This indicated the enhanced production and secretion of D1. 3 scFv in the presence of xylose and confirmed the correct function of the here used xylose-inducible promoter system. 168, DB431 and WB800N differing in the number of produced proteases. Starting with shake flasks (150?mL), the bioprocess was scaled down to microtiter plates (1250?L) as well as scaled up to laboratory-scale bioreactors (2?L). The highest extracellular concentration CGP-52411 of D1.3 scFv (130?mg?L?1) and highest spaceCtime-yield (8?mg?L?1?h?1) were accomplished with WB800N, a strain deficient in eight proteases. These results were reproduced by the production and secretion of a recombinant penicillin G acylase (Pac). Conclusions The genus provides high potential microbial host systems for the secretion of challenging heterologous proteins like antibody fragments and large proteins at CGP-52411 high titers. In this study, the highest extracellular concentration and spaceCtime-yield of a recombinant antibody fragment for a Gram-positive bacterium so far was achieved. The successful interspecies use of the here-designed plasmid originally optimized for was demonstrated Rabbit Polyclonal to MLK1/2 (phospho-Thr312/266) by two examples, an antibody fragment and a penicillin G acylase in up to five different strains. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0625-9) contains supplementary material, which is available to authorized users. Keywords: are rod-shaped aerobic or facultatively anaerobic, Gram-positive bacteria [1, 2]. This genus is one of the most diverse groups of microorganisms and CGP-52411 its representatives are widely distributed in soil, air and water [1, 2]. Different strains have been developed and engineered as industrial producers of natural enzymes such as alkaline proteases (strains are great candidates for industrial production and secretion of heterologous proteins due to several advantages. In comparison to eukaryotic systems, their cultivation is simple and their high growth rates lead to short cultivation times. Most strains are non-pathogenic and free of exo- and endotoxins. Species like and even have the generally regarded as safe (GRAS) status [10, 11]. In addition, these species have the ability to secrete proteins directly into the extracellular medium, resulting in cost-effective downstream purification processing. In contrast, Gram-negative bacteria, like the best-analyzed representative are e.g. human interferon alpha (15?mg?L?1, [14]) or epidermal growth factor (240?mg?L?1, mutants have been successfully constructed and used resulting in more effective extracellular protein production [21]. Some of the most interesting and challenging proteins heterologously produced in prokaryotes are recombinant antibodies and antibody fragments which are important and suitable tools in research and medicine. Their specific antigen binding is used in analytics, in proteome research, in diagnostics of pathogens and toxins and in therapy of inflammatory and tumor diseases [22C24]. A whole immunoglobulin G molecule is a hetero-tetramer with two heavy and two light chains connected by disulfide bridges and intramolecular disulfide bridges for stabilization [25]. Since their production requires a complicated folding apparatus and an oxidizing environment for disulfide bridge formation, many microbial host systems fail to produce significant amounts of the molecules [26]. In addition, bacterial hosts CGP-52411 usually CGP-52411 do not accomplish the correct glycosylation of the produced antibodies. However, smaller and simpler antibody fragments with full antigen binding capacity have been developed for research purposes, where biological activity is more important than structural authenticity and correct glycosylation pattern. The smallest conventional antibody fragment with high-affinity binding to an antigen is the single-chain fragment variable (scFv) [27], a heterodimer comprising the antibody heavy- and light-chain variable domains connected by a peptide linker and with natural disulfide bonds within the chains to stabilize the molecule [28]. Here, the recombinant production and secretion of the lysozyme-specific antibody fragment D1.3 scFv in and three strains differing in their protease equipment are.