Introduction
The term microbe is an umbrella term used to denote organisms of micro size. Bacteria is the major one of it and microbes have several application in different industries, in pollution treatment, health, agriculture and as biosensors. This paper is focused on collecting the informations and giving overview on the microbes and its applications in treatment of contaminated water and its industrial application for the production and enhancement in industrial products such as dairy, food, medicine and cosmetics. Since microbes are considered as the primary sources of enzymes in the above-mentioned industries, they are abundantly cultured and genetically altered by transferring target enzyme coding genes into simultaneously dividing and easily handleable other strains of microbes.1, 2, 3, 4
Most of the microbes used in industrial purposes are environmental microbes having natural ability to synthesis enzymes when sufficient nutrient medium is provided and have the capability to grow and give multiple clones of it. The first utilisation of microbial enzymes for the industries was made by Dr. Jokichi Takamine from fungus, and Boidin and Effront from bacteria twenty years later.5 In some industries like food industry, dairy industry and leather industry, microbes- such as Saccharomyces cerevisiae- are directly applied into the reactants or raw materials to carry out the fermentation process.6, 7 Nonetheless, in medical industry microbes are cultured to obtain their medically important products- like amino acids and enzymes- that are released into the bioreactors and isolated using different methods like Bio-affinity Chromatography and other purification techniques.8, 9
In addition to it, microbes are used widely is pollution treatments by bioremediation method. The industrial effluents and debris that are ejected into water and soil can be eradicated using bacterias, algae and fungi.10, 11 In a case study conducted in Indonesia on the bioremediation of liquid waste oil collected from liquid waste petroleum oil and gas companies Prabumulih South Sumatra, Indonesia, the process of bioremediation and its rate were analysed.12 In addition, the ability of Pseudomonas putida and Bacillus cereus in bioremediation of crude oil and petroleum was studied, in which P.putida degraded 60% of the oil from water sample within 7 days,13 thus makes them a best bioremediation tool for treating oil contaminated water bodies.
Materials and Methods
Searching tools and keywords
All the articles for references are taken from databases like “PubMed”, “Research gate”, “google scholar” and “Science direct” using the keywords like “microbes of dairy industry”, “bacteria for leather industry”, “microbial application in industries”, “application of microbe in food industry”, “microbes in medical industry” and “microbes for bioremediation”. The search also leads into databases like NCBI, NLM, encyclopaedia of food microbes and some other databases.
Microbes in Various Industries
Dairy industry
Lactococcus lactis
L. lactis is a gram-positive, non-motile, facultatively anaerobic bacteria. It is applied in dairy industries because of its ability to ferment lactose and produce lactic acid through hexose diphosphate pathway, hence it is also called as lactic acid bacteria.14 It is used for the production of cheese. Through the fermentation process it increases the acidity and coagulate proteins in the milk to produce cheese, apart from it this helps to gives flavour, develop texture, and preserve various cheeses.15 16 They can be cultured at a temperature of 10 °C and might become immotile at a temperature of 45 °C14 and they are very less sensitive to low pH and NaCl.17 Along with Streptococcus thermophilus, L. lactis is used for the production of yogurt.18, 19 In addition, it is also used for fermented milk production, sour cream production, kefir and butter productions.17
Streptococcus thermophilus
S. thermophilus is a gram-positive bacteria that ferments sugars like lactose, fructose, sucrose and glucose.20 They are used in the manufacturing of yogurt, hard Italian and Swiss cheeses by its fermentation activity.21 They are highly resistive against bacteriophages and especially the CRISPR system,22 and relatively sensitive to antibiotics and sanitisers.20 Their growth is promoted at an optimum temperature of 40–45 °C, and seemed to be minimum between 20–25 °C and maximum near 47–50 °C.20 In addition to it, S. thermophilus contributes to the texture and flavour development in yogurt production, and by the production of lactic acid during fermentation they contribute to the reduction of pH of dairy products and inhibit the growth of pathogens making them a good preservative of dairy products.23, 24
Propionibacterium freudenreichii
P. freudenreichii is a gram positive bacteria used in dairy industry for producing Swiss cheese and to give flavour to it.25 The carbon dioxides released during the metabolisation of lactic acid produced by other bacteria brings pore in the cheese, making it soft and of good texture.7, 25 The flavour is given by the products like propionate and acetate from lactate fermentation, short-chain fatty acids from catabolism of branched amino acids, and free fatty aids from hydrolysis of fat in the milk.26 Moreover, they contribute to the human nutrition by providing pivotal nutritional compounds like vitamin B12 and folate by fermentation, enhancing the nutritional value of Swiss cheese27 and also preserve the cheese by producing propionic acid having antimicrobial properties that can inhibit the growth of spoilers.24 P. freudenreichii are highly resistant to extreme hot and cold temperatures than other microbes of dairy industry, hence the subspecies P. freudenreichii shermanii is widely used in dairy industry that can grow in cheeses even at a temperature of 3.8 and 6.8 °C.28
Lactobacillus helveticus
L. helveticus is a proteolytic lactic acid bacteria used in production of hard and extra hard Italian and Swiss cheeses, and also contribute to improvement of texture and flavour through feunicellular) with 16 chromosomes. Since it is easy to rmentation process.29 It is also a primary microbe used for the production of dairy products like cheese, yogurt and fermented milk.30 Furthermore, L. helveticus gives peptides that are of antioxidant, antihypertensive, and antimicrobial properties, which contribute to health benefits of fermented products.31 Moreover, they provide resistance against the fungal and bacterial pathogens, and it has shown protective action against several bacterial pathogens, which was observed through in-vitro studies.32
Food industry
Saccharomyces cerevisiae
S. cerevisiae is a fungus(unicellular) with 16 chromosomes. Since it is easy to genetically manipulate S. cerevisiae, they are used to bring advantage-able alterations by adding or deleting genes using advanced recombination technology,33 hence it is considered as the best eukaryote studied.34 It helps in production of fermented beverages and breads like alcoholic drinks and sourdough breads by converting sugar into alcohol, carbon dioxide and other metabolites through the fermentation process.34, 35 The carbon dioxides released during the metabolic process creates air holes in bakery products making them soft and easy to consume, and the flavour compounds like δ-decalatone, phenylethanol, yeast extract give tasty flavour to them.33, 36 In addition, due to their high protein content, vitamin B content and minerals, they are considered as a quality nutritional supplement. Moreover, S. cerevisiae is used as a preservative for processed food products like juices, alcoholic beverages, fruit pieces, fruit yogurts and bread products by production of compounds that inhibit the growth of other microbes.33
Streptococcus thermophilus
As mentioned above in 3.1.2 it is used in dairy industries and cheese production commonly. Apart from it, S. thermophilus is also used for the production of cottage cheeses.37 Moreover, it considered as a potential and healthy probiotics in dairy products.38
Lactobacillus plantarum
L. plantarum is a gram positive lactic acid bacteria used in dairy industry, in production of fermented food items like pickles, kimchi, sauerkraut and other vegetable fermented products, furthermore in probiotic food productions.39, 40 They are widely seen in human mucosa and can survive in gastrointestinal conditions, these capabilities in them bring health benefits for the consumers. Moreover, they are applied for antioxidant activity and flavour development in rice and wheat bran due to their improved hydroxyl radical scavenging and oxygen radical scavenging activity,41, 42 and improves the vitamins and amino acid compositions of cauliflower and white beans.42, 43 Additionally, the combination of L. plantarum with chitosan improves the quality and shelf life of fresh cut apples by reducing the aerobic mesophilic bacteria.42, 44
Propionibacterium freudenreichii
As mentioned above in 3.1.3 Propionibacterium freudenreichii is commonly used in production of dairy items. Since they have the ability to produce vitamins, folate and other bioactive compounds they are applied in biotechnological industries to increase the quantity of their productions. Moreover, they contribute to improve health benefits by their ability of immunomodulation and production of bioactive peptides.
Lactobacillus acidophilus
L.acidophilus is a gram positive, homo-fermentative, micro-aerophilic, lactic acid bacteria used for food fermentation processes and developing flavour and texture in foods.45 The food items like vegetables, fish, sausages and silage are fermented using L. acidophilus.45 Moreover, they are used as a food bio-preservative as they produce lactic acid and bacteriocins.46 In addition it has the ability to survive is very acidic conditions making them a recommendable probiotic.47
Medical Industry
Escherichia coli
E. coli is generally disease-causing gram-negative bacteria, but they are also having several applications in the production of medicines. They are mainly used in production of recombinant proteins, in bioremediation, vaccine development, and gene expression studies by introduction of target foreign gene into them making them a recombinant E. coli.48 Since they can be cloned easily and produce large amount of proteins with in a short period of time, they are highly recommended for the mass cultivation of proteins48 and human insulin is a typical example for hormones produced from E.coli using recombinant technology.
Streptomyces sp
Several Streptomyces sp. are known for their application in medicinal industry for the production of antibiotics and some other bioactive compounds. Few of them are, Streptomyces griseus that produces the streptomycin- an antibiotic used in treatment of TB,49 Streptomyces erythreus that synthesis erythromycin for the treatment of several bacterial infections, 50 Streptomyces aureofaciens that gives chlortetracycline used as an alternative drug in treatment of various infections, 51 Streptomyces noursei that yields nystatin one of the anti fungal drug and Streptomyces hygroscopicus that generate hygromycin B which is used for antiviral and antibacterial treatments (Table 1). Moreover, some compound like bleomycin and mitomycin c. derived from Streptomyces sp. shows anti-cancer properties and rapamycin derived from them are used as an immunosuppressant in organ transplantation and autoimmune disease treatments.52
Table 1
Products and application of Streptomyces sp.
Bacillus subtilis
B. subtilis are not known to produce any medicines directly. But are used for the production of proteases and amylases that may help in tissue engineering and wound heeling53, 54 and used for degradation of several substrate, and this production of enzymes in the market is about 60%.55 Moreover, they are used to produce bacteriocins like subtilosin56 that can resist infections caused by other microbes.39
Corynebacterium glutamicum
C. glutamicummare does not directly involve in medicine production, but widely used as bio-refinery strain in producing essential amino acids like l-lysin and non essential amino acids like l-glutamic acid that are used in pharmaceutical sectors to increase the availability for those are insufficient of these amino acids and for some other purposes too. 57 The annual output of amino acids l-lysin and l-glutamic acid from C. glutamicummare in industries are unto 1.48 and 2.16 million tons.58 Glutamic acid derived from them are used as structural block of peptides and proteins, and also used as a vehicle to deliver certain compounds to target cells in injectable drugs due to their ability to maintain stability of that compounds.59 Moreover, they are genetically altered to make amino acids by utilising hexose and pentose.57
Leather industry
Microbes that synthesis lipases and proteases are mainly used in leather industry for de-hairing and degreasing processes of animal skin to convert them into a good looking high quality leathers for the consumers. Few of them are, Bacillus subtilis that can produce both the enzymes protease and lipase,13 Bacillus licheniformis that produces proteases for leather processing, Pseudomonas flurescens that gives thermolabile lipases,60 and Aspergillus niger a fungus that yields lipases for the processing of leather (Table 2).
Microbes in Treatment of Contaminated Water
Klebsiella aerogenes
Is a bacteria that synthesis the powerful catalyst, urease, that are applicable in hydrolysis of urea into ammonia and carbon dioxide as the gas by-products, making them a gas producing bacteria.62 The genes responsible for the production of active urease in K. aerogenes are found to be ureA, ureB, ureC, ureE, ureF and ureG.63, 64 The first three genes are responsible for the production of inactive apo-urease and rest of the three genes incorporate Ni to make the protein active, so Klebsiella aerogenes will require sufficient amount of Ni for the production of active urease.63, 64, 65 In addition, the introduction of large number K. aerogenes into the well waters might prevent the contamination of drinkable water by urea penetrated from septic tanks through soil. Moreover, the above mentioned genes can be transferred into other microbes that can tolerate adverse environmental conditions for better result.
Pseudomonas putida
Is a bacteria used in bioremediation of oil and petroleum from water bodies.66, 67 They have the efficiency to eradicate 65% of crude oil from the water with in 7 days, found from a study conducted to analyse the biodegradation activity of Pseudomonas putida.67 This method of bioremediation using naturally adapted Pseudomonas putida is applicable in oil and petroleum industries to reduce water body contamination.66, 67
Conclusion
Microbes have been using as a main source of bio-refinery for recent decades. The natural ability of microbes are mainly utilised by industries to improve quality and enhance quantity of their production. In general, this review article on overview of different microbial application in industries including their name, application, industry type and characteristics of some microbes can provide an accurate data for industries. It might help them to grab quick informations on microbes and its applications which they are looking for, by searching the database with suitable keywords. Furthermore, this article has mentioned microbes that industries can implement for bioremediation of industrial effluents like oil from water which are mainly the contributors of water pollution.
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