Screening Of Industrially Important Microorganisms Pdf To Word

Screening of industrially important microorganisms pdf to word

Diverse African traditional fermented foods and beverages, produced using different types of fermentation, have been used since antiquity because of their numerous nutritional values.

Screening of industrially important microorganisms pdf to word

Lactic acid bacteria LAB isolated from these products have emerged as a welcome source of antimicrobials and therapeutics, and are accepted as probiotics. Probiotics are defined as live microbial food supplements which beneficially affect the host by improving the intestinal microbial balance.

Screening of industrially important microorganisms pdf to word

Currently, popular probiotics are derived from fermented milk products. However, with the growing number of consumers with lactose intolerance that are affected by dietary cholesterol from milk products, there is a growing global interest in probiotics from other food sources.

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The focus of this review is to provide an overview of recent developments on the applications of probiotic LAB globally, and to specifically highlight the suitability of African fermented foods and beverages as a viable source of novel probiotics.

Traditional fermentation is a form of food processing achieved by using microorganisms, especially lactic acid bacteria LAB , and yeast. Although it is an ancient food preservation technology, it is still part of the cultural norm usually being practiced at a local or household level among indigenous communities in Africa and most of the developing world 1 — 3.

Unlike their unfermented counterparts, fermented foods are preferred by consumers because of their characteristic taste, texture, and color 4. Fermented traditional foods and beverages in developing countries constitute one of the main dietary components, with some being used as light meals or refreshments.

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LAB isolated from various fermented foods produce organic acids and a high diversity of antimicrobial agents, which are responsible for the upkeep of quality and the palatability of fermented foods. At a local level, LAB are used in African communities to produce a variety of fermented foods which include cereal-based fermented porridges, beverages, fermented fruits and vegetables including roots or tubers , fermented milks, and fermented meats 4 , 5.

Screening of industrially important microorganisms pdf to word

Of the various types of fermentations used to obtain fermented foods and beverages, lactic acid and alcoholic fermentations are the most popular. Other types are alkaline fermentation and amino acid fermentation 5. The role of LAB in improving the shelf life and nutritional quality of fermented foods and beverages, controlling diarrhea, as well as their antimicrobial properties have been established 6 — 9.

However, despite an increasing interest in probiotic LAB, there is a paucity of literature regarding novel and emerging uses of LAB as probiotics, especially from the African continent. In addition, strict regulation by international bodies has resulted in limited probiotic products passing the clinical trial stage.

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Rural communities are known to be consuming fermented foods laden with probiotic microflora, from which they derive health benefits. This paper reviews different topical traditional fermented foods and beverages in Africa which are potential sources of novel probiotics, and explores global progress on the isolation of probiotic LAB candidates.

The applications of LAB as antidiabetic agents, cholesterol-reducing agents, immune system modulation agents, and as drug-delivery vehicles, as well as their novel applications in mental and emotional well-being of humans were discussed in detail. Fermented foods have been part of the human diet since the dawn of human civilization, and have been used as a means of improving the shelf life, safety, digestibility, and nutritional value for more than 6, years 10 — Lactic acid food fermentation is a process whereby microorganisms and their enzymes are used to convert fermentable sugars in the food substrate into mainly lactic acid and other limited products.

Fermentation is widely used for food preservation in households and in food industries to develop a variety of food products This food preservation technology is inexpensive; hence, it is of economic importance in developing countries 4.

Screening of industrially important microorganisms pdf to word

Microorganisms responsible for the fermentation can be the microflora indigenously present on substrates, or they can be added as starter cultures after cooking or preparing the food or beverage.

Fermentation improves the organoleptic properties of foods and their acceptability.

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Popular fermented food products in Africa include fermented milks, sour porridges, and alcoholic and non-alcoholic beverages Cereals are a staple diet globally and they can be processed through fermentation to acquire desirable modifications of taste, flavor, acidity, and food digestibility 4.

There is a vast diversity of African traditional fermented foods and beverages distributed throughout the continent, with typical examples presented in Table 1.

In addition to the various fermented plant products, fermented meats and fish form part of the African diet and also of diet in other parts of the world 18 — 21 , although these are arguably not yet common. Nonetheless, fermented meats can be adequate purveyors of probiotic bacteria if properly applied.

Fermented meat products are defined as meat that is inoculated with a microbial starter culture during processing under controlled conditions to give desirable characteristics.


Meat fermentation can also be achieved by allowing it to spontaneously ferment by natural meat microbial flora. A recent review 22 discusses the application of novel technologies and microbial cultures in the development of functional fermented meats.

Zakpaa et al. Of these, Streptococcus and Staphylococcus spp. These results suggest that using a robust probiotic starter culture might be useful in improving the quality of fermented meats, as it may inhibit the growth of potentially pathogenic organisms.

Fermentation is one of the most important fish preservation methods in many parts of the world and particularly in the coastal regions of African countries The fermentation processes applied are generally indigenous and adaptable to the culture of the people.

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However, lack of standardization of the processing methods and hygiene levels compromise the safety and quality of fermented fish products in Africa. Thus, more research needs to be dedicated to finding solutions to these issues.

Screening of industrially important microorganisms pdf to word

Fermented foods are produced using different manufacturing techniques, raw materials, and microorganisms depending on available raw materials and local practices. However, the four main fermentation processes are alcoholic, lactic acid, acetic acid, and alkali fermentation.

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While a majority of these fermentations are carried out by bacteria, in alcohol fermentation, yeasts are the predominant microorganisms used for production of ethanol-containing beverages, such as wines and beers, where LAB play a limited role 4.

LAB are critical in the production of most fermented foods and beverages, but there is a paucity of knowledge about the specific health benefits such foods confer on consumers and the characteristics of the bacterial strains used for their production.

Food and beverage fermentation by LAB

Moreover, literature on probiotic microbes from different fermented foods from Africa that have found applications in the food and pharmaceutical industries is scarce. Ogi , iru , and gari Table 1 are the Nigerian fermented foods that have been commercialized; the rest are still being produced at the household level.

Ogi is a fermented product of maize or sorghum or millet grains.

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Iru is a fermented product of African locust bean; and Gari is a fermented cassava product, produced by peeling fresh roots, grating them into mash, and putting in sacks for fermentation The main microorganisms used for the fermentation in these products are LAB and yeasts. Borde and Shamita Table 1 are important Ethiopian traditional fermented beverages, produced by an overnight fermentation of certain cereals predominantly by LAB LAB associated with Borde and Shamita fermentation have antimicrobial properties against various food-borne pathogens; the inhibitory products are extracellular and diffusible.

Togwa Table 1 is a Tanzanian fermented beverage that could be prepared from cassava, maize, sorghum, and millet, or their combinations. Yeasts and LAB are the predominant microorganisms found in togwa Amasi or sour milk, umqombothi or sorghum beer, and amahewu Table 1 , a non-alcoholic fermented maize meal, are South African foods and beverages. Amahewu is produced with LAB starter culture, whereas umqombothi is produced from maize or sorghum via wild yeast fermentation, and LAB from malted sorghum adjuncts play a limited role 7.

Fermented beverages such as those obtained from amarula fruits using yeast and LAB are popular in parts of Limpopo and Mpumalanga Provinces in South Africa.

Isolation and Screening of Industrially Important Organisms

Sour porridge is maize or sorghum, which is fermented using mainly LAB to improve and develop palatability, flavor, and nutrition Chibuku Table 1 is a Zimbabwean traditional sorghum beer commercially produced by yeast fermentation of sorghum 9 , whereas mabisi , munkoyo , and chibwantu Table 1 are Zambian traditional food and beverages produced through yeast and lactic acid fermentations Production of these traditional fermented foods depends on the availability of infrastructure to store and transport the product.

Isolation and screening of microorganisms from natural sources has been the most effective means for obtaining robust and genetically stable strains for industrially important food products 28 , However, the microbial diversity of the different fermented foods from different localities in Africa still needs to be characterized using more reliable tools such as next generation sequencing and other molecular techniques.

This will enable the selection of more robust, probiotic microorganisms with desirable characteristics to be used as starter cultures and will ensure the safety of the foods and beverages and pharmaceutical products. Fermentation may be the most simple and economical way of improving cereal nutritional value, sensory properties, and functional qualities available at the local community level 15 , Lactic acid fermentation of cereals has been used as a strategy to decrease the content of antinutrients, such as phytate and tannins, and for improving the bioavailability of micronutrients Many bacteria associated with fermented foods produce antimicrobial bioactive molecules, such as hydrogen peroxide, organic acids, and bacteriocins, that make them effective biopreservatives 12 , 32 and produce nutraceuticals to create functional foods with increased bioavailability of nutrients 33 , Table 2 presents an overview of some of the various applications of LAB isolates.

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LAB comprise a significant component of the human gut flora and have several beneficial roles in the gastrointestinal tract. Probiotics are live microbial food supplements which beneficially affect the host by improving the intestinal microbial balance 36 — Probiotics are consumed in the form of yoghurt, fermented milks, or other fermented foods 37 , These products containing living microorganisms have been traditionally used to restore gut health Thus, bacteria known as probiotics because of their positive impact on human health and well-being have been added to various foods for the past decades 42 , Probiotic bacteria from the genus Lactobacillus are inherently present in fermented foods and many diseases caused by pathogens invading the gastrointestinal tract can be prevented by maintaining proper intestinal flora by consuming probiotics or fermented foods.

Probiotics have a great potential for improving nutrition, soothing intestinal disorders, improving the immune system, optimizing gut ecology, and promoting overall health because of their ability to compete with pathogens for adhesion sites, to antagonize pathogens, or to modulate the host's immune response 33 , 43 , Bifidobacterium species are strictly anaerobic, inhabit the large intestines, and more than 30 species have been identified.

These microbes are added in baby formula milk and dairy products such as yoghurt or their growth in the large intestines is stimulated by prebiotics from diet. They assist in the metabolism of lactose, generation of lactate ions from lactic acid, and vitamin synthesis 40 , Generally, probiotic bacteria do not colonize the human intestinal tract permanently, but some strains are able to transiently colonize and modulate the indigenous microbiota LAB are highly beneficial organisms for humans and their use should be promoted for good health.

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Candidate probiotic microbial strains must satisfy the criteria for safety, production or manufacturing, administration and application, and survival and colonization in the host In vitro experiments are used to investigate whether the selected microbial strains fulfill these criteria and enable screening of microorganisms for their potential as probiotic strains Potential probiotics are further subjected to in vivo experiments to validate their efficacy.

In this regard, it has been experimentally demonstrated that feeding day-old chicks with a commercial LAB-based probiotic culture after they were challenged with Salmonella enteritidis or Salmonella typhimurium significantly reduced recovery of Salmonella Similarly, it has been demonstrated that fish fed with probiotic-supplemented diets presented significantly higher growth rates and feeding performance than those fed with control diet Probiotic LAB isolated from fermented food samples exhibit excellent antimicrobial activity against pathogenic bacteria and fungi 3.

Bacteria with such notable probiotic properties can be used as a potential source of probiotic for use in pharmaceutical preparations, and as functional foods for the betterment of public health.

Developing countries in Asia and Africa have a rich diversity of fermented foods and beverages which can be exploited for isolation of such novel probiotics.

Most probiotic foods contain LAB belonging to the genera Lactobacillus but not exclusively Certain strains of probiotics are able to stimulate and regulate several aspects of the natural and acquired immune response, although differences in the ability of Bifidobacterium and Lactobacillus strains to influence the functioning of the immune system have been reported The interactions of these probiotics and their unique metabolic capabilities are critical to their ability to colonize the gastrointestinal tract and immune system modulation.

More than species of Lactobacillus acidophilus , Lactobacillus salivarius , Lactobacillus rhamnous , Lactobacillus brevis , and Lactobacillus casei have been characterized and identified. They are implicated in enhancing the innate and acquired immunity as well as cause inhibition of proinflammatory mediators Probiotic protective microorganisms prevent pathogens from adhering to the intestines by competing for substrates and places of adhesion, simultaneous production of antibacterial molecules, and stimulating the production of specific antibodies and mucus.

Isolation of Microorganisms: Techniques, Schemes, Strains and Everything Else

Thus, early colonization of the gut with probiotic bacteria is critical for the development of the gut protection barrier. Several studies have indicated that LAB play a positive role in modulating the host immune system and display of antimicrobial activities against common food-borne pathogens and in preventing and treating diarrhea 11 , 28 , 33 , 34 , 50 , The current understanding of the role of probiotic bacteria in the human and animal systems is preliminary, partly because of the complexity of the gastrointestinal ecosystem and the increasing variety of strains considered as probiotics However, these mechanisms may be multifactorial and each probiotic strain may have specific functions affecting the host.

Specific probiotic bacteria are known to modulate local and systemic immune responses, although the mechanisms of immune modulation are still not fully elucidated.

Nevertheless, there is an understanding that bacterial components are recognized by the immune system through their interaction with specific receptors, resulting in the modulation of the immune responses