English

Growth kinetics of newly isolated diazotrophic Bacillus sphaericus UPMB10 grown in various carbon (lactate, acetate, glycerol, malate, fructose, xylose and sucrose) and nitrogen (glutamate, yeast extract, arginine, hystadine, glycine, polypeptone, tryptophan, lysine, NH4Cl and urea) sources was investigated using 2 L stirred tank fermenter. The highest growth was obtained in a medium containing lactate as a carbon source, which gave the highest maximum cell concentration of 2.30 g/L, which is corresponding to maximum viable cell count of 4.60 x 109 cfu/mL. However, the highest cell yield (1.06 g cell/g carbon consumed) was obtained in cultivation using glycerol though slightly lower maximum viable cell count was obtained (3.22 x 109 cfu/mL). In addition, cost for the production of live cell using glycerol was about 15 times lower than the cost using lactate. Growth performance of this bacterium when yeast extract was used as a nitrogen source was comparable to the use of pure amino acid. The medium containing 1.8 g/L glycerol and 2 g/L yeast extract was suggested as optimal for growth of this bacterium, which gave carbon to nitrogen ratio (C/N) of 10:1. The maximum viable cell count obtained in cultivation using optimised medium in 2 L stirred tank fermenter was 3.34 x 109 cfu/mL and the cells maintained its capacity for N2 fixation at 18 nmol C2H2/h.mL.

BACKGROUND: Metabolisation of carbon and nitrogen substrates is a key factor during the ripening process of white soft cheeses but has not previously been examined in terms of energy substrate efficiency. Such work could be useful to improve physiological knowledge concerning Geotrichum candidum, a yeast involved in the neutralisation of curd during ripening. Its behaviour was therefore examined during batch cultures on simple (glutamate) or complex (peptones) substrates as nitrogen and carbon sources and lactate as a second carbon source.RESULTS: In addition to their assimilation as carbon and nitrogen sources, G. candidum used peptides and amino acids as energy sources during growth in preference to lactate. Contrarily, during stationary state, lactate was preferred over peptides and amino acids for carbon dissimilation for energy supply, allowing the avoidance of ammonium production. Indeed, lactate dissimilation theoretically yields 15 adenosine triphosphates (ATPs), while only nine ATPs are theoretically yielded during the dissimilation of an amino acid such as glutamate.CONCLUSION: This behaviour can be considered as an energy‐saving response. Indeed, the use of peptides and amino acids as energy sources in addition to being used as carbon and nitrogen sources during G. candidum growth can be related to its deaminating activity and was in agreement with the better energy efficiency expected from utilisation of the same substrate as both carbon and energy source. Contrarily, the better efficiency of lactate dissimilation led to its use during stationary state instead of peptides and amino acids. Copyright © 2008 Society of Chemical Industry

The automated Bioscreen C system was used for growth of four Mucor hiemalis strains isolated from the soil in the Juréia-Itatins Ecology Station (JIES), São Paulo state, in liquid culture media containing different carbon (2%) and nitrogen (1%) sources, pH 5.0, at 25ºC, and agitated at 150 rpm for 5 days. The medium containing only one nitrogen source had been added with 2% glucose. The readings were taken at lambda = 540 nm, at 2-hour intervals, up to five days. The results were compared using the Friedman Test (alpha = 5%). The best growth was obtained for strains M1, M2 and M3, reaching the log phase in 60 hours. The best carbon sources varied according to the strain, and yeast extract proved to be the best nitrogen source. Sodium acetate inhibited the growth of the four strains, being the M3 strain the most affected. The use of the automated system was very convenient for cultures in liquid media, as it is rapid and automated, providing a good technique for determination of the optimal environmental factors for growth of the filamentous fungi.

ABSTRACTPigments produced by Monascus fungi are widely used in food and biotechnology as natural colorants, flavors and preservatives. There are various factors influencing the pigments productions, among which are the nutrient media composition, pH, ambient temperature, mode of cultivation. In the present study the influence of different carbon and nitrogen sources on the pigments biosynthesis by Monascus pilosus C1 strain was investigated during batch cultivation at the following conditions: T = 30°C, pH 6.0, agitation 300 rpm and modified Chapec—Dox medium with different carbon (a range of sugars and alcohols) or nitrogen sources for 7 days. Some process kinetic parameters—YX/C, YP/C, Vav, were calculated and analized. It was found that the micelial growth, expressed as dry weight (DW) and the specific pigment production (SPP) were strongly stimulated by glucose as a carbon source. The DW and SPP reached values of 10.89 g DW l−1, and 1.97 OU mg DW−1 and 1.01 OU mg DW−1 for the total red and yellow pigments, respectively. Sodium glutamate combined with glucose increased effectively the pigments production up to 2.29 OU mg DW−1 and 1.67 OU mg DW−1 respectively for the total red and yellow pigments. The obtained yield coefficient of the studied processes indicated the feasibility of Monascus pilosus C1 strain for pigments production. None of the investigated carbon or nitrogen sources provoked citrinin biosynthesis.

Micro-organisms such as bacteria, yeasts, molds and algae that store lipid more than 20% of their biomass are called Oleaginous. Microbial lipid has a lot of similarity to the oil obtained from plants and animals and this similarity is valuable because it can be used for biodiesel production with many environmental benefits. Production of microbial oil is valuable when the cost of production is decreased by optimization of cultivation condition and using low cost substrate. In this study the effect of carbon and nitrogen sources on lipid production was investigated. These parameters have the most important effect on lipid production in many oleaginous types of yeast. Among the carbon sources which were evaluated, glucose leads to higher lipid content but from economical point of view rice bran was the best carbon source. Between nitrogen sources, yeast extract and ammonium sulfate exhibited higher lipid content. Rhodotorulla 110 had lipid content of 40%, 36% and 30% in glucose, xylose and bran as carbon source respectively with yeast extract and ammonium sulfate as nitrogen sources.

Cultures of Streptomyces lividans TK24 grown in defined media containing certain rapidly used carbon and nitrogen sources excreted high levels of organic acids. These were identified by HPLC and enzymic assays as pyruvic acid and 2-oxoglutaric acid. Acidification occurred only with glucose as the principal carbon source, and depended on the nitrogen source used. With nitrate as the sole nitrogen source, high levels of pyruvate and small amounts of 2-oxoglutarate were produced. Carbon from D[U-14C]glucose was converted into both organic acids. Combining glucose with a selection of amino acids as primary nitrogen/secondary carbon sources yielded less pyruvate and more 2-oxoglutarate. Carbon from both 14C-labelled glucose and amino acids was metabolized to both organic acids. Adding nitrate to this combination caused a reversion of the acid production pattern to that of the glucose-nitrate combination, as if the amino acids were absent. Addition of ammonium salts to any combination of carbon and nitrogen sources completely prevented organic acid formation.

Objective: The aim of the study was to isolate bacterial consortium from the effluent contaminated site that is used in the mineralizing both natural rubber and synthetic rubber, to optimise the growth conditions for efficient mineralisation and to biochemically characterise and to use 16s RNA sequencing for identifying the bacterial strains. Materials and Methods: Natural rubber mineralizing bacterial consortium was isolated from effluent contaminated soil. The mineralisation study was performed for five days at every 24 h interval. Optimization studies were performed with different parameters such as varying concentrations of latex, pH, carbon sources, nitrogen sources, mixed carbon and nitrogen source and different temperature. The bacterial consortium mineralizing nr latex was used to mineralize synthetic rubber gloves (SRG) using the same medium for 40 days at every 5 days interval. Effect of pre-treatment was studied by pre-treating the SRG with acetone and exposing it to sunlight. Mineralisation of the Rubber was confirmed by spectrophotometric and Fourier Transform Infra-Red (FTIR) studies. Results: Isolated organism was identified as Enterobater cloacae, Microbacterium laevaniformans and Methylobacterium rhodesianum. Maximum mineralisation of (1.66 × 10-4) was shown on the 4th day of incubation. Conformation of NR degradation was done by FTIR analysis that shows the presence of aldehye and ketone produced due to bacterial degradation. The parameters giving optimum results were concentration of latex -1%, pH- 8.5, carbon source- Xylose, nitrogen source- Ammonium Nitrate, temperature- 37°C. Maximum mineralisation of synthetic rubber was shown on the 20th day (1.3 × 10-4). Among the pre-treated and the untreated samples most prominent distortions were visible on the surface of the sunlight sample when visualized under scanning electron microscopy. Conclusion: From the present investigation, it can be concluded that the isolated bacterial consortium containing the strains Enterobater cloacae, Microbacterium laevaniformans and Methylobacterium rhodesianum were able to mineralize natural rubber as well as synthetic rubber. Which could be applied in the removal of waste rubber products present in the environment.

Microorganisms are capable of producing vitamins as metabolites, which are essential nutrients, in the metabolism of energy production. So, microbial production has been researched for years. Riboflavin is one of the fewest B-vitamins biotechnologically produced. There are many factors that affect riboflavin biosynthesis, which varies in each microorganism. However, few studies of the effect of different carbons and nitrogen sources on riboflavin production have been done. Thus, our objective in this study was to work on the effect of previously selected carbon and nitrogen sources on riboflavin production by screened wild-type yeast Candida sp. LEB 130. Classical shaken fermentation vessel system was used, controlling temperature and agitation, with fixed oxygen concentration. A 25 screening design was used to analyze the effect of the medium components such as sucrose, flaxseed oil, and yeast extract. A second experiment factorial design 24 yielded a riboflavin production of 105.7 ug/mL, 4.2-fold higher than 25 design. Riboflavin analysis was done in a spectrophotometer. Screening design as a medium performance evaluation ended up being very advantageous for riboflavin production by this yeast.

Improvement in raw sago starch degrading enzyme production from Acremonium sp. endophytic fungus using carbon and nitrogen sources.

Xylanases are hydrolytic enzymes with wide range of applications in food processing, bleaching of pulp in paper manufacturing industry, bio-conversion of biomass wastes to fermentable sugars and enhancing nutrient digestibility in animal feeds. The optimization of growth conditions and evaluation of an appropriate substrate as carbon source among cassava peels, corn cobs, wheat bran and rice husk on xylanase production by novel strain of Aspergillus tubingensis under Solid State Fermentation (SSF) was investigated. The fungal isolate was identified based on ribosomal RNA gene and ITS gene sequencing analysis as Aspergillus tubingensis. Results showed that Corn cobs had the highest xylanase production among the four substrates. Corn cobs recorded the highest value of xylanase production at pH of 6.0 (107.97 U/g), after incubation period of 72 hour (111.23 U/g), at temperature of 30oC (44.26 U/g) and at ratio 1:3 (45.68 U/g). The optimum growth conditions for xylanase production by Aspergillus tubingensis were: pH 6.0, incubation period of 72 hours, temperature of 30oC and substrate concentration of 1:3 (4g of substrate per 12ml of fermentation medium). Corn cobs showed the highest yield of xylanase activity (111.23±0.31 U/g), followed by Rice husk (101.91±0.72 U/g), Wheat bran (89.30±1.16 U/g) and Cassava peel (87.03±0.57 U/g). In conclusion, among the various agro residues that were used as carbon sources, Corn cobs had maximum xylanase activity. Various culture conditions were optimized by using one factor at a time method and the maximum xylanase production was obtained at pH of 6.0, incubation period of 72 hour, temperature of 30oC and substrate concentration of 1:3 under solid state fermentation. It is therefore suggested that some other notable environmental and fermentation factors that influence metabolism-mediated production yields of xylanase like aeration, agitation, carbon and nitrogen sources, metal ion requirement, inoculum size etc. should be optimized for maximum production of enzyme. Keywords: Solid State Fermentation, Cassava peels, Corn cobs, Wheat bran, Rice husk

A specific symbiotic Bacillus species isolated from a rhabditid entomopathogenic nematode, Rhabditis (Oscheius) sp. was found to produce a number of bioactive compounds. The present study was conducted to determine the effect of six different nitrogen sources in combination with fructose on the production of antifungal crude extract by Bacillus sp. against Penicillium expansum. The yield of crude extract and antifungal activity against the test fungi differed significantly when the nitrogen sources in the fermentation media were changed. The highest yield was recorded for beef extract plus fructose (921 mg/L). The antifungal activity was higher in yeast extract plus fructose [P. expansum (46.5 ± 2.12 mm)], followed by beef extract. High performance liquid chromatography analysis of the crude antimicrobial substances revealed different peaks with different retention times indicating that they produced different compounds. When a carbon source was not included in the fermentation medium, the antimicrobial production was substantially reduced almost eight times. Carbon source in the fermentation medium plays a vital role in the production of antimicrobial substances. Yeast extract and fructose as nitrogen and carbon sources in the fermentation medium produced maximum antimicrobial activity.

This study was performed to evaluate the efficiency of using softwood as the sawdust medium for Lentinula edodes cultivation, effect of nutrient on the mycelial growth, spawning, the mushroom yield, and quality. The nitrogen nutrition significantly enhanced the mycelial growth of L. edodes. The glutamic acid in the L. leptolepis and P. koraiensis, and asparagine in the P. densiflora were appeared to slight increase in the mycelial growth. The vegetable oil showed very effective on the mycelial growth in the P. koraiensis sawdust medium. Carbon/nitrogen ratio of all the test was reduced after mycelial growth. The mycelial growth was exclusively dependent on reduction of carbon. The mushroom yield (32.7%) of the P. densiflora sawdust medium (carbon source: 3% active carbon, nitrogen source: 0.4% asparagines) was the best in mushroom production of L. edodes, followed by the Q. variabilis sawdust (35.4%) of the control medium. The diameter of mushroom cap was obtained from the P. densiflora sawdust (carbon source: 3% sucrose, nitrogen source: 0.4% potassium nitrate) and P. koraiensis sawdust (carbon source: 3% sucrose, nitrogen source: 0.4% potassium nitrate), and the P. koraiensis sawdust (carbon source: 3% xylose, nitrogen source: 0.4% glutamic acid, supplement: 0.05% amino acid), with values 71.5 mm, 71.5 mm and 72.1 mm, respectively. In the polypropylene bag cultivation, the weight losses of the block medium gradually increased for 80 days in the dark (13.8~16.8%) and then became stable in the range of 20.7~25.8%.

Investigation of collagen hydrolysate used as carbon and nitrogen source in the fermentation of Bacillus pumilus

Twenty five (25) rhizobial strains were isolated from root nodules of Vigna trilobata cultivars grew in  soils collected from all districts of Andhra Pradesh, India. Five out of 25 rhizobial strains which produced copious amount of Exopolysaccharides (EPS) on Yeast Extract Mannitol Agar (YMA) medium with congo red were identified by sequencing of their 16S rDNAs. The amount of EPS produced by these five strains increased during the first 72 h of incubation but it declined afterwards. The amount of EPS produced correlated positively with increase in mannitol concentration from 1 to 3% (m/v). However, there was a decrease in EPS production when mannitol concentration was equal or higher than 4%. All the five strains studied preferred mannitol and sodium nitrate as the best carbon and nitrogen sources for EPS production. Sinorhizobium kostiense MRR104 produced maximum levels of EPS 892 mg/100 ml when mannitol was used as carbon source, while S. xinjiangense MRR110 produced maximum levels of EPS 377 mg/100 ml when sodium nitrate was used as nitrogen source. Variation among the rhizobial strains in utilization of carbon and nitrogen sources for EPS production was clearly evident from this study. All the strains analysed in the present study can be exploited for production of commercial biopolymer (gum), due to their non pathogenic nature and their ability to produce copious amounts of EPS when compared to strains studied in earlier reports.   Key words: Rhizobial strains, V. trilobata, Exopolysaccharides (EPS), carbon and nitrogen sources.

This work evaluates the effect of different carbon and nitrogen sources on conidiophore and conidia formation in Penicillium sp. HC1, a cellulolytic and xylanolytic fungi arousing industrial interest. A factorial design was used having two variables: A carbon source (glucose, sucrose, cassava starch, wheat bran, and rice flour) and a nitrogen source (tryptose, yeast extract, (NH4)2HPO4, and KNO3). The resulting 20 combinations were evaluated in both solid and liquid medium. Different C:N ratios (5:1, 10:1, 20:1, and 40:1) were also evaluated for one of the combinations. The results revealed the influence of both carbon and nitrogen sources on conidiophore and conidia morphology and the amount of conidia produced; however, this depended on culture condition. A particular culture’s condition could also influence conidia tolerance to stressful conditions; conidia having close to 100% tolerance were obtained in liquid media having complex carbon sources and inorganic nitrogen sources. Regarding the C:N ratio, it was found out that nitrogen limitation increased conidia tolerance for both conditions (solid, liquid), the effect being more noticeable in submerged conditions. Understanding the effects of nutrition on conidia production and quality in fungi having industrial interest is a key issue when developing large-scale production. Key words: Complex carbon source, conidia, conidiophore, inorganic nitrogen source, medium conditions.