Mitochondrial functions are essential for life, critical for development, maintenance of stem cells, adaptation to physiological changes, responses to stress and aging. The complexity of mitochondrial biogenesis requires coordinated nuclear and mitochondrial gene expression, owing to the need of stoichiometrically assemble the OXPHOS system for ATP production. It requires, in addition, the import of thousands of proteins from the cytosol to keep optimal mitochondrial function and metabolism. Moreover, mitochondria require lipid supply for membrane biogenesis, while it is itself essential for the synthesis of membrane lipids. To achieve mitochondrial homeostasis, multiple mechanisms of quality control have evolved to ensure that mitochondrial function meets cell, tissue and organismal demands. Herein, we give an overview of mitochondrial mechanisms that are activated in response to stress, including mitochondrial dynamics, mitophagy and the mitochondrial unfolded protein response (UPR^mt). We then discuss the role of these stress responses in aging, with particular focus on Caenorhabditis elegans. Finally, we review observations that point to the mitochondrial PHB (prohibitin) complex as a key player in mitochondrial homeostasis, being essential for mitochondrial biogenesis and degradation, and responding to mitochondrial stress. Understanding how mitochondria responds to stress and how such responses are regulated is pivotal to combat aging and disease.

The aim of this study was to analyse the biocompatibility of a material based on lactic acid (PLA)/polyhydroxybutyrate(PHB)/thermoplastic starch (TPS) in combination with additives (plasticizers: acetyltributyl citrate (ATBC) and oligomeric lactic acid ( OLA)). Three types of materials were tested: I: PLA/PHB/TPS + 25% OLA, II: PLA/PHB/TPS + 30% ATBC, III: PLA/PHB/TPS + 30% OLA. The 3D printing itself was preceded by the creation of filaments from granulate and the design of samples. A filament production machine – Composer 450 (3devo; The Netherlands) was used to produce the filaments. Experimental samples were produced by FDM technology on a 3D printer DeltiQ2 (Trilab, Czech Republic). The evaluation of the biocompatibility of the materials included cytotoxicity tests such as the monitoring of viability, proliferation, morphology of cells, and their settlement on the surface of the materials. The cell line 7F2 osteoblasts (Mus musculus) was used in the experiments. Based on the tests, results confirmed the significant influence of plasticizers and their proportions in the mixtures. PLA/PHB/ATBC + 25% OLA was evaluated as the optimal material for biocompatibility with 7F2 osteoblasts. The tested biomaterials have the potential for further investigation, with a possible change in the proportion of the plasticizer, which has a fundamental impact on their biological properties.

Magnesium and its alloys are not normally used as bio-resorbable temporary implants due to their high and uncontrolled degradation rate in physiological liquid environment. The improvement of corrosion resistance to simulated body fluids (SBF) of a Magnesium alloy (AZ31) coated with poly-β-hydroxybutyrate (PHB) was investigated. Scanning electron microscopy, Fourier transform infrared spectrometer, and contact angle measurements were used to characterize surface morphology, material composition and wettability, respectively. pH modification of the SBF corroding medium, mass of Mg2+ ions released, and weight loss of the samples exposed to the SBF solution, and electrochemical experiment were used to describe the corrosion process and its kinetics. Materials biocompatibility was described by evaluating the effect of corrosion by products collected in the SBF equilibrating solution on hemolysis ratio, cytotoxicity, Nitric Oxide (NO), and total antioxidant capacity (T-AOC). The results showed that the PHB coating can diffusively control the degradation rate of Magnesium alloy improving its biocompatibility: hemolysis rate of materials was lower than 5%, while in vitro Human Umbilical Vein Endothelial Cells（HUVECs) compatibility experiments showed that PHB coated Mg alloy promoted cell proliferation and had no effect on the NO content, the T-AOC was enhanced compared with the normal group and bare AZ31 alloy. PHB coated AZ31 Magnesium alloy extraction fluids have a less toxic behavior due to the lower concentration of corrosion by-products deriving from the diffusion control exerted by the PHB coating films both from metal surface to the solution and vice versa. These findings provide more reference value for the selection of such system as tunable bioresorbable prosthetic materials

Water pollution in developing countries affects the public health of humans and the environment. It is therefore essential to develop environmentally friendly biopolymer, sustainable and low-cost membranes. Biopolymer nanofiber membranes are made by an electrospinning process of polylactic acid (PLLA) with additives. The main objective of this study is to manufacture biodegradable nanofiber membranes for use in filtering the suspended elements in wastewater at the level of drinkable or in agricultural fields. It is known that PLLA is brittle and therefore it is difficult to apply in industry. To solve this problem and enhance its flexibility. Flexible biopolymer polypropylene carbonate (PPC) and plasticizer are the addition in PLLA to reduce its glass transition and enhance its crystallization by adding Poly(3-hydroxy butyrate) PHB. In this work, 20 wt% of PPC was added to PLLA matrix to improve its elasticity and elongation at break. DSC shows that the addition of PPC, PHB, and TEC did affect the thermal properties like T_g, T_cc and T_m of the PLLA blends. The position of the T_g, T_cc, and T_m is shifting, the consequence the chain mobility is increased, therefore the crystallinity is enhanced. Electrospun fibers of PLLA/PPC/PHB/TEC were successfully manufactured. Tensile tester showed the increase in elongation at break of PLLA blend films, the elongation at break increases by 285 times. It observed with the increasing the elongation at break, a decrease in stress strength. After improving the mechanical properties with the higher elongation at break values, this blend is optimal for filtrations process.

The Bacillus megaterium LVN01 species native to Colombia has demonstrated the ability to metabolize different co-products or industrial waste (such as fique juice, cane molasses, residual glycerol) and accumulate polyhydroxybutyrate (PHB), giving it potential in the bioplastics industry. In this research, the potential of liquid digestate as a carbon source for the production of PHA in fermentation processes with this bacterial strain was evaluated. Favorably, it was found that B. megaterium utilizes the nutrients from this residual substrate to multiply appropriately and efficiently synthesize poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). Bench scale aerobic batch fermentation, under the operational conditions of this research [Volume: 3L; Temperature: 30.8°C; Agitation: 400 rpm; pH: 7.0 ± 0.2; Disolved Oxygen: 100% saturation; Antifoam 10% (v/v)], generated maximum values of DCW (0.56 g cell L-1) at 60 h, while the maximum PHB yield (360 mg PHB L-1) occurred at 16 h, which is very favorable for sustainable degradable bioplastics production. Additionally, GC-MS and NMR analyses confirmed that the PHBV copolymer synthesized by B. megaterium is made up of the monomers 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV). Furthermore, the thermal properties determined by TGA (Tonset=283.1 ºC, Tendset= 296.98 ºC. Td =290.114 °C) and DSC (Tm= ºC155.7 °C, ΔHf= 19.80 J g-1, Xcr = 18.17%), indicate that it is a thermally stable biopolymer with low percentages of crystallinity, providing flexibility that facilitates molding, adaptation, and application in various industrial sectors.

Polyhydroxyalcanoates (PHAs) are biodegradable polymers synthesized in cytoplasmic granules in bacteria, such as Cupriavidus necator (Ralstonia eutropha), Alcaligenes latus, Pseudomonas spp., Comamonas spp. and other species. PHAs accumulation occurs in response to stress conditions, i.e. under high carbon and low nitrogen (24:1 ratio). PHA can be synthesized using recombinant microorganisms (provided with the operon phbA/phbB/phbC), escaping the constrains of nutrient request, except addition of high amount of sugar (glucose, lactose, fructose). In this study; E. coli was genetically modified for PHB production in biofermentors. The production of PHA at industrial scale requires a continuous supplementation of fermentable sugars to support the availability of nutrients and to assess the level of the exponential growth phase; since sugars are required either for bacterial growth either for PHA synthesis and energy storage. The biofermentors need to be run in automated system. Sensors are used at many points in fermentators; in the evaluation of parameters: consumption of sugars; cell density; quantification of PHB synthesis. The need of operational control during the fermentation has prompted us to application of three measurements; one unit linked to a Nanodrop to evaluate OD; one linked to a reaction chamber to measure sugars consumed by enzyme based fluorescence detection; and one for bacteria Nile Blue staining and fluorescence intensity reads. The growth of bacteria on three different plant by-products was monitored and PHB production in four days using a banana by-product feed was optimised. These detectors will make possible to exploit the full potential of bioreactors optimizing the time of use and maximizing the number of bacteria synthesizing PHA.