Inheritance pattern and genetic correlations among growth and wood quality traits in Para rubber tree (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis>) and implications for breeding

Inheritance pattern of wood traits viz. specific gravity, fibre dimensions and fibre-derived biometrical indices and their interactions among themselves and with that of growth are reported in Hevea brasiliensis. Girth (h² =???0.02?±?0.44 to h² =?0.35?±?0.24) showed moderate genetic control. Among wood traits, specific gravity (h²?=?0.15?±?0.31 to h² =?0.33?±?0.28) was found to be under moderate genetic control. Fibre traits viz., fibre length (h² =???0.26?±?0.30 to h² =?0.50?±?0.34), fibre diameter (h² =?0.19?±?0.49 to h² =?0.70?±?0.11), fibre lumen diameter (h² =???0.18?±?0.35 to h² =?0.56?±?0.47) and fibre wall thickness (h² =???5.17?±?5.26 to h² =?0.50?±?0.50) were under moderate to strong genetic control. Among fibre-derived indices, flexibility coefficient (h² =?0.48?±?0.21 to h² =?0.89?±?0.29) showed moderate to very strong genetic control. The Runkel ratio (h² =???0.40?±?0.27 to h² =?0.42?±?0.29) and slenderness ratio (h² =???0.36?±?0.29 to h² =?0.43?±?0.28) showed moderate genetic control. Girth showed very strong positive genetic correlation with fibre wall thickness and strong positive correlation with fibre width indicating scope of indirect selection potential for these traits. Wood specific gravity was not correlated with either girth or fibre traits. Hence, it would be possible to concomitantly improve growth and fibre traits without adversely affecting wood specific gravity. Moderate to very high estimates of heritability for fibre traits, girth and specific gravity indicated that considerable genetic gain can be realised for these traits. Implications of the above findings in genetic improvement of wood in Hevea are discussed.     

Characterization of bacteriocins produced by strains of <Emphasis Type="Italic">Pediococcus pentosaceus</Emphasis> isolated from Minas cheese

Interest in obtaining bacteriocin-producing strains of lactic acid bacteria (LAB) from different sources has been increasing in recent years due to their multiple applications in health and food industries. This study focused on the isolation and characterization of metabolically active populations of bacteriocinogenic LAB and the evaluation of their antimicrobial substances as well as of some nutritional requirements of them. One hundred and fifty colonies of LAB from artisanal cheeses produced in Minas Gerais state (Brazil) were isolated and screened for their antimicrobial activity. According to their activity against Listeria monocytogenes, ten strains were selected and subsequently identified using biochemical and molecular techniques including 16s rRNA amplification and sequencing as Enterococcus faecalis, Lactobacillus spp., and Pediococcus pentosaceus. Antimicrobial substances produced by four of the selected strains, P. pentosaceus 63, P. pentosaceus 145, P. pentosaceus 146, and P. pentosaceus 147, were biochemically characterized, and presented sensitivity to proteolytic enzymes (suggesting their proteinaceous nature) and to extreme pH. Antimicrobial activity showed stability after treatment with lipase, catalase, α-amylase, and chemicals. Growth kinetics of the P. pentosaceus selected showed maximal bacteriocin production at 37 °C during the end of the exponential growth phase (25,600 AU/mL) and stable production during 24 h of incubation. Dextrose, maltose, and a mixture of peptone, meat extract, and yeast extract increased bacteriocin production. This study demonstrated that dairy products provide a good alternative for obtaining LAB, with the ability to produce antimicrobial substances such as bacteriocins that have potential use as biopreservatives in food.     

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.     

Parasitism Rate of <Emphasis Type="Italic">Habrobracon hebetor</Emphasis> to <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> Larvae: Residual Effect of Deltamethrin,Fenvalerate and Azadirachtin

Sublethal concentrations of chemical insecticides may cause changes in some behavioral characteristics of natural enemies such as functional responses. The residual effect of three synthetic insecticides including deltamethrin, fenvalerate and azadirachtin were studied on functional response of Habrobracon hebetor Say to Ephestia kuehniella Zeller larvae. Seven host densities (2, 4, 8, 16, 32, 64 and 96) were used during a 24 h period. The resulting data were appropriately fit to Type II functional response models in all treatments: (1) control (0.0916 h^?1; and T _h  = 0.2011 h); (2) deltamethrin (a = 0.0839 h^?1; and T _h  = 0.3560 h); (3) fenvalerate (a = 0.0808 h^?1 and T _h  = 0.3623 h); and (4) azadirachtin (a = 0.0900 h^?1 and T _h  = 0.2042 h). Maximum theoretical parasitism rate (T/T _h ) was 119.34 estimated for control wasps. There was no significant difference between the values of attack rates (a and a + D _a ) in all treatments while the handling time was statistically affected in female wasps treated with fenvalerate. Our findings will be useful in safe application of these insecticides in pest management programmes.     

Growth kinetics and scale-up of <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

Production of recombinant proteins in plants through Agrobacterium-mediated transient expression is a promising method of producing human therapeutic proteins, vaccines, and commercial enzymes. This process has been shown to be viable at a large scale and involves growing large quantities of wild-type plants and infiltrating the leaf tissue with a suspension of Agrobacterium tumefaciens bearing the genes of interest. This study examined one of the steps in this process that had not yet been optimized: the scale-up of Agrobacterium production to sufficient volumes for large-scale plant infiltration. Production of Agrobacterium strain C58C1 pTFS40 was scaled up from shake flasks (50–100 mL) to benchtop (5 L) scale with three types of media: Lysogeny broth (LB), yeast extract peptone (YEP) media, and a sucrose-based defined media. The maximum specific growth rate (μ _max) of the strain in the three types of media was 0.46 ± 0.04 h^?1 in LB media, 0.43 ± 0.03 h^?1 in YEP media, and 0.27 ± 0.01 h^?1 in defined media. The maximum biomass concentration reached at this scale was 2.0 ± 0.1, 2.8 ± 0.1, and 2.6 ± 0.1 g dry cell weight (DCW)/L for the three media types. Production was successfully scaled up to a 100-L working volume reactor with YEP media, using k _L a as the scale-up parameter.     

Bacteriocin production by <Emphasis Type="Italic">Streptococcus thermophilus</Emphasis> in complex growth media

Objective

To test if the production of bacteriocins by Streptococcus thermophilus is influenced when grown in various complex media commonly used for the culturing of lactic acid bacteria.

Results

Forty-one strains of S. thermophilus were screened for the production of bacteriocins in tryptone/yeast extract/lactose (TYL), M17-lactose (M17L), M17-glucose (M17G) and MRS media. Two strains, ST144 and ST145, were identified as novel bacteriocin producers, with constitutive production observed only in M17G. Strains ST110, ST114 and ST134 constitutively produced bacteriocins in all growth media but ST114 required growth in MRS for its antimicrobial activity to persist in a 24 h culture. The addition of a synthetic quorum sensing peptide (BlpC) induced bacteriocin production by ST106 in all media tested; and by ST118 in TYL and M17L. Strain ST109, which constitutively produced a bacteriocin in TYL and M17 broths, required BlpC induction when grown in MRS. Real-time PCR analysis showed that the natural expression of blpC in ST109 was lower when grown in MRS, suggesting that something in medium interfered with the blp quorum sensing system.

Conclusion

As the choice of growth medium influences both bacteriocin production and peptide stability, several types of production media should be tested when screening for novel bacteriocin-producing strains of S. thermophilus.

     

Purification and antibacterial mechanism of fish-borne bacteriocin and its application in shrimp (<Emphasis Type="Italic">Penaeus vannamei</Emphasis>) for inhibiting <Emphasis Type="Italic">Vibrio parahaemolyticus</Emphasis>

Vibrio parahaemolyticus: is recognized as the main cause of gastroenteritis associated with consumption of seafood. Bacteriocin-producing Lactobacillus plantarum FGC-12 isolated from golden carp intestine had strong antibacterial activity toward V. parahaemolyticus. The fish-borne bacteriocin was purified by a three-step procedure consisting of ethyl acetate extraction, gel filtration chromatography and high performance liquid chromatography. Its molecular weight was estimated at 4.1 kDa using SDS-PAGE. The fish-borne bacteriocin reached the maximum production at stationary phase after 20 h. It was heat-stable (30 min at 121?°C) and remained active at pH range from 3.0 to 5.5, but was sensitive to nutrasin, papain and pepsin. Its minimum inhibitory concentration for V. parahaemolyticus was 6.0 mg/ml. Scanning electron microscopy analysis showed that the fish-borne bacteriocin disrupted cell wall of V. parahaemolyticus. The antibacterial mechanism of the fish-borne bacteriocin against V. parahaemolyticus might be described as action on membrane integrity in terms of the leakage of electrolytes, the losses of Na⁺K⁺-ATPase, AKP and proteins. The addition of the fish-borne bacteriocin to shrimps leaded V. parahaemolyticus to reduce 1.3 log units at 4?°C storage for 6 day. Moreover, a marked decline in total volatile base nitrogen and total viable counts was observed in bacteriocin treated samples than the control. It is clear that this fish-borne bacteriocin has promising potential as biopreservation for the control of V. parahaemolyticus in aquatic products.     

Productivity and biochemical composition of <Emphasis Type="Italic">Tetradesmus obliquus</Emphasis> and <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis>: effects of different cultivation approaches

The present work evaluated biomass productivity, carbon dioxide fixation rate, and biochemical composition of two microalgal species, Phaeodactylum tricornutum (Bacillariophyta) and Tetradesmus obliquus (Chlorophyta), cultivated indoors in high-technology photobioreactors (HT-PBR) and outdoors both in pilot ponds and low-technology photobioreactors in a greenhouse in southern Italy. Microalgae were grown in standard media, under nitrogen starvation, and in two liquid digestates obtained from anaerobic digestion of agro-zootechnical and vegetable biomass. P. tricornutum, cultivated in semi-continuous mode in indoor HT-PBRs with standard medium, showed a biomass productivity of 21.0?±?2.3 g m^?2 d^?1. Applying nitrogen starvation, the lipid productivity increased from 2.3 up to 4.5?±?0.5 g m^?2 d^?1, with a 24 % decrease of biomass productivity. For T. obliquus, a biomass productivity of 9.1?±?0.9 g m^?2 d^?1 in indoor HT-PBR was obtained using standard medium. Applying liquid digestates as fertilizers in open ponds, T. obliquus gave a biomass productivity (10.8?±?2.0 g m^?2 d^?1) not statistically different from complete medium such as P. tricornutum (6.5?±?2.2 g m^?2 d^?1). The biochemical data showed that the fatty acid composition of the microalgal biomass was affected by the different cultivation conditions for both microalgae. In conclusion, it was found that the microalgal productivity in standard medium was about doubled in HT-PBR compared to open ponds for P. tricornutum and was about 20 % higher for T. obliquus.     

Purification and Characterization of Exo-Inulinase from <Emphasis Type="Italic">Paenibacillus</Emphasis> sp. d9 Strain

This study intended to purify and characterise exo-inulinase of diesel-degrading Paenibacillus sp. D9. The whole genome sequencing of Paenibacillus sp. D9 revealed to possess the sacC gene that is encoded as exo-inulinase/levanase. This isolate was capable of producing a maximum of 50.9 IU/mL of exo-inulinase activity within 3 days at 30?°C, 200 rpm and pH of 7.0 on minimal salt medium agar supplemented with 1% (w/v) inulin. An exo-inulinase of 58.5 kDa was purified using ammonium sulphate precipitation, HiTrap QFF column and MMC column chromatographies with a specific activity of 4333 IU/mg, 7.1% recovery and a 4.3-fold increase in purity. The purified D9 exo-inulinase had temperature and pH optimum at 40?°C and pH 4.0, respectively, with the Michaelis constant of 5.5 mM and a maximal velocity of 476.2 IU/mg, respectively. Catalytic constant, k _cat was calculated to be 42.6 s^?1 with a catalytic efficiency (k _cat /K _m ) of 7.6 s^?1 mM^?1. The presence of Ca²⁺ enhanced the activity of D9 exo-inulinase while Hg²⁺ completely inhibited the activity, other compounds such as Fe³⁺ and Cu²⁺ had an inhibitory effect. The results of amino acid alignment and the complete degradation of inulin into fructose by the purified enzyme confirmed that inulinase from Paenibacillus sp. D9 is an exo-form. The phylogenetic tree based on the protein sequences indicates that bacterial exo-inulinases possess a common ancestry.     

Cloning,deletion, and overexpression of a glucose oxidase gene in <Emphasis Type="Italic">Aureobasidium</Emphasis> sp. P6 for Ca<Superscript>2+</Superscript>-gluconic acid overproduction

This study aimed to overexpress a glucose oxidase gene (GOD1) in Aureobasidium sp. P6 to achieve Ca²⁺-gluconic acid (GA) overproduction. The GOD1 gene was cloned, deleted, and overexpressed. A protein deduced from the GOD1 gene of Aureobasidium sp. P6 strain had 1824 bp that encoded a protein with 606 amino acids, with a conserved NADB-ROSSMAN domain and a GMC-oxred domain. Deleting the GOD1 gene made the disruptant GOK1 completely lose the ability to produce GA and GOD1 activity, whereas overexpressing the GOD1 gene rendered the transformant GOEX8 to produce considerably more Ca²⁺-GA (160.5?±?5.6 g/L) and higher GOD1 activity (1438.6?±?73.2 U/mg of protein) than its parent P6 strain (118.7?±?4.3 g/L of Ca²⁺-GA and 1100.0?±?23.6 U/mg of GOD1 protein). During a 10-L fermentation, the transformant GOEX8 grown in the medium containing 160.0 g/L of glucose produced 186.8?±?6.0 g/L of Ca²⁺-GA, the yield was 1.2 g/g of glucose, and the volumetric productivity was 1.7 g/L/h. Most of the produced GOD1 were located in the yeast cell wall. The purified product was identified to be a GA. The transformant GOEX8 overexpressing the GOD1 gene could produce considerably more Ca²⁺-GA (186.8?±?6.0 g/L) than its wild-type strain P6.     

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.     

Enhanced citric acid production by a yeast <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> over-expressing a pyruvate carboxylase gene

In this study, after the expression of a pyruvate carboxylase gene (PYC) cloned from Meyerozyma guilliermondii in a marine-derived yeast Yarrowia lipolytica SWJ-1b, a transformant PG86 obtained had much higher PYC activity than Y. lipolytica SWJ-1b. At the same time, the PYC gene expression and citric acid (CA) production by the transformant PG86 were also greatly enhanced. When glucose concentration in the medium was 60.0 g L^?1, CA concentration formed by the transformant PG86 was 34.02 g L^?1, leading to a CA yield of 0.57 g g^?1 of glucose. During a 10-L fed-batch fermentation, the final concentration of CA was 101.0 ± 1.3 g L^?1, the yield was 0.89 g g^?1 of glucose, the productivity was 0.42 g L^?1 h^?1 and only 5.93 g L^?1 reducing sugar was left in the fermented medium within 240 h of the fed-batch fermentation. HPLC analysis showed that most of the fermentation products were CA.     

Oral fast-dissolving films containing lutein nanocrystals for improved bioavailability: formulation development, <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> evaluation

Lutein is widely used as diet supplement for prevention of age-related macular degeneration. However, the application and efficacy of lutein in food and nutritional products has been hampered due to its poor solubility and low oral bioavailability. This study aimed to develop and evaluate the formulation of oral fast-dissolving film (OFDF) containing lutein nanocrystals for enhanced bioavailability and compliance. Lutein nanocrystals were prepared by anti-solvent precipitation method and then encapsulated into the films by solvent casting method. The formulation of OFDF was optimized by Box-Behnken Design (BBD) as follows: HPMC 2.05% (w/v), PEG 400 1.03% (w/v), Cremophor EL 0.43% (w/v). The obtained films exhibited uniform thickness of 35.64 ± 1.64 μm and drug content of 0.230 ± 0.003 mg/cm² and disintegrated rapidly in 29 ± 8 s. The nanocrystal-loaded films with reconstituted particle size of 377.9 nm showed better folding endurance and faster release rate in vitro than the conventional OFDFs with raw lutein. The microscope images, thermograms, and diffractograms indicated that lutein nanocrystals were highly dispersed into the films. After administrated to SD rats, t _max was decreased from 3 h for oral solution formulation to less than 0.8 h for OFDF formulations, and C _max increased from 150 ng/mL for solution to 350 ng/mL for conventional OFDF or 830 ng/mL for nanocrystal OFDF. The AUC _0-24h of conventional or nanocrystal OFDF was 1.37 or 2.08-fold higher than that of the oral solution, respectively. These results suggested that drug nanocrystal-loaded OFDF can be applied as a promising approach for enhanced bioavailability of poor soluble drugs like lutein.     

<Emphasis Type="Italic">Microbacterium rhizosphaerae</Emphasis> sp. nov., isolated from a Ginseng field,South Korea

A novel Gram-stain positive, aerobic, short rod-shaped, non-motile bacterium, designated strain CHO1^T, was isolated from rhizosphere soil from a ginseng agriculture field. Strain CHO1^T was observed to form yellow colonies on R2A agar medium. The cell wall peptidoglycan was found to contain alanine, glycine, glutamic acid, d-ornithine and serine. The cell wall sugars were identified as galactose, mannose, rhamnose and ribose. Strain CHO1^T was found to contain MK-11, MK-12, MK-13 as the predominant menaquinones and anteiso-C_15:0, iso-C_16:0, and anteiso-C_17:0 as the major fatty acids. Diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, an unidentified phospholipid and three unidentified glycolipids were found to be present in strain CHO1^T. Based on 16S rRNA gene sequence analysis, strain CHO1^T was found to be closely related to Microbacterium mangrovi DSM 28240^T (97.81 % similarity), Microbacterium immunditiarum JCM 14034^T (97.45 %), Microbacterium oryzae JCM 16837^T (97.33 %) and Microbacterium ulmi KCTC 19363^T (97.10 %) and to other species of the genus Microbacterium. The DNA G+C content of CHO1^T was determined to be 70.1 mol %. The DNA–DNA hybridization values of CHO1^T with M. mangrovi DSM 28240^T, M. immunditiarum JCM 14034^T, M. oryzae JCM 16837^T and M. ulmi KCTC 19363^T were 46.7 ± 2, 32.4 ± 2, 32.0 ± 2 and 29.2 ± 2 %, respectively. On the basis of genotypic, phenotypic and phylogenetic properties, it is concluded that strain CHO1^T represents a novel species within the genus Microbacterium, for which the name Microbacterium rhizosphaerae sp. nov. is proposed. The type strain of M. rhizosphaerae is CHO1^T (= KEMB 7306-513^T = JCM 31396^T).     

Assessing biodegradation of furfuryl alcohol using <Emphasis Type="Italic">Pseudomonas putida</Emphasis> MTCC 1194 and <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> MTCC 1034 and its kinetics

The biodegradation of furfuryl alcohol (FA) in shake flask experiments using a pure culture of Pseudomonas putida (MTCC 1194) and Pseudomonas aeruginosa (MTCC 1034) was studied at 30 °C and pH 7.0. Experiments were performed at different FA concentrations ranging from 50 to 500 mg/l. Before carrying out the biodegradation studies, the bacterial strains were acclimatized to the concentration of 500 mg/l of FA by gradually raising 100 mg/l of FA in each step. The well acclimatized culture of P. putida and P. aeruginosa degraded about 80 and 66% of 50 mg/l FA, respectively. At higher concentration of FA, the percentage of FA degradation decreased. The purpose of this study was to determine the kinetics of biodegradation of FA by measuring biomass growth rates and concentration of FA as a function of time. Substrate inhibition was calculated from experimental growth parameters using the Haldane equation. Data for P. putida were determined as µ _max ?=?0.23 h^?1, K _s ?=?23.93 mg/l and K _i ?=?217.1 mg/l and for P. aeruginosa were determined as µ _max ?=?0.13 h^?1, K _s ?=?21.3 mg/l and K _i ?=?284.9 mg/l. The experimental data were fitted in Haldane, Aiba and Edwards inhibition models.     

<Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> isolated from cheese: production and partial characterization of bacteriocin B391

Lactobacillus plantarum B391, a strain isolated from an artisanal French cheese, is a producer of a bacteriocin, expressing activity against Enterococcus faecalis NCTC 775, Clostridium perfringens NCTC 13170 and several Listeria monocytogenes strains. High stability was recorded after heat treatment at 121 °C for 20 min and when stored at 4 °C for more than 40 days. A challenge test performed in milk for 11 days showed potential for the control of L. monocytogenes. In the presence of the lytic bacteriocin B391, L. monocytogenes cells present numerous morphology modifications of cell shape and surface structure as well as in the cell division pattern, resulting ultimately in lysis. The high level of Listeria growth inhibition obtained in the presence of Lb. plantarum B391, and the stability of B391 bacteriocin for a long period of time, make this strain potentially interesting to use in milk products to increase food safety.     

<Emphasis Type="Italic">Acorus calamus</Emphasis> Linn.: phytoconstituents and bactericidal property

Acorus calamus Linn. of the family Araceae (Acoraceae), commonly known as Sweet Flag and Vacha. The rhizome of this plant has medicinal properties against bugs, moths, lice and emetic stomach in dyspepsia. Chemical composition of the hydro-distilled essential oil obtained from the rhizomes of A. calamus was analyzed by gas chromatography equipped with flame ionization detector and gas chromatography coupled with mass spectrometry. The essential oil of A. calamus and its major compound β-asarone were tested against five Gram-positive, eight Gram-negative bacteria, and three fungi by the tube-dilution method at a concentration rang of 5.0–0.009 mg/mL. Forty constituents were identified which comprised 98.3 % of the total oil. The major compound β-asarone (80.6 %) was identified and confirm by NMR (¹H– & ¹³C–) in rhizome oil of A. calamus. The organism Micrococcus luteus was found to be more susceptible to the oil with minimum bactericidal concentration (MBC) value of 0.032 ± 0.004 mg/mL, followed by Aspergillus fumigatus, Aspergillus niger and Micrococcus flavus with MBC values of 0.104 ± 0.016, 0.117 ± 0.017 and 0.143 ± 0.013 mg/mL, respectively. The compound β-asarone was susceptible to the microorganism A. niger with MBC value 0.416 ± 0.065 mg/mL. The present study revealed that tetraploid variety of A. calamus is growing in this region with substantial amount of β-asarone. The oil showed bactericidal property against tested bacteria and fungi. The β-asarone exhibited poorer bactericidal activity against test microorganisms.     

Sucrose dependent mineral phosphate solubilization in <Emphasis Type="Italic">Enterobacter asburiae</Emphasis> PSI3 by heterologous overexpression of periplasmic invertases

Enterobacter asburiae PSI3 solubilizes mineral phosphates in the presence of glucose by the secretion of gluconic acid generated by the action of a periplasmic pyrroloquinoline quinone dependent glucose dehydrogenase. In order to achieve mineral phosphate solubilization phenotype in the presence of sucrose, plasmids pCNK4 and pCNK5 containing genes encoding the invertase enzyme of Zymomonas mobilis (invB) and of Saccharomyces cerevisiae (suc2) under constitutive promoters were constructed with malE signal sequence (in case of invB alone as the suc2 is secreted natively). When introduced into E. asburiae PSI3, E. a. (pCNK4) and E. a. (pCNK5) transformants secreted 21.65 ± 0.94 and 22 ± 1.3 mM gluconic acid, respectively, in the presence of 75 mM sucrose and they also solubilized 180 ± 4.3 and 438 ± 7.3 µM P from the rock phosphate. In the presence of a mixture of 50 mM sucrose and 25 mM glucose, E. a. (pCNK5) secreted 34 ± 2.3 mM gluconic acid and released 479 ± 8.1 µM P. Moreover, in the presence of a mixture of eight sugars (10 mM each) in the medium, E. a. (pCNK5) released 414 ± 5.3 µM P in the buffered medium. Thus, this study demonstrates incorporation of periplasmic invertase imparted P solubilization ability to E. asburiae PSI3 in the presence of sucrose and mixture of sugars.     

Growth kinetics and fucoxanthin production of <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis> and <Emphasis Type="Italic">Isochrysis galbana</Emphasis> cultures at different light and agitation conditions

Fucoxanthin is a carotenoid that exerts multiple beneficial effects on human health. However, reports comparing microalgae culture conditions and their effect on growth and fucoxanthin production are still limited. Isochrysis galbana and Phaeodactylum tricornutum cultures in different light (62.0, 25.9, 13.5, or 9.1 μmol photons m^-2 s^-1), mixing conditions (1 vvm aeration or 130 rpm agitation), and media compositions (F/2 and Conway medium) were studied for comparison of cellular growth and fucoxanthin production on F/2 medium. I. galbana showed a better adaptation to tested culture conditions in comparison with P. tricornutum, reaching 2.15?×?10⁷?±?4.07?×?10⁶ cells mL^-1 and a specific growth rate (μ) of 1.12?±?0.05 day^-1 under aerated conditions and 62.0 μmol photons m^-2 s^-1 light intensity. Fucoxanthin concentration was about 25 % higher in P. tricornutum cultures under 13.5 μmol photons m^-2 s^-1 light intensity and aerated conditions, but the highest fucoxanthin total production was higher in I. galbana, where 3.32 mg can be obtained from 1 L batch cultures at the 16th day under these conditions. Moreover, higher cell densities (~32.41 %), fucoxanthin concentration (~42.46 %), and total production (~50.68 %) were observed in I. galbana cultures grown in Conway medium, if compared with cultures grown in F/2 medium. The results show that the best growth conditions did not result in the best fucoxanthin production for either microalgae, implying that there is not a direct relationship between cellular growth and fucoxanthin production. Moreover, the results suggest that I. galbana cultures on Conway medium are strong candidates for fucoxanthin production, where 1.2 to 15 times higher fucoxanthin concentration are observed in comparison to macroalgal sources.