Effectiveness in Sterilization of Objects Produced by 3D Printing with Polylactic Acid Material: Comparison Between Autoclave and Ethylene Oxide Methods / Eficácia na esterilização de objetos produzidos pela impressão 3D com material ácido polilático: Comparação entre os métodos autoclave e óxido de etileno

Abstract Objective Due to the popularity of 3D technology, surgeons can create specific surgical guides and sterilize them in their institutions. The aim of the present study is to compare the efficacy of the autoclave and ethylene oxide (EO) sterilization methods for objects produced by 3D printing with polylactic acid (PLA) material. Methods Forty cubic-shaped objects were printed with PLA material. Twenty were solid and 20 were hollow (printed with little internal filling). Twenty objects (10 solid and 10 hollow) were sterilized in autoclave, forming Group 1. The others (10 solid and 10 hollow) were sterilized in EO, composing Group 2. After sterilization, they were stored and referred to culture. Hollow objects of both groups were broken during sowing, communicating the dead space with the culture medium. The results obtained were statistically analyzed (Fisher exact test and residue analysis). Results In group 1 (autoclave), there was bacterial growth in 50% of solid objects and in 30% of hollow objects. In group 2 (EO), growth occurred in 20% of hollow objects, with no bacterial growth in solid objects (100% of negative samples). The bacteria isolated in the positive cases was non-coagulase-producing Staphylococcus Gram positive. Conclusions Sterilization by both autoclave and EO was not effective for hollow printed objects. Solid objects sterilized by autoclave did not demonstrate 100% of negative samples and were not safe in the present assay. Complete absence of contamination occurred only with solid objects sterilized by EO, which is the combination recommended by the authors.

Resumo Objetivo Devido à popularidade da tecnologia 3D, cirurgiões podem criar guias cirúrgicos específicos e esterilizá-los nas suas instituições. O objetivo do presente estudo é comparar a eficácia dos métodos de esterilização por autoclave e óxido de etileno (OE) de objetos produzidos pela impressão 3D com material ácido polilático (PLA, na sigla em inglês). Métodos Quarenta objetos em formato cúbico foram impressos com material de PLA. Vinte eram sólidos e 20 eram ocos (impressos com pouco enchimento interno). Vinte objetos (10 sólidos e 10 ocos) foram esterilizados em autoclave, formando o Grupo 1. Os demais (10 sólidos e 10 ocos) foram esterilizados em OE, compondo o Grupo 2. Após a esterilização, os objetos foram armazenados e encaminhados para cultura. Objetos ocos de ambos os grupos foram quebrados durante a semeadura, comunicando o espaço morto com o meio de cultura. Os resultados obtidos foram analisados estatisticamente (teste exato de Fisher e análise de resíduo). Resultados No grupo 1 (autoclave) houve crescimento bacteriano em 50% dos objetos sólidos e em 30% dos objetos ocos. No grupo 2 (OE) o crescimento ocorreu em 20% dos objetos ocos, com ausência de crescimento bacteriano nos objetos sólidos (100% de amostras negativas). A bactéria isolada nos casos positivos foi Staphylococcus Gram positivo não produtor de coagulase. Conclusões A esterilização tanto em autoclave quanto pelo OE não foi eficaz para objetos impressos no formato oco. Objetos sólidos esterilizados em autoclave não demonstraram 100% de amostras negativas, não sendo seguro no presente ensaio. Ausência completa de contaminação ocorreu apenas com objetos sólidos esterilizados pelo OE, sendo a combinação recomendada pelos autores.

Advances on the production of organic acids by yeast / 生物工程学报

Organic acids are organic compounds that can be synthesized using biological systems. They often contain one or more low molecular weight acidic groups, such as carboxyl group and sulphonic group. Organic acids are widely used in food, agriculture, medicine, bio-based materials industry and other fields. Yeast has unique advantages of biosafety, strong stress resistance, wide substrate spectrum, convenient genetic transformation, and mature large-scale culture technology. Therefore, it is appealing to produce organic acids by yeast. However, challenges such as low concentration, many by-products and low fermentation efficiency still exist. With the development of yeast metabolic engineering and synthetic biology technology, rapid progress has been made in this field recently. Here we summarize the progress of biosynthesis of 11 organic acids by yeast. These organic acids include bulk carboxylic acids and high-value organic acids that can be produced naturally or heterologously. Finally, future prospects in this field were proposed.

Recent progress in the biosynthesis of dicarboxylic acids, a monomer of biodegradable plastics / 生物工程学报

Plastics are one of the most important polymers with huge global demand. However, the downsides of this polymer are that it is difficult to degrade, which causes huge pollution. The environmental-friendly bio-degradable plastics therefore could be an alternative and eventually fulfill the ever-growing demand from every aspect of the society. One of the building blocks of bio-degradable plastics is dicarboxylic acids, which have excellent biodegradability and numerous industrial applications. More importantly, dicarboxylic acid can be biologically synthesized. Herein, this review discusses the recent advance on the biosynthesis routes and metabolic engineering strategies of some of the typical dicarboxylic acids, in hope that it will help to provide inspiration to further efforts on the biosynthesis of dicarboxylic acids.

Advance in the degradation of biodegradable plastics in different environments / 生物工程学报

With the continuously increasing demands of plastic products in the current society, the challenge of disposing plastic waste is constantly increasing, leading to the urgent need of mitigating plastic pollution. As a consequence, much attention has been paid to biodegradable plastics due to their degradability in a bio-active environment under certain conditions. Biodegradable plastics herald vast development potentials and considerable market prospects. The degradation of numerous types of biodegradable plastics will be affected by many factors. A thorough understanding of degradation mechanisms as well as functional microbial strains and enzymes is the key to comprehensive utilization and efficient treatment and disposal of biodegradable plastics. The article summarized the types, properties, advantages and disadvantages, and main applications of common biodegradable plastics. The degradation mechanisms, functional microbial strains and enzymes, as well as the degradation degree and duration under different environmental conditions, were also summarized. This review may help better understand the degradation of biodegradable plastics wastes.

Dual application of black soldier fly (Hermetia illucens): Protein-rich animal feed and biological extraction agent for polyhydroxybutyrate

Aims@#The primary aim of the present study is to evaluate the effect of rearing substrates on the nutritional content of black soldier fly larvae (BSFL) by incorporating Cupriavidus necator cells containing intracellular polyhydroxybutyrate (PHB) in BSFL diet to further increase the protein content and simultaneously to biologically extract the polymer by utilizing the digestive system of BSFL. The potential application of BSFL as a biological PHB extraction agent was determined.@*Methodology and results@#Two feeding strategies consists of a mixture of protein (P) to carbohydrate (C) with a ratio of P50:C50 food waste (control feeding) and feed with bacterial cells (modified feeding). A comparison on the proximate analysis between this research and two commercially available products were conducted. Feeding BSFL with P50:C50 food waste revealed the highest crude protein content of 81.3 ± 0.2%. Additional bacteria cells in the BSFL diet, however, showed a negligible decrease in crude protein content of 0.67% as compared to the control feeding. Howbeit, this results comparably higher in contrast to the commercial products, with increment of crude protein content by 12.1% and 40.8%, respectively.@*Conclusion, significance and impact of study@#Two desirable products were obtained from the feeding with cells: (1) high protein content of BSFL and (2) biologically extracted polymer. This is the first study to demonstrate the utilization of BSFL as a biological extraction agent to partially extract biopolymer and increase the protein content by feeding with cells.

Implantation of a biodegradable rectum balloon implant: Tips, Tricks and Pitfalls

ABSTRACT Introduction: A rectum balloon implant (RBI) is a new device to spare rectal structures during prostate cancer radiotherapy. The theoretical advantages of a RBI are to reduce the high radiation dose to the anterior rectum wall, the possibility of a post-implant correction, and their predetermined shape with consequent predictable position. Objective: To describe, step-by-step, our mini-invasive technique for hands-free transperineal implantation of a RBI before start of radiotherapy treatment. Materials and Methods: We provide step-by-step instructions for optimization of the transperineal implantation procedure performed by urologists and/or radiation oncologists experienced with prostate brachytherapy and the use of the real-time bi-plane transrectal ultrasonography (TRUS) probe. A RBI was performed in 15 patients with localised prostate cancer. Perioperative side-effects were reported. Results: We provide 'tips and tricks' for optimizing the procedure and proper positioning of the RBI. Please watch the animation, see video in https://vimeo.com/205852376/789df4fae4. The side-effects included mild discomfort to slight pain at the perineal region in 8 out of 15 patients. Seven patients (47%) had no complaints at all. Two patients developed redness of the skin, where prompt antibiotic regimen was started with no further sequelae. One patient revealed a temporary urine retention, which resolved in a few hours following conservative treatment. Further no perioperative complications occurred. Conclusion: This paper describes in detail the implantation procedure for an RBI. It is a feasible, safe and very well-tolerated procedure.

Bioconversion of cassava starch by-product into bacillus and related bacteria polyhydroxyalkanoates

Background: Unlike petroleum-based synthetic plastics, biodegradable biopolymer generation from industrial residue is a key strategy to reduce costs in the production process, as well as in the waste management, since efficient industrial wastewater treatment could be costly. In this context, the present work describes the prospection and use of bacterial strains capable to bioconvert cassava starch by-product into biodegradable polyhydroxyalkanoates (PHAs). Results: The first step of this study was the bacterial competence screening which was conducted with 72 strains covering 21 Bacillus and related species. The microorganism growth in a medium with a starch substrate was measured by an innovative MTT assay, while the ability of the bacteria to secrete amylase and produce PHA was evaluated by the Nile Red Dye method. Based on growth and potential for PHA production, four isolates were selected and identified as Bacillus megaterium by 16S rRNA sequencing. When cultivated in hydrolyzed cassava starch by-product, maximum production reached 4.97 g dry biomass/L with 29.7 percent of Poly-(3-hydroxybutyrate) (characterized by FTIR). Conclusions: MTT assay proved to be a reliable methodology for monitoring bacterial growth in insoluble media. Selected amylolytic strains could be used as an alternative industrial process for biodegradable plastics production from starchy residues, reducing costs for biodegradable biopolymer production and wastewater treatment operations.