Safety aspects, genetic diversity and technological characterisation of wild-type Streptococcus thermophilus strains isolated from north Italian traditional cheeses

Morandi, Stefano; Brasca, Milena

doi:10.1016/j.foodcont.2011.07.011

Cited by 30 publications

(18 citation statements)

References 37 publications

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“…In addition, 1 strain of L. plantarum from fermented dairy drink harbored the tetS gene. Other tetracycline resistance genes have also been identified in lactobacilli and S. thermophilus [7,31]; however, these were not detected in any of these strains in the present study. The corresponding resistance genes were absent in various resistant strains, thereby suggesting that other resistance mechanisms may be responsible for their resistance to antimicrobial drugs.…”

Section: Discussioncontrasting

confidence: 82%

Characterization and transfer of antimicrobial resistance in lactic acid bacteria from fermented dairy products in China

Yang¹,

2019

J Infect Dev Ctries

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Introduction: Lactic acid bacteria (LAB) are commonly found in foods and are also natural intestinal inhabitants in humans and most animals. However, information regarding antimicrobial resistance and the transfer of resistance genes of LAB from fermented dairy products in China is limited. Methodology: In this study, LAB isolates (n = 82) of Lactobacillus (n = 43) and Streptococcus thermophilus (n = 39) were isolated from 51 commercial fermented food samples in China. All isolates were subjected to pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility, detecting resistance genes, as well as investigating the transferability of resistance genes. Results: The 43 Lactobacillus isolates yielded 24 PFGE patterns and the 34 isolates of S. thermophilus generated 32 different PFGE patterns. Among the 43 Lactobacillus strains, the most commonly observed resistance was that to streptomycin (83.7%) and gentamycin (83.7%). Among the 39 S. thermophilus strains, the most frequently observed resistance was that to streptomycin (92.3%), gentamycin (87.2%), ciprofloxacin (79.5%), and chloramphenicol (71.8%), whereas the lowest level of resistance was that against erythromycin (7.7%). Antimicrobial resistance genes for erythromycin (emrB), gentamycin (aac(6')-aph(2")), streptomycin (ant(6)), sulfamethoxazole (sulI and sulII), tetracycline (tetM and tetS) were detected in the 18 resistance LAB strains. Conjugation experiments showed that tetM from L. delbrueckii subsp. bulgaricus R6 and tetS from L. plantarum R41 were successfully transferred to L. monocytogenes by filter mating. Conclusions: LAB strains could potentially act as reservoirs of resistance genes and play an active role in the transfer of resistance to humans via the food chain.

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Section: Discussioncontrasting

confidence: 82%

Characterization and transfer of antimicrobial resistance in lactic acid bacteria from fermented dairy products in China

Yang¹,

2019

J Infect Dev Ctries

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“…thermophilus strains are normally well represented in the spontaneous microbial consortia of artisanal cheeses and fermented milks. This is in part favored by the production of organic acids and bacteriocins that hamper proliferation of competitor microorganisms (Morandi & Brasca, 2012).…”

Section: Bacteriocin Productionmentioning

confidence: 99%

“…Considering the number of Italian cheese factories involved in dairy productions (ISTAT, 2014), the Italian dairy microbiota can be considered a potential important source of new S. thermophilus strains. Nonetheless, until now such biodiversity has been explored only partially both from the genetic and phenotypic point of view (Andrighetto et al, 2002, Morandi andBrasca, 2012). Thanks to the next generation sequencing technology, whole S. thermophilus genome sequences are publicly available.…”

Section: Introductionmentioning

confidence: 99%

Genome comparison and physiological characterization of eight Streptococcus thermophilus strains isolated from Italian dairy products

Vendramin¹,

Treu

Campanaro

et al. 2017

Food Microbiology

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Eight Streptococcus thermophilus strains of dairy origin isolated in Italy were chosen to investigate autochthonous bacterial diversity in this important technological species. In the present study a comparative analysis of all the 17 S. thermophilus genomes publicly available was performed to identify the core and the variable genes, which vary among strains from 196 to 265. Additionally, correlation between the isolation site and the genetic distance was investigated at genomic level. Results highlight that the phylogenetic reconstruction differs from the geographical strain distribution. Moreover, strain M17PTZA496 has a genome of 2.15 Mbp, notably larger than that of the others, determined by lateral gene transfer (including phage-mediated incorporation) and duplication events. Important technological characters, such as growth kinetics, bacteriocin production, acidification kinetics and surface adhesion capability were studied in all the Italian strains. Results indicate a wide range of variability in adhesion properties that significantly clustered strains into four groups. Genomic differences among strains in relation to these characters were identified but a clear correlation between genotype and phenotype was not always found since most of the genomic modifications arise from single nucleotide polymorphisms. This research represents a step forward in the identification of strains-specific functions in Streptococcus thermophilus and it has also the potential to provide valuable information to predict strain specific behaviors in industrial processes.

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“…The acidification rate of strains depends on their sugar utilization ability. A number of works indicate that utilization of glucose, lactose and fructose by S. thermophilus is a common characteristic in all existing studies, while galactose, mannose, sucrose, maltose, melibiose, and raffinose utilizations have variable profiles [40,41,42,43,44,45,46,47]. At the same time, it has been found that carbohydrate metabolism is essential for the colonization of S. thermophilus in the digestive tract of gnotobiotic rats [48].…”

Section: Technological and Functional Properties Of S Thermophilusmentioning

confidence: 99%

New Insights into Various Production Characteristics of Streptococcus thermophilus Strains

Cui

et al. 2016

IJMS

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Streptococcus thermophilus is one of the most valuable homo-fermentative lactic acid bacteria, which, for a long time, has been widely used as a starter for the production of fermented dairy products. The key production characteristics of S. thermophilus, for example the production of extracellular polysaccharide, proteolytic enzymes and flavor substances as well as acidifying capacity etc., have an important effect on the quality of dairy products. The acidification capacity of the strains determines the manufacturing time and quality of dairy products. It depends on the sugar utilization ability of strains. The production of extracellular polysaccharide is beneficial for improving the texture of dairy products. Flavor substances increase the acceptability of dairy products. The proteolytic activity of the strain influences not only the absorption of the nitrogen source, but also the formation of flavor substances. Different strains have obvious differences in production characteristics via long-time evolution and adaptation to environment. Gaining new strains with novel and desirable characteristics is an important long-term goal for researchers and the fermenting industry. The understanding of the potential molecular mechanisms behind important characteristics of different strains will promote the screening and breeding of excellent strains. In this paper, key technological and functional properties of different S. thermophilus strains are discussed, including sugar metabolism, proteolytic system and amino acid metabolism, and polysaccharide and flavor substance biosynthesis. At the same time, diversity of genomes and plasmids of S. thermophilus are presented. Advances in research on key production characteristics and molecular levels of S. thermophilus will increase understanding of molecular mechanisms of different strains with different important characteristics, and improve the industrialization control level for fermented foods.

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Safety aspects, genetic diversity and technological characterisation of wild-type Streptococcus thermophilus strains isolated from north Italian traditional cheeses

Cited by 30 publications

References 37 publications

Characterization and transfer of antimicrobial resistance in lactic acid bacteria from fermented dairy products in China

Characterization and transfer of antimicrobial resistance in lactic acid bacteria from fermented dairy products in China

Genome comparison and physiological characterization of eight Streptococcus thermophilus strains isolated from Italian dairy products

New Insights into Various Production Characteristics of Streptococcus thermophilus Strains

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