Antarctic Polyester Hydrolases Degrade Aliphatic and Aromatic Polyesters at Moderate Temperatures.

Polyethylene terephthalate (PET) is one of the most widely used synthetic plastics in the packaging industry, and consequently has become one of the main components of plastic waste found in the environment. However, several microorganisms have been described to encode enzymes that catalyze the depolymerization of PET. While most known PET hydrolases are thermophilic and require reaction temperatures between 60°C and 70°C for an efficient hydrolysis of PET, a partial hydrolysis of amorphous PET at lower temperatures by the polyester hydrolase IsPETase from the mesophilic bacterium Ideonella sakaiensis has also been reported. We show that polyester hydrolases from the Antarctic bacteria Moraxella sp. strain TA144 (Mors1) and Oleispira antarctica RB-8 (OaCut) were able to hydrolyze the aliphatic polyester polycaprolactone as well as the aromatic polyester PET at a reaction temperature of 25°C. Mors1 caused a weight loss of amorphous PET films and thus constitutes a PET-degrading psychrophilic enzyme. Comparative modeling of Mors1 showed that the amino acid composition of its active site resembled both thermophilic and mesophilic PET hydrolases. Lastly, bioinformatic analysis of Antarctic metagenomic samples demonstrated that members of the Moraxellaceae family carry candidate genes coding for further potential psychrophilic PET hydrolases. IMPORTANCE A myriad of consumer products contains polyethylene terephthalate (PET), a plastic that has accumulated as waste in the environment due to its long-term stability and poor waste management. One promising solution is the enzymatic biodegradation of PET, with most known enzymes only catalyzing this process at high temperatures. Here, we bioinformatically identified and biochemically characterized an enzyme from an Antarctic organism that degrades PET at 25°C with similar efficiency to the few PET-degrading enzymes active at moderate temperatures. Reasoning that Antarctica harbors other PET-degrading enzymes, we analyzed available data from Antarctic metagenomic samples and successfully identified other potential enzymes. Our findings contribute to increasing the repertoire of known PET-degrading enzymes that are currently being considered as biocatalysts for the biological recycling of plastic waste.

Moraxella bovis, Moraxella ovis and Moraxella bovoculi: biofilm formation and lysozyme activity.

AIMS: This study aimed to verify the formation of biofilms by Moraxella bovis, Moraxella ovis and Moraxella bovoculi isolates from ruminants. In addition, the lysozyme activity against the isolates of M. bovis, M. ovis and M. bovoculi in free form and in biofilms was determined. METHODS AND RESULTS: In this study, 54 isolates of Moraxella sp. obtained from bovine and ovine clinical samples were evaluated in vitro for capacity of biofilm formation and lysozyme susceptibility in planktonic and sessile cells. In addition, biofilms produced by four Moraxella sp. isolates were visualized under scanning electron microscope (SEM). It was possible to demonstrate, for the first time, the ability to form biofilms by M. ovis and M. bovoculi. The isolates of Moraxella sp. have the capacity to form biofilms in different intensities, varying among weak, moderate and strong. It was verified that the lysozyme shows activity on Moraxella sp. in planktonic form. However, on biofilms there was a reduction in the production, but without impairing its formation, and on consolidated biofilms the lysozyme did not have the capacity to eradicate the preformed biofilms. CONCLUSIONS: This work shows the capacity of biofilm formation by Moraxella sp. of veterinary importance. The lysozyme susceptibility of Moraxella sp. in planktonic form shows that this enzyme has bacteriostatic activity on this micro-organism and it reduced the production of biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: Based on the results, it is possible to infer that the biofilm formation capacity by Moraxella sp. and the resistance to lysozyme concentrations equal to or greater than the physiological levels of the ruminant tear may be linked not only to the capacity to colonize the conjunctiva, but also to remain in this place even after healing of the lesions, being a reservoir of Moraxella sp. in a herd.

Conjunctival bacterial flora of healthy ovines in Pernambuco State, Brazil / Flora conjuntival bacteriana de ovinos sadios da raça Santa Inês e seus mestiços criados na microrregião de Garanhuns, Pernambuco

In all the animals there is a normal conjunctive bacterial flora. For correct evaluation of the results of any culture technique, it is necessary to know the microorganisms considered as part of the normal flora, differentiating them from the pathogenic ones. This study cared to determine bacteriologic patterns from healthy ovine"s conjunctival sacks. Sixty unaffected eyes were studied. For bacterial isolation and Mycoplasma search, conjunctival swabs were done. Moraxella sp. was the most frequent bacteria in healthy eyes, 28.33% (17/60), followed by Staphylococcus sp., 23.33% (14/60). Streptococcus sp., 5.00% (3/60), Micrococcus sp., 5.00% (3/60), Corynebacte¬rium sp., 3.33% (2/60), Bacillus sp., 3.33% (2/60) and Serratia sp., 1.67% (1/60). Mycoplasma conjunctivae was present in 15.00% (9/60) of samples.

Em todos os animais existe uma flora bacteriana conjuntival normal. Para correta avaliação dos resultados de qualquer técnica de cultura, é necessário conhecer os microrganismos considerados como parte da flora normal, diferenciando-os dos patogênicos. Neste estudo o objetivo foi estabelecer padrões bacteriológicos de sacos conjuntivais de ovinos sadios. Avaliou-se 60 olhos de 30 animais sem altera-ções clínicas aparentes. Para o isolamento bacteriano e pesquisa de Mycoplasma, utilizou-se swab do saco conjuntival. Moraxella sp. foi a bactéria mais isolada, presente em 28,33% (17/60) dos olhos sadios, seguido por Staphylococcus sp., 23,33% (14/60). Streptococcus sp., 5,00% (3/60), Micrococcus sp., 5,00% (3/60), Corynebacterium sp., 3,33% (2/60), Bacillus sp., 3,33% (2/60) e Serratia sp., 1,67% (1/60). O Mycoplasma conjunctivae esteve presente em 15,00% (9/60) das amos¬tras estudadas.

Conjunctival bacterial flora of healthy ovines in Pernambuco State, Brazil / Flora conjuntival bacteriana de ovinos sadios da raça Santa Inês e seus mestiços criados na microrregião de Garanhuns, Pernambuco

In all the animals there is a normal conjunctive bacterial flora. For correct evaluation of the results of any culture technique, it is necessary to know the microorganisms considered as part of the normal flora, differentiating them from the pathogenic ones. This study cared to determine bacteriologic patterns from healthy ovine"s conjunctival sacks. Sixty unaffected eyes were studied. For bacterial isolation and Mycoplasma search, conjunctival swabs were done. Moraxella sp. was the most frequent bacteria in healthy eyes, 28.33% (17/60), followed by Staphylococcus sp., 23.33% (14/60). Streptococcus sp., 5.00% (3/60), Micrococcus sp., 5.00% (3/60), Corynebacte¬rium sp., 3.33% (2/60), Bacillus sp., 3.33% (2/60) and Serratia sp., 1.67% (1/60). Mycoplasma conjunctivae was present in 15.00% (9/60) of samples.

Em todos os animais existe uma flora bacteriana conjuntival normal. Para correta avaliação dos resultados de qualquer técnica de cultura, é necessário conhecer os microrganismos considerados como parte da flora normal, diferenciando-os dos patogênicos. Neste estudo o objetivo foi estabelecer padrões bacteriológicos de sacos conjuntivais de ovinos sadios. Avaliou-se 60 olhos de 30 animais sem altera-ções clínicas aparentes. Para o isolamento bacteriano e pesquisa de Mycoplasma, utilizou-se swab do saco conjuntival. Moraxella sp. foi a bactéria mais isolada, presente em 28,33% (17/60) dos olhos sadios, seguido por Staphylococcus sp., 23,33% (14/60). Streptococcus sp., 5,00% (3/60), Micrococcus sp., 5,00% (3/60), Corynebacterium sp., 3,33% (2/60), Bacillus sp., 3,33% (2/60) e Serratia sp., 1,67% (1/60). O Mycoplasma conjunctivae esteve presente em 15,00% (9/60) das amos¬tras estudadas.