Malaysia.
Tel: 603-7967-6740; Fax: 603-7967-4178;
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Abstract.
Selected organic and inorganic nitrogen sources were evaluated for growth of Pseudomonas putida PGA1 and its production of medium-chain-length poly-(3-hydroxyalkanoates) (PHA_MCL). The effect of these nitrogen sources on the cells growth, PHA_MCL yield, monomer composition and molecular weight when this bacterium was cultivated on saponified palm kernel oil (SPKO) as the major carbon source was investigated. It was found that bacto-peptone gave significantly higher yield of residual biomass (PHA-free biomass) and PHA_MCL as compared to ammonium salt, urea, yeast extract and beef extract. No significant difference in the monomer composition of the PHA_MCL produced was observed with the different nitrogen sources. All the PHA_MCL produced had high molecular weight, with the weight average (M_w) ranging from 90,000 to 127,000 and polydispersities (M_w/M_n) ranging from 1.7 to 1.9.

*Author for Correspondence.
Malaysian Palm Oil Board,
No 6 Persiaran Institusi, Bandar Baru Bangi
43000, Kajang, Selangor, Malaysia.
Tel: 603-87694585. Fax: 603-89261995.
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract.
The potential health benefits of carotenoids as anti cancer and antioxidant agents have recently been demonstrated. Oil palm, Elaeis oleifera in particular, is known to be the richest natural source for carotene. However, the species has not been commercially exploited due to its extremely low oil yield. The current work describes the isolation of a cDNA clone coding for phytoene synthase (psy) from E. oleifera by RT-PCR amplification. A pair of psy gene specific primers was successfully used to amplify a 899 bp fragment that codes for a partial length (300 amino acids) of oil palm psy. The DNA and amino acid sequences were shown to share a high level of identity to phytoene synthase from other plants at about 83%. Further analysis also showed the presence of conserved aspartate-rich catalytic domains within the clone. Work was also carried out to obtain the expression pattern of oil palm psy in developing fruits by real-time PCR analysis. Results indicated that the gene is highly regulated during the course of oil palm fruit development. The pattern of psy expression was shown to be well correlated to the accumulation of lutein in the young mesocarp and α- and β-carotenes in the older tissues. This observation demonstrated that oil palm psy was highly regulated for tissue development and accumulation of carotenes for storage.

*Author for Correspondence.
Departamento de Ciencias Agrarias y Forestales,
Universidad Católica del Maule, Chile.
Avenida San Miguel, No.3605.

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Abstract.
Sweet potato is a major world crop and its behavior under in vitro culture is genotype dependent. We study several factors influencing the regeneration and transformation efficiency of two recalcitrant cultivars: Jewel and CEMSA 78354. Growth regulators, explant preparation and removal of apical dominance were evaluated in order to optimize the regeneration steps. At the same time, the influence of environmental conditions for the interaction between Agrobacterium tumefaciens and leaves were evaluated to obtain higher transformation efficiencies.
For Jewel, the best results were obtained when intact leaf explants were cultivated on MS medium supplemented with 0.5 mgL^-1 indol-3-acetic acid for four weeks (Regeneration frequency, RF= 2.02). However, for CEMSA 78354 the best results were obtained by culturing leaf explants on MS medium supplemented with 1.0 mgL^-1 paclobutrazol and 1.0 mgL^-1 naftalenacetic acid (RF= 0.98).
Optimal transformation conditions were obtained for both cultivars by co-cultivating leaf explants with Agrobacterium tumefaciens in liquid MS medium for 24 hours at 28°C in stationary cultures in the dark. Acetosyringone influence on the transformation efficiency was found to be dependent on the co-cultivation temperature but it did not increase the transformation efficiencies. Molecular evidences by PCR, Southern blot and Dot blot demonstrated the effectiveness of the transformation procedure. The protocol described here is currently in use to produce transgenic sweet potatoes from different cultivars with high efficiency.

*Author for Correspondence.
Tel: +60-(0)3-79675872;
Fax: +60-(0)3-79675908;
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract.
In this study, we employed a modified method to extract DNA from forest topsoil that was suitable for construction of large insert soil metagenomic library. The DNA extraction method used produced considerable DNA yield with DNA fragments ranging from 48 kb up to 290 kb. The recovery of soil DNA suitable for PCR and metagenomic library construction is difficult because soil DNA is often co-purified with polyphenolics and contaminants that interfere with the downstream applications.
PCR amplification of 16S and fungal 18S SSU rRNA genes from the extracted soil DNA suggesting that the DNA isolated using this modified method contained low concentration of PCR inhibitory substances and had sufficient purity for PCR without the need of further purification. Sequence analysis of PCR amplicons revealed this extraction method can efficiently capture a wide range of microorganisms including the hard-to-lyse Gram-positive bacteria and fungi. We have also successfully constructed a metagenomic fosmid library with insert size of between 23.1 kb – 40 kb. This metagenomic library will serve as basis for screening of novel biocatalysts from the soil metagenome.