Tannase production by Bacillus licheniformis

Bacillus licheniformis KBR 6 produced maximum extracellular tannase activity at 0.21 U ml^–1 with 1.5% (w/v) tannic acid either in the absence or presence of glucose (1 g l^–1) after 18–21 h growth though the organism did not attain maximum growth until 36 h.     

Production of cellulases in batch culture using a mutant strain of Trichoderma reesei growing on soluble carbon source

Trichoderma reesei Rut-C30 is a highly derepressed mutant which synthesised active cellulases in culture media containing glucose and lactose as the only carbon sources. The maximum biomass, filter paper and specific filter paper activities for cell growth on 20 g glucose l^–1 were 20 g dry cell wt l^–1, 1.9 FPU ml^–1 and 4.8 FPU mg^–1 protein respectively, while on 40 g glucose l^–1 were 25 g dry cell wt l^–1, 4.5 FPU ml^–1 and 6.2 FPU mg^–1 protein, respectively. This strain had a higher specific filter paper activity (6.2 FPU mg^–1 protein) than was produced by other T. reesei mutants (3.6 FPU mg^–1 protein).     

Impact of carbon and nitrogen nutrition on the quality, yield and composition of blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus

The impact of growing cultures of Paecilomyces fumosoroseus in liquid media containing four combinations of glucose and casamino acids (8 g l^–1 or 80 g l^–1 glucose, 1.32 g l^–1 or 13.2 g l^–1 casamino acids) was evaluated, based on blastospore production, germination rate, viability after freeze-drying and short-term storage stability. When blastospores were produced using a high casamino acid concentration, blastospore yields and germination rates were significantly higher (13.2–18.5×10⁷ blastospores ml^–1, 50–60% germination after 4 h), compared to cultures grown in media containing lower casamino acid concentrations (0.4–2.3×10⁷ blastospores ml^–1, 10–20% germination after 4 h). Chemical analyses of blastospore composition showed that accelerated blastospore germination may be related to increased proteinaceous reserves rather than to glycogen or lipid accumulation. Tolerance to freeze-drying by blastospores suspended in spent medium was enhanced by a high initial casamino acid concentration in the culture medium (75% survival) and by the residual glucose concentrations in the spent medium. Under the conditions of this study, the storage stability of blastospores of P. fumosoroseus was unaffected by the nutritional condition in which they were produced.     

Overproduction and secretion of Bacillus circulans endo-β-1,3-1,4-glucanase gene (bglBC1) in B. subtilis and B. megaterium

A gene coding for endo--1,3-1,4-glucanase (lichenase) containing a recombinant plasmid, pLL200K, was transferred from Bacillus circulans into a new shuttle plasmid, pLLS920, by ligating linearized DNAs of pLL200K and pUB110. B. subtilis RM125 and B. megaterium ATCC14945 transformed with pLLS920 produced the endo--1,3-1,4-glucanase. The enzyme was produced during active growth with maximum activity. The B. subtilis (pLLS920) enzyme was 83 times (8522 mU ml^–1) more active than that of the gene donor cells (103 mU ml^–1). The B. megaterium (pLLS920) enzyme was 7 times (735 mU ml^–1) more active than that of the gene donor cells. While E. coli secreted only about 10% of the produced enzyme, B. subtilis excreted the enzyme completely into the medium and B. megaterium by about 98%. The plasmid pLLS920 was stable in B. megaterium (98%), and in B. subtilis (51%) but not in E. coli (29%).     

Quantification of the contribution of surface outgrowth to biocatalysis in sol-gels: oxytetracycline production by <Emphasis Type="Italic">Streptomyces rimosus</Emphasis>

A technique was developed for differentiating the activity of microbes solely within sol gels by using the contribution of biomass outgrowth. Streptomyces rimosus was immobilised in colloidal silica gels and biomass growth, oxytetracycline synthesis, pH and carbohydrate consumption were compared for UV surface-sterilised gels, untreated gels, and liquid cultures. Absolute and biomass specific oxytetracycline yields were higher for non-sterile gels than for liquid culture. Biomass solely within colloidal silica gels (1.7 mg ml^–1), and gels obtained from colloidal silica modified by addition of larger silica particles (1.2 mg ml^–1) yielded 27 and 21 g ml^–1 oxytetracycline compared with 97 and 104 g ml^–1 for unsterilised gels (3.6 and 5.2 mg ml^–1 biomass) displaying outgrowth. It was therefore apparent that biomass and antibiotic production within the gels was limited and that optimisation requires gel modification.     

Phenotypic expression of Vogesella indigofera upon exposure to hexavalent chromium,Cr6+

A eubacterium producing a blue pigment was isolated from a drinking water filter, and subsequently identified as Vogesella indigofera. This bacterium was further investigated for its morphological and biochemical characteristics after exposure to hexavalent chromium, Cr⁶⁺. The threshold Cr⁶⁺ concentration inhibiting the pigment production by V. indigofera was 200–300 g ml^–1 in liquid cultures of nutrient broth and 100–150 g ml^–1 on nutrient agar plates. The Cr⁶⁺ concentration preventing V. indigofera growth was 300–400 g ml^–1 in liquid cultures, but greater than 150 g ml^–1 on agar plates. Moreover, rugose colonies without the blue pigmentation were observed on agar plates amended with 150 (g Cr⁶⁺) ml^–1. The biochemical utilization profiles of the colonies without pigmentation did not differ from the original pigment-producing ones, indicating phenotypic plasticity of this bacterium. The difference of phenotypic expression of V. indigofera under various Cr⁶⁺ concentrations might have potential application as a pollution bioindicator for heavy metals.     

Enhanced nisin and pediocin production on whey supplemented with different nitrogen sources

Production of nisin and pediocin were followed, respectively, in Lactococcus lactis subsp. lactis CECT 539 and Pediococcus acidilactici NRRL B-5627 grown with lactose and four different nitrogen sources. Neither NH₄Cl nor glycine improved production of the bacteriocins. Both yeast extract and Casitone increased pediocin production from 55 BU ml^–1 to 195 BU ml^–1 and 185 BU ml^–1, respectively. Nisin increased from 21 BU ml^–1 to 74 BU ml^–1 and 59 BU ml^–1 with these nitrogen sources.     

Efficient production by Escherichia coli of recombinant protein using salting-out effect protecting against proteolytic degradation

To produce glucoamylase efficiently as a recombinant protein, E. coli was grown with 20 g (NH₄)₂SO₄ l^–1 which removed proteolytic activity but did not effect cell growth. Growth in M9 medium with 20 g (NH₄)₂SO₄ l^–1 produced 11 U glucoamylase ml^–1 compared to 7 U ml^–1 without addition. Furthermore, the glucoamylase activity was maintained at about 9 U ml^–1.     

Novel lignocellulolytic ability of Candida utilis during solid-substrate cultivation on apple pomace

Lignocellulolytic enzymes from conventional and non-conventional yeasts are not commonly studied, and they have never been described for Candida utilis species. After solid-substrate cultivation of C. utilis (CCT 3469) on apple pomace, degradation of cellulose, pectin and lignin fragments was observed. Production of the main lignocellulolytic enzymes by C. utilis was investigated and high activity for pectinase (239 U ml^–1) as well as a significant manganese-dependent peroxidase (19.1 U ml^–1) activity was found. Low cellulase (3.0 U ml^–1) and xylanase (1.2 U ml^–1) activities were also observed suggesting that C. utilis may have lignocellulose degradation ability.     

Two extracellular endoxylanases from alkaliphilic Bacillus firmus differ in their synthesis

To investigate the synthesis of two extracellular endoxylanases, xylan-binding and unbound xylanases from an alkaliphilic Bacillus firmus, washed cells were incubated in alkaline mineral salt media containing various carbon sources. The 23 kDa xylan-binding endoxylanase (XBE), which hydrolyses insoluble xylan, was produced before the 45 kDa, unbound endoxylanase. All the carbon sources tested at 5 mg ml^–1, including glucose, induced production of XBE but the unbound xylanase was totally repressed by glucose. The production of XBE increased when glucose concentration increased but was not synthesized until the glucose in the medium was less than 1 mg ml^–1.     

Anaerobic and aerobic continuous cultures of<Emphasis Type="Italic"> Saccharomyces cerevisiae</Emphasis>: comparison of plasmid stability and<Emphasis Type="Italic"> EXG1</Emphasis> gene expression

Two bioreactor continuous cultures, at anaerobic and aerobic conditions, were carried out using a recombinant Saccharomyces cerevisiae strain that over-expresses the homologous gene EXG1. This recombinant system was used to study the effect of dissolved oxygen concentration on plasmid stability and gene over-expression. Bioreactor cultures were operated at two dilution rates (0.14 and 0.03 h^–1) to investigate the effect of other process parameters on EXG1 expression. Both cultures suffered severe plasmid instability during the first 16 generations. Segregational plasmid loss rate for the aerobic culture was two-fold that of the anaerobic operation. In spite of this fact, exo--glucanase activity at aerobic conditions was 12-fold that of the anaerobic culture. This maximal activity (30 U ml^–1) was attained at the lowest dilution rate when biomass reached its greatest value and glucose concentration was zero.     

Control of xylanase production without protease activity in Bacillus sp. by selection of nitrogen source

Maximum xylanase activity, of 380 IU ml^–1, with negligible protease activity, occurred when Bacillus SSP-34 was grown for 96 h with yeast extract and peptone each at 0.25%. Other concentrations of the combination gave xylanase activities less than 66% of that with the optimum nitrogen source concentration and protease activities in the range of 0.01–0.045 IU ml^–1.     

Bacterial response to extracellular dissolved organic carbon released from healthy and senescent Fragilaria crotonensis (Bacillariophyceae) in experimental systems

Responses of bacteria to dissolved organic carbon (DOC) released from healthy and senescent Fragilaria crotonensis (Bacillariophyceae) were examined in experimental systems. The alga released DOC actively, although the concentration fluctuated greatly in both the axenic (the alga alone) and the mixed (the alga plus the enriched bacteria) cultures. In the control (the bacteria alone) cultures, both DOC concentration and bacterial density were low and almost constant throughout the experiment: 5.0 mg C 1^–1 and 1.1 × 10⁵ cells ml^–1, respectively. In the mixed cultures, bacterial growth was negligible during the exponential growth phase of the alga, but rapid proliferation of the bacteria occurred after the onset of the stationary growth phase. As the bacterial population grew, the density of senescent algal cells also increased. When the bacteria were fed on the DOC from healthy algae, their growth rate was relatively low (0.44 d^–1), but the maximum cell density was high (6.4 × 10⁵ cells ml^–1). Conversely, when the bacteria fed on the DOC of senescent algae, they grew at a relatively high rate (0.51 d^–1), but the maximum cell density was low (2.8 × 10⁵ cells ml^–1). These results suggest that DOCs released from dominant phytoplankton species in different physiological states affect the biomass and activity of bacteria.     

Induction of diapausing amictic eggs in Synchaeta pectinata

Amictic females of a clone of S. pectinata from Star Lake (Norwich, Vermont) may produce diapausing as well as non-diapausing (subitaneous) eggs. The proportion of diapausing eggs produced in cultures was unaffected by temperature (12 vs 19 °C) or rotifer population density (minima of 0.33 vs 3 ind. ml^–1) at 19 °C. However, at 19 °C this proportion was higher in cultures maintained at a low food level suppressing reproduction (5 × 10³ cells ml^–1 Cryptomonas erosa) than in those maintained at a high food level (2 × 10⁴ cells ml^–1); the treatment effect was marginally significant (p=0.067). Consistent with the effect of low food availability, a period of starvation was very effective in inducing the development of diapausing eggs. None of 19 females cultured individually from hatching at 19 °C on C. erosa (2 × 10⁴ cells ml^–1) in 1-ml volumes produced any diapausing eggs in 4 days (0 out of 349 eggs), while 13 out of 16 females subjected to a 15-hour starvation period 6 hours after birth produced one or more diapausing eggs during that time (34% of the 158 eggs produced by the 16 females were diapausing). Diapausing eggs produced and left at 19 °C hatched after 4 to 13 days. Those produced in cultures with a low food level took significantly longer to hatch (9.7 days) than those produced in cultures with a high food level (8.1 days) (p=0.022). In natural communities, S. pectinata should be able to respond directly and rapidly to poor food conditions by producing eggs that undergo an obligatory dormant period before resuming development.     

Improvement of phenylethanoid glycosides production by a fungal elicitor in cell suspension culture of Cistanche deserticola

When, on the 15th day of growth, an elicitor from Fusarium solani was added at 40 mg l^–1 to Cistanche deserticola cell suspension cultures, the contents of echinacoside, acteoside and total phenylethanoid glycosides (PeGs) in cultured cells all increased over the next 27 d by over 100% to 15 mg g^–1 dry wt, 9 mg g^–1 dry wt and 57 mg g^–1 dry wt, respectively. The final biomass (1.3 mg dry wt ml^–1) was not affected.     

Towards an understanding of human impact upon the hydrology of Lake Naivasha,Kenya

The growth of a strain of Moina macrocopa (Straus 1820) isolated from an experimental stabilization pond in Marrakesh, was examined at seven concentrations of algae (6.25–6.25 × 10⁵ cells ml^–1 and at 5 different temperatures (15–30 °C)). Feeding conditions influenced the growth rate as well as the maximum size that reached 1.8 mm at 25 °C and at the highest algal concentration (6.25 × 10⁵ cell ml^–1). The life span and number of moltings reached a maximum (17.4 days and 13 moltings) at average nutrient concentrations (6.25 × 10⁵ cell ml^–1). Juvenile stages varied from 1 to 3 and adult ones from 6 to 8. In the temperature interval tested, growth rate increased with temperature while longevity decreased. Temperature had less effect on maximal size than nutrient availability. Population density (but not crowding) influenced longevity and survival but had no effect on growth.     

Culture conditions of tannase production by Lactobacillus plantarum

Lactobacillus plantarum produced an extracellular tannase after 24 h growth on minimal medium of amino acids containing 2 g tannic acid l^–1. Enzyme production (6 U ml^–1) was optimal at 37 °C and pH 6 with 2 g glucose l^–1 and 7 g tannic acid l^–1 in absence of O₂.     

Production of thermostable xylanases in batch and continuous culture by Thermomonospora fusca KW 3

Summary The actinomycete Thermomonospora fusca KW 3 produced novel thermostable xylanases in batch and continuous cultures in media containing insoluble xylan. The production of xylanases could be induced with oat spelt or beech xylan. Very low activities were detected when the strain was grown on glucose or xylose. In continuous cultivations, mycelial wall growth could be prevented using a stirrer speed controller. Homogeneous mixing of the insoluble substrate was obtained by vibrating the flexible tubes. T. fusca KW 3 could be grown on insoluble xylan at growth rates as high as 0.23 h^–1, equivalent to a doubling time of 3 h. Xylanase activity decreased from maximum levels of 2.5 units (U) ml^–1 with increasing dilution rate and was nearly constant at a level of 0.5 U ml^–1 with dilution rates greater than 0.1 h^–1. Correspondence to: P. Röthlisberger     

Optimizing Production of Extracellular Laccase from Grammothele Subargentea CLPS No. 436 Strain

The production of extracellular laccase by the Grammothele subargentea CLPS no. 436 strain in liquid cultures grown on a carbon-limited basal medium was significantly enhanced when culture conditions, including the addition of CuSO₄·5H₂O or veratryl alcohol, were consecutively optimized. A laccase activity as high as 1954.5 mU ml⁻¹ of liquid medium was obtained under optimum conditions, which corresponded to non-agitated cultures supplemented with 0.6 mM CuSO₄·5H₂O. Veratryl alcohol at 1 mM was less effective than CuSO₄·5H₂O for increasing laccase activity levels; the supplementation of veratryl alcohol resulted only in maximum levels of 44 mU ml⁻¹ in non-agitated cultures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Transesterification of divinyladipate with glucose at various temperatures by an alkaline protease of Streptomyces sp.

The transesterification of 1 M divinyladipate with 0.25 M glucose in dimethylformamide (DMF) catalyzed by 5 mg ml^–1 alkaline protease (24 units mg^–1 min^–1) from Streptomyces sp. gave 6-O-vinyladipoyl d-glucose as the main product with yields are between 60 and 90%. The optimum temperature for the reaction was about 50 °C.