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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Tubulin refers to the major protein component of the microtubules of eukaryotic cells. It is one of several members of a small family of globular proteins. The tubulin superfamily includes five distinct families: the alpha-, beta-, gamma-, delta-, and epsilon-tubulins; and a sixth family (zeta-tubulin) which is present only in kinetoplastid protozoa. The most common members of the tubulin family are α-tubulin and β-tubulin, the proteins that make up microtubules. Each has a molecular weight of approximately 55,000 Daltons. Microtubules are assembled from dimers of aand β-tubulin. These subunits are slightly acidic with an isoelectric point between 5.2 and 5.8. Tubulin was long thought to be specific to eukaryotes. Recently, however, the prokaryotic cell division protein FtsZ was shown to be related to tubulin.
The Sustainable Production of Polyhydroxyalkanoates from Crude Glycerol
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Neha Rani Bhagat, Preeti Kumari, Arup Giri, Geeta Gahlawat
Genetic manipulation to change bacterial shape/morphology allows the exploitation of bacterial shapes from rods to small spheres, small to large spheres, and fibers. The advantages of doing morphological changes for PHA production include high cell density, simplified downstream processing, space enlargement to allow more PHA accumulation, and more economical bio-production [94]. To the best of our knowledge, there are no reports to date on bacterial shape engineering based PHA production from glycerol. However, several shape-related genes can be exploited for availing of crude glycerol based process benefits, where the exploitation of relevant genes modulate the bacterial length and diameter limit. Enhancement of these limits can enhance the competitiveness in bio-processing, including improvement in the effectiveness of up- and downstream processing. Thus, enhancing bacterial morphology limits can create a promising enhancement in polymer production from glycerol [94–96]. Moreover, the rigid cell wall plays a limiting role for inclusion bodies accumulation inside the bacterial cells by limiting the space, as the weak cell wall allows easy cell size expansion, thus allowing increased storage of PHA granules [94]. So, the rigidity determining genes can also be exploited for enhancing polymer accumulation and production. Other reports have shown the role of essential genes, mreB and ftsZ, encoding for the cytoskeleton protein, MreB, and the cell division protein, FtsZ, in dividing the bacterial cytoskeleton [95]. Thus, the inactivation of these genes could result in an increase in cell sizes and lengths. So, a lot of effort has been made in this area for enhancing PHA production.
Facile and large-scale synthesis of curcumin/PVA hydrogel: effectively kill bacteria and accelerate cutaneous wound healing in the rat
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Fei He, Hongjing Jiao, Yu Tian, Libo Zhao, Xiaozhu Liao, Zengjie Fan, Bin Liu
Wound infection caused by bacterial proliferation around the wound is the main reason why delaying the wound healing, so it is important to design the hydrogels with high antibacterial ability [4]. In this study, Cur was used as the antibacterial agent to improve the antibacterial performance of PVA hydrogel, and the photos of antibacterial against S. aureus and E. coli were shown in Figure 6(A)–(H). We can see that the antibacterial against S. aureus and E. coli of PVA and Cur/PVA serial hydrogels increased with increasing the concentration of Cur, and 20% Cur/PVA hydrogel had the least number of survival bacteria than that of the other samples. Meanwhile, the antibacterial ratio of various hydrogels was statistically analyzed and the results were shown in Figure 6(I). For PVA hydrogel, 67.31% antibacterial ratio to S. aureus and 40.93% antibacterial ratio to E. coli can be observed, the antibacterial ability of PVA hydrogel may be caused by the addition of boric acid. After introduction of Cur into PVA, the hydrogel presented high antibacterial ability than counterpart of PVA hydrogel. For Cur/PVA hydrogels, the antibacterial ability increased with the increase of the concentration of Cur, and the antibacterial ratio of 20% Cur/PVA hydrogel to S. aureus and E. coli was 97% and 85.6%, respectively, which was higher than that of the other samples. The results of antibacterial ratio were consistent with the results of optical photos. The antibacterial activities improvement maybe the reason that the amount of Cur introduced into PVA networks increased and the bigger pores of hydrogel networks facilitated the rapid release of Cur from PVA networks. The results showed the antibacterial ability of hydrogel gradually increased with the increase of Cur concentrations, this change trend has been confirmed by some literatures [48,49]. However, the antibacterial mechanism has not been completely understood so far. Speculatively, damage of the membrane is a key mechanism of Cur mediated killing of S. aureus and E. coli [50]. In addition, some studies have showed that the Cur can inhibit the shikimate pathway, necessary for synthesis of aromatic amino acids in bacteria [51], or inhibit the bacterial proliferation by inhibiting the assembly dynamics of FtsZ (a bacterial protofilament) [52].