Detecting SARS-CoV-2 in sludge samples: A systematic review.

AIMS: This paper aims to review the main sludge concentration methods used for SARS-CoV-2 detection in sewage sludge samples, discussing the main methods and sample volume related to increased viral load. In addition, we aim to evaluate the countries associated with increased positivity rates for SARS-CoV-2 in sludge samples. METHODS: This systematic methodology was registered in PROSPERO and followed the PRISMA guidelines. The search was carried out in the SciELO, PubMed/MEDLINE, Lilacs, and Google Scholar databases in January-March 2022. Quantitative studies with conclusive results were included in this review. Concentration methods (polyethylene glycol (PEG), PEG + NaCl, gravity thickening, skimmed milk flocculation, ultrafiltration, filtration using charged filters, primary sedimentation, and anaerobic digestion), as well as detection methods (RTqPCR and reverse transcription droplet digital PCR assay) were evaluated in this review. The SPSS v23 software program was used for statistical analysis. RESULTS: PEG (with or without NaCl addition) and gravity thickening were the most used sludge concentration methods to detect SARS-CoV-2. The main method associated with increased viral load (>2,02 × 10^4 copies/mL) was PEG + NaCl (p < 0.05, Mann-Whitney test). The average positivity rate for SARS-CoV-2 in sludge samples was 61 %, and a correlation was found between the sludge volume and the viral load (ro 0.559, p = 0.03, Spearman correlation). CONCLUSION: The sludge volume may influence the SARS-CoV-2 load since the virus can adhere to solid particles in these samples. Other factors may be associated with SARS-CoV-2 load, including the methods used; especially PEG + NaCl may result in a high viral load detected in sludge, and may provide a suitable pH for SARS-CoV-2 recovery.

Impact of immobilization strategies on the activity and recyclability of lipases in nanomagnetic supports.

The use of enzymes immobilized on nanomagnetic supports has produced surprising results in catalysis, mainly due to the increase in surface area and the potential for recovery and reuse. However, the meticulous control of the process and difficulties in reproducibility have made industrial-scale applications unfeasible. Furthermore, the role of conjugation strategies in the catalytic activity and recycling of catalysts is unclear. Therefore, the objective of this study was to compare the conjugation of enzymes on nanomagnetic supports through physical adsorption (naked) or covalent bonding with mercaptopropyltrimethoxysilane (MPTS) and aminopropyltriethoxysilane (APTS) ligands. The free lipase obtained from Rhizomucor miehei was used as a model enzyme. Total protein and enzyme activity were determined using spectrophotometry (UV-Vis) and the p-nitrophenyl palmitate (p-NPP) hydrolysis method. The results indicated that a more significant enzyme surface loading does not always mean better immobilization success. The physical adsorption binding strategy had higher surface loading and low catalytic activity. On the other hand, covalent coupling with free NH2 had an excellent catalytic activity with very low surface loading. Finally, we show that recyclability can be improved with conjugation mediated by disulfide bonds. The findings presented here are essential for developing nanoconjugates with high enzymatic activity, which can guarantee the success of several industrial applications.

Optimization of lipase production using fungal isolates from oily residues.

Lipases are triacylglycerol hydrolases that catalyze hydrolysis, esterification, interesterification, and transesterification reactions. These enzymes are targets of several industrial and biotech applications, such as catalysts, detergent production, food, biofuels, wastewater treatment, and others. Microbial enzymes are preferable for large scale production due to ease of production and extraction. Several studies have reported that lipases from filamentous fungi are predominantly extracellular and highly active. However, there are many factors that interfere with enzyme production (pH, temperature, medium composition, agitation, aeration, inducer type, and concentration, etc.), making control difficult and burdening the process. This work aimed to optimize the lipase production of four fungal isolates from oily residues (Penicillium sp., Aspergillus niger, Aspergillus sp., and Aspergillus sp.). The lipase-producing fungi isolates were morphologically characterized by optical and scanning electron microscopy. The optimal lipase production time curve was previously determined, and the response variable used was the amount of total protein in the medium after cultivation by submerged fermentation. A complete factorial design 32 was performed, evaluating the temperatures (28 °C, 32 °C, and 36 °C) and soybean oil inducer concentration (2%, 6%, and 10%). Each lipase-producing isolate reacted differently to the conditions tested, the Aspergillus sp. F18 reached maximum lipase production, compared to others, under conditions of 32 °C and 2% of oil with a yield of 11,007 (µg mL-1). Penicillium sp. F04 achieved better results at 36 °C and 6% oil, although for Aspergillus niger F16 was at 36 °C and 10% oil and Aspergillus sp. F21 at 32 °C and 2% oil. These results show that microorganisms isolated from oily residues derived from environmental sanitation can be a promising alternative for the large-scale production of lipases.

Genetic diversity of indigenous common bean (Phaseolus vulgaris L) rhizobia from the state of Minas Gerais, Brazil

We characterized indigenous common bean rhizobia from five districts of the state of Minas Gerais, Brazil. The isolates were trapped by two common bean varieties, the Mineiro Precoce (Andean origin) and Ouro Negro (Mesoamerican origin). Analysis by BOX-PCR of selected isolates detected a high level of genetic diversity.

Genetic diversity of indigenous common bean (Phaseolus vulgaris L.) rhizobia from the state of Minas Gerais, Brazil.

We characterized indigenous common bean rhizobia from five districts of the state of Minas Gerais, Brazil. The isolates were trapped by two common bean varieties, the Mineiro Precoce (Andean origin) and Ouro Negro (Mesoamerican origin). Analysis by BOX-PCR of selected isolates detected a high level of genetic diversity.

Efeito de extratos de própolis verde sobre bactérias patogênicas isoladas do leite de vacas com mastite / Effect of green propolis extracts on patogenic bacteria isolated from milk of cows with mastitis

A sensibilidade, in vitro, de amostras de Staphylococcus aureus, Staphylococcus sp. coagulase negativos, Streptococcus agalactiae e bactérias do grupo dos coliformes, isoladas do leite de vacas com mastite, a diferentes extratos de própolis, na concentraçäo de 100 mg/ml, foi avaliada pela técnica do antibiograma em discos de papel de filtro com sobrecamada de meio de cultura. Os resultados mostraram que o extrato etanólico de própolis comercial, os extratos etanólico e, em menor proporçäo, o metanólico inibiram o crescimento das amostras de bactérias Gram-positivas, Staphylococcus aureus, Staphylococcus sp. coagulase negativos e Streptococcus agalactiae. Os extratos obtidos através da água, do acetato de etila e do clorofórmio näo inibiram nenhuma amostra bacteriana, assim como os veículos etanol e metanol puros utilizados como controle. A bactéria Gram-negativa testada, do tipo coliforme, näo apresentou sensibilidade a nenhum dos extratos. Verificaram-se diferenças significativas (p < 0,05) na sensibilidade aos extratos entre amostras bacterianas de uma mesma espécie, mas de origens diferentes. Nas amostras de Streptococcus agalactiae, os diâmetros dos halos de inibiçäo do crescimento bacteriano ao redor do disco foram maiores que aqueles observados para as amostras de Staphylococcus aureus e Staphylococcus sp. coagulase negativos. Todos estes resultados estimulam o prosseguimento de novas pesquisas sobre a utilizaçäo de extratos de própolis, em veículos adequados, com vistas ao tratamento da mastite bovina