Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

The current issues of the depletion of fossil fuels reserve and environmental changes have increased the concern for the hunt of sustainable renewable energy for the future generations. Biofuels emerged as a promising viable alternative to replace the existing fossil fuels. Among these, bioethanol outstands due to its ability to substitute gasoline.

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Herein, we describe the synthesis of 11new thiazolyl coumarin derivatives and evaluation of their potential role as antibacterial and antituberculosis agents. The structures of the synthesized compounds were established by extensive spectroscopic studies (Fourier transform infrared spectroscopy, 1 H-nuclear magnetic resonance, 13 Cnuclear magnetic resonance, 2D-nuclear magnetic resonance and liquid chromatography-mass spectrometry) and elemental analysis.

In this study, the efficacy of four DNA markers and their combinations (rbcL, matK, ITS, trnH-psbA) as barcode markers were tested across the endangered Paphiopedilum species from Peninsular Malaysia. Four species of Paphiopedilum were sampled and barcoded. The DNA barcodes reliabilities were evaluated using NCBI BLASTn program, phylogenetic tree via Neighbour-Joining method with 1000 bootstrap replicates in MEGA 6 and barcoding gap assessment. matK is the most promising barcode with high sequence quality (100%), high accuracy in BLASTn (100%), clear resolution of species in Neighbour-Joining phylogenetic tree (100%) and a distinct barcoding gap followed by ITS, trnH-psbA and rbcL. The combination of barcode regions revealed the lack of variation in rbcL and trnH-psbA but they are still useful for preliminary identification followed up by matK for accurate identification.

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Dimorphorchis lowii is a rare epiphytic orchid endemic to Borneo and very popular due to its ornamental value. For the purpose of mass propagation, procedures for in vitro propagation through callus were developed. The objectives of this study were to determine the effects of plant growth regulators (PGRs) on callus induction from leaf tip explant and the effects of complex additives on PLBs formation and shoot development. The best combination of PGR was 3.0 mg L -1 Thidiazuron (TDZ) with 0.046 mg L -1 NAA supplemented in half-strength medium (½ MS) (Murashige & Skoog, 1962). The percentage of survival and callus formation obtained were 96.0 % ± 19.8 and 52.0 % ± 16.5 respectively. Maximum shoot proliferation from PLBs was observed in Knudson C (KC) medium enriched with 15 % (v/v) coconut water. In this treatment, 10.2 ± 6.2 shoots were produced from one callus explant. Shoots were rooted on KC medium containing 15 % (v/v) coconut water and transferred in a medium mixture containing sphagnum moss, charcoal, brick and coco peat with the ratio of 1:1:1:1. After 2 months being acclimatized in the glasshouse, 78 % of plantlets survived. Histology observations showed that embryogenic callus derived from leaf tip explants might originate from epidermis and mesophyll cells and was capable of developing into complete plantlets.

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