Lab Fermenter Research Articles

Investigation on the film-forming properties of lab fermenter scale produced scleroglucans from Sclerotium rolfsii ATCC 201126

The film-forming capacity of the biopolymer scleroglucan produced on the lab fermenter scale by Sclerotium rolfsii ATCC 201126 was studied. The effect of a freeze–thawing process on the physical properties of scleroglucan films was investigated with hydrogels of three different scleroglucan samples. Films were made from 1% (w/w) scleroglucan hydrogels using 2% (w/w) glycerol as plasticizer by applying two different protocols: (1) a room-temperature drying method and, (2) a freeze–thawing cyclic process (prior to the application of room-temperature drying). The obtained materials were characterized by physical studies including swelling, water vapor transmission, and environmental scanning electron microscopy. Based on the results obtained, when eight freezing–thawing cycles were applied during scleroglucan film preparation, a reinforcement of the structure was achieved pointing to an increase in the number of crosslinking points by H-bonding. All exopolysaccharides produced by S. rolfsii ATCC 201126 at lab fermenter scale showed a general promising behavior for the preparation of reinforced films, opening new perspectives for their potential use in either controlled release systems or the formulation of additive-complemented films for specific applications.

Antitumour compounds from a saline soil isolate, Streptomyces griseoincarnatus CTF15

A new actinomycete strain designated as Streptomyces sp. CTF15 was isolated from a saline soil using casein–KNO3 agar medium. The strain Streptomyces sp. CTF15 exhibited promising antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Streptomyces viridochromogens Tü57 and high cytotoxicity (91.2% mortality) against Artimia salina in biological screening. The cultivation of this strain in a 50 L lab fermenter and subsequent isolation and purification by a series of chromatographic techniques and structure elucidation by MS and NMR analysis of the active metabolites revealed that it is a highly stable producer of resistomycin (1), tetracenomycin D (2) and actinomycin D (3), even under non-optimised culture conditions. The morphological, microscopic, biochemical and physiological characterisation suggested that the strain CTF15 belongs to the genus Streptomyces. A partial 16S rRNA gene sequence (1429 bp) from the strain CTF15 was determined and found to have high identity (99%) with Streptomyces griseoincarnatus. As such, this is the first report of a strain of S. griseoincarnatus capable of producing these three bioactive compounds simultaneously.

Extracellular β-glucosidase production by the yeast Debaryomyces pseudopolymorphus UCLM-NS7A: optimization using response surface methodology

beta-Glucosidase production by Debaryomyces pseudopolymorphus UCLM-NS7A using a simple nutrient medium containing cellobiose was evaluated under several biochemical and physiological parameters in submerged fermentation. Enzyme induction was also examined using different carbon and nitrogen sources. Cellobiose and ammonium nitrate were the best C and N sources to enhance beta-glucosidase production. The addition of NaCl, MgSO(4), yeast extract, ethanol and Tween 80 to the nutrient medium before inoculation was also compared. A factorial design to optimize enzyme production was developed using four variables that most influenced beta-glucosidase production and data analyzed by the response surface method. Optimal conditions to produce beta-glucosidase in shake-flasks were 1.25% cellobiose, 0.05% Tween 80, 0.4% NH(4)NO(3) over 72 hours. In another factorial design to further increase enzyme production, a lab fermenter using prior-determined shake-flask optimized conditions resulted in higher beta-glucosidase titres at 72 hours, pH controlled at 6.25 and agitation of 200 rpm.

A marked enhancement in the production of a highly alkaline and thermostable pectinase by Bacillus pumilus dcsr1 in submerged fermentation by using statistical methods

The production of a highly alkaline and thermostable pectinase of Bacillus pumilus was optimized in submerged fermentation using Plackett–Burman design and response surface methodology. Three fermentation variables (C:N ratio, K 2HPO 4, and pH), which were identified to significantly affect pectinase production by Plackett–Burman design were further optimized using response surface methodology of central composite design (CCD). An over all 34- and 41-fold increase in enzyme production was achieved in shake flasks and lab fermenter by the optimization of variables using statistical approaches, respectively. The enzyme was optimally active at pH 10.5 and 50 °C, and selectively degraded only the noncellulosic gummy material of ramie ( Boehmeria nivea) fibres causing 10.96% fibre weight loss, and therefore, the enzyme could find application in fibre processing industry. The use of the enzyme in fibre processing reduces the use of alkali, and the associated alkalinization of water bodies.

Kinetic studies of amylase and biomass production by calvatia gigantea

Production of alpha-amylase (alpha-4, glucan 4-glucanohydrolase, EC 3.2.1.1) by microorganisms has been practiced for many years in small and large scale operations and the literature on this enzyme is voluminous. Aspergillus niger and Aspergillus oryzae have been reported as the main fungal species used for commercial production of the enzyme. On the other hand, large volumes of low-cost agricultural products such as acorn (the perisperm-free dry seed contains approximately 60% starch) are wasted in many countries and provide a challenge to biotechnology to efficiently utilize these rich sources of starch for the production of high added value products like enzymes. C. gigantea is an edible puffball excreting high levels of alpha-amylase when cultivated on different sources of starch containing elevated quantities of toxic tannic compounds. This fungus has been employed for the production of microbial protein from wastes and acorns containing high levels of toxic tannic compounds. The same fungus was also reported to grow on both hydrolyzable and condensed tannins as sole carbon sources. The present work was undertaken to investigate certain kinetic characteristics of alpha-amylase and biomass production by C. gigantea grown on soluble and acorn starch in a lab fermenter. (Refs. 18).