Xylanase Production by Penicillium citrinum in Laboratory-scale Stirred Tank Reactor

Xylanase constitutes an important class of hydrolases, and is used in numerous industrial applications. The aim of the present work was to study the production of xylanase from Penicillium citrinum MTCC 9620 in a 5 L stirred tank bioreactor. Effect of various process parameters; pH, temperature, aeration, agitation rates, substrate concentration, and, dissolved oxygen (DO) concentration on xylanase production were studied. Combination of all the optimized parameters resulted in 2.5 times higher enzyme activity as compared to the shake flask fermentation after 96 h. Effect of varying agitation and aeration on the volumetric mass transfer coefficient (KLa) was determined. It revealed that KLa is influenced by both aeration and agitation. Growth kinetics of P. citrinum MTCC 9620 in bioreactor was studied using Monod, Moser, Contois and Edward equation. Based on R2, SE and pattern of residuals, the microbial growth kinetics of P. citrinum MTCC 9620 was effectively represented by Moser equation

Optimization of Xylanase Production from Penicillium citrinum in Solid-State Fermentation

Solid-state fermentation of sugarcane bagasse by Penicillium citrinum MTCC 2553 was optimized to maximize the yield of xylanase. Preliminary experiments carried out with various lignocellulosic materials revealed sugarcane bagasse to be the most suitable substrate for producing xylanase. Response surface methodology was used in the optimization. Xylanase activity was maximized in a 5-day batch fermentation carried out under the following conditions: a substrate-to-moisture ratio of 1:5 by mass, an initial pH of 7.0 and an incubation temperature of 30 °C. Under the optimal conditions, the final activity of xylanase was 1645 U g–1 of dry substrate. Xylanase was recovered from an extract of the fermented solids by ammonium sulfate precipitation. The crude enzyme was further purified by dialysis. The activity of the enzyme was enhanced in the presence of Na+, Mg2+, Mn2+, Fe3+, Zn2+, Cu2+, Co2+ and Tween 80. The enzyme was inhibited by Hg2+, Ca2+ and the chelating agent ethylene diamine tetra acetic acid (EDTA)

Partially responsive celiac disease resulting from small intestinal bacterial overgrowth and lactose intolerance

BACKGROUND: Celiac disease is a common cause of chronic diarrhea and malabsorption syndrome all over the world. Though it was considered uncommon in India in past, it is being described frequently recently. Some patients with celiac disease do not improve despite gluten free diet (GFD). A study described 15 cases of celiac disease unresponsive to GFD in whom small intestinal bacterial overgrowth (SIBO) or lactose intolerance was the cause for unresponsiveness. CASE PRESENTATION: During a three-year period, 12 adult patients with celiac disease were seen in the Luminal Gastroenterology Clinic in a tertiary referral center in northern India. Two of these 12 patients (16.6%), who did not fully respond to GFD initially, are presented here. Unresponsiveness resulted from SIBO in one and lactose intolerance in the other. The former patient responded to antibiotics and the latter to lactose withdrawal in addition to standard GFD. CONCLUSION: In patients with celiac disease partially responsive or unresponsive to GFD, SIBO and lactose intolerance should be suspected; appropriate investigations and treatment for these may result in complete recovery

The XX--model with boundaries. Part I: Diagonalization of the finite chain

This is the first of three papers dealing with the XX finite quantum chain with arbitrary, not necessarily hermitian, boundary terms. This extends previous work where the periodic or diagonal boundary terms were considered. In order to find the spectrum and wave-functions an auxiliary quantum chain is examined which is quadratic in fermionic creation and annihilation operators and hence diagonalizable. The secular equation is in general complicated but several cases were found when it can be solved analytically. For these cases the ground-state energies are given. The appearance of boundary states is also discussed and in view to the applications considered in the next papers, the one and two-point functions are expressed in terms of Pfaffians.Comment: 56 pages, LaTeX, some minor correction

Neutrino mixing schemes and neutrinoless double beta decay

We study the possible structure of the neutrino mass matrix taking into consideration the solar and atmospheric neutrinos and the neutrinoless double beta decay. We emphasize on mass matrices with vanishing elements. There are only a very few possibilities remaining at present. We concentrate on three generation scenarios and find that with three parameters there are few possibilities with and without any vanishing elements. For completeness we also present a five parameter four neutrino (with one sterile neutrino) mass matrix which can explain all these experiments and the LSND result.Comment: 12 pages late

Unusual Tumors Causing Extrahepatic Portal Venous Obstruction

Extrahepatic portal vein obstruction has been reported to be associated with tumors of liver, bile ducts and pancreas. We report two cases, one with gastric leiomyosarcoma and another with Non Hodgkin’s lymphoma, complicated by portal vein block and presenting with gastric variceal bleeding. Portal vein block in both cases was due to direct vascular infiltration. Development of portal hypertension posed difficulties in management

Spectrum and antibiotic sensitivity of bacteria contaminating the upper gut in patients with malabsorption syndrome from the tropics

BACKGROUND: Various causes of malabsorption syndrome (MAS) are associated with intestinal stasis that may cause small intestinal bacterial overgrowth (SIBO). Frequency, nature and antibiotic sensitivity of SIBO in patients with MAS are not well understood. METHODS: Jejunal aspirates of 50 consecutive patients with MAS were cultured for bacteria and colony counts and antibiotic sensitivity were performed. Twelve patients with irritable bowel syndrome were studied as controls. RESULTS: Culture revealed growth of bacteria in 34/50 (68%) patients with MAS and 3/12 controls (p < 0.05). Colony counts ranged from 3 × 10(2 )to 10(15 )(median 10(5)) in MAS and 100 to 1000 (median 700) CFU/ml in controls (p 0.003). 21/50 (42%) patients had counts ≥10(5 )CFU/ml in MAS and none of controls (p < 0.05). Aerobes were isolated in 34/34 and anaerobe in 1/34. Commonest Gram positive and negative bacteria were Streptococcus species and Escherichia coli respectively. The isolated bacteria were more often sensitive to quinolones than to tetracycline (ciprofloxacin: 39/47 and norfloxacin: 34/47 vs. tetracycline 19/47, <0.01), ampicillin, erythromycin and co-trimoxazole (21/44, 14/22 and 24/47 respectively vs. tetracycline, p = ns). CONCLUSIONS: SIBO is common in patients with MAS due to various causes and quinolones may be the preferred treatment. This needs to be proved further by a randomized controlled trial

Low-temperature nonequilibrium transport in a Luttinger liquid

The temperature-dependent nonlinear conductance for transport of a Luttinger liquid through a barrier is calculated in the nonperturbative regime for $g=1/2-\epsilon$, where $g$ is the dimensionless interaction constant. To describe the low-energy behavior, we perform a leading-log summation of all diagrams contributing to the conductance which is valid for $|\epsilon| << 1$. With increasing external voltage, the asymptotic low-temperature behavior displays a turnover from the $T^{2/g-2}$ to a universal $T^2$ law.Comment: 13 pages RevTeX 3.0, accepted by Physical Review

External voltage sources and Tunneling in quantum wires

We (re) consider in this paper the problem of tunneling through an impurity in a quantum wire with arbitrary Luttinger interaction parameter. By combining the integrable approach developed in the case of Quantum Hall edge states with the introduction of radiative boundary conditions to describe the adiabatic coupling to reservoirs, we are able to obtain the exact equilibrium and non equilibrium current. One of the most striking features observed is the appearance of negative differential conductances out of equilibrium in the strongly interacting regime g <=.2. In spite of the various charging effects, a remarkable form of duality is still observed. New results on the computation of transport properties in integrable impurity problems are gathered in appendices. In particular, we prove that the TBA results satisfy a remarkable relation, originally derived using the Keldysh formalism, between the order T^2 correction to the current out of equilibrium and the second derivative of this current at T=0 with respect to the voltage.Comment: 16 pages, 7 figure

Extended Holomorphic Anomaly in Gauge Theory

The partition function of an N=2 gauge theory in the Omega-background satisfies, for generic value of the parameter beta=-eps_1/eps_2, the, in general extended, but otherwise beta-independent, holomorphic anomaly equation of special geometry. Modularity together with the (beta-dependent) gap structure at the various singular loci in the moduli space completely fixes the holomorphic ambiguity, also when the extension is non-trivial. In some cases, the theory at the orbifold radius, corresponding to beta=2, can be identified with an "orientifold" of the theory at beta=1. The various connections give hints for embedding the structure into the topological string.Comment: 25 page