L-Asparaginase II signal peptide was used for the secretion of recombinant cyclodextrin glucanotransferase (CGTase) into the periplasmic space of E. coli. Despite its predominant localisation in the periplasm, CGTase activity was also detected in the extracellular medium, followed by cell lysis. Five mutant signal peptides were constructed to improve the periplasmic levels of CGTase. N1R3 is a mutated signal peptide with the number of positively charged amino acid residues in the n-region increased to a net charge of +5. This mutant peptide produced a 1.7-fold enhancement of CGTase activity in the periplasm and significantly decreased cell lysis to 7.8% of the wild-type level. The formation of intracellular inclusion bodies was also reduced when this mutated signal peptide was used as judged by SDS-PAGE. Therefore, these results provide evidence of a cost-effective means of expression of recombinant proteins in E. coli.

The red hybrid tilapia (Oreochromis spp.) and the black tilapia, including the genetically improved farmed tilapia (GIFT) (Oreochromis niloticus (Linnaeus, 1758)) collectively contributed to about 30.7 % of the total freshwater aquaculture production in Malaysia in 2018. The red hybrid tilapia is the most important, accounting for 94 % of total tilapia production. Among the major problems encountered in tilapia farming is the inconsistent supply of quality and adequate seeds, which could be solved through systematic breeding programmes. Among the major problems encountered in tilapia species farming is the inconsistent supply of quality and adequate seeds, which could be solved through systematic breeding programmes. This paper discusses the status of the red hybrid tilapia breeding programme in Malaysia, including issues and future perspectives. In brief, the first systematic breeding programme was initiated by the Fisheries Research Institute (FRI) in 2008. Selected founder stocks from Malaysia, Taiwan and Thailand were used to establish a base population for the programme. In this programme, the combined selection was practised which produced six generations of selection and successfully improved 12.5 % of harvest body weight per generation. The 6th generation was used as one of the founder stocks, apart from FRI Glami Lemi, Negeri Sembilan and Pahang populations to improve resistance to Streptococcus agalactiae. In 2017, the scope of the programme was expanded to include molecular tool in identifying markers for growth. Ten SNP markers associated with high growth performance traits were discovered. The provision of better breeding stocks for the aquaculture industry and the development of safe and productive operations are expected to result in more stable fish production and an improved income for farmers.

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Galactooligosaccharides (GOS) synthesis has received much attention due to its prebiotic function. Beta-1,4-galactanase responsible for the hydrolysis of galactan plays an important role in producing GOS from biodegradation of this pectin component. In this study, beta-1,4-galactanase (BgcGC) from a thermophilic Geobacillus mahadii Geo-05 was heterologously expressed in Escherichia coli (E. coli) and characterized. The optimum temperature of BgcGC was at 60°C and stable from 20-60°C while optimum pH was at 6 and stable from pH 4-10. BgcGC showed high catalytic efficiency towards potato galactan (873.8 ml mg-1 s-1) and lupin galactan (1694.4 ml mg-1 s-1). The activity of BgcGC was not significantly affected with the presence of 100 mM K+, Tween-20 and 2-mercaptoethanol. Application of BgcGC towards pectin-containing galactan oligomer extracted from sweet potato peels resulted in galactose and GOS synthesis as revealed by high performance liquid chromatography analysis. Thus, this enzyme has a potential to be one of the enzyme candidates involves in pectin complex degradation to produce GOS.