Production of pullulan by Aureobasidium pullulans from Asian palm kernel: a novel substrate.

Production of a commercially important biodegradable polymer, pullulan, by Aureobasidium pullulans from four agricultural wastes namely wheat bran, rice bran, coconut kernel and palm kernel was evaluated in solid state fermentation. Under the experimental conditions, palm kernel resulted in highest concentration of pullulan (16 g/L) among the four solid substrates. Optimum initial pH and moisture content for pullulan production were found out to be 6.5 and 50% respectively. 18.43 g/L of pullulan was produced from Asian palm kernel with initial pH 6.5 after 7 days of fermentation and yeast like morphology was predominant under this condition. Among different nitrogen sources tried in this study, yeast extract was found to the best. The pullulan produced from palm kernel was characterized by FTIR and (1)H NMR. The results were matching with that of commercial pullulan. Thus, Asian palm kernel appears to be an attractive low cost carbon source for the production of pullulan.

Studies on application of teak leaf powders for the removal of color from synthetic and industrial effluents.

Batch studies were conducted to investigate the potential of untreated teak leaf powder (TLP) to remove color from synthetic and industrial effluents. Langmuir and Freundlich isotherms were used to analyze the equilibrium data. Langmuir isotherm was found to be the best-fitting isotherm. The monolayer adsorption capacity was found to be 99.1, 145.2, 188.7 and 207.9 mg methyleneblue/gTLP at 293, 303, 313 and 323 K, respectively. It was also found from the thermodynamic analysis that the adsorption of methylene blue onto TLP was spontaneous, chemisorption and exothermic in nature. The color of the effluent was quantified in terms of the area under absorbance spectrum. Percentage color, COD and total dissolved solids (TDS) removed from a diluted effluent (10% effluent by vol.) were found to be 57.41, 45.95 and 49.46, respectively. The monolayer capacity was calculated in terms of TDS and was found to be 219 mg/g.

Kinetics of methylene blue removal from aqueous solution using gulmohar (Delonix regia) plant leaf powder: multivariate regression analysis.

Effects of process variables namely pH, dye concentration, adsorbent dosage, temperature, particle size and agitation speed on kinetics of methylene blue adsorption onto gulmohar plant leaf powder were investigated. Quadratic models were proposed to predict pseudo second order rate constant and equilibrium uptake in terms of the process variables. Model coefficients were determined by multiple regression analysis. Statistical tools like Student's t-test, F-test, ANOVA and lack-of-fit were used to define the most important process variables. The proposed models could predict the rate constant and equilibrium dye uptake with high R(2) values (0.94 and 0.947). It was found that rate constant increased with decrease in concentration, decrease in particle size, increase in adsorbent dosage, increase in agitation speed and increase in temperature. Meanwhile, it was found that equilibrium dye uptake increased with increase in concentration and decrease in dosage. Apart from these combined effects of the process variables were established through multiple regression analysis. Langmuir monolayer adsorption capacity of GUL was found to be 186.22 mg/g.

Sorption of distillery spent wash onto fly ash: kinetics, mechanism, process design and factorial design.

Batch and continuous experiments were performed for the sorption of distillery spent wash onto fly ash particles. The Freundlich and pseudo-second order equation were found to fit the equilibrium data perfectly. The Weber-Morris intraparticle diffusion isotherm equation was used to predict the sorption mechanism and the predicted equation for 10% dilution of spent wash sorption is q(t)=1.1344t(0.5)+33.304. The optimization using 2(3) factorial design of experiments provides optimal removal of color of 93% for dilution (5%), dosage of adsorbent (10g) and temperature (293K). The actual color removal at optimal conditions was 92.24%, confirms close to the factorial design results. The complete error analysis using six non-linear error functions: Chi-square (chi(2)); sum of square errors (SSE); composite fractional error function (HYBRD); derivative of Marquardt's percent standard deviation (MPSD); average relative error (ARE); sum of absolute errors (EABS) were calculated. Free energy of adsorption at 293K (DeltaG(0)=-1574.67J), enthalpy change (DeltaH(0)=-32.5487KJ) and entropy change (DeltaS(0)=105J/K) were calculated to predict the nature of adsorption. Adsorption studies in a packed column were evaluated using Bed depth service time model, Thomas model and Adams-Bohart model.

Guava (Psidium guajava) leaf powder: novel adsorbent for removal of methylene blue from aqueous solutions.

Batch sorption experiments were carried out using a novel adsorbent, guava leaf powder (GLP), for the removal of methylene blue (MB) from aqueous solutions. Potential of GLP for adsorption of MB from aqueous solution was found to be excellent. Effects of process parameters pH, adsorbent dosage, concentration, particle size and temperature were studied. Temperature-concentration interaction effect on dye uptake was studied and a quadratic model was proposed to predict dye uptake in terms of concentration, time and temperature. The model conforms closely to the experimental data. The model was used to find optimum temperature and concentration that result in maximum dye uptake. Langmuir model represent the experimental data well. Maximum dye uptake was found to be 295mg/g, indicating that GLP can be used as an excellent low-cost adsorbent. Pseudo-first-order, pseudo-second order and intraparticle diffusion models were tested. From experimental data it was found that adsorption of MB onto GLP follow pseudo second order kinetics. External diffusion and intraparticle diffusion play roles in adsorption process. Free energy of adsorption (DeltaG degrees ), enthalpy change (DeltaH degrees ) and entropy change (DeltaS degrees ) were calculated to predict the nature of adsorption. Adsorption in packed bed was also evaluated.

Biosorption of reactive dye using acid-treated rice husk: factorial design analysis.

A factorial experimental design technique was used to investigate the biosorption of reactive red RGB (lambda(max)=521 nm) from water solution on rice husk treated with nitric acid. Biosorption is favored because of abundance of biomass, low cost, reduced sludge compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (2 and 7), temperature (20 and 40), adsorbent dosage (5 and 50mg/L) and initial concentration of the dye (50 and 250 mg/L) at two levels low and high. The efficiency of color removal was determined after 60 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student's t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage dye removal. The most significant variable was thus found to be pH.

Styrene induced pancreatic changes in rodents.

Subchronic oral exposure to styrene in rodents (25 or 50 mg/kg/day in mice; 160 or 320 mg/kg/day in rats and guinea pigs, 5 days/week) for 4 weeks resulted in moderate congestion of pancreatic lobules, focal inflammatory reactions around islets (in mice) and altered serum insulin level while blood glucose levels remained unaffected. Increased beta cell degranulation together with characteristic neoformation of islets were predominantly seen in pancreas of guinea pigs.

Immunomodulation due to coexposure to styrene and dioctyl phthalate in mice.

Pathomorphological and immunological alterations caused by a mixture of styrene and dioctyl phthalate were studied in albino mice following oral administration of 0.02, 0.03, 0.05 x LD50 of the mixture. The chemicals were mixed together proportionate to their respective LD50 values and fed in ground nut oil, 5 d/wk for 4 weeks. Histological examination of spleen revealed considerable depletion of cellular population of lymphoid follicles which corresponded to the dose dependent decrease in splenic mononuclear cell population count. The thymic lobules revealed slight atrophy but accompanied by a significant increase in thymocyte population. Correspondingly few significant histological changes were observed in mesenteric and peripheral lymph nodes. The treatment caused impairment of primary humoral immune response to SRBC (IgM) but there was a significant increase in response of splenocytes to B-cell mitogen LPS. There was a suppression of cutaneous delayed type hypersensitivity and increase in splenic lymphocyte response to T-cell mitogen PHA. Simultaneously, indirect immunity represented by decreased phagocytosis and enhanced metabolic function of reducing NBT by peritoneal exudate cells was observed. The in vitro exposure of vero cells to the mixture caused dose dependent protective effect. The results of present study indicate that subchronic exposure to low doses of mixture of styrene and dioctyl phthalate under certain conditions may modulate some of the immune functions as compared to exposure to either chemicals alone.

Host resistance assays as predictive models in styrene immunomodulation.

Three infection models namely an oncogenic virus Encephalomyocarditis (EMCV), a rodent strain of malaria, Plasmodium berghei, and a rodent hookworm parasite, Nippostrongylus brasiliensis, were used to confirm the in vivo immunotoxic potential of styrene reported in our previous communication. The altered host resistance to these challenge infections was evaluated in rodents pre-treated with 0, 0.02, 0.03 or 0.05 x LD50 dose of styrene (5 days/week) for 4 weeks. Significantly increased mortality in mice was observed at the various tested dose levels of styrene when challenged with EMCV. Similarly the results obtained in the malaria infection model indicated increased blood parasitaemia as well as significantly enhanced mortality in styrene-treated animals. Also the rejection of N. brasiliensis was also found to be significantly impaired in animals treated with a higher dose of styrene. These results indicate that the exposure of rodents to styrene can markedly impair host resistance which may have biological significance.

Modulatory effects of metanil yellow on immunity in rodents.

Pathomorphological and immunological studies were carried out on rodents following oral administration of 0, 0.1, 0.25 and 0.5% (w/w) metanil yellow, mixed in diet, for 30 days. No significant change in hematologic parameters and histologic architecture of liver, kidney, mesenteric lymph node, thymus and urinary bladder was observed except for mild desquamation of intestinal villi and moderate changes in Peyer's patches of small intestine with higher doses. Among immunological parameters, significant enhancement in the primary humoral immune response (anti-SRBC IgM plaque forming cells of spleen) was observed with the lowest dose of metanil yellow while higher doses produced opposing effects. An elevated cutaneous delayed type hypersensitivity (DTH) reaction to SRBC was seen in 0.1% metanil yellow treated animals but higher doses did not influence the reaction. The treatment also caused changes in functional capabilities of macrophages. Although these immune alterations could hardly influence the local immunity of gut, as measured by the capacity of animals to cause rejection of Nippostrongylus brasiliensis parasite, the potential to modulate the immunity in general by metanil yellow however assumes considerable biological significance.

Styrene-induced immunomodulation in mice.

Male mice given different oral doses (0.05, 0.03 or 0.02 x LD50/animal/day) of styrene (LD50 = 1 g/kg) daily for 5 days did not incite any overt toxicity in lymphoid organs or on hematologic parameters. At the tested dose levels styrene produced a mild reduction in the organ weight of adrenal and spleen and slight reduction in the cellular viability of lymph nodes. There was a dose-dependent suppression in the humoral immune response (IgM-producing PFCs of spleen and serum anti-SRBC HA titre) to SRBC. The proliferative response to the B-cell mitogen, LPS however revealed a significant increase in the incorporation of 3HT with middle and lowest doses of styrene. The results of cell-mediated immunity appeared somewhat unexpected and more complex as exposure resulted in a dose-dependent enhancement in the cutaneous DTH reaction to SRBC together with increased blastogenic response of splenic lymphocytes to phytohaemagglutinin (PHA). Additionally, there was significant impairment in the functional activity (NBT reduction, attachment and phagocytic indices) of nonadherent and adherent peritoneal exudate cells. Based on the present data the study identifies the immunotoxic potential of styrene and which acts differently on various arms of the rodent's immune system.