Current Knowledge on Polyethylene Terephthalate Degradation by Genetically Modified Microorganisms

The global production of polyethylene terephthalate (PET) is estimated to reach 87.16 million metric tons by 2022. After a single use, a remarkable part of PET is accumulated in the natural environment as plastic waste. Due to high hydrophobicity and high molecular weight, PET is hardly biodegraded by wild-type microorganisms. To solve the global problem of uncontrolled pollution by PET, the degradation of plastic by genetically modified microorganisms has become a promising alternative for the plastic circular economy. In recent years many studies have been conducted to improve the microbial capacity for PET degradation. In this review, we summarize the current knowledge about metabolic engineering of microorganisms and protein engineering for increased biodegradation of PET. The focus is on mutations introduced to the enzymes of the hydrolase class—PETase, MHETase and cutinase—which in the last few years have attracted growing interest for the PET degradation processes. The modifications described in this work summarize the results obtained so far on the hydrolysis of polyethylene terephthalate based on the released degradation products of this polymer.

LED control of gene expression in a nanobiosystem composed of metallic nanoparticles and a genetically modified E. coli strain

Background Within the last decade, genetic engineering and synthetic biology have revolutionized society´s ability to mass-produce complex biological products within genetically-modified microorganisms containing elegantly designed genetic circuitry. However, many challenges still exist in developing bioproduction processes involving genetically modified microorganisms with complex or multiple gene circuits. These challenges include the development of external gene expression regulation methods with the following characteristics: spatial–temporal control and scalability, while inducing minimal permanent or irreversible system-wide conditions. Different stimuli have been used to control gene expression and mitigate these challenges, and they can be characterized by the effect they produce in the culture media conditions. Invasive stimuli that cause permanent, irreversible changes (pH and chemical inducers), non-invasive stimuli that cause partially reversible changes (temperature), and non-invasive stimuli that cause reversible changes in the media conditions (ultrasound, magnetic fields, and light). Methods Opto-control of gene expression is a non-invasive external trigger that complies with most of the desired characteristics of an external control system. However, the disadvantage relies on the design of the biological photoreceptors and the necessity to design them to respond to a different wavelength for every bioprocess needed to be controlled or regulated in the microorganism. Therefore, this work proposes using biocompatible metallic nanoparticles as external controllers of gene expression, based on their ability to convert light into heat and the capacity of nanotechnology to easily design a wide array of nanostructures capable of absorbing light at different wavelengths and inducing plasmonic photothermal heating. Results Here, we designed a nanobiosystem that can be opto-thermally triggered using LED light. The nanobiosystem is composed of biocompatible gold nanoparticles and a genetically modified E. coli with a plasmid that allows mCherry fluorescent protein production at 37 °C in response to an RNA thermometer. Conclusions The LED-triggered photothermal protein production system here designed offers a new, cheaper, scalable switchable method, non-destructive for living organisms, and contribute toward the evolution of bioprocess production systems.

Probiotic-Based Vaccines May Provide Effective Protection against COVID-19 Acute Respiratory Disease

Severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) infection, the causative agent of COVID-19, now represents the sixth Public Health Emergency of International Concern (PHEIC)—as declared by the World Health Organization (WHO) since 2009. Considering that SARS-CoV-2 is mainly transmitted via the mucosal route, a therapy administered by this same route may represent a desirable approach to fight SARS-CoV-2 infection. It is now widely accepted that genetically modified microorganisms, including probiotics, represent attractive vehicles for oral or nasal mucosal delivery of therapeutic molecules. Previous studies have shown that the mucosal administration of therapeutic molecules is able to induce an immune response mediated by specific serum IgG and mucosal IgA antibodies along with mucosal cell-mediated immune responses, which effectively concur to neutralize and eradicate infections. Therefore, advances in the modulation of mucosal immune responses, and in particular the use of probiotics as live delivery vectors, may encourage prospective studies to assess the effectiveness of genetically modified probiotics for SARS-CoV-2 infection. Emerging trends in the ever-progressing field of vaccine development re-emphasize the contribution of adjuvants, along with optimization of codon usage (when designing a synthetic gene), expression level, and inoculation dose to elicit specific and potent protective immune responses. In this review, we will highlight the existing pre-clinical and clinical information on the use of genetically modified microorganisms in control strategies against respiratory and non-respiratory viruses. In addition, we will discuss some controversial aspects of the use of genetically modified probiotics in modulating the cross-talk between mucosal delivery of therapeutics and immune system modulation.

THE FITNESS OF A RECOMBINANT STRAIN OF PSEUDOMONAS AERUGINOSA BACTERIA COMPARING WITH ITS PARENT STRAINS UNDER THE EGYPTIAN ENVIRONMENTAL CONDITIONS (MOWAS RIVER) IN 2020

The present study aimed to study the fitness between a trans-conjugant (recombinant strain) of Pseudomonas aeruginosa bacteria with its parents after transferring genetic material by conjugation mechanism. Whereas, environmental fitness expresses the interaction of an organism with its environment therefore it is considered a good indicator for the assessment of genetically engineered microorganisms (GEM) released into nature. Incubation time was carried out in vitro and incubating time in situ in Mowas River Zagazig city during winter and summer. Accordingly, the fitness of the parents and the recombinant strain was studied. The three strains of Pseudomonas aeruginosa (PAO1, MAM2 and PU21) were tested on chloramphenicol and tetracycline. Strain MAM2 was resistant to chloramphenicol 1200 µg/ml while was sensitive to tetracycline and has been used as the recipient. While strain PAO1 was resistant to tetracycline 200 µg/ml and was sensitive to chloramphenicol and has been used as the donor. Results proofed the presence of the plasmid in the donor and trans conjugant strains. The donor was treated with acridine orange to match the results obtained with the results at the molecular level. It was observed that bacterial fitness continued for up to 35 days in vitro, while in situ during the summer it did not last at the site for only 21 days. While it lasted 28 days during the summer. So, the risks that may be caused by releasing the genetically modified microorganisms into environments have been canceled. In addition to its ability to preserve the new genetic material, it may be able to transfer this new genetic material to other strains and species that may be live in the same ecosystem, as it is largely stable in the environment. In genetically modified microorganisms that are added to the environments for agricultural uses such as increasing soil fertility (bio-fertilizer) or biodegradation for a harmful substance such as pesticides, the soil must be re-inoculated in