Bacillus subtilis and Bacillus licheniformis are widely used for the large-scale industrial production of proteins. These strains can efficiently secrete proteins into the culture medium using the general secretion (Sec) pathway. A characteristic feature of all secreted proteins is their N-terminal signal peptides, which are recognized by the secretion machinery. Here, we have studied the production of an industrially important secreted protease, namely, subtilisin BPN from Bacillus amyloliquefaciens. One hundred seventy-three signal peptides originating from B. subtilis and 220 signal peptides from the B. licheniformis type strain were fused to this secretion target and expressed in B. subtilis, and the resulting library was analyzed by high-throughput screening for extracellular proteolytic activity. We have identified a number of signal peptides originating from both organisms which produced significantly increased yield of the secreted protease. Interestingly, we observed that levels of extracellular protease were improved not only in B. subtilis, which was used as the screening host, but also in two different B. licheniformis strains. To date, it is impossible to predict which signal peptide will result in better secretion and thus an improved yield of a given extracellular target protein. Our data show that screening a library consisting of homologous and heterologous signal peptides fused to a target protein can identify more-effective signal peptides, resulting in improved protein export not only in the original screening host but also in different production strains.Gram-positive bacteria of the genus Bacillus are industrially well-established microorganisms for the production of extracellular proteins. Due to the availability of relatively cheap large-scale production systems combined with the ability of bacteria to secrete up to 20 to 25 g/liter of a target protein into the growth medium, about 60% of commercially available enzymes are presently produced in Bacillus species (14, 28).The closely related species Bacillus subtilis and Bacillus licheniformis are widely used as production hosts on an industrial scale, and, in contrast to the well-known production species Escherichia coli, they are free of endotoxin and have GRAS (generally regarded as safe) status. The complete genome sequences of strains B. subtilis 168 (1, 18) and B. licheniformis DSM13 (isogenic to ATCC 14580) (26, 32) are available, greatly facilitating the construction of improved production strains.The Sec pathway constitutes the main secretion pathway in B. subtilis and B. licheniformis. Proteins secreted via the Sec pathway are initially synthesized with an N-terminal hydrophobic signal peptide (SP) consisting of a positively charged N domain followed by a longer, hydrophobic H domain and a C domain consisting of three amino acids which form the signal peptidase recognition site (35). Targeting of a secreted protein to the membrane, the translocation process itself, and subsequent processing by a signal peptidase represent the majo...

Due to the lack of an outer membrane, Gram-positive bacteria (e.g., Bacillus species) are considered as promising host organisms for the secretory production of biotechnologically relevant heterologous proteins. However, the yields of the desired target proteins were often reported to be disappointingly low. Here, we used saturation mutagenesis of the positively charged N-domain (positions 2-7) of the signal peptide of the Bacillus subtilis alpha-amylase (AmyE) as a novel approach for the improvement of the secretion of a heterologous model protein, cutinase from Fusarium solani pisi, by the general secretory pathway of B. subtilis. Automated high-throughput screening of the resulting signal peptide libraries allowed for the identification of four single point mutations that resulted in significantly increased cutinase amounts, three of which surprisingly reduced the net charge of the N-domain from +3 to +2. Characterization of the effects of the identified mutations on protein synthesis and export kinetics by pulse-chase analyses indicates that an optimal balance between biosynthesis and the flow of the target protein through all stages of the B. subtilis secretion pathway is of crucial importance with respect to yield and quality of secreted heterologous proteins.

Today, the cheosphere’s and biosphere’s compositions of the planet are changing faster than experienced during the past thousand years. CO2 emissions from fossil fuel combustion are rising dramatically, including those from processing, manufacturing and consuming everyday products; this rate of greenhouse gas emission (36.2 Giga-tons accumulated in 2022) is raising global temperatures and destabilizing the climate, which is one of the most influential forces on our planet. As our world warms up, our climate will enter a period of constant turbulence, affecting more than 85% of our ecosystems, including the delicate web of life on these systems and impacting socioeconomic networks. How do we deal with the green transition to minimize climate change and its impacts while we are facing these new realities? One of the solutions is to use renewable natural resources. Indeed, nature itself, through the working parts of its living systems, the enzymes, can significantly contribute to achieve climate neutrality and good ecological/biodiversity status. Annually they can help decreasing CO2 emissions by 1 to 2.5 Billion-tons, carbon demand by about 200 Million-tons, and chemical demand by about 90 Million-tons. With current climate change goals, we review the consequences of climate change at multiple scales and how enzymes can counteract or mitigate them. We then focus on how they mobilize sustainable and greener innovations in consumer products that have a high contribution to global carbon emissions. Finally, key innovations and challenges to be solved at the enzyme and product levels are discussed. LAY SUMMARY Accumulated greenhouse gas emissions are expected to increase from 36.2 Giga-tons (Gt) to 60 Gt over the next three decades. The global surface temperature has increased by + 1.09 °C since 2001, and might increase by + 2.2 °C in 2100, +3.6 °C in 2200 and +4.6 °C in 2500. These emissions and temperature rises cannot be reduced in their entirety, but they can be lowered by using enzymes. Enzymes are proteins that catalyze biochemical reactions that make life possible since 3.8 billion years ago. Scientists have been able to "domesticate" them in such a way that enzymes, and their engineered variants, are now key players of the circular economy. With a world production of 117 Kilo-tons and a trade of 14.5 Billion-dollars, they have the potential to annually decrease CO2 emissions by 1 to 2.5 Billion-tons (Bt), the carbon demand to synthesise chemicals by 200 Million tons (Mt), the amount of chemicals by 90 Mt, and the economic losses derived from global warming by 0.5%, while promoting biodiversity and our planet’s health. Our success to increase these benefits will depend on better integration of enzymatic solutions in different sectors.

We present the development of highly selective variants of the Parvibaculum lavamentivorans alcohol dehydrogenase. Four amino acids (A158, N162, K202, L224) in the second sphere of the catalytic site were identified to determine the selectivity for 3-quinuclidone reduction significantly. The best variant (A158H/N162G/K202Q/L224W) was able to increase the ee for (R)-3-quinuclidinol production from 84.3 % (wild-type) to ≥99 % and concomitantly to enhance conversion by 43.5 %.