Alumina-doped alginate gel as a cell carrier for ethanol production in a packed-bed bioreactor

Alumina-doped alginate gel (AEC) was developed as a new type of cell carrier to be used in ethanol fermentation. The presence of the alumina particles in alginate gel not only improved the porous structure of the carrier, but also provided many advantageous characteristics including good mechanical strength, high stability, and high immobilization yield. The attachment of alumina particles and yeast cells by electrostatic attraction was shown to promote cell growth and increase ethanol productivity. The AEC carrier was found to be more effective for the immobilization of Saccharomyces cerevisiae M30 than the conventional Ca-alginate bead. Ethanol productivities of 1.4 and 7.9 ∼ 12.6 g/(L/h) were obtained using the AEC cultures in batch and continuous modes of operation, respectively, with an ethanol yield of 43.9 ∼ 46.7% and an immobilized yield of 81.4 ∼ 84.5%. Ethanol fermentation in a continuous packed-bed reactor using the AEC carrier was stable for > 30 days.     

Four novel species of the anamorphic yeast genus Candida found in Thailand and Taiwan

Four strains of yeasts isolated in Thailand and Taiwan were found to represent four distinct novel species of the ascomycetous anamorphic yeast genus Candida. These strains are located in the Clavispora-Metschnikowia clade in a phylogenetic tree based on the D1/D2 domain sequences of the large subunit rRNA genes. Together with Candida picinguabensis and Candida saopaulonensis, the four novel species constitute a well-separated subclade from other species of the Clavispora-Metschnikowia clade. Three species from Thailand are described as Candida bambusicola sp. nov. (type strain, ST-50(T) = BCC 7750(T) = NBRC 106734(T) = CBS 11723(T)), Candida nongkhaiensis sp. nov. (type strain, ST-95(T) = BCC 8331(T) = NBRC 105874(T) =CBS 11724(T)) and Candida succicola sp. nov. (type strain, ST-631(T) = BCC 15314(T) = NBRC 106736(T) = CBS 11726(T)), respectively, and the species from Taiwan is described as Candida touchengensis sp. nov. (type strain, SY4S03(T) = NBRC 102647(T) = BCRC 23097(T) = CBS 10585(T)).     

High-Temperature Ethanol Fermentation and Transformation with Linear DNA in the Thermotolerant Yeast Kluyveromyces marxianus DMKU3-1042

We demonstrate herein the ability of Kluyveromyces marxianus to be an efficient ethanol producer and host for expressing heterologous proteins as an alternative to Saccharomyces cerevisiae. Growth and ethanol production by strains of K. marxianus and S. cerevisiae were compared under the same conditions. K. marxianus DMKU3-1042 was found to be the most suitable strain for high-temperature growth and ethanol production at 45°C. This strain, but not S. cerevisiae, utilized cellobiose, xylose, xylitol, arabinose, glycerol, and lactose. To develop a K. marxianus DMKU3-1042 derivative strain suitable for genetic engineering, a uracil auxotroph was isolated and transformed with a linear DNA of the S. cerevisiae ScURA3 gene. Surprisingly, Ura⁺ transformants were easily obtained. By Southern blot hybridization, the linear ScURA3 DNA was found to have inserted randomly into the K. marxianus genome. Sequencing of one Lys⁻ transformant confirmed the disruption of the KmLYS1 gene by the ScURA3 insertion. A PCR-amplified linear DNA lacking K. marxianus sequences but containing an Aspergillus α-amylase gene under the control of the ScTDH3 promoter together with an ScURA3 marker was subsequently used to transform K. marxianus DMKU3-1042 in order to obtain transformants expressing Aspergillus α-amylase. Our results demonstrate that K. marxianus DMKU3-1042 can be an alternative cost-effective bioethanol producer and a host for transformation with linear DNA by use of S. cerevisiae-based molecular genetic tools.     

Candida sirachaensis sp. nov. and Candida sakaeoensis sp. nov. two anamorphic yeast species from phylloplane in Thailand

Three strains (LM008^T, LM068 and LM078^T), representing two novel yeast species were isolated from the phylloplane of three plant species by an enrichment technique. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and the sequence analysis of the D1/D2 domain of the large subunit rRNA gene and the internal spacer region, the three strains were assigned as two novel Candida species. Strain LM008^T was assigned to be Candida sirachaensis sp. nov. (type strain LM008^T = BCC 47628^T = NBRC 108605^T CBS 12094^T) in the Starmerella clade. Two strains (LM068 and LM078^T) represent a single species in the Lodderomyces-Spathaspora clade for which the name Candida sakaeoensis sp. nov. is proposed with the type strain LM078^T = BCC 47632^T = NBRC 108895^T = CBS 12318^T.     

Impaired renal organic anion transport 1 (SLC22A6) and its regulation following acute myocardial infarction and reperfusion injury in rats

Acute kidney injury (AKI) is a high frequent and common complication following acute myocardial infarction (AMI). This study examined and identified the effect of AMI-induced AKI on organic anion transporter 1 (Oat1) and Oat3 transport using clinical setting of pre-renal AKI in vivo. Cardiac ischaemia (CI) and cardiac ischaemia and reperfusion (CIR) were induced in rats by 30-min left anterior descending coronary artery occlusion and 30-min occlusion followed by 120-min reperfusion, respectively. Renal hemodynamic parameters, mitochondrial function and Oat1/Oat3 expression and function were determined along with biochemical markers. Results showed that CI markedly reduced renal blood flow and pressure by approximately 40%, while these parameters were recovered during reperfusion. CI and CIR progressively attenuated renal function and induced oxidative stress by increasing plasma BUN, creatinine and malondialdehyde levels. Correspondingly, SOD, GPx, CAT mRNAs were decreased, while TNFα, IL1β, COX2, iNOS, NOX2, NOX4, and xanthine oxidase were increased. Mitochondrial dysfunction as indicated by increasing ROS, membrane depolarisation, swelling and caspase3 activation were shown. Early significant detection of AKI; KIM1, IL18, was found. All of which deteriorated para-aminohippurate transport by down-regulating Oat1 during sudden ischaemia. This consequent blunted the trafficking rate of Oat1/Oat3 transport via down-regulating PKCζ/Akt and up-regulating PKCα/NFκB during CI and CIR. Thus, this promising study indicates that CI and CIR abruptly impaired renal Oat1 and regulatory proteins of Oat1/Oat3, which supports dysregulation of remote sensing and signalling and inter-organ/organismal communication. Oat1, therefore, could potentially worsen AKI and might be a potential therapeutic target for early reversal of such injury.     

Candida kazuoi sp. nov. and Candida hasegawae sp. nov., two new species of ascomycetous anamorphic yeasts isolated from insect frass in Thailand

Two strains of anamorphic yeasts isolated from insect frass collected in southern Thailand were assigned to the genus Candida based on the conventional taxonomic criteria used for yeast classification. In the phylogenetic tree based on the D1/D2 domain of the 26S rDNA, these strains are distant from the known species of yeasts and considered to represent two different new species. They are named Candida kazuoi sp. nov. and Candida hasegawae sp. nov.     

Torulaspora maleeae sp. nov., a novel ascomycetous yeast species from Japan and Thailand

Nine strains of a new Torulaspora species were isolated from natural samples collected in Japan and Thailand including one strain obtained from a leaf of Rhizophora stylosa (NBRC 11061T), one strain from soil (NBRC 11062), six strains from mosses (ST-14, ST-266, ST-510, ST-511, ST-513 and ST-581) and one strain from sediment in mangrove forest (RV-51). On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and the sequence analyses of the D1/D2 domain of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) (ITS1-5.8S rRNA gene-ITS2) region, the nine strains were found to represent a single novel species of the genus Torulaspora, which were named Torulaspora maleeae sp. nov. The type strain is NBRC 11061T (BCC 25515T=CBS 10694T). In the phylogenetic trees based on the sequences of the D1/D2 domain of the LSU rRNA gene, T. maleeae showed a close relationship with the five recognized species of the genus Torulaspora, Torulaspora delbrueckii, Torulaspora franciscae, Torulaspora globosa, Torulaspora microellipsoides and Torulaspora pretoriensis. Torulaspora maleeae differed from the five recognized species of the genus Torulaspora by six to 12 nucleotide substitutions (1.1-2.1%) in the D1/D2 domain of the LSU rRNA gene and by 6.4-11.7% nucleotide substitutions in the ITS (ITS1-5.8S rRNA gene-ITS2) region.     

Fed-batch fermentation of indole-3-acetic acid production in stirred tank fermenter by red yeast <Emphasis Type="Italic">Rhodosporidium paludigenum</Emphasis>

Indole-3-acetic acid (IAA) is a significant secondary metabolite that is the most important auxin of plant hormones. Production of IAA is considered to be a key trait to support plant growth. The improvement of IAA production by a basidiomycetous red yeast Rhodosporidium paludigenum DMKU-RP301 was investigated. Batch and fed-batch fermentation of R. paludigenum DMKU-RP301 were conducted in a 2 L stirred tank fermenter. Using batch fermentation, it was found that when cultivated at an agitation speed of 200 rpm and a 3 L/min aeration rate, this yeast produced IAA at its maximum level of 1,627.1 mg/L (9.7 mg/L/h). In fed-batch fermentation, a higher level of maximum IAA production than that found in batch fermentation was observed, i.e. 2,743.9 mg/L (25.4 mg/L/h). It is therefore suggested that fed-batch fermentation improves the efficiency of IAA production in terms of product concentration and IAA productivity. Moreover, yeast carotenoid production was also investigated using R. paludigenum DMKU-RP301, and found a maximum carotenoid production of 3.05 mg/L.     

Candida chanthaburiensis sp. nov., Candida kungkrabaensis sp. nov. and Candida suratensis sp. nov., three novel yeast species from decaying plant materials submerged in water of mangrove forests

In a taxonomic study of yeasts isolated from decaying plant materials submerged in water of mangrove forests in Thailand, three strains isolated from tree bark (EM33^T), a fallen leaf (EM40^T) and a detached branch (SM56^T) were found to represent three novel yeast species. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, the sequence analysis of the D1/D2 domain of the large subunit (LSU) rRNA gene, and the phylogenetic analysis, the three strains were assigned as three novel Candida species. They were named as Candida chanthaburiensis sp. nov. (type strain EM33^T = BCC 23057^T = NBRC 102176^T = CBS 10926^T), Candida kungkrabaensis sp. nov. (type strain EM40^T = BCC 23060^T = NBRC 102179^T = CBS 10927^T), and Candida suratensis sp. nov. (type strain SM56^T = BCC 25961^T = NBRC 103858^T = CBS 10928^T).     

Candida wangnamkhiaoensis sp. nov., an anamorphic yeast species in the Hyphopichia clade isolated in Thailand

Two strains representing a single novel yeast species were isolated from a flower of Calycoopteris floribunda Lame (SK170^T) and insect frass (ST-122) collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and the sequence analysis of the D1/D2 domain of the large subunit rRNA gene and the internal transcribed spacer region, the two strains were assigned as a single novel Candida species in the Hyphopichia clade for which the name Candida wangnamkhiaoensis sp. nov. is proposed. The type strain is SK170^T=BCC 39604^T=NBRC 106724^T=CBS 11695^T).