Papers by Keyword: Biodegradation

Abstract: Has been analysed the aging, biodegradation and toxic effects of biomedical implants in dentistry. Physico-chemical aspects of aging as well as biodegradation and toxicity of polymer dental implants were viewed. The prospects of development and application of polymer smart implants in dentistry are described.

Abstract: The paper deals with laboratory testing of PAHs biodegradation in samples of sleeper subsoil via two chosen microorganisms, bacteria Pseudomonas monteilii and Rhodococcus degradans. The obtained results show that the pure bacterial culture R. degradans removed 46 % PAHs in 28 days. Bacterium P. monteilii was far more successful in degrading PAHs, it managed to remove 74 % PAHs. The worst result was from the mixture of both bacteria which degraded only 34 % PAHs.

Abstract: Biodegradable plastics are viewed as one of the most promising solutions to plastic waste dilemma due to its natural degradative properties. Fossil fuel-based polymers have been infused with bio-based additives (e.g. starch) and have been used to produce biodegradable plastic products such as bags and cutleries. While several studies have dealt with degradation of polymers with bio-based additives, there is work yet to be done on degradation of commercially-available biodegradable plastic products. Here we evaluate degradability upon exposure to soil incubation and UV of three common starch-based plastic utensil brands in the Philippines that claim biodegradability. Analysis of IR absorbance spectra of post-exposure samples indicated high propensity towards photodegradation. Furthermore, estimation of full degradation period confirmed the biodegradability of starch-amended plastics which were limited to two brands. The presence of 19.22% and 24.18% starch in the plastic showed complete decomposition period of 156 and 92 days, respectively. This is a significant improvement over poor degradability exhibited by conventional plastics which often takes 450 to 1000 years. The reduction of degradation time through starch incorporation may prove to benefit manufacturers in fabricating more environmentally-friendly plastic products in the future.

Abstract: Ecological harm and human health risks caused by environmental pollution with active pharmaceutical ingredients (API) nowadays is recognised as issue of growing concern. Widespread presence of human and veterinary API in aquatic environment clearly indicates persistence and low removal efficiency of these compounds at conventional pharmaceutical and municipal wastewater treatment plants (WWTP). Bioaugmentation of activated sludge systems with specialized microorganisms could be a powerful and environmentally friendly tool to enhance the removal efficiency of recalcitrant API. Selection of inoculum strains, that have appropriate enzymatic pathways to metabolise complex molecules of API, belonging to different therapeutic classes, is of great importance. This study evaluated the potential of pure cultures of 10 bacteria, 10 yeasts and 3 filamentous fungi previously isolated from activated sludge of pharmaceutical WWTP to degrade less investigated API – Oxytocin, Zopiclone and Meldonium dihydrate as sole carbon source and in cometabolic manner with presence of skim milk powder as additional nutrient source. Bacteria Sphingobacterium thalpophilum and filamentous fungi Fusarium solani and Fusarium udum showed very high treatment efficiency of all tested API in laboratory-scale bioaugmentation tests and were recognized as culture with high metabolic potential to be used in bioaugmentation for removal of pharmaceutical micropollutants.

Abstract: The effect of organic nutrient on the biodegradation of hydrocarbon contaminated marine sediment in Malaysia was investigated. Biodegradation was assessed in microcosm experiments containing 10% (w/w) of crude oil amended with fertilizers in three ways, which were with inorganic nutrients (NP), organic matter in the form of plant-based (Elaeis guineensis) and fish-amendments (Scomber australasicus). It was observed that hydrocarbon degradation occurred in all treatments, with the highest biodegradation rates in S. australasicus supplemented sediment. The addition of S. australasicus managed to reduce the oil concentration to 48% while the addition of E. guineensis and inorganic NP reduced the final oil concentration to 66% and 63% respectively. All three amendments show faster degradation rate compared to the control. Isolation of the soil sample on specific nutrient agar, centrimide, revealed the presence of Pseudomonas aeruginosa that are well known for its ability to degrade hydrocarbon in crude oil.

Abstract: This paper represents the biodegradation characterization of thermoplastic starch (TPS) films derived from Tacca leontopetaloides starch; namely thermoplastic starch with glycerol as plasticizer (TPS/GLY), thermoplastic starch with glycerol added with acetic acid (TPS/ACE) and thermoplastic starch with glycerol added with acetic acid with rice husk biochar reinforcement (TPS/BCRH) after aerobic biodegradation under controlled composting conditions. From the experiments, scanning electron micrograph (SEM) of the films showed homogeneous and even surface before the biodegradation but changed into grainy and uneven after subjecting to 45 days of biodegradation. Mechanical properties of all TPS films reduced significantly as expected. Even so, adding rice husk biochar did offer some strength to the TPS formulation. However, Fourier transform infrared (FT-IR) analysis suggested that 45 days of aerobic biodegradation was not capable to alter the chemical structure of the films as the characteristic peaks of all films are quite similar to before the biodegradation took place. The study also found that Aspegillus sp was the degrading TPS microorganism.

Abstract: In the current work, the degradation of poly (3-hydroxybutyrate) (PHB) and poly (3-hydroxybutyrate-co-3-hydroxy-4-methylvalerate) (PHB4MV) films was studied in vitro by pancreatic lipase. The changes in film properties were traced by several analytical methods: the change of weight, molecular weight, and Young’s modulus (by nanoindentation) were measured. During the six months of polymer films degradation the weight of samples decreased slightly, while a great increase in Young's modulus due to the relatively fast degradation of the amorphous areas was observed, as well as molecular weight of polymers decreased significantly. Weight loss of PHB4MV is faster than degradation rate of PHB, but the molecular weight of PHB 1700 decrease rapidly than PHB4MV; the Young’s modulus of polymers remained relatively unchanged.

Abstract: Disorders related to the bone health are becoming a significant concern due to subsequent rise in ageing human population. It is estimated that more than two million bone-surgeries are performed worldwide with an annual cost of $2.5 billion. In order to replace damaged bone-tissues and restore their function, biomaterials consisting of stainless steels, cobalt-chromium and titanium alloys are implanted. However, these permanent (non-biodegradable) implants often lead to stress-shielding effects and ions release as they interact with the cells and fluids in the body. It is required to overcome these issues by improving the quality of implant materials and increasing their service life. Recently, research in biodegradable materials, consisting of magnesium alloys in particular, has received global attention owning to their biocompatibility and closer mechanical properties to the natural bone. However, due to their rapid corrosion rate in the body fluids, clinical applications of Mg-alloys as viable bone-implants have been restricted. A number of Mg-alloys have been tested since (both in vivo and in vitro) to optimize their biodegradation rare and corrosion properties. The present review summarizes the most recent developments in Mg-alloys designed with biodegradation tailored to the bone-cells growth and highlights the most successful ways to optimize their surface properties for optimum cell/material interaction.

Abstract: The submitted article deals with a relatively new phenomenon, which is monitoring and solution to minimization of microorganisms ́ occurrence on the surface of the External Thermal Insulation Composite Systems (ETICS). The importance of the solution has been becoming more important both from the point of view of health risk for inhabitants and accelerated degradation of particular layers of the ETICS due to the presence of these microorganisms. The article submits conceptual methodological solution to the reduction of count of microorganisms on the ETICS surface from diagnosis, setting out criteria for the necessity of determination of macrobiotic biodeteriogens to subsequent rehabilitation design.

Abstract: This paper deals with natural degradation of PLA (polylactic acid) composites with natural fiber reinforcement in non-simulated conditions. Composite material was made of PLA and 6 different types of biodegradable fibers. Fibers made from pulp, wool, bamboo, soya, flax and hemp. All samples had 20% volume of fibers. Three of each composite sample were placed in compost (aerobic surrounding) for 72 weeks. All samples were examined at the beginning every 2 weeks to observe if the degradation process occurred and all samples were examined at the end of 72 weeks period to observe results of degradation of each composite material.