This is the first report to show AR gene dynamics and persistency of potentially pathogenic bacteria through metagenomic approach in cattle manure ambient temperature anaerobic digestion.

ABSTRACT. Even though several in vitro studies have focused on bacterial biology, the extent of such knowledge is not complete when considering an actual infection. As culture-independent microbiology methods such as high-throughput sequencing became available, important aspects of host-bacterium interactions will be elucidated. Based on microbiological relevance, we considered Bacteroides fragilis in a murine experimental infection as a model system to evaluate the in vivo bacterial transcriptome in host exudates. A disproportionate number of reads belonging to the host genome were retrieved in the first round of pyrosequencing, even after depletion of ribosomal RNA; the average number of reads related to the eukaryotic genome was 71.924-67.7%, whereas prokaryotic reads represented 34.338-32.3% in host exudates. Thus, different treatments were used to improve the prokaryotic RNA yield: i) centrifugation; ii) ultrasonic treatment; and iii) ultrasonic treatment followed by centrifugation. The latter treatment was found to be the most efficient in generating bacterial yields, as it resulted in a higher number of Bacteroides cells. However, the RNA extracted after this treatment was not of sufficient quality to be used in cDNA synthesis. Our results suggest that the methodology routinely used for RNA extraction in transcriptional analysis is not appropriate for in vivo studies in complex samples. Furthermore, the most efficient treatment for generating good bacterial cell yields was not suitable to retrieve high-quality RNA. Therefore, as an alternative methodological approach to enable in vivo studies on host-bacterium interactions, we advise increasing the sequencing depth despite the high costs.

The SARS-CoV-2 pandemic has demonstrated the need for genomic epidemiology surveillance. To date, various methodologies have been applied, including metagenomic ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 21 (1): gmr19018C.P. Targueta et al. 2 approaches and amplicon-based sequencing associated with highthroughput sequencing platforms. We adapted some details in amplicon-based sequencing using a SARS-CoV-2 community panel (Illumina AmpliSeq), with additional modifications for balanced and high-quality sequencing using the MiSeq platform. The modified protocol was used to detect circulating SARS-CoV-2 variants in Goiás state, Brazil. Initially, RNA samples were obtained from swab samples from 15 patients from the state of Goiás, Brazil, in November/2020 and February/2021 to validate protocol steps. The libraries were prepared following AmpliSeq for Illumina workflow with modifications; subsequently, we analyzed 305 positive samples collected from the state of Goiás from December 2020 to July 2021. For protocol improvement, we removed the need to treat samples with DNAse and demonstrated the importance of quantification by qPCR before and after library dilution. No fragmentation pattern was observed in the samples analyzed with Bioanalyzer. The libraries returned sequencing results that were used for genome assembly and variant detection. We were able to assemble SARS-CoV-2 genomes from 318 samples, which were used to identify 13 variants of coronavirus circulating in Goiás throughout those months. Variants of concern, such as Alpha (B.1.1.7), Gamma (P.1) and Delta (B.1.617.2) were detected; the latter was detected at first in Goiás in April 2021. The modifications in the workflow we developed were successfully applied to detect SARS-CoV-2 variants, resulting in high coverage genome assembly, and they can be used to increase the number of genome sequences and aid in epidemiological surveillance in Brazil.