Bacterial Diversity in Traditional Doogh in Comparison to Industrial Doogh

Abstract

Forty-four samples of traditional Doogh and yoghurt were collected from 13 regions of 4 provinces in west of Iran (13 area) and analyzed using molecular methods including PCR, denaturing gradient gel electrophoresis (DGGE) of 16S rDNA, and sequencing. Moreover, collected samples as well as samples from industrially Doogh were analyzed with quantitative real-time PCR (RT-PCR). Analyzed 16S rRNA gene sequences of Doogh samples could be allocated to the presence of Lactobacillus spp. The typical yoghurt starter culture bacteria included four different Lactobacillus species with possible probiotic properties, L. acidophilus, L. helveticus, L. kefiranofaciens, and L. amylovorus. DGGE of traditional Doogh and yoghurt and RT-PCR of traditional Doogh and yoghurt and also industrial Doogh samples demonstrated that traditional Doogh and yoghurt show a higher abundance of total bacteria and lactobacilli and a higher bacterial diversity, respectively. Considering diversity and higher probiotic bacteria content in traditional Doogh, consumers’ healthiness in tribes and villages could be promoted with these indigenous products.

Lactobacillus kefiranofaciens: From Isolation and Taxonomy to Probiotic Properties and Applications

“…Finally, during a study comparing the microbiota of the traditional doogh and industrial yogurt samples of Iran, L. kefiranofaciens was detected using PCR-DGGE and RT-PCR [81]. Doogh is a fermented milk drink obtained by diluting yogurt with drinking water, addition of salt and heat treatment, therefore commercial starters are used for its industrial production.…”

“…On the contrary, traditional doogh is a buttermilk occurring as a byproduct of butter production from yogurt in goatskin or musk bags. Sayevand et al reported collecting the home-made samples directly from the skin bags or the containers used for storing [81].…”

Microbial and Chemical Characteristics of Doogh (Iranian Fermented Milk Drink)

“…It is confirmed to have multiple health beneficial features like antifungal, antibacterial, antiallergic, antioxidant, anti-inflammatory, and antitumor effects [2]. Doogh is another fermented Iranian dairy drink produced from adding salt (maximum 1%), water (50-60%), and also, an essence of aromatic vegetables (e.g., thyme, mint, and oregano) [3] to set yoghurt (40-50%) [4][5][6], which is finally acidified (pH < 4:5) by fermentative bacteria including Streptococcus thermophilus and Lactobacillus delbrueckii ssp. Bulgaricus [5,7].…”

“…It is also known with other titles such as "Ayran" in Turkey and "Lassi" in India [4]. Doogh has turned to the most favorite traditional dairy drink in the Middle East [6,7]. Considering its probiotic bacterial content, high value of nutrients and also several healthpromoting potentials (i.e., ameliorating lactose digestion, agitating the immune system, and lowering serum cholesterol levels) [8], as well as pleasant organoleptic properties, this fermented product is also a unique source of high-quality proteins, phosphorus, calcium, magnesium, zinc, and B vitamins like riboflavin (B 2 ), niacin (B 3 ), pyridoxine (B 6 ), and cobalamin (B 12 ).…”

“…Thus, microbial putrefaction referable to fungi describes as a serious complication for dairy industries, because of their capability to survive at low temperatures and acidic pH [10]. Different factors like the initial microbial quality of raw milk, inadequate thermal processing of milk, used starter cultures, and secondary microbial contaminations via equipment, air, ventilation, and packaging material have alter the quality and shelf life of the final product which in turn lead to the spoilage of Doogh by acid-resistant microorganisms, especially yeasts, molds, and bacteria during storage and safety reduction of this product [4,6,11,12]. Fungal spoilage of Doogh is not only related to its consumers' acceptability and as a result of economic losses but also the growth of specific fungi can induce the production of mycotoxins, which are known to be severely harmful to humans [10].…”