Production of pullulan by a thermotolerant Aureobasidium pullulans strain in non-stirred fed batch fermentation process

Total 95 isolates of Aureobasidium pullulans were isolated from different flowers and leaves samples, out of which 11 thermotolerant strains produced pullulan. One thermotolerant non-melanin pullulan producing strain, designated as RG-5, produced highest pullulan (37.1±1.0 g/l) at 42ºC, pH 5.5 in 48h of incubation with 3% sucrose and 0.5% ammonium sulphate in a non-stirred fed batch fermentor of 6 liters capacity. The two liters of initial volume of fermentation medium was further fed with the 2 liters in two successive batches at 5 h interval into the fermentor. The sterile air was supplied only for 10h at the rate of 0.5 vvm.

Rapid screening of tannase producing microbes by using natural tannin

Use of natural tannin in the screening of tannase producing microbes is really promising. The present work describes about the possibility and integrity of the newly formulated method over the previously reported methods. Tannin isolated from Terminalia belerica Roxb. (Bahera) was used to differentiate between tanninolytic and nontanninolytic microbes. The method is simple, sensitive and superior for the rapid screening and isolation of tannase-producing microbes.

Amylase production by endophytic fungi Cylindrocephalum sp. isolated from medicinal plant Alpinia calcarata (Haw.) Roscoe

Amylases are among the most important enzymes used in modern biotechnology particularly in the process involving starch hydrolysis. Fungal amylase has large applications in food and pharmaceutical industries. Considering these facts, endophytic fungi isolated from the plant Alpinia calcarata (Haw.) Roscoe were screened for amylolytic activity on glucose yeast extract peptone agar (GYP) medium. Among thirty isolates of endophytic fungi, isolate number seven identified as Cylindrocephalum sp. (Ac-7) showed highest amylolytic activity and was taken for further study. Influence of various physical and chemical factors such as pH, temperature, carbon and nitrogen sources on amylase production in liquid media were studied. The maximal amylase production was found to be at 30ºC and at pH 7.0 of the growth medium. Among the various carbon and nitrogen sources tested, maltose at 1.5% and Sodium nitrate at 0.3% respectively gave optimum amylase production.

Physiological studies on carboxymethyl cellulase formation by Aspergillus terreus DSM 826

Physiological studies were conducted to determine the optimum cultural conditions for maximal carboxymethyl cellulase (CMCase) formation by Aspergillus terreus DSM 826. Shaking condition at 150 rpm is favorable for the production of CMCase from rice straw and sugar cane bagasse. The highest enzyme yield was obtained at the third day of incubation at 30ºC for both cases; however CMCase formation occurred at a broad range of pH values, with maximal formation of A. terreus DSM 826 CMCase at pH 4.5 and 5.0 when rice straw and sugar cane bagasse were used as sole carbon source, respectively. Carboxymethyl cellulose (CMC) was found to be a good inducer for CMCase formation in both agricultural wastes with CMC concentrations of 0.5 and 1.0 % (w/v) in case of rice straw and sugar cane bagasse, respectively. High level of enzyme formation was obtained with the addition of ammonium chloride as nitrogen source in both cases and at a concentration of 0.4 % (v/v Tween-80) as an addition to medium containing rice straw. However this addition did not influence the production of CMCase in case of using sugar cane bagasse as carbon source.

Production of inulinase from Kluyveromyces marxianus using Dahlia tuber extract

Various carbon sources were evaluated for production of inulinase by yeast, Kluyveromyces marxianus MTCC 3995. Highest inulinase activity was observed with Dahlia extract (25.3 nkat mL-1) as carbon source. The enzyme activity was 1.4 folds higher than that observed in media containing pure chicory inulin (17.8 nkat mL-1). The yeast showed good growth on a simple medium containing dahlia extract (20% w/v) and yeast extract (2%w/v) as carbon and nitrogen source respectively, in 96 h. at 28°C and 120 rpm. Lowest inulinase yield (4.8 nkat mL-1) was seen in the medium containing glucose as C-source. Although varied inulinase levels were noticed on different C- sources, Inulinase: Sucrase (I/S) ratios were noticed to be similar. Among various protein sources tested, yeast extract was found to be the best source followed by beef extract (17.9 nkat mL-1) and peptone (13.8 nkat mL-1). The enzyme was optimally active at pH (4.0) and 50°C. TLC analysis of end product revealed that inulinase hydrolyzed inulin exclusively into fructose. Results suggest that the dahlia extract induced exoinulinase synthesis in Kluyveromyces marxianus and can be utilized as a potential substrate for inulinase production.

Seasonality and host preference of arbuscular mycorrhizal fungi of five plant species in the inner Mongolia steppe, China

The seasonal change and host preference of arbuscular mycorrhizal (AM) colonization and community composition of five common plant species Agropyron cristatum, Anemarrhena asphodeloides, Cleistogenes squarrosa, Leymus chinensis, and Stipa grandis in the Inner Mongolia steppe were investigated. The AM root length colonization rates were different among the five plant species and were generally high in early (May and June) and late (September) growth seasons and low in August. A total of 18 AM fungal species representing five genera were isolated from rhizosphere soils of the five plant species, and most AM fungi had not host specificity, except that Acaulospora sp., Glomus constrictum, G. diaphanum and Glomus sp. showed a certain degree of host preference. Glomus albidum, G. etunicatum and G. geosporum were the dominant species and showed various sporulation patterns in the five plants during the growth seasons. The AM fungal spore densities and species richness increased from May to September and decreased in October and were different in the same month in the five plants. Multivariate analyses revealed that season and host significantly co-affected the AM fungal spore density, species richness, and Shannon-Wiener diversity index, and the season had higher influence than the host.

Kinetics of high-level of ß-glucosidase production by a 2-deoxyglucose-resistant mutant of Humicola lanuginosa in submerged fermentation / Cinética de produção de ß-glucosidase por um mutante de Hemicola lanuginosa resistente a 2-deoxiglucose em fermentação submersa

A 2-deoxyglucose-resistant mutant (M7) of Humicola lanuginosa was obtained by exposing conidia to γ-rays and permitting expression in broth containing 0.6 percent 2-deoxyglucose (DG) and cellobiose (1 percent) before plating on DG esculin-ferric ammonium citrate agar medium from which colonies showing faster and bigger blackening zones were selected. Kinetic parameters for enhanced ß-glucosidase (BGL) synthesis by M7 were achieved when corncobs acted as the carbon source. The combination between corncobs and corn steep liquor was the best to support higher values of all product formation kinetic parameters. Effect of temperature on the kinetic and thermodynamic attributes of BGL production equilibrium in the wild organismand M7was studied using batch process at eight different temperatures in shake-flask studies. The best performance was found at 45ºC and 20 g L-1 corncobs in 64 h. Both growth and product formation (17.93 U mL-1) were remarkably high at 45ºC and both were coupled under optimum working conditions. Product yield of BGL from the mutant M7 (1556.5 U g-1 dry corncobs) was significantly higher than the values reported on all fungal and bacterial systems. Mutation had thermo-stabilization influence on the organism and mutant required lower activation energy for growth and lower magnitudes of enthalpy and entropy for product formation than those demanded by the wild organism, other mesophilic and thermo-tolerant organisms. In the inactivation phase, the organisms needed lower values of activation energy, enthalpy and entropy for product formation equilibrium, confirming thermophilic nature of metabolic network possessed by the mutant organism.

Um mutante de Hemicola lanuginosa resistente a 2-deoxiglucose(M7) foi obtido através de exposição de conídios a raios γ, permitindo a expressão em caldo contendo 0,6 por cento de 2-deoxiglucose (DG) e celobiose (1 por cento) antes da semeadura em ágar DG esculina citrato de ferro amoniacal, da qual foram selecionadas as colônias com halo negro. Os parâmetros cinéticos para produção aumentada de ß-glucosidase (BGL) foram obtidos empregando-se sabugo de milho como fonte de carbono. A combinação de espiga de milho com água de maceração de milho foi a que forneceu os valores mais altos nos parâmetros cinéticos de formação de todos os produtos. O efeito da temperatura na cinética e atributos termodinâmicos da produção de BGL pelas cepas selvagem e M7 foi avaliado empregando-se processo de batelada em oito temperaturas diferentes in frascos em agitação. O melhor desempenho foi observado a 45ºC e 20g.l-1 de espiga de milho em 64h. Tanto a multiplicação quanto a formação do produto foram muito altas a 45ºC e ambas estavam ligadas em condições ótimas de trabalho. O rendimento de BGL produzido pelo mutante M7 (1556 U.g-1 de espiga seca) foi significativamente superior aos valores reportados para todos os sistemas fúngicos e bacterianos. A mutação influenciou a termoestabilização no microrganismo, sendo que o mutante necessitou de energia de ativação mais baixa para multiplicação e valores mais baixos de entalpia e entropia para a formação do produto quando comparado à cepa selvagem e a outros microrganismos mesofilicos e termotolerantes. Na fase de inativação, os microrganismos necessitaram valores mais baixos de energia de ativação, entalpia e entropia para o equilíbrio da formação de produto, confirmando a natureza termofílica da máquina metabólica do mutante.

A cysteine protease of Dieffenbachia maculata.

Plants of the genus Dieffenbachia, very popular as indoor ornamental plants, are known for their toxic as well as therapeutic properties. Their toxic manifestations have been partly attributed to their proteolytic activity. The work described in the present paper shows that stem leaves and petiole of Dieffenbachia maculata Schott, a commonly grown species, contain significant proteolytic activity, different parts showing different types of protease activities. Stem showed the highest enzyme activity and this protease was purified about 55 fold by solvent precipitation, gel filtration and ion exchange chromatography. The enzyme has a relative molecular mass of 61 kDa as determined by SDS-PAGE and has an optimum pH of 8.0 and optimum temperature of 50 degrees C. Effects of various substrates, inhibitors and activators indicate that the enzyme is a cysteine protease with leucylpeptidase activity.