Chemical and genetic diversity of two Mediterranean subspecies of Teucrium polium L.

Chemical and genetic diversity of Teucrium polium L. subsp. polium from western Algeria and T. polium L. subsp. capitatum from Corsica were investigated. Diversity within and among the two populations of subspecies was assessed according to the chemical composition of their essential oils and the genetic diversity. Chemical analysis was performed using a combination of capillary GC-RI and GC/MS after fractionation using column chromatography. Genetic structures were mapped using three polymorphic genetic markers: two chloroplast markers (RPL32-TRNL and TRNL-F) and ribosomal nuclear markers (ITS region). The statistical analysis showed that both subspecies were clearly distinguished by these chemical and genetic markers. The oil chemical compositions differed qualitatively and quantitatively between the subspecies. Both collective oils were dominated by hydrocarbon compounds however the Algerian sample oils exhibited higher amounts of hydrocarbon sesquiterpenes than those of Corsica (31.2 g/100 g vs. 4.4 g/100 g) while the latter displayed higher amounts of hydrocarbon monoterpenes than the first (59.3 g/100 g vs. 34.3 g/100 g). Neighbor-joining, Maximum likelihood and Bayesian trees constructed from chloroplast markers and nuclear ITS region sequences showed the existence of two groups associated with taxonomic and chemical characteristics. The study indicated that variation in the essential oil composition within subspecies depends on genetic background. The samples of subsp. capitatum from Corsica are a homogeneous group, in contrast to samples of subsp. polium from Algeria which were clustered in two groups. Chemical and genetic diversity of Algerian populations could be explained by geographical isolation of the populations. In addition, the morphological polymorphism observed throughout the colour of flowers could be explained by environmental parameters as well as the soil pH.     

LC–MS quantification of parthenolide and cholinesterase inhibitory potential of selected Tanacetum L. (Emend. Briq.) taxa

The acetonitrile extracts of various Tanacetum L. (Emend. Briq.) taxa from Turkey as well as parthenolide, a sesquiterpene lactone found in Tanacetum species as active substance were investigated for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in pathogenesis of Alzheimer's disease, at 100 μg mL⁻¹ using ELISA microplate assay. Most of the extracts displayed a remarkable AChE inhibition where the leaf of Tanacetum argenteum subsp. flabellifolium had the highest inhibition (96.68 ± 0.35%). The extracts had moderate inhibition toward BChE, among which the stem of Tanacetum argyrophyllum var. argyrophyllum-1 exerted the best inhibition (63.81 ± 3.64%). However, parthenolide exhibited low inhibition against both of the enzymes. Total flavonoid content of the extracts was determined spectrophotometrically. Parthenolide, a sesquiterpene lactone, was quantified in these taxa by LC–MS and the leaf of T. argenteum subsp. argenteum possessed the richest parthenolide amount (2.261 ± 0.002%), while most of the species screened were found to contain the required percentage (0.2% minimum) by European Pharmacopeia.     

Serotonin transporter protein (SERT) and P-glycoprotein (P-gp) binding activity of montanine and coccinine from three species of Haemanthus L. (Amaryllidaceae)

The alkaloid rich extracts from an acid/base extraction of bulb material of Haemanthus coccineus L., H. montanus Baker and H. sanguineus Jacq. revealed that two montanine type Amaryllidaceae alkaloids, montanine (1) and coccinine (2) were the major alkaloid constituents. Together these two alkaloids constituted 88, 91 and 98% of the total alkaloid extract from each species respectively. GC–MS analysis revealed that H. coccineus and H. sanguineus had a relative abundance of coccinine (74 and 91% respectively) to montanine (14 and 7% respectively); whereas H. montanus had 20% coccinine and 71% montanine. The three extracts and two isolated alkaloids were evaluated for binding to the serotonin transporter protein (SERT) in vitro. Affinity to SERT was highest in H. coccineus (IC₅₀ = 2.0 ± 1.1 μg/ml) followed by H. montanus (IC₅₀ = 6.8 ± 1.0 μg/ml) and H. sanguineus (IC₅₀ = 28.7 ± 1.1 μg/ml). Montanine (IC₅₀ = 121.3 ± 3.6 μM or 36.56 ± 1.14 μg/ml; K_i = 66.01 μM) was more active than coccinine (IC₅₀ = 196.3 ± 3.8 μM or 59.15 ± 1.08 μg/ml; K_i = 106.8 μM), both of which were less active than the total alkaloid extracts of each species investigated. The possible synergistic effects of two coccinine/montanine mixtures (80:20 and 20:80) were investigated, however the mixtures gave similar activities as the pure compounds and did not show any increase in activity or activity similar to the total alkaloid extracts. Thus the considerably higher activity observed in the total alkaloid extracts is not correlated to the relative proportions of coccinine and montanine in the extracts and thus are likely to be due to more potent unidentified minor constituents. Both alkaloids exhibited low binding affinity to P-glycoprotein (P-gp) as demonstrated by low inhibition of calcein-AM efflux in the MDCK-MDR1 cell line. This indicates that P-gp efflux will not be limiting for blood–brain-barrier passage of the alkaloids.     

Solution for promoting egl3 gene of Trichoderma reesei high-efficiency secretory expression in Escherichia coli and Lactococcus lactis

The objective of this study was to develop a solution for promoting egl3 gene of Trichoderma reesei (coding β-1,4-endoglucanase, EGIII) high-efficiency secretory expression in Escherichia coli and Lactococcus lactis and to investigate the effect of the best recombinant on degrading paper and wheat straw. The coding sequence of the egl3 gene fused with a gene fragment of Usp45 (usp45) of L. lactis was cloned to pMG36e and was expressed in E. coli DH 5α (DH 5α) and L. lactis subsp. lactis MG1363 (MG1363). The maximal productivity in recombinant DH 5α was 226 mU mL⁻¹ for extracellular EGIII and 535 mU mL⁻¹ for intracellular EGIII. The maximal productivity in recombinant MG1363 was 1118 mU mL⁻¹ for extracellular EGIII and 761 mU mL⁻¹ for intracellular EGIII. The plasmid stability in recombinant MG1363 was higher than 85% at 60 generations. Recombinant MG1363 vigorously degraded paper and wheat straw and produced sufficient acids. This study provided EGIII transgenic lactic acid bacteria for processing agricultural byproducts.     

The 1.6 Mb chromosome carrying the avirulence gene AvrPik in Magnaporthe oryzae isolate 84R-62B is a chimera containing chromosome 1 sequences

A genetic map was constructed previously from a cross between Magnaporthe oryzae isolates 84R-62B and Y93-245c-2, and genetic markers closely linked to the cultivar-specific avirulence (Avr) gene, AvrPik, were assigned to a 1.6 Mb small chromosome of 84R-62B that is absent from Y93-245c-2. In the present study, the 1.6 Mb chromosome was characterized by using contour-clamped homogeneous electric fields (CHEF) electrophoresis and hybridization analysis. CHEF electrophoresis analysis showed that the 1.6 Mb chromosome was inherited in Mendelian fashion, and co-segregated with AvrPik. Southern hybridization analysis revealed that the 1.6 Mb chromosome carried sequences only distributed to the supernumerary chromosome in M. oryzae isolates, as well as sequences corresponding to those in the supercontig 17 of chromosome 1 in the M. grisea database. Thus, we conclude that the Mendelian 1.6 Mb chromosome is a chimera containing sequences from chromosome 1 and from supernumerary chromosomes in M. oryzae.     

Capillary zone electrophoresis for enumeration of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus in yogurt

Enumeration of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus is a priority due to their importance in yogurt production. Capillary electrophoresis (CE) of both bacteria could be achieved in 7.2 min with a resolution of 3.2 in the background electrolyte (BGE) containing 4.5 mM Tris(hydroxymethyl) amminomethane (TRIS)–4.5 mM boric acid–0.1 mM ethylenediamine tetraacetate (EDTA) (TBE) buffer (pH 8.4) and 0.05% (v/v) polyethylene oxide (PEO), using a capillary of 47.5 cm (effective length) × 100 μm i.d., injection of 50 mbar × 3 s followed by ?5 kV × 120 s, a voltage and temperature of 20 kV and 25 °C, respectively. Appropriate amounts of PEO in the BGE, sample preparation (i.e. vortex) and introduction were key factors for their separation. A short hydrodynamic injection followed by applying reversed polarity voltage could compress the bacteria into narrow zones, which were detected as separated single peaks. Method linearity (r² > 0.99), precision (%RSDs < 9.3%), recovery (%R = 91.7–106.7%) and limit of quantitation (1.0 × 10⁶ colony forming unit per mL (CFU/mL)) were satisfactory. Results from the CE analysis of both bacteria in yogurt were not statistically different from those of the plate count method (P > 0.05). The CE method can be used as an alternative for quantitation of L. delbrueckii subsp. bulgaricus and S. thermophilus in yogurt since it was reliable, simple, cost and labor effective and rapid, allowing the analysis of 3 samples/h (comparing to 2d/sample by plate count method).     

Population structure and genetic diversity of Dysosma versipellis (Berberidaceae), a rare endemic from China

Dysosma versipellis (Berberidaceae) is an endangered and endemic species in China. To provide scientific foundation for formulating conservation strategies, we sampled six extant populations of this species and assessed the levels and patterns of genetic diversity using ISSR markers (11 primers). Of 144 bands detected 57.64% were polymorphic, but on average only 20.72% were polymorphic within populations. Our results revealed a low level of intraspecific genetic diversity (at population level: H_pop = 0.082, H_B = 0.177, SI = 0.1194; at species level: H_pop = 0.207, H_B = 0.378, SI = 0.3069). A high level of genetic differentiations among populations was detected based on Nei's genetic diversity analysis (60%), AMOVA analysis (65%), and Bayesian analysis (53%). The low levels of heterozygosity and high genetic differentiation observed in D. versipellis may be the consequence of low rate of natural recruitment, clonal growth, gene drift, and habitat fragmentation. Based on this, we suggest that in situ conservation be an important and practical measure for maintaining the genetic diversity of this species. Ex situ conservation should sample from different populations across the distribution range of the species to conserve high genetic diversity.     

Multilocus phylogeography of the Wedge-billed Woodcreeper Glyphorynchus spirurus (Aves,Furnariidae) in lowland Amazonia: Widespread cryptic diversity and paraphyly reveal a complex diversification pattern

Amazonian rivers function as important barriers to dispersal of Amazonian birds. Studying population genetics of lineages separated by rivers may help us to uncover the dynamics of biological diversification in the Amazon. We reconstructed the phylogeography of the Wedge-billed Woodcreeper, Glyphorynchus spirurus (Furnariidae) in the Amazon basin. Sampling included 134 individuals from 63 sites distributed in eight Amazonian areas of endemism separated by major Amazonian rivers. Nucleotide sequences were generated for five genes: two mtDNA genes (1047 bp for cyt b and 1002 bp for ND2) and three nuclear genes (647 bp from the sex-linked gene ACO, 319 bp from the intron of G3PDH, and 619 bp from intron 2 of MYO). In addition, 37 individuals were randomly selected from the Rondônia and Inambari areas of endemism for genomic fingerprinting, using five ISSR primers. Our results reveal allopatric and well-supported lineages within G. spirurus with high levels of genetic differentiation (p-distances 0.9–6.3%) across opposite banks of major Amazonian rivers. The multilocus phylogenetic reconstructions obtained reveal several incongruences with current subspecies taxonomy. Within currently recognized subspecies, we found high levels of both paraphyly and genetic differentiation, indicating deep divergences and strong isolation consistent with species-level differences. ISSR fingerprinting supports the existence of genetically differentiated populations on opposite sides of the Madeira River. Molecular dating suggests an initial vicariation event isolating populations from the Guiana center of endemism during the Late Miocene/Early Pliocene, while more recent events subdivided Brazilian Shield populations during the Lower Pleistocene.     

Molecular distinction of C × R hybrid (Coffea congensis × Coffea canephora) from morphologically resembling male parent using rbcL and matK gene sequences

Interspecific C × R hybrid (Coffea congensis × Coffea canephora) in India is cultivated as mixed population with male parent C. canephora as this species is an efficient pollen donor for enhanced yield. But distinction of C × R hybrid from C. canephora in old plantation is difficult due to varying plant sizes of C × R hybrid and often resembles with C. canephora. C × R hybrid cultivated under different agroclimatic conditions show distinct vegetative growth pattern with varying yields. Thus development of DNA marker for identification of C × R hybrid is important for clonal propagation and seed preparation from selective individuals. In this study, two DNA bar coding loci of chloroplast genome (rbcL and matK) of parents, F1 hybrid and its back cross progeny were partially sequenced to identify SNPs as DNA marker for distinction of C × R hybrid from C. canephora. Seven SNPs in the matK gene sequence and three nucleotides in the rbcL gene sequence were identified as DNA markers for the genetic identity of C. congensis. These SNPs were found in F1 and advanced progenies of C × R hybrid due to maternal inheritance. Large number of samples of C × R hybrids with varying morphological features revealed no polymorphism among C × R hybrid and C. congensis. Thus, the SNPs in C. congensis can be used as DNA markers for precise identification of C × R hybrid for production of clones besides tagging the chloroplast inheritance in advanced progenies.     

A transcriptomic analysis on gene expressions in the infective third and pathogenic fifth larval stages of Angiostrongylus cantonensis

Although Angiostrongylus cantonensis is a parasite of rats, it is an important etiologic agent of eosinophilic meningitis and eosinophilic meningoencephalitis in humans. This study was designed to compare the gene expression in the third- and fifth-stage (L3 and L5) by analysis of expressed sequence tags (ESTs). After removing low quality sequences, vector trimming, clustering and contig assembly, there remained 1437 clusters (285 contigs and 1152 singletons). Among these clusters, 779 (54.2%) showed significant similarity to the known proteins in the non-redundant protein database of GenBank (E-value < 1 × 10^− 10) and species of the best hit sequences mainly belonged to nematodes. These clusters included 869 (60.5%) that were entirely comprised of ESTs from L3 (L3-biased clusters), 518 (36.0%) entirely from L5 (L5-biased clusters) and 50 (3.5%) from both stages (stage-shared clusters). Functional annotations by the Gene Ontology (GO) comparing with the eukaryotic clusters of orthologous groups of proteins (KOG) indicate that the L3-biased clusters significantly related to metabolism and the L5-biased clusters to growth, development, sexual differentiation and reproduction. Moreover, L3 were found to have expressions of metalloproteases, aspartic proteases, and cysteine proteases whereas expressions of cysteine, aspartic and serine proteases were revealed in L5. The results indicate that earlier developmental stages of nematodes may have a gene expression profile towards metabolism and later stages towards growth and development.     

White shrimp Litopenaeus vannamei catalase: Gene structure,expression and activity under hypoxia and reoxygenation

Catalase (EC 1.11.1.6) is an antioxidant enzyme involved in redox equilibrium, regulating hydrogen peroxide (H₂O₂) concentration, a harmful reactive oxygen species (ROS) that is produced during hypoxia. Hypoxia occurs commonly in aquatic environments and in shrimp farms. We studied the catalase gene of the shrimp Litopenaeus vannamei and tested its expression and enzyme activity during hypoxia (1.5 mg/L O₂; 6 and 24 h) and reoxygenation (1 h after hypoxia). The complete gene is 2974 bp long and has four introns of 821, 223, 114 and 298 bp, respectively. The first intron has tree microsatellites, with GT and (T)AT(GT) repeated sequences. L. vannamei catalase is part of an invertebrate clade including crustaceans and rotifers. Catalase expression and activity is different in gills and hepatopancreas. Expression in gills increased 3.2 and 3-fold in response to hypoxia and reoxygenation (6 and 24 h hypoxia, followed by 1 h reoxygenation) compared to normoxia, while no differences were detected in the expression and activity in hepatopancreas. Catalase activity in gills had a contrary response to expression in hypoxia and reoxygenation.     

Peptidomic analysis of skin secretions supports separate species status for the tailed frogs,Ascaphus truei and Ascaphus montanus

The tailed frog Ascaphus truei Stejneger, 1899 is the most primitive extant anuran and the sister taxon to the clade of all other living frogs. The species occupies two disjunct ranges in the Northwest region of North America: the Cascade Mountains and coastal area from British Columbia to Northern California, and an inland range in the northern Rocky Mountains and the Blue and Wallowa mountains. A previous study led to the isolation of eight peptides with antimicrobial activity (termed the ascaphins) from skin secretions of A. truei from the coastal range. The present study has used peptidomic analysis to identify the products of orthologous ascaphin genes in electrically-stimulated skin secretions from inland range specimens. Structural characterization of the peptides demonstrated that ascaphins from the inland range contained the following amino acid substitutions compared with orthologs from the coastal range frogs: ascaphin-1 (Ala¹² → Glu), ascaphin-3 (Asp⁴ → Glu), ascaphin-4 (Ala¹⁹ → Ser), ascaphin-5 (Lys¹² → Thr), and ascaphin-7 (Gly⁸ → Ser and Ser²⁰ → Asn). Orthologs of ascaphins-2, -6, and -8 were not identified but a paralog of ascaphin-5, identical to ascaphin-5 from coastal range frogs, was found. The data support the claims, derived from analysis of the nucleotide sequences of mitochondrial genes, that the inland populations of the tailed frog should be recognized as a distinct species, the Rocky Mountain tailed frog Ascaphus montanus and that the divergence of the species from A. truei probably occurred in the late Miocene (approximately 10 Mya).     

Chloroplast DNA variation and phylogeographic patterns in the Chinese endemic marsh herb Sagittaria potamogetifolia

We examined chloroplast DNA (cpDNA) atpB–rbcL intergenic spacer sequences variation within Sagittaria potamogetifolia, an endangered and endemic marsh herb in China. Sequence data were obtained from 54 individuals in six extant populations of the species. Sequences appeared to evolve neutral (Tajima's criterion D = −1.59826, 0.1 > P > 0.05 and Fu and Li's tests D* = −1.44484, P > 0.1; F* = −1.83446, P > 0.1). Eleven haplotypes were identified in S. potamogetifolia. A relatively high level of haplotype diversity (h = 0.0.699) and low level of nucleotide diversity (pi = 0.0035 ± 0.0020) were detected in S. potamogetifolia. Pairwise comparisons of F_st and Nm deduced from cpDNA variation suggested no significant genetic differentiation between populations of S. potamogetifolia excepted for the WY-1 population. Low genetic differentiation among populations and also among regions was consistently indicated by both hierarchical analyses of molecular variance (AMOVA) and the structure of a neighbor-joining tree. Lack of population differentiation between populations or between regions in cpDNA sequences may be due to effects of lower substitution rates or lineage sorting. In the minimum spanning network, all tip haplotypes except for the haplotype J were unique to a particular population, while the interior nodes except for the haplotype E were widespread (haplotype A). From nested clade analysis (NCA), the evolutionary events such as restricted gene flow with isolation by distance and allopatric fragmentation were inferred to responsible for the current distribution of S. potamogetifolia populations, as well as their genetic diversity.     

Signal-to-noise ratio of diffusion weighted magnetic resonance imaging: Estimation methods and in vivo application to spinal cord

Diffusion tensor imaging (DTI) and tractographic reconstruction may be applied for in vivo clinical spinal cord studies. However, this structure represents a challenge to current acquisition and reconstruction strategies, due to its small size, motion artifacts, partial volume effects and low signal-to-noise-ratio (SNR). Aims of this work were to select the best approach for the estimate of SNR and to use it for spinal cord diffusion weighted (DW) sequence optimization.Seven methods for the estimate of SNR were compared on uniform phantom DW images, and the best performing approach (single ROI for signal and noise, difference of images—SNR_diff) was applied for the following in vivo sequence evaluations.Fifteen sequences with different parameters (voxel size, repetition (TR) and echo (TE) times) were compared according to SNR, resolution, fractional anisotropy (FA) and tractography performances on three healthy volunteers. In vivo optimization of DW sequences resulted in: axial sequence, with voxel size = 1.5 mm × 1.5 mm × 3.5 mm, TR = 3200 ms and TE = 89 ms, sagittal sequence with voxel size = 2.2 mm × 2.2 mm × 2 mm, TR = 3000 ms and TE = 84 ms.An objective method tested on phantom and a practical index for in vivo spinal cord DTI SNR estimation allowed to obtain axial and sagittal optimized sequences, providing excellent tractographic results, with acceptable acquisition times for in vivo clinical applications.     

Morphological and molecular characterization of Thelohanellus macrovacuolaris n. sp. (Myxosporea: Bivalvulida) infecting the palate in the mouth of common carp Cyprinus carpio L. in China

Thelohanellus macrovacuolaris n. sp. is described during a survey on myxozoan diversity of common carp Cyprinus carpio L. in China. It is characterized by the presence of round or ellipsoidal plasmodium in the palate in the mouth of host. Mature spores were pyriform in frontal view, lemon shaped in lateral view, measuring 21.6 ± 0.9 (19.3–23.8) long, 12.5 ± 0.7 (10.3–13.6) wide, and 10.2 ± 0.4 (9.8–11.8) thick. Most spores were surrounded by the membrane sheath. Single polar capsule was round with an apophysis at its top end presented close to apex of spore, measuring 9.1 ± 0.6 (8.0–10.0) in length, 8.6 ± 0.5 (7.8–9.6) in width. Polar filaments coiled, with 7 to 8 turns. A large, round iodinophilous vacuole was present, with 5.8–7.5 in diameter. The present species is morphologically distinct from all other Thelohanellus species. The BLAST search indicated that the newly obtained small subunit ribosomal RNA (ssrRNA) gene sequence of T. macrovacuolaris n. sp. did not match any available sequences in GenBank. Phylogenetically, T. macrovacuolaris n. sp. was placed sister to Thelohanellus wangi in the Thelohanellus clade. Both morphology and ssrRNA gene sequence data revealed that the present parasite is a new species of genus Thelohanellus.     

Cloning and sequencing of three new putative toxin genes from Clostridium bifermentans CH18

Three new open reading frames were found downstream from cbm71, a toxin gene from Clostridium bifermentans malaysia (Cbm) strain CH18. The first one (91 bp downstream) called cbm72, is 1857 bp long and encodes a 71 727-Da protein (Cbm72) with a sequence similar to that of Bacillus thuringiensis delta-endotoxins. This protein shows no significant toxicity to mosquito larvae. The two others, cbm17.1 (462 bp) and cbm17.2 (459 bp), are copies of the same gene encoding Cbm P18 and P16 polypeptides and located 426 bp and 1022 bp downstream from cbm72, respectively. They encode 17 189-Da and 17 451-Da proteins with sequences 44.6% similar to that of Aspergillus fumigatus hemolysin; however, they were not hemolytic in the conditions tested.     

Overexpression of polyphosphate kinase gene (ppk) increases bioinsecticide production by Bacillus thuringiensis

Polyphosphate (polyP), synthesized by polyP kinase (PPK) using the terminal phosphate of ATP as substrate, performs important functions in every living cell. The present work reports on the relationship between polyP metabolism and bioinsecticide production in Bacillus thuringiensis subsp. israelensis (Bti). The ppk gene of Bti was cloned into vector pHT315 and the effect of its overexpression on endotoxin production was determined. Endotoxin production by the recombinant strain was found to be consistently higher than that by the wild type strain and the strain that carried the empty plasmid. The toxicity of the recombinant mutant strain (LC₅₀ 5.8 ± 0.6 ng ml^?1) against late 2nd instar Culex quinquefasciatus was about 7.7 times higher than that of Bti (LC₅₀ 44.9 ± 7 ng ml^?1). To our knowledge this is the first reported study which relates polyP metabolism with bioinsecticide biosynthesis.     

Effect of chito-oligosaccharide on the oral absorptions of phenolic acids of Flos Lonicerae extract

Phenolic acids, the main active ingredients in Flos Lonicerae extract possess strong antibacterial, antioxidant and antiviral effects, and their contents was higher largely than that of other ingredients such as flavones, but the absolute bioavailability orally was significantly low, which is significant low influencing clinical efficacies of its oral preparations. In the present study, in vitro Caco-2 cell, in situ single-pass intestinal perfusion and in vivo pharmacokinetics study were performed to investigate the effects of COS on the intestinal absorption of phenolic acids. The pharmacological effects such as antiviral activity improvement by COS were verified by MDCK cell damage inhibition rate after influenza virus propagation. The observations from in vitro Caco-2 cell showed that the absorption of phenolic acids in Flos Lonicerae extract could be improved by COS. Meanwhile, COS at the same low, medium and high concentrations caused a significant, concentration-dependent increase in the P_app-value for phenolic acids compared to the control group (p < 0.05), and was all safe for the Caco-2 cells. The observations from single-pass intestinal perfusion in situ model showed that the intestinal absorption of phenolic acids can be enhanced by COS. Meanwhile, the absorption enhancing effect of phenolic acids might be saturable in different intestine sites. In pharmacokinetics study, COS at dosage of 25 mg/kg improved the bioavailability of phenolic acids in Flos Lonicerae extract to the greatest extent, and was safe for gastrointestine from morphological observation. Besides, treatment with Flos Lonicerae extract with COS at dosage of 25 mg/kg prevented MDCK cell damage upon influenza virus propagation better than that of control. All findings above suggested that COS at dosage of 25 mg/kg might be safe and effective absorption enhancer for improving the bioavailability of phenolic acids and the antiviral activity in vitro in Flos Lonicerae extract.     

Kinetic modeling and implementation of superior process strategies for β-galactosidase production during submerged fermentation in a stirred tank bioreactor

This paper reports development and implementation of superior fermentation strategies for β-galactosidase production by Lactobacillus acidophilus in a stirred-tank bioreactor. Process parameters (aeration and agitation) were optimized for the process by application of Central Composite Design. Aeration rate of 0.5 vvm and agitation speed of 250 rpm were most suitable for β-galactosidase production (2001.2 U/L). Further improvement of the operation in pH controlled environment resulted in 2135 U/L of β-galactosidase with productivity of 142.39 U/L h. Kinetic modeling for biomass and enzyme production and substrate utilization were carried out at the aforementioned pH controlled conditions. The logistic regression model (X₀ = 0.01 g/L; X_max = 2.948 g/L; μ_max = 0.59/h; R² = 0.97) was used for mathematical interpretation of biomass production. Mercier's model proved to be better than Luedeking–Piret model in describing β-galactosidase production (P₀ = 0.7942 U/L; P_max = 2169.3 U/L; P_r = 0.696/h; R² = 0.99) whereas the latter was more efficient in mathematical illustration of lactose utilization (m = 0.187 g/g h; Y_x/s = 0.301 g/L; R² = 0.98) among the two used in this study. Strategies like fed-batch fermentation (3694.6 U/L) and semi-continuous fermentation (5551.9 U/L) further enhanced β-galactosidase production by 1.8 and 2.8 fold respectively.