Slovak raw goat milk as a source of variable, biofilm‐forming staphylococci, and their susceptibility to lantibiotic bacteriocins

Abstract

Background: Goat milk and products from it are popular with the public in Slovakia.Consumers demand safe food. Therefore, methods to eliminate spoilage bacteria are necessary. This study focuses on susceptibility to lantibiotic bacteriocins of variable staphylococci, which were isolated from raw goat milk. A total of 53 raw goat milk samples collected from 283 goats in the regions of central and eastern Slovakia were analyzed.Results: In total, 37 strains were identified to use a combination of matrix-assisted laser desorption ionization time-of-flight spectrometry and phenotypization. They were allotted to 14 species, which can be involved in 7 different clusters. Staphylococci showed mostly low-grade biofilm formation ability; six different strains were high-grade biofilmforming. Staphylococcus xylosus SX 17/1 showed the highest biofilm formation ability value (3.16 AE 1.77). Staphylococci were deoxyribonuclease and mostly hemolysis negative (γ-hemolysis). They all were susceptible to bacteriocins (inhibition activity up to 204,800 AU/ml).Conclusions: Variable staphylococcal species were detected in raw goat milk, mostly coagulase-negative species, involving Staphylococcus arlettae. The species Staphylococcus hominis dominated. However, also the coagulase-positive species Staphylococcus delphini and Staphylococcus schleiferi were detected. This is the first study involving detailed testing of staphylococci from Slovak raw goat milk and indication of a promising practical tool and prophylaxis using bacteriocins.

Microbiome Associated with Slovak Raw Goat Milk, Trace Minerals, and Vitamin E Content

“…Also the genera Arthrobacter, Dialister, Planococcus, Clostridium SS1, Escherichia-Shigella, or Haemophilus were determined, however with very low abundance. The prevalence of the genus Staphylococcus was found; it is in association with the most frequently detected staphylococcal species in raw goat milk as previously reported by Lauková et al [13]. The following 14 species were detected, which can be involved in seven different clusters (Staphylococcus arlettae, S. capitis, S. delphini, S. epidermidis, S. equorum, S. hominis, S. lentus, S. pasteuri, S. sciuri, S. simulans, S. schleiferi, S. vitulinus, S. warneri, and S. xylosus.…”

“…Bacteriocins produced mainly by some enterococci [ 19 , 20 , 21 , 6 ] can be used to reduce/protect goat milk against spoilage bacteria such as those from detected phyla Bacteroidetes or Proteobacteria and families Pseudomonadaceae , Moraxellaceae , Enterobacteriaceae , and/or Clostridiaceae . The antimicrobial effect of enterocins against representatives of the families mentioned was already reported [ 22 , 23 , 13 ]. However, the antimicrobial effect can interact also with lactic acid production.…”

“…Sampling was performed from 51 individual goats, and two pooled milk samples were taken [ 13 , 14 ]. Those milk samples were treated using the standard microbiological method as previously mentioned by Lauková et al [ 13 , 6 , 9 ]. However later, for next-generation technique analysis, lastly sampled 26 milks (G24-G50) from different animals were used.…”

“…A total of 53 raw goat milk samples from healthy goats were collected in central and eastern Slovakia farms involving 283 goats as previously reported by Lauková et al [13,14]. Sampling was performed from 51 individual goats, and two pooled milk samples were taken [13,14]. Those milk samples were treated using the standard microbiological method as previously mentioned by Lauková et al [13,6,9].…”

“…Although strict hygienic and zoohygienic conditions are kept during milk processing, spoilage microbiota, e.g., staphylococci, can contaminate goat milk because of farming production [ 9 ]. There exist studies mapping the occurrence of beneficial and/or spoilage bacteria in raw milks using standard microbiological analyses [ 9 , 10 , 11 , 12 , 13 , 14 ] and also next-generation sequencing techniques [ 10 , 14 , 15 ]. However, regarding the microbial consortium (microbiome) mapping in Slovak raw goat milk by using next-generation sequencing technique only, a lack of information exists.…”