Microbiological changes, shelf life and identification of initial and spoilage microbiota of sea bream fillets stored under various conditions using 16S rRNA gene analysis

Odontogenic abscesses are usually caused by bacteria of the oral microbiome. However, the diagnostic culture of these bacteria is often prone to errors and sometimes fails completely due to the fastidiousness of the relevant bacterial species. The question arises whether additional pathogen diagnostics using molecular methods provide additional benefits for diagnostics and therapy. Experimental 16S rRNA gene analysis with next-generation sequencing (NGS) and bioinformatics was used to identify the microbiome of the pus in patients with severe odontogenic infections and was compared to the result of standard diagnostic culture. The pus microbiome was determined in 48 hospitalized patients with a severe odontogenic abscess in addition to standard cultural pathogen detection. Cultural detection was possible in 41 (85.42%) of 48 patients, while a pus-microbiome could be determined in all cases. The microbiomes showed polymicrobial infections in 46 (95.83%) cases, while the picture of a mono-infection occurred only twice (4.17%). In most cases, a predominantly anaerobic spectrum with an abundance of bacteria was found in the pus-microbiome, while culture detected mainly Streptococcus, Staphylococcus, and Prevotella spp. The determination of the microbiome of odontogenic abscesses clearly shows a higher number of bacteria and a significantly higher proportion of anaerobes than classical cultural methods. The 16S rRNA gene analysis detects considerably more bacteria than conventional cultural methods, even in culture-negative samples. Molecular methods should be implemented as standards in medical microbiology diagnostics, particularly for the detection of polymicrobial infections with a predominance of anaerobic bacteria.

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Spoilage potential of spore-forming bacteria from refrigerated raw milk

Semina Ciências Agrárias ◽

10.5433/1679-0359.2018v39n5p2049 ◽

2018 ◽

Vol 39 (5) ◽

pp. 2049 ◽

Cited By ~ 2

Author(s):

José Carlos Ribeiro Júnior ◽

Ronaldo Tamanini ◽

André Luís Martinez de Oliveira ◽

Juliane Ribeiro ◽

Vanerli Beloti

Keyword(s):

16S Rrna ◽

16S Rrna Gene ◽

Shelf Life ◽

Lipolytic Activity ◽

Raw Milk ◽

Rrna Gene ◽

16S Rrna Gene Analysis ◽

Pasteurized Milk ◽

Bacillus Spp ◽

Aerobic Spores

Aerobic bacterial spores are an important group of microorganisms in raw milk. These microbes are thermoduric, whereas the vegetative forms are thermophilic, thermoduric and psychrotrophic and reduce the shelf life of pasteurized milk. In Brazil, there are a lack of studies on the load of aerobic spores in raw milk; thus, little is known about the spoilage activity of these organisms. The aim the present study was to quantify the aerobic spores in Brazilian refrigerated raw milk of dairy region of Castro, Paraná state, assess the potential proteolytic and/or lipolytic isolates and identify the microorganisms derived from the germination. Twenty milk samples were evaluated, and the aerobic spore count was performed after plating the samples following heat treatment at 80°C for 12 min. The activity proteolytic and lipolytic isolates were evaluated through subculture on milk agar and tributyrin agar, respectively, and these microorganisms were identified using partial 16S rRNA gene sequences that were compared through GenBank. The aerobic spore counts ranged from 1 to 3.7 log CFU.mL-1, with a mean of 1.75 (± 0.59) log CFU.mL-1. After spore germination, 137 aerobic bacterial isolates were obtained, 40 of which (29.2%) showed milk spoilage activity. Among these, 31 isolates (77.5%) were proteolytic and lipolytic, seven isolates (17.5%) were exclusively lipolytic and two isolates (5%) were only proteolytic. Based on the 16S rRNA gene analysis, Bacillus licheniformis (55%), Bacillus spp. (27.5%), Paenibacillus spp. (7.5%), Bacillus pumilus (5%), Bacillus circulans (2.5%) and Brevibacillus spp. (2.5%) were identified. Studies of Brazilian raw milk microbiota have not yet described B. circulans which are frequently detected in milk from other countries. Among the 22 B. licheniformis isolates, 21 microbes (95.5%) showed proteolytic and lipolytic activity, and one isolate (4.5%) exhibited only proteolytic activity. The two B. pumilus isolates were proteolytic and lipolytic, whereas the B. circulans isolate was only lipolytic. Among the 11 Bacillus spp. isolates, eight isolates (72.7%) were proteolytic and lipolytic, one isolate (9.1%) was proteolytic and the other two isolates (18.2%) were lipolytic. The three Paenibacillus spp. and Brevibacillus spp. isolates were primarily lipolytic. Therefore, to extend the shelf life of pasteurized milk, preventive measures must be adopted to reduce contamination with spores because one-third of these microorganisms exhibited proteolytic and/or lipolytic activity.

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