ABSTRACT
There is currently a growing interest in the consumption of probiotic foods due to their reported health benefits. Most probiotic foods are milk based and do not form staple foods in most of Africa including Nigeria. This study focuses on the isolation and characterization of probiotic microorganisms from some locally fermented foods consumed as staples: Ogi, Okpei, Ogiri, and Ugba. De Man Rogosa and Sharpe media was used to isolate potential probiotics from selected foods by the dilution method. The isolates were identified using Bergey̛̛̛s Manual of Determinative Bacteriology,routine morphological and biochemical procedures. The probiotic potentials of the isolate was studied by performing tests including; growth in bile salts medium, resistance to acidity and antibiotic resistance. The result from this study showed that only one Gram positive large rod, which was identified as Bacillus coagulans demonstrated probiotic properties. Bacillus coagulans was isolated from fermented food, Ugba. The probiotic properties showed that the organism grew optimally at pH of 6. The antibiotic test showed that the organism was resistant to Septrin, Gentamycin, Zinacef, Rocephin, and Pefloracin but was sensitive to Ciprofloxacin, Streptomycin, Erythromycin, Ampiclox and Amoxicillin. Even though Bacillus coagulans is still under investigation as a probiotic, locally fermented food products “ugba” should be taken as an alternative source of probiotic instead of the more expensive dairy products.
1.0 INTRODUCTION
Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO, 2001). Probiotics is a general name for microorganisms that are associated with beneficial effects for humans and animals. They contribute to intestinal microbial balance and play a role in maintaining health (Soccol et al., 2010). Probiotics play a vital role in increasing host resistance to colonization by exogenous, potentially pathogenic organisms. This is achieved through different mechanisms such as production of lactic acid, hydrogen peroxide or acetic acid which increases the acidity of the intestine and inhibits the reproduction of numerous pathogenic bacteria (Reid et al., 2003). Probiotics has been found in dairy and non – dairy products (Soccol et al., 2010). They are usually consumed after antibiotic therapy which destroys the microbes present in the digestive tract. Regular consumption of food containing probiotic microorganisms is recommended to establish a positive balance of the population of beneficial microbes in the intestinal flora (Soccol et al., 2010). Benefits of consumption of probiotics include the prevention and treatment of infantile diarrhea, colon cancer, constipation, antibiotic induced diarrhea, hypercholesterolaemia, lactose intolerance, vaginitis and intestinal infections (Marchand and Vandenplas, 2000). Probiotic organisms used in foods must have the ability to resist gastric juices, exposure to bile, and be able to proliferate and colonize the digestive tract. The most commonly used probiotic bacteria belong to the heterogeneous group of lactic acid bacteria (Lactobacillus, Enterococcus) and to the genus Bifidobacterium, however, yeasts and other microbes have also been developed as potential probiotics during recent years (Ouwehand et al., 2002).
Traditional fermented foods represent a rich source of microorganisms. Among fermented foods, dairy products are considered to be the major source of probiotic bacteria isolation with numerous studies confirming this theory (Losio et al., 2015; Zago et al., 2011; Maragkoudakis et al., 2006). Although these products have been exploited in depth as both source and carrier of probiotic lactic acid bacteria, research has been conducted with other fermented products as well, such as fruits and vegetables (Vitali et al., 2012), table olives (Botta et al., 2014) and (Argyri et al., 2013) fermented cereals (Manini et al., 2016; Rivera and Gallardo, 2010) and fermented meat (Pennacchia et al., 2004 and Papamonoli et al., 2004). For example, Keshik which is a Jordanian traditional fermented food made up of barboiled dried wheat and butter milk is of interest (Tamime and O’Connor, 1995). The product is similar to Tarhana (Turkish traditional fermented food) which proved to be a rich source of probiotic Lactic acid bacteria (Sengun, 2009). Among other potential foods also is the fermented eggplant (locally named Makdoos) made up of baby Aubergine stuffed with ground wall-nut, garlic, parsley and fermented in olive oil. Jameed which is solar-dried curd of sheep or goat naturally-fermented milk prepared and used traditionally by Jordanian Beduins (the old desert dwellers) is another unique source of probiotic bacteria. Recently, probiotic lactic acid bacteria have been isolated from unpasturized natural camel milk with superior probiotic characteristics (Yateem et al., 2008; Khedid et al., 2009). These are just few examples of traditional foods in Jordan as part of the Middle East and many other countries of the orient would probably be richer especially traditional fermented foods of South East Asia and India, which invites more research in this direction. The long shelf-life of such traditional foods could probably indicate the presence of antimicrobial compounds among other characteristics exhibited by the indigenous bacteria which makes it a good probiotic candidate. Linking this to the increased consumer demand for natural and additive free foods would definitely maximize the interest in search for new sources of probiotic strains (Müller et al., 2009).
Bacillus coagulans, a nonpathogenic/nontoxicogenic microorganism, is a rod shaped, gram positive, endospore forming (spore is formed within the cell) bacteria. It is facultative anaerobe, grows optimally at 37°C and pH in the range 5.5 to 6.2. Bacillus coagulans requires nutritionally complex environment in which it derives energy through fermentation or catabolism of carbohydrates. It is more acid tolerant than pathogenic and spoilage microorganisms. When ingested, spores of Bacillus coagulans can withstand the acidic environment of the stomach. Spores then germinate and proliferate within the gastrointestinal tract within a few hours. After germination, Bacillus coagulans is metabolically active as part of facultative anaerobes in the intestine, producing L (+) lactic acid, as primary product of fermentation. The main mechanism for survival and proliferation of Bacillus coagulans is “Competitive Exclusion”. Competitive exclusion is generally applied through competition for limited nutrients. However, the acidic environment created by production of L-(+)-lactic acid prevents the growth of pathogenic microbes and allows growth of Bacillus coagulans which ultimately dominate the microflora. Furthermore, Bacillus coagulans also produces bacteriocins (antimicrobial proteinaceous compounds) that are inhibitory towards both Gram positive and Gram negative bacteria. In the vegetative form, Bacillus coagulans cells appear as Gram positive, mobile rods, occurring singly or, rarely, in short chains of variable lengths. They optimally grow at a temperature range of 35-50°C and at pH values comprised between 5.5 and 6.5. Metabolically, they are facultative anaerobes and produce acids but no gas from fermentation of maltose, mannitol, raffinose, sucrose and trehalose. These characteristics favour growth of Bacillus coagulans in acid foods and it has been often reported to spoil milk products, vegetables or fruits because of production of high amount of lactic acid (Cosentino et al., 1997; Roman-Blanco et al., 1999; DeClerck et al., 2004).
1.1 AIM
The aim of this study was to examine some locally fermented foods for the occurrence of the probiotics Bacillus coagulans. Such foods can be used as source and also route for the administration of probiotics to consumers.
- OBJECTIVES
- To isolate and identify Bacillus coagulans from locally fermented foods.
- To determine the probiotic characteristics of Bacillus coagulans isolated from locally fermented food.
