Mechanism of Polysaccharides from Two Spleen-invigorating Chinese Medicine Prescriptions in Regulating Growth of Bacteroides fragilis in vitro： Based on Differential Expression of Polysaccharide Utilization Loci / 中国实验方剂学杂志

ObjectiveTo investigate the effects of using the polysaccharides from two Chinese medicine compound prescriptions as the carbon source on the growth of Bacteroides fragilis and to decipher the mechanism from the perspective of differential expression of polysaccharide utilization loci （PULs） based on transcriptomics. MethodThe media with different carbon sources ［20% polysaccharides of Lizhongtang， polysaccharides of Shenling Baizhusan， glucose， and brain heart infusion （BHI） Broth］ were used for the anaerobic culture of B. fragile ATCC25285. The effects of different carbon sources on the growth of B. fragilis ATCC25285 were determined by continuous sampling and spectrophotometry. Then， transcriptome sequencing was performed for the cultures obtained with different carbon sources to study the mechanism of different carbon sources in regulating bacterial growth. ResultThe concentration of bacteria with the polysaccharide of Lizhongtang， polysaccharide of Shenling Baizhusan， BHI Broth， and glucose as the carbon sources peaked at 26， 32， 26， 38 h， respectively， and the bacteria in all the four groups achieved robust growth. Gene ontology （GO） enrichment indicated that the differentially expressed genes in the Lizhongtang polysaccharide group and Shenling Baizhusan polysaccharide group were concentrated in the transport and transmembrane transport of dicarboxylic acid. The Shenling Baizhusan polysaccharide and BHI Broth groups showed high expression of PUL 4 and 27， glycoside hydrolase 13 （GH13）， and glycosyl transferases 5 （GT5）. PUL9 was highly expressed in Shenling Baizhusan polysaccharide group， and PUL 17， 19， and 20， GH3， and GH144 in the BHI Broth group. PUL27 and GT5 were highly expressed in Shenling Baizhusan polysaccharide and glucose groups. PUL 4 and 9 and GH13 were only highly expressed in Shenling Baizhusan polysaccharide group， and PUL 2， 17， and 19 and GH2 in the glucose group. Both Lizhongtang polysaccharide group and BHI group highly expressed PUL 4， 17， 19， 20， and 27， GH3， and GH144. PUL 2， 8， 23， and 27， GH2， and GH57 were highly expressed in Lizhongtang polysaccharide group， while GH13 showed high expression in the BHI group. Both the glucose and Lizhongtang polysacharride groups showed high expression of PUL 4 and 27 and GH2. PUL 4， 8， 20， and 23， GH3， and GH144 were highly expressed in Lizhongtang polysaccharide group， while PUL30 was highly expressed in the glucose group. ConclusionThe in vitro experiments and transcriptome sequencing results confirmed that the expression of PULs and GH may provide benefits or costs to the adaptive growth of Bacteroides fragilis ATCC25285 cultured with different carbon sources， which may be one of the mechanisms by which polysaccharides from Chinese medicine compound prescriptions regulate the growth of B. fragilis ATCC25285. The findings can provide a reference for further research on the relationship between B. fragilis metabolic pathway and polysaccharides of Chinese medicine compound prescriptions.

Media development and process parameter optimization using statistical experimental designs for the production of nonribosomal peptides in Escherichia coli

BACKGROUND: Nonribosomal peptide synthases (NRPS) can synthesize functionally diverse bioactive peptides by incorporating nonproteinogenic amino acids, offering a rich source of new drug leads. The bacterium Escherichia coli is a well-characterized production host and a promising candidate for the synthesis of nonribosomal peptides, but only limited bioprocess engineering has been reported for such molecules. We therefore developed a medium and optimized process parameters using the design of experiments (DoE) approach. RESULTS: We found that glycerol is not suitable as a carbon source for rhabdopeptide production, at least for the NRPS used for this study. Alternative carbon sources from the tricarboxylic acid cycle achieved much higher yields. DoE was used to optimize the pH and temperature in a stirred-tank reactor, revealing that optimal growth and optimal production required substantially different conditions. CONCLUSIONS: We developed a chemically defined adapted M9 medium matching the performance of complex medium (lysogeny broth) in terms of product concentration. The maximum yield in the reactor under optimized conditions was 126 mg L-1, representing a 31-fold increase compared to the first shaking-flask experiments with M9 medium and glycerol as the carbon source. Conditions that promoted cell growth tended to inhibit NRPS productivity. The challenge was therefore to find a compromise between these factors as the basis for further process development.

Engineering progress in microbial production of polyhydroxyalkanoates / 生物工程学报

Polyhydroxyalkanoates (PHAs) are polymers obtained by esterification of hydroxy fatty acid monomers. Due to similar mechanical characteristics of traditional petroleum-based plastics, 100% biodegradability and biocompatibility, PHAs are considered to be one of the most potential green materials. However, the application and promotion of PHAs as a green and environmentally friendly material are difficult because of the high production costs. This article focuses on the current methods to reduce production cost of PHAs effectively, such as cell morphology regulation, metabolic pathway construction, economic carbon source utilization and open fermentation technology development. Despite most research results are still limited in laboratory, the research methods and directions provide theoretical guidance for the industrial production of economic PHAs.

Determination of the biodegradability of chitosan utilizing the most probable number technique

The present work aimed to evaluate the degradability of the chitosan polymer by soil microorganisms.This evaluation was accomplished using the Most Probable Number (MPN) method by plating in drops so that soil microorganisms capable of degrading the polymeric material could be quantified. Soil samples diluted in three specific culture media for each typeof microorganism were plated –bacteria, fungi and actinobacteria–and they were maintained at 28°C for seven days to determine the growth rate of fungi and actinobacteria, and for 48hoursfor the development of bacteria. Significant differences in the MPN of actinobacteriarelative to the other groups analyzed were observed. Thus, the method used was effective for determining the degradability of the chitosan biopolymer when observing the development of microorganisms subjected to the replacement of thecarbonsource by the addition of 2% w v-1of the chitosan biopolymer to the culture medium. The formation of clear regions around the microbial colonies was a strong indicator of biodegradation.

Effect of thymol and environmental factors on growth and biofilm formation by Listeria monocytogenes / Efecto del timol y factores ambientales sobre el crecimiento y formación de biopelícula por Listeria monocytogenes

Thymol (2-isopropyl-5-methylphenol) is an aromatic monoterpene found in essential oils extracted from plants belonging to the Lamiaceae family, such as Thymus, Ocimum, Origanum, Satureja, Thymbra and Monarda genera. Growth and biofilm formation by Listeria monocytogenes CLIP 74902 were evaluate using three carbon sources in the presence of thymol. Specific growth rate (h-1) values at 37o with glucose, trehalose and cellobiose with the addition of thymol (µg/mL) 0 (control) and 750, were respectively: 0.22, 0.07; 0.14, 0.04; 0.11, 0.04. Lag periods obtained under the same conditions were (h): 8.19, 13.2; 22.5, 27.5; 23.1, 28.1. A marked antibiofilm activity was observed against the exposure with 750 µg/mL of thymol, showing a high percentage of inhibition: glucose (99 %), trehalose (97 %) and cellobiose (98%), compared to the control. The results suggest that thymol could be used to inhibit the growth and production of biofilms by L. monocytogenes in the food industry.

Timol (2-isopropil-5-metilfenol) es un monoterpeno aromático presente en los aceites esenciales extraídos de plantas pertenecientes a la familia Lamiaceae, como los géneros Thymus, Ocimum, Origanum, Satureja, Thymbra y Monarda. El crecimiento y formación de biopelícula por Listeria monocytogenes CLIP 74902 fueron evaluados utilizando tres fuentes de carbono en presencia de timol. La velocidad específica de crecimiento (h-1) a 37o con glucosa, trehalosa y celobiosa con la adición de timol (µg/mL) 0 (control) y 750, fueron respectivamente: 0.22, 0.07; 0.14, 0.04, 0.11, 0,04. Los períodos lag obtenidos en las mismas condiciones fueron (h): 8.19, 13.2; 22.5, 27.5; 23.1, 28.1. Una marcada actividad antibiofilm fue obtenida con 750 µg/mL de timol, mostrando un alto porcentaje de inhibición con glucosa (99%), trehalosa (97%) y celobiosa (98%), respecto al control. Los resultados sugieren que timol podría ser usado para inhibir el crecimiento y producción de biopelículas por L. monocytogenes en la industria alimentaria.

Research Progress of Polysaccharide Utilization Loci and Its Application in Pharmacological Research of Chinese Medicinal Herb / 中国实验方剂学杂志

Polysaccharide utilization loci (PULs) are a group of gene clusters related to polysaccharides catabolism and located in specific areas, including starch utilization system(SusC), SusD, encoding outer membrane glycoprotein binding proteins, and carbohydrate active enzymes. The wide existence of PULs in Bacteroides, and the extraordinary ability of utilizing polysaccharide is its survival strategy to adapt to the intestinal tract. On one hand, Bacteroides feature a high abundance and variety, making it the most important bacterial target group regulated by traditional Chinese medicine(TCM). On the other hand, polysaccharide is an important effective constituent among TCM chemicals, with a high content, and can also be used as a competitive carbon source for intestinal bacteria. Therefore, what is the mechanism of regulating the intestinal flora based on the carbon source of polysaccharide is an important part of the pharmacological research of TCM. According to the latest literatures, this paper introduces the gene and protein composition of PULs, reviews the latest developments in PULs research, and analyzes the structure of PULs in the genomes of Bacteroides fragilis and Bacteroides thetaiotaomicron. Furthermore, we also put forward a prospect for the pharmacological micro-ecological mechanism of TCM based on PULs based on our carbon source experiments, which focuses the effects of Bacteroides by TCM polysaccharides in vitro. This research is not only the new content of bacterial PULs researches, but also the important part of researches of "human-drug-bacteria" holistic view and TCM spleen-tonifying concept.

Cost Effective Pilot-scale Ajmalicine Production by Catharanthus roseus Cell Suspension Cultures in a 100 Lit Bioreactor

Aims: The cosmic production of biomass and bioactive compounds at pilot scale with minimum production costs is an important task to achieve feasible production process of corresponding secondary metabolites at a commercial level. Materials and Methods: The cell suspension cultures of Catharanthus roseus in MS medium supplemented with 2, 4-dichlorophenoxyacetic acid (9.05 µM), kinetin (4.52 µM) were scaled up in a pilot plant bioreactor (100 lit). The cost of production was reduced by addition of substitute carbon source in a basal medium which hardly costs 30% in the medium. Preliminary studies were performed in the 7-lit bioreactor. A 100 lit stainless steel bioreactor equipped with helical impeller top mounted was used for scale-up of C. roseus suspension cultures and ajmalicine production. Results: The culture medium reduced the cost by 36% by addition of commercial grade sugar whereas medium consist of tissue culture grade sucrose costs 53 USD per 100 lit. The suspension cultures were cultivated in a 100 lit bioreactor containing MS medium fortified with cost-effective carbon source produced ajmalicine 73.18 mg/l DW and achieved 36 kg of fresh biomass on day 20. Conclusion: The results of the present finding demonstrated the feasible and cost-effective production process of ajmalicine at pilot scale.

Carbon metabolism influenced for promoters and temperature used in the heterologous protein production using Pichia pastoris yeast

Abstract Nowadays, it is necessary to search for different high-scale production strategies to produce recombinant proteins of economic interest. Only a few microorganisms are industrially relevant for recombinant protein production: methylotrophic yeasts are known to use methanol efficiently as the sole carbon and energy source. Pichia pastoris is a methylotrophic yeast characterized as being an economical, fast and effective system for heterologous protein expression. Many factors can affect both the product and the production, including the promoter, carbon source, pH, production volume, temperature, and many others; but to control all of them most of the time is difficult and this depends on the initial selection of each variable. Therefore, this review focuses on the selection of the best promoter in the recombination process, considering different inductors, and the temperature as a culture medium variable in methylotrophic Pichia pastoris yeast. The goal is to understand the effects associated with different factors that influence its cell metabolism and to reach the construction of an expression system that fulfills the requirements of the yeast, presenting an optimal growth and development in batch, fed-batch or continuous cultures, and at the same time improve its yield in heterologous protein production.

Carbon metabolism influenced for promoters and temperature used in the heterologous protein production using Pichia pastoris yeast

Abstract Nowadays, it is necessary to search for different high-scale production strategies to produce recombinant proteins of economic interest. Only a few microorganisms are industrially relevant for recombinant protein production: methylotrophic yeasts are known to use methanol efficiently as the sole carbon and energy source. Pichia pastoris is a methylotrophic yeast characterized as being an economical, fast and effective system for heterologous protein expression. Many factors can affect both the product and the production, including the promoter, carbon source, pH, production volume, temperature, and many others; but to control all of them most of the time is difficult and this depends on the initial selection of each variable. Therefore, this review focuses on the selection of the best promoter in the recombination process, considering different inductors, and the temperature as a culture medium variable in methylotrophic Pichia pastoris yeast. The goal is to understand the effects associated with different factors that influence its cell metabolism and to reach the construction of an expression system that fulfills the requirements of the yeast, presenting an optimal growth and development in batch, fed-batch or continuous cultures, and at the same time improve its yield in heterologous protein production.

Cultivation of Pichia pastoris carrying the scFv anti LDL (-) antibody fragment. Effect of preculture carbon source

Abstract Antibodies and antibody fragments are nowadays among the most important biotechnological products, and Pichia pastoris is one of the most important vectors to produce them as well as other recombinant proteins. The conditions to effectively cultivate a P. pastoris strain previously genetically modified to produce the single-chain variable fragment anti low density lipoprotein (-) under the control of the alcohol oxidase promoter have been investigated in this study. In particular, it was evaluated if, and eventually how, the carbon source (glucose or glycerol) used in the preculture preceding cryopreservation in 20% glycerol influences both cell and antibody fragment productions either in flasks or in bioreactor. Although in flasks the volumetric productivity of the antibody fragment secreted by cells precultured, cryopreserved and reactivated in glycerol was 42.9% higher compared with cells precultured in glucose, the use of glycerol in bioreactor led to a remarkable shortening of the lag phase, thereby increasing it by no less than thrice compared to flasks. These results are quite promising in comparison with those reported in the literature for possible future industrial applications of this cultivation, taking into account that the overall process time was reduced by around 8 h.

Production of docosahexaenoic acid by Aurantiochytrium sp. ATCC PRA-276

Abstract The high costs and environmental concerns associated with using marine resources as sources of oils rich in polyunsaturated fatty acids have prompted searches for alternative sources of such oils. Some microorganisms, among them members of the genus Aurantiochytrium, can synthesize large amounts of these biocompounds. However, various parameters that affect the polyunsaturated fatty acids production of these organisms, such as the carbon and nitrogen sources supplied during their cultivation, require further elucidation. The objective of this investigation was to study the effect of different concentrations of carbon and total nitrogen on the production of polyunsaturated fatty acids, particularly docosahexaenoic acid, by Aurantiochytrium sp. ATCC PRA-276. We performed batch system experiments using an initial glucose concentration of 30 g/L and three different concentrations of total nitrogen, including 3.0, 0.44, and 0.22 g/L, and fed-batch system experiments in which 0.14 g/L of glucose and 0.0014 g/L of total nitrogen were supplied hourly. To assess the effects of these different treatments, we determined the biomass, glucose, total nitrogen and polyunsaturated fatty acids concentration. The maximum cell concentration (23.9 g/L) was obtained after 96 h of cultivation in the batch system using initial concentrations of 0.22 g/L total nitrogen and 30 g/L glucose. Under these conditions, we observed the highest level of polyunsaturated fatty acids production (3.6 g/L), with docosahexaenoic acid and docosapentaenoic acid ω6 concentrations reaching 2.54 and 0.80 g/L, respectively.

Characterization of rhizobia isolates obtained from nodules of wild genotypes of common bean

Abstract This study aimed to evaluate the tolerance to salinity and temperature, the genetic diversity and the symbiotic efficiency of rhizobia isolates obtained from wild genotypes of common bean cultivated in soil samples from the States of Goiás, Minas Gerais and Paraná. The isolates were subjected to different NaCl concentrations (0%, 1%, 2%, 4% and 6%) at different temperatures (28 °C, 33 °C, 38 °C, 43 °C and 48 °C). Genotypic characterization was performed based on BOX-PCR, REP-PCR markers and 16S rRNA sequencing. An evaluation of symbiotic efficiency was carried out under greenhouse conditions in autoclaved Leonard jars. Among 98 isolates about 45% of them and Rhizobium freirei PRF81 showed a high tolerance to temperature, while 24 isolates and Rhizobium tropici CIAT899 were able to use all of the carbon sources studied. Clustering analysis based on the ability to use carbon sources and on the tolerance to salinity and temperature grouped 49 isolates, R. tropici CIAT899 and R. tropici H12 with a similarity level of 76%. Based on genotypic characterization, 65% of the isolates showed an approximately 66% similarity with R. tropici CIAT899 and R. tropici H12. About 20% of the isolates showed symbiotic efficiency similar to or better than the best Rhizobium reference strain (R. tropici CIAT899). Phylogenetic analysis of the 16S rRNA revealed that two efficient isolates (ALSG5A1 and JPrG6A8) belong to the group of strains used as commercial inoculant for common bean in Brazil and must be assayed in field experiments.

The Mutagenesis of Lactobacillus Thermophilus for Enhanced L-(+)-Lactic Acid Accumulation Induced by Heavy Ion Irradiation

ABSTRACT Screening promising L. thermophiles with high productivity, high efficiency and strong adaptability are very important in lactic acid industry. For this purpose, 80MeV/u carbon ions were applied to irradiate L. thermophiles. After high-throughput screening, a mutant, named SRZ50, was obtained. Different carbon sources or nitrogen sources were provided to investigate carbon or nitrogen source utilization between mutant SRZ50 and wild type, and different fermentation periods were also chose to study fermentation characteristic between mutant SRZ50 and wild type. The results showed that mutant SRZ50 exhibited the enhanced L-(+)-lactic acid production from wild type. When glucose or fructose was the sole carbon source, the L(+)-lactic acid production by mutant SRZ50 was both the highest, respectively, 23.16 ± 0.72 g/L or 23.24 ± 0.66 g/L, which had a significant increase from that of wild type (P<0.01), following obvious increase in biomass (P<0.05). When yeast powder was the sole nitrogen source, it can promote mutant SRZ50 to accumulate the highest L-(+)-lactic acid accumulation, which also had a significant increase from that of wild type (P<0.01). Under different fermentation periods, it was obtained that mutant SRZ50 all exhibited significant increase in L-(+)-lactic acid accumulation from wild type. In conclusion, a mutant strain with improved production profiles for L-(+)-lactic acid, was obtained, indicating that heavy ions can be an efficient tool to improve metabolic product accumulations in microbes.

Effect of carbon source on production, characterization and bioactivity of exopolysaccharide produced by Phellinus vaninii Ljup

ABSTRACT The effect on different three carbon source (i.e. glucose, fructose and sucrose) on production, chemical characterization and antioxidant activity of exopolysaccharide (EPS) produced by Phellinus vaninii Ljup was investigated in this study. Amongst carbon sources examined, glucose and sucrose were favorable for the mycelia growth, while the maximum EPS yield was achieved when sucrose was employed. The predominant carbohydrate compositions in EPSs identified were gluconic acid, glucose, mannose and galactose acid. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. EPSs molecule exist as nearly globular shape form in aqueous solution. The variation also affects antioxidant activities by investigated by using hydroxyl and DPPH radical scavenging assay. Sucrose was best carbon source from the viewpoint of antioxidant activity due to the relatively high contents of galactose in the EPS with moderate molecular weight and polydispersity.

Citric acid production by Aspergillus niger using different substrates

Aims: Citric acid is a commercially important acid that has many applications in varying sectors of industries. It is produced by various substrates through solid state or submerged fermentation. The capabilities of potato and rice as substrates for citric acid production using Aspergillus niger were tested in this experiment under submerged fermentation. Methodology and results: Potato and rice extract media were prepared and inoculated with A. niger and titrations were carried out to determine the amount of citric acid produced. It was shown that rice extract media proved more useful than potato extract media as it produced the highest citric acid production. Rice extract media was supplemented with varying concentrations of glucose and sucrose and 5% sucrose (w/v) proved to be the best as it produced the highest amount of citric acid. The rice extract media with 5% sucrose (w/v) were supplemented with varying concentrations of ammonium nitrate and ammonium sulphate and 0.25% ammonium nitrate proved more effective in citric acid production. A low pH (1.9-2.3) was found during the maximum production of citric acid. Conclusion, significance and impact of study: The results depict that potato and rice extract media can produce citric acid, hence providing an alternate substrate for citric acid production.

Effects of External Carbon Source Concentration on Sulphate Removal by Selected Bacterial and Fungal species.

The aim of this study was to investigate the role of initial external carbon source concentration on sulphate removal by four bacterial and four fungal isolates under shake flask conditions. The test wastewater was filtered and supplemented with sodium acetate as the external carbon source at respective concentrations of 5g/L, 10g/L, 15g/L and 20g/L, before dispensing in 200mL quantity in 250mL capacity conical flasks, sterilised and inoculated with the test microbial isolates. Prior inoculation and at 24h interval, for 96 h for the estimation of sulphate concentration in the wastewater using standard methods. The results revealed remarkable sulphate removal in the absence of the sodium acetate and on its 5g/L addition. An increase in the concentration of the sodium acetate caused a corresponding decrease in the level of sulphate removal. Percentage sulphate removals in presence of the test isolates were observed to range from 47.01 to 57.81%, 18.66 to 51.66%, -1.64 to 11.03%, 5,38 to 22.37% and -3.59 to 5.18%, at sodium acetate concentrations of 0g/L, 5g/L, 10g/L, 15g/L and 20g/L, respectively. This trend was irrespective of the isolates used for investigation. The study was able to provide an insight to the role of carbon concentration on sulphate removal by the test microbial isolates.

Cultural Characteristics of Ophiocordyceps heteropoda Collected from Korea

Isolates of Ophiocordyceps heteropoda (Kobayasi) collected from Mt. Halla on Jeju-do, Korea were tested for mycelial growth on different agar media and in the presence of different carbon and nitrogen sources. Similarly, isolates were also incubated at different temperatures as well as under continuous light and dark conditions. Growth was better on Hamada agar, basal medium, and malt-yeast agar, but poor on Czapek-Dox agar. Different carbon sources such as dextrin, saccharose, starch, lactose, maltose, fructose, and dextrose resulted in better growth. Complex organic nitrogen sources such as yeast extract and peptone revealed the most effective growth. Mycelial growth was best at 25degrees C. The growth rate was faster in the dark than the light, but mycelial density was less compact in the dark.

Growth and Cultural Characteristics of Ophiocordyceps longissima Collected in Korea

We investigated the effect of nutritional and environmental factors on Ophiocordyceps longissima mycelial growth. The longest colony diameter was observed on Schizophyllum (mushroom) genetics complete medium plus yeast extract, Schizophyllum (mushroom) genetics minimal medium, and Sabouraud dextrose agar (SDA); however, malt-extract yeast-extract agar, SDA plus yeast extract, yeast-extract malt-extract peptone dextrose agar, SDA, oatmeal agar, and potato dextrose agar showed higher mycelia density. A temperature of 25degrees C was optimum and 7.0 was the optimum pH for mycelial growth. Colony diameter was similar under light and dark conditions. Maltose and yeast extract showed the highest mycelial growth among carbon and nitrogen sources respectively. The effect of mineral salts was less obvious; however, K3PO4 showed slightly better growth than that of the other mineral salts tested. Among all nutrition sources tested, complex organic nitrogen sources such as yeast extract, peptone, and tryptone were best for mycelial growth of O. longissima. Ophiocordyceps longissima composite medium, formulated by adding maltose (2% w/v), yeast extract (1% w/v), and K3PO4 (0.05% w/v) resulted in slightly longer colony diameter. In vitro mycelial O. longissima growth was sustainable and the production of fruiting bodies could be used for commercial purposes in the future.

Characteristics of Metacordyceps yongmunensis, a New Species from Korea

Metacordyceps yongmunensis is a newly reported species from Korea, which is very similar to Cordyceps species in morphological characters. It grows on large lepidopteran pupa, and numerous white stromata grow on a single host. Mycelial growth characteristics of M. yongmunensis isolates were studied in different media and at different temperatures. Also, different carbon sources, nitrogen sources, and mineral salts were tested for mycelial growth of M. yongmunensis. Schizophyllum (mushroom) genetics complete medium plus yeast extract, Schizophyllum (mushroom) genetics minimal medium, and Martin's peptone dextrose agar produced longer colony diameters and more compact mycelial density than other media. The optimum temperature for mycelial growth was 25degrees C. Carbon sources such as sucrose, soluble starch, dextrose, glucose, dextrin, maltose, and fructose showed better mycelial growth, whereas peptone, yeast extract and tryptone resulted in the best mycelial growth of all of the nitrogen sources tested. All of the mineral salts tested showed similar growth as the control, except K2HPO4 which showed longer colony diameter and more compact mycelial density. The compact colonies were white and cottony with a greenish margin. The results showed that M. yongmunensis is an easy fungus to growas it grew from 30 to more than 50 mm in 2 wk.

Effect of Temperature and Carbon Source on the N-acyl-homoserine Lactones Production by Food-derived Pseudomonas / 中国生物工程杂志

7.5). Overall,the research demonstrates the effect of environmental parameters (temperature and carbon source) on AHL profile production by food-derived Pseudomonas. It lays the foundation for further investigation to elucidate the relationship between quorum sensing and food spoilage,and for the development of new food preservative by blocking the quorum sensing of food spoilage bacteria.