Bacillus subtilis: a universal cell factory for industry, agriculture, biomaterials and medicine.

Due to its clear inherited backgrounds as well as simple and diverse genetic manipulation systems, Bacillus subtilis is the key Gram-positive model bacterium for studies on physiology and metabolism. Furthermore, due to its highly efficient protein secretion system and adaptable metabolism, it has been widely used as a cell factory for microbial production of chemicals, enzymes, and antimicrobial materials for industry, agriculture, and medicine. In this mini-review, we first summarize the basic genetic manipulation tools and expression systems for this bacterium, including traditional methods and novel engineering systems. Secondly, we briefly introduce its applications in the production of chemicals and enzymes, and summarize its advantages, mainly focusing on some noteworthy products and recent progress in the engineering of B. subtilis. Finally, this review also covers applications such as microbial additives and antimicrobials, as well as biofilm systems and spore formation. We hope to provide an overview for novice researchers in this area, offering them a better understanding of B. subtilis and its applications.

MicroRNA expression profile of human periodontal ligament cells under the influence of Porphyromonas gingivalis LPS.

Periodontitis is a chronic inflammatory disease which is caused by bacterial infection and leads to the destruction of periodontal tissues and resorption of alveolar bone. Thus, special attention should be paid to the mechanism under lipopolysaccharide (LPS)-induced periodontitis because LPS is the major cause of periodontitis. However, to date, miRNA expression in the LPS-induced periodontitis has not been well characterized. In this study, we investigated miRNA expression patterns in LPS-treated periodontal ligament cells (PDLCs). Through miRNA array and differential analysis, 22 up-regulated miRNAs and 28 down-regulated miRNAs in LPS-treated PDLCs were identified. Seven randomly selected up-regulated (miR-21-5p, 498, 548a-5p) and down-regulated (miR-495-3p, 539-5p, 34c-3p and 7a-2-3p) miRNAs were examined by qRT-PCR, and the results proved the accuracy of the miRNA array. Moreover, targets of these deregulated miRNAs were analysed using the miRWalk database. Database for Annotation, Visualization and Integration Discovery software were performed to analyse the Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes pathway of differential expression miRNAs, and the results shown that Toll-like receptor signalling pathway, cAMP signalling pathway, transforming growth factor-beta signalling pathway, mitogen-activated protein kinase (MAPK) signalling pathway and other pathways were involved in the molecular mechanisms underlying LPS-induced periodontitis. In conclusion, this study provides clues for enhancing our understanding of the mechanisms and roles of miRNAs as key regulators of LPS-induced periodontitis.

A 3D bioprinted decellularized extracellular matrix/gelatin/quaternized chitosan scaffold assembling with poly(ionic liquid)s for skin tissue engineering.

Currently, a suitable bioink for 3D bioprinting and capable of mimicking the microenvironment of native skin and preventing bacterial infection remains a major challenge in skin tissue engineering. In this study, we prepared a tissue-specific extracellular matrix-based bioink, and dECM/Gel/QCS (dGQ) 3D scaffold assembling with poly(ionic liquid)s (PILs) (dGQP) was obtained by an extrusion 3D bioprinting technology and dynamic hydrogen bonding method. The morphologies, mechanical properties, porosity, hydrophilicity, biodegradation, hemostatic effect, antibacterial ability, and biocompatibility of the hybrid scaffolds were characterized and evaluated. Results showed that the rapid release (2 h) of PILs on the dGQP scaffold can quickly kill gram-negative (E. coli) and gram-positive (S. aureus) bacteria with almost 100 % antibacterial activity and maintained a stable sterile environment for a long time (7 d), which was superior to the dGQ scaffold. The hemostasis and hemolysis test showed that the dGQP scaffold had a good hemostatic effect and excellent hemocompatibility. In vitro cytocompatibility studies showed that although the cell growth on dGQP scaffold was slow in the early stage, the cells proliferated rapidly since day 4 and had high ECM secretion at day 7. Overall, this advanced dGQP scaffold has a considerable potential to be applied in skin tissue engineering.

Recent advances in cell membrane camouflage-based biosensing application.

Cell membrane, a semi-permeable membrane composed of phospholipid bilayers, is a natural barrier to prevent extracellular substances from freely entering the cell. Cell membrane with selective permeability and fluidity ensures the relative stability of the intracellular environment and enables various biochemical reactions to smoothly operate in an orderly manner. Inspired by the natural composition and transport process, various cell membranes and synthetic bionic films as the mimics of cell membranes have emerged as appealing camouflage materials for biosensing applications. The membranes are devoted to surface modification and substance delivery, and realize the detection or in situ analysis of multiple biomarkers, such as glucose, nucleic acids, virus, and circulating tumor cells. In this review, we summarize the recent advances in cell membrane camouflage-based biosensing applications, mainly focusing on the use of the membranes extracted from natural cells (e.g., blood cells and cancer cells) as well as biomimetic membranes. Materials and surfaces camouflaged with cell membranes are shown to have superior stability and biocompatibility as well as intrinsic properties of original cells, which greatly facilitate their use in biosensing. In specific, camouflage with blood cell membranes bestows low immunogenicity and prolonged blood circulation time, camouflage with cancer cell membranes provides homologous targeting ability, and camouflage with biomimetic membranes endows considerable plasticity for functionalization. Further research is expected to focus on the deeper understanding of cell-specific properties of membranes and the exploration of hybrid membranes, which might provide new development opportunities for cell membrane camouflage-based biosensing application.

A biological functional hybrid scaffold based on decellularized extracellular matrix/gelatin/chitosan with high biocompatibility and antibacterial activity for skin tissue engineering.

Nowadays, decellularized extracellular matrix (dECM) has received widespread attention due to its diversity in providing the unique structural and functional components to support cell growth, and finding material with good biocompatibility and anti-infection capability for skin tissue engineering is still a challenge. In this study, a novel dECM/Gel/CS scaffold with appropriate mechanical strength, good antibacterial activity and high biocompatibility was prepared using a one-pot method. The results showed that the immune components such as cells and DNA (about 98.1%) were successfully removed from the porcine skin tissue. The dECM/Gel/CS scaffolds exhibited an interconnected pore structure and had a high porosity (>90%) to promote cell growth. Moreover, the appropriate elastic modulus (≥482.17 kPa) and degradability (≥80.04% for 15 days) of the scaffolds offered stout "houses" for cell proliferation and suitable degradation rate to match the new tissue formation in skin tissue engineering. Furthermore, the addition of chitosan endowed the scaffold with good antibacterial activity, water and protein absorption capacity to avoid wound infection, and maintain the moisture and nutrition balance. In vitro cytocompatibility studies showed that the presence of dECM effectively enhanced the cell proliferation. Overall, the advanced dECM/Gel/CS scaffold has considerable potential to be applied in skin tissue engineering.