Enhancement of Nisin Production by <Emphasis Type="Italic">Lactococcus lactis</Emphasis> subsp. <Emphasis Type="Italic">lactis</Emphasis>

Lactococcus lactis subsp lactis BSA (L. lactis BSA) was isolated from a commercial fermented product (BSA Food Ingredients, Montreal, Canada) containing mixed bacteria that are used as starter for food fermentation. In order to increase the bacteriocin production by L. lactis BSA, different fermentation conditions were conducted. They included different volumetric combinations of two culture media (the Man, Rogosa and Sharpe (MRS) broth and skim milk), agitation level (0 and 100 rpm) and concentration of commercial nisin (0, 0.15, and 0.30 µg/ml) added into culture media as stimulant agent for nisin production. During fermentation, samples were collected and used for antibacterial evaluation against Lactobacillus sakei using agar diffusion assay. Results showed that medium containing 50 % MRS broth and 50 % skim milk gave better antibacterial activity as compared to other medium formulations. Agitation (100 rpm) did not improve nisin production by L. lactis BSA. Adding 0.15 µg/ml of nisin into the medium-containing 50 % MRS broth and 50 % skim milk caused the highest nisin activity of 18,820 AU/ml as compared to other medium formulations. This activity was 4 and ~3 times higher than medium containing 100 % MRS broth without added nisin (~4700 AU/ml) and 100 % MRS broth with 0.15 µg/ml of added nisin (~6650 AU/ml), respectively.     

The ectomycorrhizae of <Emphasis Type="Italic">Lactarius rimosellus</Emphasis> and <Emphasis Type="Italic">Lactarius acatlanensis</Emphasis> with the endangered <Emphasis Type="Italic">Fagus grandifolia</Emphasis> var. <Emphasis Type="Italic">mexicana</Emphasis>

Gut bacterium Pantoea sp. is one of the predominant bacterial species in the larval gut of the diamondback moth, Plutella xylostella. The phenotypic characters of Pantoea sp. were investigated with BIOLOG phenotype MicroArray (PM) in this study. Totally 950 different metabolic phenotypes were tested using the PM plates 1–10. Results exhibited that Pantoea sp. was able to metabolize 37.37 % of the tested carbon sources, 91.32 % of nitrogen sources, 100 % of sulfur sources, and 98.31 % of phosphorus sources. Most informative utilization patterns for carbon sources of Pantoea sp. were organic acids and carbohydrates, and for nitrogen were various amino acids. The bacterium had 94 different biosynthetic pathways. It had a wide range of adaptabilities, and could still metabolize in osmolytes with up to 9 % sodium chloride, 6 % potassium chloride, 5 % sodium sulfate, 20 % ethylene glycol, 4 % sodium formate, 4 % urea, 5 % sodium lactate, 200 mmol/L sodium phosphate (pH 7.0), 100 mmol/L ammonium sulfate (pH 8.0), 100 mmol/L sodium nitrate, and 100 mmol/L sodium nitrite, respectively. It also exhibited active metabolism under pH values between 4.5 and 10. Pantoea sp. showed active decarboxylase activities while poor deaminase activities in the presence of various amino acids. The phenotypic characterization of Pantoea sp. increased our knowledge of the bacterium, in particular its interactions with insect hosts and the adaptability in gut environments, and showed us some possible approaches to controlling diamondback moth through decreasing Pantoea sp. density.     

Polyhydroxyalkanoate Production and Degradation Patterns in <Emphasis Type="Italic">Bacillus</Emphasis> Species

Bacteria under stress conditions of excess of carbon (C) and limitations of nutrients divert its metabolism towards C storage as energy reservoir—polyhydroxyalkanoate (PHA). Different Bacillus species—B. cereus and B. thuringiensis, were monitored to produce PHA from different C sources—glucose, crude glycerol and their combination at 37 °C for period up to 192 h. PHA production and its composition was found to vary with feed and bacterial strains. PHA production on crude glycerol continued to increase up to 120 h, reaching a maximum of 2725 mg/L with an effective yield of 71% of the dry cell mass. Depolymerization of PHA was observe to initiate after 96 h of incubation up to 192 h. PHA degradation products have been envisaged to be applied in medical field: tissue engineering, drug carriers, memory enhancers, antiosteoporosis, biodegradable implants. The PHA production and degradation cycle for 192 h has not been reported previously in literature.     

<Emphasis Type="Italic">R</Emphasis>-acetoin accumulation and dissimilation in <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis>

Klebsiella pneumoniae is a 2,3-butanediol producer, and R-acetoin is an intermediate of 2,3-butanediol production. R-acetoin accumulation and dissimilation in K. pneumoniae was studied here. A budC mutant, which has lost 2,3-butanediol dehydrogenase activity, accumulated high levels of R-acetoin in culture broth. However, after glucose was exhausted, the accumulated R-acetoin could be reused by the cells as a carbon source. Acetoin dehydrogenase enzyme system, encoded by acoABCD, was responsible for R-acetoin dissimilation. acoABCD mutants lost the ability to grow on acetoin as the sole carbon source, and the acetoin accumulated could not be dissimilated. However, in the presence of another carbon source, the acetoin accumulated in broth of acoABCD mutants was converted to 2,3-butanediol. Parameters of R-acetoin production by budC mutants were optimized in batch culture. Aerobic culture and mildly acidic conditions (pH 6–6.5) favored R-acetoin accumulation. At the optimized conditions, in fed-batch fermentation, 62.3 g/L R-acetoin was produced by budC and acoABCD double mutant in 57 h culture, with an optical purity of 98.0 %, and a substrate conversion ratio of 28.7 %.     

Inactivation of the transcription factor <Emphasis Type="Italic">mig1</Emphasis> (<Emphasis Type="Italic">YGL035C</Emphasis>) in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> improves tolerance towards monocarboxylic weak acids: acetic,formic and levulinic acid

Toxic concentrations of monocarboxylic weak acids present in lignocellulosic hydrolyzates affect cell integrity and fermentative performance of Saccharomyces cerevisiae. In this work, we report the deletion of the general catabolite repressor Mig1p as a strategy to improve the tolerance of S. cerevisiae towards inhibitory concentrations of acetic, formic or levulinic acid. In contrast with the wt yeast, where the growth and ethanol production were ceased in presence of acetic acid 5 g/L or formic acid 1.75 g/L (initial pH not adjusted), the m9 strain (Δmig1::kan) produced 4.06?±?0.14 and 3.87?±?0.06 g/L of ethanol, respectively. Also, m9 strain tolerated a higher concentration of 12.5 g/L acetic acid (initial pH adjusted to 4.5) without affecting its fermentative performance. Moreover, m9 strain produced 33% less acetic acid and 50–70% less glycerol in presence of weak acids, and consumed acetate and formate as carbon sources under aerobic conditions. Our results show that the deletion of Mig1p provides a single gene deletion target for improving the acid tolerance of yeast strains significantly.     

Antimicrobial Peptide from <Emphasis Type="Italic">Bacillus</Emphasis> Strain K1R Exhibits Ameliorative Potential Against Vancomycin-Resistant <Emphasis Type="Italic">Enterococcus</Emphasis> Group of Organisms

Microorganisms secrete antimicrobial peptides (AMPs) which are part of the innate immune system and rapidly increase in concentration in the host upon challenge by pathogens, which they produce themselves. Kimchi, a traditional Korean food fermented by Bacillus organisms, is found to be ideal for AMP production. Our aim was to investigate the therapeutic potential of antimicrobial substances produced by Bacillus species. Peptide K1R was subjected to fermentation in a culture media containing carbon and nitrogen sources and metal ions. A protein band around 4.6 kDa was detected in tricine-SDS-PAGE and confirmed by in situ inhibitory activity of the gel. Peptide K1R was stable over a broad range of pH (6.5–9), thermo tolerant up to 60?°C and showed unaltered activity at low temperatures (0–4?°C). The complete amino acid sequence of peptide K1R was AVQGTLEDALNLSKGALNQVQKAIQNGDXLTVXGXLGTIXLAVSX. The antagonistic effect of peptide K1R against multiple drug resistant (MDR) pathogens such as Salmonella Typhimurium and Enterococcus sp. verified its potential application in treating MDR cases. The antioxidant activity of peptide K1R was also comparable to that of standard ascorbic acid.     

Nisin Z produced by <Emphasis Type="Italic">Lactococcus lactis</Emphasis> from bullfrog hatchery is active against <Emphasis Type="Italic">Citrobacter freundii</Emphasis>, a red-leg syndrome related pathogen

Lactococcus lactis subsp. lactis CRL 1584 isolated from a bullfrog hatchery produces a bacteriocin that inhibits both indigenous Citrobacter freundii (a Red-Leg Syndrome related pathogen) and Lactobacillus plantarum, and Listeria monocytogenes as well. Considering that probiotics requires high cell densities and/or bacteriocin concentrations, the effect of the temperature on L. lactis growth and bacteriocin production was evaluated to find the optimal conditions. Thus, the growth rate was maximal at 36 °C, whereas the highest biomass and bacteriocin activity was achieved between 20 and 30 °C and 20–25 °C, respectively. The bacteriocin synthesis was closely growth associated reaching the maximal values at the end of the exponential phase. Since bacteriocins co-production has been evidenced in bacterial genera, a purification of the bacteriocin/s from L. lactis culture supernatants was carried out. The active fraction was purified by cationic-exchange chromatography and then, a RP-HPLC was carried out. The purified sample was a peptide with a 3353.05 Da, a molecular mass that matches nisin Z, which turned out to be the only bacteriocin produced by L. lactis CRL 1584. Nisin Z showed bactericidal effect on C. freundii and L. monocytogenes, which increased in the presence l-lactic acid?+?H₂O₂. This is the first report on nisin Z production by L. lactis from a bullfrog hatchery that resulted active on a Gram-negative pathogen. This peptide has potential probiotic for raniculture and as food biopreservative for bullfrog meat.     

Endocellulase Production by <Emphasis Type="Italic">Cotylidia pannosa</Emphasis> and its Application in Saccharification of Wheat Bran to Bioethanol

For efficient bioconversion of lignocellulosic materials to bioethanol, the study screened 19 white-rot fungal strains for their endocellulolytic activity and saccharification potential. Preliminary qualitative and quantitative screening revealed Cotylidia pannosa to be the most efficient endocellulase producing fungal strain when compared to the standard strain of Trichoderma reesei MTCC 164. Ensuing initial screening, the production of endocellulase was further optimized using submerged fermentation to recognize process parameters such as temperature, time, agitation pH, and supplementation of salts in media required for achieving maximum production of endocellulase. The strain C. pannosa produced the maximum amount of endocellulase (8.48 U/mL) under submerged fermentation with wheat bran (2%) supplemented yeast extract peptone dextrose (YEPD) medium after an incubation time of 56 h at 30 °C and pH 5.0 at an agitation rate of 120 rpm with a saccharification value of 50.5%. The fermentation of wheat bran hydrolysate with Saccharomyces cerevisiae MTCC 174 produced 4.12 g/L of bioethanol after 56 h of incubation at 30 °C. The results obtained from the present investigation establish the potential of white-rot fungus C. pannosa for hydrolysis and saccharification of wheat bran to yield fermentable sugars for their subsequent conversion to bioethanol, suggesting its application in efficient bioprocessing of lignocellulosic wastes.     

A new source of resistance to 2-furaldehyde from <Emphasis Type="Italic">Scheffersomyces</Emphasis> (<Emphasis Type="Italic">Pichia</Emphasis>) <Emphasis Type="Italic">stipitis</Emphasis> for sustainable lignocellulose-to-biofuel conversion

Aldehyde inhibitory compounds derived from lignocellulosic biomass pretreatment have been identified as a major class of toxic chemicals that interfere with microbial growth and subsequent fermentation for advanced biofuel production. Development of robust next-generation biocatalyst is a key for a low-cost biofuel production industry. Scheffersomyces (Pichia) stipitis is a naturally occurring C-5 sugar utilization yeast; however, little is known about the genetic background underlying its potential tolerance to biomass conversion inhibitors. We investigated and identified five uncharacterized putative aryl-alcohol dehydrogenase genes (SsAADs) from this yeast as a new source of resistance against biomass fermentation inhibitor 2-furaldehyde (furfural) by gene expression, gene cloning, and direct enzyme assay analysis using partially purified proteins. All five proteins from S. stipitis showed furfural reduction using cofactor NADH. An optimum active temperature was observed at 40 °C for SsAad1p; 30 °C for SsAad3p, SsAad4p, and SsAad5p; and 20 °C for SsAad2p. SsAad2p, SsAad3p, and SsAad4p showed tolerance to a wide range of pH from 4.5 to 8, but SsAad1p and SsAad5p were sensitive to pH changes beyond 7. Genes SsAAD2, SsAAD3, and SsAAD4 displayed significantly enhanced higher levels of expression in response to the challenge of furfural. Their encoding proteins also showed higher levels of specific activity toward furfural and were suggested as core functional enzymes contributing aldehyde resistance in S. stipitis.     

Functional Expression of a Thermostable Endoglucanase from <Emphasis Type="Italic">Thermoascus aurantiacus</Emphasis> RCKK in <Emphasis Type="Italic">Pichia pastoris</Emphasis> X-33 and Its Characterization

Thermostable cellulases offer several advantages like higher rates of substrate hydrolysis, lowered risk of contamination, and increased flexibility with respect to process design. In the present study, a thermostable native endoglucanase nEG (EC 3.2.1.4) was purified and characterized from T. aurantiacus RCKK. Further, it was cloned in P. pastoris X-33 and processed for over expression. Expression of recombinant endoglucanase (rEG) of molecular size ~?33 kDa was confirmed by SDS-PAGE and western blotting followed by in gel activity determination by zymogram analysis. Similar to nEG, the purified rEG was characterized to harbor high thermostability while retaining 50% of its initial activity even after 6- and 10-h incubation at 80 and 70 °C, respectively, and exhibited considerable stability in pH range 3.0–7.0. CD spectroscopy revealed more than 20% β-sheets in protein structure consistently when incubated upto 85 °C as a speculated reason for protein high thermostability. Interestingly, both nEG and rEG were found tolerant up to 10% of the presence of 1-ethyl-3-methylimidazolium acetate [C2mim][OAc]. Values of the catalytic constants K_m and V_max for rEG were recorded as 2.5 mg/ml and 303.4 µmol/mg/min, respectively. Thermostability, pH stability, and resistance to the presence of ionic liquid signify the potential applicability of present enzyme in cellulose hydrolysis and enzymatic deinking of recycled paper pulp.     

High temperature enhances lipid accumulation in nitrogen-deprived <Emphasis Type="Italic">Scenedesmus obtusus</Emphasis> XJ-15

This study investigated the changes in lipid and starch contents, lipid fraction, and lipid profile in the nitrogen-starved Scenedesmus obtusus XJ-15 at different temperatures (17, 25, and 33 °C). The optimal temperature for both growth and lipid accumulation under nitrogen-sufficient condition was found to be 25 °C. However, under nitrogen deprivation, the total and neutral lipids increased with increasing temperature, and achieved the highest lipid content of 47.60 % of dry cell weight and the highest TAG content of 79.66 % of total lipid at 33 °C. In the meantime, the stored cellular starch content decreased with the increasing temperature. Thus, high temperature induced carbon flux from starch toward TAG accumulation in microalgae during nitrogen starvation. In addition, the decreased polar lipids may also serve for TAG synthesis under high temperature, and high temperature further reduced the degree of the fatty acid unsaturation and favored a better biodiesel production. These results suggested that high-temperature stress can be a good strategy for enhancing biofuel production in oleaginous microalgae during nitrogen deficiency.     

Bioreduction of hexavalent chromium by <Emphasis Type="Italic">Pseudomonas stutzeri</Emphasis> L1 and <Emphasis Type="Italic">Acinetobacter baumannii</Emphasis> L2

Bioreduction of the very toxic hexavalent chromium ion [Cr(VI)] to the non-toxic trivalent chromium ion [Cr(III)] is a key remediation process in chromium-contaminated sites. In this study, we investigated the bioreduction of Cr(VI) by Pseudomonas stutzeri L1 and Acinetobacter baumannii L2. The optimum pH (5–10), temperature (27, 37 and 60 °C) and initial chromium Cr(VI) concentration (100–1000 mg L^?1) for Cr(VI) reduction by strains L1 and L2 were determined using the diphenylcarbazide method. In the presence of L1 and L2, the bioreduction rate of Cr(VI) was 40–97 and 84–99%, respectively. The bioreduction of Cr(VI) by L2 was higher, reaching up to 84%—than that by L1. The results showed that strain L2 was able to survive even if exposed to 1000 mg L^?1 of Cr(VI) and that this tolerance to the effects of Cr(VI) was linked to the activity of soluble enzyme fractions. Overall, A. baumannii L2 would appear to be a potent Cr(VI)-tolerant candidate for the bioremediation of chromium (VI)-contaminated wastewater effluent.     

Expression and characterization of glutamate decarboxylase from <Emphasis Type="Italic">Lactobacillus brevis</Emphasis> HYE1 isolated from <Emphasis Type="Italic">kimchi</Emphasis>

A putative gene (gadlbhye1) encoding glutamate decarboxylase (GAD) was cloned from Lactobacillus brevis HYE1 isolated from kimchi, a traditional Korean fermented vegetable. The amino acid sequences of GADLbHYE1 showed 48% homology with the GadA family and 99% identity with the GadB family from L. brevis. The cloned GADLbHYE1 was functionally expressed in Escherichia coli using inducible expression vectors. The expressed recombinant GADLbHYE1 was successfully purified by Ni–NTA affinity chromatography, and had a molecular mass of 54 kDa with optimal hydrolysis activity at 55 °C and pH 4.0. Its thermal stability was determined to be higher than that of other GADs from L. brevis, based on its melting temperature (75.18 °C). Kinetic parameters including K_m and V_max values for GADLbHYE1 were 4.99 mmol/L and 0.224 mmol/L/min, respectively. In addition, the production of gamma-aminobutyric acid in E. coli BL21 harboring gadlbhye1/pET28a was increased by adding pyridoxine as a cheaper coenzyme.     

Reduced methanol input induces increased protein output by <Emphasis Type="Italic">AOX1</Emphasis> promoter in a <Emphasis Type="Italic">trans</Emphasis>-acting elements engineered <Emphasis Type="Italic">Pichia pastoris</Emphasis>

High oxygen consumption and heat release caused by methanol catabolism usually bring difficulties to industrial scale-up and cost for protein expression driven by methanol-induced AOX1 promoter in Pichia pastoris. Here, reduced methanol feeding levels were investigated for expression of insulin precursor in a trans-acting elements engineered P. pastoris strain MF1-IP. Insulin precursor expression level reached 6.69 g/(L supernatant) at the methanol feeding rate of 6.67 mL/(h·L broth), which was 59% higher than that in the wild-type strain WT-IP at the methanol feeding rate of 12 mL/(h·L broth). Correspondingly, the insulin precursor expression level in fermentation broth and maximum specific insulin precursor production rate was 137 and 77% higher than the WT-IP, respectively. However, oxygen consumption and heat evolution were reduced, and the highest oxygen consumption rate and heat evolution rate of the MF1-IP were 18.0 and 37.7% lower than the WT-IP, respectively.     

Molecular Cloning,Expression and Characterization of Pectin Methylesterase (<Emphasis Type="Italic">Ct</Emphasis>PME) from <Emphasis Type="Italic">Clostridium thermocellum</Emphasis>

Many phytopathogenic micro-organisms such as bacteria and fungi produce pectin methylesterases (PME) during plant invasion. Plants and insects also produce PME to degrade plant cell wall. In the present study, a thermostable pectin methylesterase (CtPME) from Clostridium thermocellum belonging to family 8 carbohydrate esterase (CE8) was cloned, expressed and purified. The amino acid sequence of CtPME exhibited similarity with pectin methylesterase from Erwinia chrysanthemi with 38% identity. The gene encoding CtPME was cloned into pET28a(+) vector and expressed using Escherichia coli BL21(DE3) cells. The recombinant CtPME expressed as a soluble protein and exhibited a single band of molecular mass approximately 35.2 kDa on SDS-PAGE gels. The molecular mass, 35.5 kDa of the enzyme, was also confirmed by MALDI-TOF MS analysis. Notably, highest protein concentration (11.4 mg/mL) of CtPME was achieved in auto-induction medium, as compared with LB medium (1.5 mg/mL). CtPME showed maximum activity (18.1 U/mg) against citrus pectin with >85% methyl esterification. The optimum pH and temperature for activity of CtPME were 8.5 and 50 °C, respectively. The enzyme was stable in pH range 8.0–9.0 and thermostable between 45 and 70 °C. CtPME activity was increased by 40% by 5 mM Ca²⁺ or Mg²⁺ ions. Protein melting curve of CtPME gave a peak at 80 °C. The peak was shifted to 85 °C in the presence of 5 mM Ca²⁺ ions, and the addition of 5 mM EDTA shifted back the melting peak to 80 °C. CtPME can be potentially used in food and textile industry applications.     

Production of <Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12-conjugated linoleic acid using permeabilized whole-cell biocatalyst of <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>

Objective

To improve the production of trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) from linoleic acid in recombinant Yarrowia lipolytica.

Results

Cells of the yeast were permeabilized by freeze/thawing. The optimal conditions for t10,c12-CLA production by the permeabilized cells were at 28 °C, pH 7, 200 rpm with 1.5 g sodium acetate l^?1, 100 g wet cells l^?1, and 25 g LA l^?1. Under these conditions, the permeabilized cells produced 15.6 g t10,c12-CLA l^?1 after 40 h, with a conversion yield of 62 %. The permeabilized cells could be used repeatedly for three cycles, with the t10,c12-CLA extracellular production remaining above 10 g l^?1.

Conclusion

Synthesis of t10,c12-CLA was achieved using a novel method, and the production reported in this work is the highest value reported to date.

     

Expression and Characterization of Glucose Oxidase from <Emphasis Type="Italic">Aspergillus niger</Emphasis> in <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>

Glucose oxidase (GOX) is currently used in clinical, pharmaceutical, food and chemical industries. The aim of this study was expression and characterization of Aspergillus niger glucose oxidase gene in the yeast Yarrowia lipolytica. For the first time, the GOX gene of A. niger was successfully expressed in Y. lipolytica using a mono-integrative vector containing strong hybrid promoter and secretion signal. The highest total glucose oxidase activity was 370 U/L after 7 days of cultivation. An innovative method was used to cell wall disruption in current study, and it could be recommended to use for efficiently cell wall disruption of Y. lipolytica. Optimum pH and temperature for recombinant GOX activity were 5.5 and 37 °C, respectively. A single band with a molecular weight of 80 kDa similar to the native and pure form of A. niger GOX was observed for the recombinant GOX in SDS-PAGE analysis. Y. lipolytica is a suitable and efficient eukaryotic expression system to production of recombinant GOX in compered with other yeast expression systems and could be used to production of pure form of GOX for industrial applications.     

Efficient extracellular expression of <Emphasis Type="Italic">Bacillus deramificans</Emphasis> pullulanase in <Emphasis Type="Italic">Brevibacillus choshinensis</Emphasis>

In this study, the pullulanase gene from Bacillus deramificans was efficiently expressed in Brevibacillus choshinensis. The optimal medium for protein expression was determined through a combination of single-factor experiments and response surface methodology. The initial pH of the medium and the culture temperature were optimized. The pullulanase yield increased 10.8-fold through medium and condition optimization at the shake-flask level. From the results of these experiments, the dissolved oxygen level was optimized in a 3-L fermentor. Under these optimized conditions, the pullulanase activity and the specific pullulanase productivity reached 1005.8 U/mL and 110.5 × 10³ U/g dry cell weight, respectively, with negligible intracellular expression. The Brevibacillus choshinensis expression system has proven to be valuable for the extracellular production of pullulanase.     

A review of the history of research and control of <Emphasis Type="Italic">Rhipicephalus</Emphasis> (<Emphasis Type="Italic">Boophilus</Emphasis>) <Emphasis Type="Italic">microplus</Emphasis>, babesiosis and anaplasmosis in Uruguay

The effect of five constant temperatures (16, 20, 24, 28 and 32 °C) on the development, survival and reproduction of Tetranychus cinnabarinus (Boisduval) [=?Tetranychus urticae Koch (red form)] fed on cassava leaves was examined in the laboratory at 85% relative humidity. Development time of various immature stages decreased with increasing temperature, with total egg-to-adult development time varying from 27.7 to 6.7 days. The lower thermal threshold for development was 10.8 °C and the thermal constant from egg to adult was 142.4 degree-days. Pre- and post-oviposition period and female longevity all decreased as temperature increased. The longest oviposition period was observed at 20 °C with 20.4 days. Under different temperatures, mated females laid, on average, 1.0, 2.9, 4.7, 4.7 and 4.9 eggs per day, respectively. The maximum fecundity (81.5 eggs per female) was at 28 °C and the intrinsic rate of increase (r _m ) was highest (0.25) at 32 °C. The results of this study indicate that T. cinnabarinus population could increase rapidly when cassava leaves serve as a food source. At the appropriate temperature T. cinnabarinus could seriously threaten growth of cassava.     

<Emphasis Type="Italic">Arthrospira</Emphasis> (<Emphasis Type="Italic">Spirulina</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis> extract improves oxidative stability and product quality of Chinese-style pork sausage

Arthrospira (Spirulina) platensis extract (APE) was used as a natural antioxidant in Chinese-style sausage during storage at 4 °C for 18 days. As compared to control, we examined the effect of APE on physical, chemical, microbiological, and sensory qualities of sausages, as well as on change in pH, color, thiobarbituric value (TBARS), volatile basic nitrogen (VBN), and total viable counts of mesophilic and psychrotrophic bacteria. The sensory qualities including color, aroma, taste, texture, and overall acceptability were evaluated. It was found that APE sausages displayed lower changes in pH, lightness (L*), redness (a*), yellowness (b*), TBARS value, and sensory attributes than control. However, there was no significant difference in VBN and microbiological status between APE and control sausages. Successful inhibition of lipid oxidation in samples was possible with the incorporation of APE in the refrigerated Chinese-style sausages. Our results suggest that the incorporation of APE into Chinese-style pork sausages enhance the antioxidant and maintains product quality.