Production of clavulanic acid and cephamycin C by Streptomyces clavuligerus under different fed-batch conditions

Environmental Factors Modulate the Role of orf21 Sigma Factor in Clavulanic Acid Production in Streptomyces Clavuligerus ATCC27064

Sigma factors and sigma factor-related mechanisms control antibiotic production in Streptomyces. In this contribution, the orf21 gene was overexpressed in the wild-type strain of Streptomyces clavuligerus ATCC2764, yielding S. clavuligerus/pIORF21, to further evaluate its regulatory effect on clavulanic acid (CA) biosynthesis under different culture medium conditions. The orf21 overexpression, regulated under the constitutive promoter ermE*, led to 2.6-fold increase in CA production in GSPG medium, and a 1.8-fold decrease using ISP medium. As for GYM and MYM media, S. clavuligerus/pIORF21 strain showed higher aerial mycelium production compared to control. Glycerol uptake rate profile was affected by orf21 overexpression. Furthermore, in GSPG, S. clavuligerus/pIORF21 slightly increased the expression of adpA and gcas genes, whilst, in ISP, the claR gene expression was drastically reduced, which is consistent with a decreased CA production, observed in this medium. These findings suggest the protein encoded by the orf21 gene plays a role in the regulation of CA biosynthesis as a response to the nutritional composition of the medium.

Active pharmaceutical ingredient (API) chemicals: a critical review of current biotechnological approaches

The aim of this article was to generate a framework of bio-based economy by an effective utilization of biomass from the perspectives of agriculture for developing potential end bio-based products (e.g. pharmaceuticals, active pharmaceutical ingredients). Our discussion is also extended to the conservatory ways of bioenergy along with development of bio-based products and biofuels. This review article further showcased the fundamental principles for producing these by-products. Thereby, the necessity of creating these products is to be efficaciously utilization by small-scale farmers that can aid the local needs for bio-based materials and energy. Concurrently, the building up of small markets will open up the avenues and linkages for bigger markets. In nutshell, the aim of the review is to explore the pathway of the biotechnological approaches so that less chosen producers and underdeveloped areas can be allied so that pressure on the systems of biomass production can be relaxed.

Statistical Optimizing of Medium for Clavulanic Acid Production by Streptomyces clavuligerus Using Response Surface Methodology

Clavulanic acid (CA) is a naturally occurring antibiotic produced by Streptomyces clavuligerus. Statistical optimization of the fermentation medium for CA production by Streptomyces clavuligerus was carried out. Multiple carbon sources, glycerol, dextrin, and triolein, were considered simultaneously. A two-level fractional factorial design experiment was conducted to identify the significant components of medium on CA production. Statistical analysis of the results showed that soybean meal, dextrin, and triolein were the most significant medium ingredients on CA production. The optimal level of these screened components was obtained by RSM based on the result of a Box-Behnken design, in which the values of dextrin, soybean meal, and triolein in CA fermentation medium were 12.37 g/L, 39.75 g/L, and 26.98 ml/L, respectively. Using the proposed optimized medium, the model predicted 938 mg/L of CA level and via experimental rechecking the model, 946 mg/L of CA level was attained in shake flask fermentation, significantly high than 630 mg/L of original medium. The optimized medium was further verified in 50-L stirred fermenter, and compared with performance of original medium in parallel, CA titer was increased from 889 to 1310 mg/L; a 47% increase was achieved through medium optimization by statistical approaches.

TCA Cycle and Its Relationship with Clavulanic Acid Production: A Further Interpretation by Using a Reduced Genome-Scale Metabolic Model of Streptomyces clavuligerus

Streptomyces clavuligerus (S. clavuligerus) has been widely studied for its ability to produce clavulanic acid (CA), a potent inhibitor of β-lactamase enzymes. In this study, S. clavuligerus cultivated in 2D rocking bioreactor in fed-batch operation produced CA at comparable rates to those observed in stirred tank bioreactors. A reduced model of S. clavuligerus metabolism was constructed by using a bottom-up approach and validated using experimental data. The reduced model was implemented for in silico studies of the metabolic scenarios arisen during the cultivations. Constraint-based analysis confirmed the interrelations between succinate, oxaloacetate, malate, pyruvate, and acetate accumulations at high CA synthesis rates in submerged cultures of S. clavuligerus. Further analysis using shadow prices provided a first view of the metabolites positive and negatively associated with the scenarios of low and high CA production.

Clavulanic Acid Production by Streptomyces clavuligerus: Insights from Systems Biology, Strain Engineering, and Downstream Processing

Clavulanic acid (CA) is an irreversible β-lactamase enzyme inhibitor with a weak antibacterial activity produced by Streptomyces clavuligerus (S. clavuligerus). CA is typically co-formulated with broad-spectrum β‑lactam antibiotics such as amoxicillin, conferring them high potential to treat diseases caused by bacteria that possess β‑lactam resistance. The clinical importance of CA and the complexity of the production process motivate improvements from an interdisciplinary standpoint by integrating metabolic engineering strategies and knowledge on metabolic and regulatory events through systems biology and multi-omics approaches. In the large-scale bioprocessing, optimization of culture conditions, bioreactor design, agitation regime, as well as advances in CA separation and purification are required to improve the cost structure associated to CA production. This review presents the recent insights in CA production by S. clavuligerus, emphasizing on systems biology approaches, strain engineering, and downstream processing.

Homologous expression of lysA encoding diaminopimelic acid (DAP) decarboxylase reveals increased antibiotic production in Streptomyces clavuligerus

lysA gene encoding meso-diaminopimelic acid (DAP) decarboxylase enzyme that catalyzes L-lysine biosynthesis in the aspartate pathway in Streptomyces clavuligerus was overexpressed, and its effects on cephamycin C (CephC), clavulanic acid (CA), and tunicamycin productions were investigated. Multicopy expression of lysA gene under the control of glpF promoter (glpFp) in S. clavuligerus pCOlysA led to higher expression levels ranging from 2- to 6-fold increase at both lysA gene and CephC biosynthetic gene cluster at T₃₆ and T₄₈ of TSBG fermentation. These results accorded well with CephC production. Thus, 1.86- and 3.14-fold higher volumetric as well as 1.26- and 1.71-fold increased specific CephC yields were recorded in S. clavuligerus pCOlysA in comparison with the wild-type and its control strain, respectively, at 48th h. Increasing the expression of lysA provided 4.3 times more tunicamycin yields in the recombinant strain. These findings suggested that lysA overexpression in S. clavuligerus made the strain more productive for CephC and tunicamycin. The results also supported the presence of complex interactions among antibiotic biosynthesis pathways in S. clavuligerus.

Application of Acid and Cold Stresses to Enhance the Production of Clavulanic Acid by Streptomyces clavuligerus

Clavulanic acid (CA) is frequently prescribed for treatment of bacterial infections. Despite the large number of studies concerning CA production, there is still a need to search for more effective and productive processes because it is mainly produced by biochemical route and is chemically unstable. This paper evaluates the influence of acid and cold stresses on CA production by Streptomyces clavuligerus in bench scale stirred tank bioreactor. Four batch cultures were conducted at constant pH (6.8 or 6.3) and temperature (30, 25, or 20 °C) and five batch cultures were performed with application of acid stress (pH reduction from 6.8 to 6.3), cold stress (reduction from 30 to 20 °C), or both. The highest maximum CA concentration (684.4 mg L^-1) was obtained in the culture conducted at constant temperature of 20 °C. However, the culture under acid stress, in which the pH was reduced from 6.8 to 6.3 at a rate of 0.1 pH unit every 6 h, provided the most promising result, exhibiting a global yield coefficient of CA relative to cell formation (Y_CA/X) of 851.1 mg_CA g_X^-1. High Y_CA/X values indicate that a small number of cells are able to produce a large amount of antibiotic with formation of smaller amounts of side byproducts. This could be especially attractive for decreasing the complexity and cost of the downstream processing, enhancing CA production.

Degradation Kinetics of Clavulanic Acid in Fermentation Broths at Low Temperatures

Clavulanic acid (CA) is a β-lactam antibiotic inhibitor of β-lactamase enzymes, which confers resistance to bacteria against several antibiotics. CA is produced in submerged cultures by the filamentous Gram-positive bacterium Streptomyces clavuligerus; yield and downstream process are compromised by a degradation phenomenon, which is not yet completely elucidated. In this contribution, a study of degradation kinetics of CA at low temperatures (−80, −20, 4, and 25 °C) and pH 6.8 in chemically-defined fermentation broths is presented. Samples of CA in the fermentation broths showed a fast decline of concentration during the first 5 h followed by a slower, but stable, reaction rate in the subsequent hours. A reversible-irreversible kinetic model was applied to explain the degradation rate of CA, its dependence on temperature and concentration. Kinetic parameters for the equilibrium and irreversible reactions were calculated and the proposed kinetic model was validated with experimental data of CA degradation ranging 16.3 mg/L to 127.0 mg/L. Degradation of the chromophore CA-imidazole, which is commonly used for quantifications by High Performance Liquid Chromatography, was also studied at 4 °C and 25 °C, showing a rapid rate of degradation according to irreversible first-order kinetics. A hydrolysis reaction mechanism is proposed as the cause of CA-imidazole loss in aqueous solutions.

Production of β-Lactamase Inhibitors by Streptomyces Species

β-Lactamase inhibitors have emerged as an effective alternative to reduce the effects of resistance against β-lactam antibiotics. The Streptomyces genus is known for being an exceptional natural source of antimicrobials and β-lactamase inhibitors such as clavulanic acid, which is largely applied in clinical practice. To protect against the increasing prevalence of multidrug-resistant bacterial strains, new antibiotics and β-lactamase inhibitors need to be discovered and developed. This review will cover an update about the main β-lactamase inhibitors producers belonging to the Streptomyces genus; advanced methods, such as genetic and metabolic engineering, to enhance inhibitor production compared with wild-type strains; and fermentation and purification processes. Moreover, clinical practice and commercial issues are discussed. The commitment of companies and governments to develop innovative strategies and methods to improve the access to new, efficient, and potentially cost-effective microbial products to combat the antimicrobial resistance is also highlighted.

Screening of medium constituents for clavulanic acid production by Streptomyces clavuligerus

Clavulanic acid is a β-lactam compound with potent inhibitory activity against β-lactamases. Studies have shown that certain amino acids play essential roles in CA biosynthesis. However, quantitative evaluations of the effects of these amino acids are still needed in order to improve CA production. Here, we report a study of the nutritional requirements of Streptomyces clavuligerus for CA production. Firstly, the influence of the primary nitrogen source and the salts composition was investigated. Subsequently, soybean protein isolate was supplemented with arginine (0.0-3.20gL^-1), threonine (0.0-1.44gL^-1), ornithine (0.0-4.08gL^-1), and glutamate (0.0-8.16gL^-1), according to a two-level central composite rotatable design. A medium containing ferrous sulfate yielded CA production of 437mgL^-1, while a formulation without this salt produced only 41mgL^-1 of CA. This substantial difference suggested that Fe²⁺ is important for CA biosynthesis. The experimental design showed that glutamate and ornithine negatively influenced CA production while arginine and threonine had no influence. The soybean protein isolate provided sufficient C5 precursor for CA biosynthesis, so that supplementation was unnecessary. Screening of medium components, together with experimental design tools, could be a valuable way of enhancing CA titers and reducing the process costs.

Streptomyces clavuligerus shows a strong association between TCA cycle intermediate accumulation and clavulanic acid biosynthesis

Clavulanic acid (CA) is produced by Streptomyces clavuligerus (S. clavuligerus) as a secondary metabolite. Knowledge about the carbon flux distribution along the various routes that supply CA precursors would certainly provide insights about metabolic performance. In order to evaluate metabolic patterns and the possible accumulation of tricarboxylic acid (TCA) cycle intermediates during CA biosynthesis, batch and subsequent continuous cultures with steadily declining feed rates were performed with glycerol as the main substrate. The data were used to in silico explore the metabolic capabilities and the accumulation of metabolic intermediates in S. clavuligerus. While clavulanic acid accumulated at glycerol excess, it steadily decreased at declining dilution rates; CA synthesis stopped when glycerol became the limiting substrate. A strong association of succinate, oxaloacetate, malate, and acetate accumulation with CA production in S. clavuligerus was observed, and flux balance analysis (FBA) was used to describe the carbon flux distribution in the network. This combined experimental and numerical approach also identified bottlenecks during the synthesis of CA in a batch and subsequent continuous cultivation and demonstrated the importance of this type of methodologies for a more advanced understanding of metabolism; this potentially derives valuable insights for future successful metabolic engineering studies in S. clavuligerus.

Fermentation Conditions that Affect Clavulanic Acid Production in Streptomyces clavuligerus: A Systematic Review

The β-lactamase inhibitor, clavulanic acid is frequently used in combination with β-lactam antibiotics to treat a wide spectrum of infectious diseases. Clavulanic acid prevents drug resistance by pathogens against these β-lactam antibiotics by preventing the degradation of the β-lactam ring, thus ensuring eradication of these harmful microorganisms from the host. This systematic review provides an overview on the fermentation conditions that affect the production of clavulanic acid in the firstly described producer, Streptomyces clavuligerus. A thorough search was conducted using predefined terms in several electronic databases (PubMed, Medline, ScienceDirect, EBSCO), from database inception to June 30th 2015. Studies must involve wild-type Streptomyces clavuligerus, and full texts needed to be available. A total of 29 eligible articles were identified. Based on the literature, several factors were identified that could affect the production of clavulanic acid in S. clavuligerus. The addition of glycerol or other vegetable oils (e.g., olive oil, corn oil) could potentially affect clavulanic acid production. Furthermore, some amino acids such as arginine and ornithine, could serve as potential precursors to increase clavulanic acid yield. The comparison of different fermentation systems revealed that fed-batch fermentation yields higher amounts of clavulanic acid as compared to batch fermentation, probably due to the maintenance of substrates and constant monitoring of certain entities (such as pH, oxygen availability, etc.). Overall, these findings provide vital knowledge and insight that could assist media optimization and fermentation design for clavulanic acid production in S. clavuligerus.

Dissociation of cephamycin C and clavulanic acid biosynthesis by 1,3-diaminopropane in Streptomyces clavuligerus

Streptomyces clavuligerus produces simultaneously cephamycin C (CephC) and clavulanic acid (CA). Adding 1,3-diaminopropane to culture medium stimulates production of beta-lactam antibiotics. However, there are no studies on the influence of this diamine on coordinated production of CephC and CA. This study indicates that 1,3-diaminopropane can dissociate CephC and CA productions. Results indicated that low diamine concentrations (below 1.25 g l(-1)) in culture medium increased CA production by 200%, but not that of CephC. Conversely, CephC production increased by 300% when 10 g l(-1) 1,3-diaminopropane was added to culture medium. Addition of just L-lysine (18.3 g l(-1)) to culture medium increased both biocompounds. On the other hand, while L-lysine plus 7.5 g l(-1) 1,3-diaminopropane increased volumetric production of CephC by 1100%, its impact on CA production was insignificant. The combined results suggest that extracellular concentration of 1,3-diaminopropane may trigger the dissociation of CephC and CA biosynthesis in S. clavuligerus.