Secretion of active human lysozyme by Acremonium chrysogenum using a Fusarium alkaline protease promoter system

A Combinational Strategy for Effective Heterologous Production of Functional Human Lysozyme in Pichia pastoris

Human lysozyme (hLYZ), known for its bacteriolytic activity, is widely applied in the food and pharmaceutical industries as an antimicrobial agent. However, its extensive application was limited by its low large-scale production efficiency. In this study, a combinational method of integrating codon optimization, multiple gene copies, and ER molecular chaperone co-expression was developed to improve the heterologous production of hLYZ in Pichia pastoris GS115. Our results showed that increasing the copy number of the optimized hLYZ gene in P. pastoris could enhance its secretory production level up to 1.57-fold. The recombinant opt-hLYZ-6C strain that contains six copies of opt-hLYZ gene exhibited the highest mRNA transcription levels, giving the highest production of 0.22 ± 0.02 mg/mL of hLYZ in the medium supernatant with a bacteriolytic activity of 14,680 ± 300 U/mL against Micrococcus lysodeikticus in the shaking flask experiment. Moreover, co-overexpression of ER retention molecular chaperones, such as Pdi1 or Ero1, in the recombinant opt-hLYZ-6C strain both presented positive effects on the secretory production of hLYZ. Our further characterization indicated that tandem co-expression of Ero1 and Pdi1 together presented an added-up effect. The secretory production of hLYZ in the medium supernatant reached 0.34 ± 0.02 mg/mL of the recombinant opt-hLYZ-6C-EP strain in the shaking flask experiment, with a bacteriolytic activity of 21,200 ± 400 U/mL. Compared to the recombinant opt-hLYZ-1C strain, these final improvements were calculated as 2.43-fold and 2.30-fold on secretory protein levels and antibacterial activity, respectively. Finally, the recombinant opt-hLYZ-6C-EP strain was applied for high-density cultivation in 5 L of fermenter, in which the secretory yield of hLYZ reached 2.34 ± 0.02 mg/mL in the medium supernatant, with a bacteriolytic activity of 1.76 ± 0.02 × 10⁵ U/mL against M. lysodeikticus. All these numbers presented the highest heterologous production levels of hLYZ in microbial systems.

A chemiluminescence sensor for determination of lysozyme using magnetic graphene oxide multi-walled carbon nanotube surface molecularly imprinted polymers

In this paper, a new chemiluminescence sensor possessing high selectivity and sensitivity was established for determination of lysozyme using magnetic graphene oxide–multi-walled carbon nanotube surface molecularly imprinted polymer.

Recent advances for the production and recovery methods of lysozyme

Lysozyme is an antimicrobial peptide with a high enzymatic activity and positive charges. Therefore, it has applications in food and pharmaceutical industries as an antimicrobial agent. Lysozyme is ubiquitous in both animal and plant kingdoms. Currently, egg-white lysozyme is the most commercially available form of lysozyme. The main concerns of egg-white lysozyme are high recovery cost, low activity and most importantly the immunological problems to some people. Therefore, human lysozyme production has gained importance in recent years. Scientists have developed transgenic plants, animals and microorganisms that can produce human lysozyme. Out of these, microbial production has advantages for commercial productions, because high production levels are achievable in a relatively short time. It has been reported that fermentation parameters, such as pH, temperature, aeration, are key factors to increase the effectiveness of the human lysozyme production. Moreover, purification of the lysozyme from the fermentation broth needs to be optimized for the economical production. In conclusion, this review paper covers the mechanism of lysozyme, its sources, production methods and recovery of lysozyme.

Construction and in vivo evaluation of a mammary gland-specific expression vector for human lysozyme

A mammary gland-specific expression vector p205C3 was constructed with the 5'- and 3'-flanking regions of β-lactoglobulin gene and the first intron of β-casein gene of Chinese dairy goat as regulatory sequences. Human lysozyme (hLYZ) cDNA from mammary gland was cloned into p205C3 and the recombinant vector was used to generate transgenic mice by microinjection. Based on the lysoplate assay, four female offspring of one male founder were detected expressing recombinant hLYZ in their milk at the levels of 5-200 mg/l, and the expressed protein had the same molecular weight as that of normal hLYZ. Besides mammary glands, ectopic expressions were also found in the spleens and the small intestines of the transgenic mice. Among the offspring, the female transgenic mice maintained and expressed the transgene stably with a highest expression level of 750 mg/l. Therefore, p205C3 could be used to develop animal mammary gland bioreactors expressing hLYZ.

Expression and purification of active recombinant equine lysozyme in Escherichia coli

Equine lysozyme (EL) is a calcium (Ca)-binding lysozyme and is an intermediary link between non-Ca-binding C-type lysozyme and alpha-lactalbumin. The feature of lysozymes to assemble into the fibrils has recently gained considerable attention for the investigation of the functional properties of these proteins. To study the structural and functional properties of EL, a synthetic gene was cloned and EL was overexpressed in Escherichia coli as a fused protein. The His-tagged recombinant EL was accumulated as inclusion bodies. Up to 50 mg/l of the recombinant EL could be achieved after purification by Ni(2+) affinity chromatography, refolding in the presence of arginine, CM-Sepharose column purification following TEV protease cleavage. The purified protein was functionally active, as determined by the lysozyme activity, proving the proper folding of protein. The purified lysozyme was used for the oligomerisation studies. The protein formed amyloid fibrils during incubation in acidic pH and elevated temperature. The recombinant EL forms two types of fibrils: ring shaped and linear, similar to the native EL.

Growth-rate-independent production of recombinant glucoamylase by Fusarium venenatum JeRS 325

Most recombinant proteins generated in filamentous fungi are produced in fed-batch cultures, in which specific growth rate normally decreases progressively with time. Because of this, such cultures are more suited to the production of products that are produced efficiently at low-growth rates (e.g., penicillin) than to products which are produced more efficiently at high-growth rates (e. g., glucoamylase). Fusarium venenatum A3/5 has been transformed (JeRS 325) to produce Aspergillus niger glucoamylase (GAM) under the control of the Fusarium oxysporum trypsin-like protease promoter. No glucoamylase was detected in the culture supernatant during exponential growth of F. venenatum JeRS 325 in batch culture. In glucose-limited chemostat cultures, GAM concentration increased with decrease in dilution rate, but the specific production rate of GAM (g GAM [g biomass](-1) h(-1)) remained approximately constant over the dilution-rate range 0.05 h to 0.19 h(-1), i.e., the recombinant protein was produced in a growth-rate-independent manner. The specific production rate decreased at dilution rates of 0.04 h(-1) and below. Specific production rates of 5.8 mg and 4.0 mg GAM [g biomass](-1) h(-1) were observed in glucose-limited chemostat cultures in the presence and absence of 1 g mycological peptone L(-1). Compared to production in batch culture, and for the same final volume of medium, there was no increase in glucoamylase production when cultures were grown in fed-batch culture. The results suggested that a chemostat operated at a slow dilution rate would be the most productive culture system for enzyme production under this trypsin-like promoter.