Seasonal Diversity of Lactic Acid Bacteria in Artisanal Yoghurt and Their Antibiotic Susceptibility Pattern

Abstract

The microbiological quality of artisanal yoghurt marketed in some regions of Cameroon was evaluated during the dry and rainy seasons alongside three commercial brands and the susceptibility of isolates to some conventional antibiotics. A total of ninety-six (96) samples were collected, and the microbiological quality was based on the total count of lactic acid bacteria (lactobacilli and cocci) as well as the identification of species present using identification kits. The susceptibility of isolates was determined using the microdilution method. The lactobacillus counts of locally made yoghurts during both seasons were lower than those of the commercial samples. However, there was a general reduction of viable count of lactobacilli within the samples during the rainy season when compared to the dry season while a general increase in the total coccus count was observed during the rainy season except samples from Bamenda which instead decreased. Five (5) Lactobacillus species belonging to one genera were identified from 29 lactobacillus isolates. Lactobacillus bulgaricus was the highest (64.28%), present in 71.42%, 50.00%, 33.33%, and 33.33% (dry season) compared to 85.71%, 100%, 33.33%, and 25.00% (rainy season) from Bamenda, Dschang, Bafoussam, and commercial, respectively. More so, 14 cocci, 3 coccobacilli, and 1 rod species belonging to 5, 3, and 1 genera were identified, from 74 cocci, 12 coccobacilli, and 3 rod isolates, respectively, with Streptococcus thermophilus being the highest (35.55%). However, 93.33% of the lactobacillus isolates were very sensitive to the antibiotics used, while only 20% of cocci were sensitive. This result suggests that the paucity of the appropriate lactic acid bacteria (LAB) and presence of pathogenic LAB caused by the absence of quality control and ignorance might hinder its health benefits and protection offered to consumers with a resultant exposure to high risk of food borne infection and intoxication coupled to the resistant strains.

Dairy streptococcal cell wall and exopolysaccharide genome diversity

“…The CRISPR spacer array profiles can be used as unique identifiers of distinct strains [31,32]. A number of studies have highlighted the presence of dairy streptococci in artisanal fermented foods from a range of geographical locations through metagenomic and/or microbiological approaches [33][34][35][36][37]. Isolates have been characterized largely based on technologically relevant properties including EPS production and structural characteristics [37], antibiotic sensitivity, milk acidification ability and/or gelling capabilities [34].…”

Identification of Bacteriocin Gene in Lactobacillus acidophilus

“…Besides lactic acid, they produce bacteriocins and organic acids that have antimicrobial activity [2]. Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus, and Weissella are considered the primary LAB genera [3]. LAB have been used in the last decades for preservation techniques such as fermentation, pharmacological product, and even new antibiotics development.…”