applied food biotechnology
Volume:8 Issue: 1, Winter 2020

Increasing concerns over the use of antibiotics in aquaculture have emerged researchers to focus on short chain fatty acids and other biocompatible molecules as alternatives for disease prophylaxis and treatment. Polyhydroxyalkanoates well studied as biopolymeric materials for using in packaging and biomedicine were not focused much for their abilities to act as antimicrobial agents in aquaculture until recent years. Application studies of polyhydroxyalkanoates as aquafeed additives have highlighted their promising roles as eco-friendly alternatives for commercial antibiotics with strong immunomodulatory effects in fish-es and shrimps. The major aim of this review was to explore up-to-date scientific research studies on use of polyhydroxyalkanoates as aquafeed additives and their immunomodulatory effects.

Up-to-date, limited scientific literatures have been published on the use of polyhydroxyalkanoates and their copolymers as alternatives to antibiotics in aquaculture. This research field includes a great scope of development due to the promising immu-nomodulatory and antimicrobial activity of polyhydroxyalkanoates against common pathogens in aquaculture, as reported in literatures. Although several hypothesis and research data for explaining the mechanisms behind their immunostimulatory effects were suggested by variousresearchers, genetic and molecular bases underlying these phenomena are yet to be explored. Further research and development in this area can introduce these biopolymers as the most promising eco-friendly alternatives for antibiotics in aquaculture

Enzymatic modification of protein-base materials is fast emerging as a promising tool for chemical catalysts based on increasing knowledge in enzyme reaction and devotion to achieve sustainable systems. Enzymes actively used in protein modification include proteases, especially keratinases, and their most interesting features include ability to degrade keratin to finer molecules. This review summarizes strategies for the modification of keratin using keratinase to increase functional protein-based feedstocks up-to-date.

Keratinases are useful safe agents for feather waste modification in animal feeds. Modification can be carried out either using whole microbial cells or enzyme activities throughfermentation processes in costeffective environmental-friendly manners. In this study, promising outcomes in feather waste management were achieved and hence studies can be continued to treat wastes of other sources.

Milk agar is recommended for enumeration of microorganisms in dairy products. Most of the commonly used media are imported to Nigeria and hence available in-housesubstitutes are necessary. In this study, microbial growth enhancement values of compounded milk agar were compared to imported milk agar using two milk brands. Dawadawa (fermented locust beans), yeast powder and peptone in theproportions of 1: 3: 5, respectively, were used as nutrient sources.

Growth enhancement values of the compounded media were assessed on three bacterial species of Staphylococcus aureus, Escherichia coliand Lactobacillus plantarum. Furthermore, imported milk agar served as the control.

Significant differences were seen in nutritional contents of the compounded milk agar and imported milk agaras well as the elemental compositions of compounded milk agar and imported milk agar. No significant differences were seen between the total viable counts of Staphylococcus aureusand Lactobacillus plantarumon compounded milk agar and imported milk agar.However, significant differences were reported in the total viable counts of Escherichia colion compounded milk agar and imported milk agar. Media containing Cowbell milk powder recorded the highest total viable counts (1.3 105, 1.8 106 and 2.0 106CFU ml-1) for Staphylococcus aureus, Escherichia coliand Lactobacillus plantarum, respectively. In conclusion, the Cowbell milk powder in combination with yeast extract and peptone is the best milk of choice for compounding milk agar when using local resources

In this study, nine Lactobacillus kefiriand one Lactobacillus rhamnosusisolates with kefir grain origin have been demonstrated to include potentials as probiotics. The aim of this study was to investigate ability of the isolates to produce compounds with α-glucosidase inhibitory and antioxidant activities and identify peptides with MW of ≤ 3 kDa in cell-free supernatants.

All isolates were cultured in de Man, Rogosa and Sharpebroth media at 37 oC for 24 h. Assessment of α-glucosidase inhibitory and antioxidant activities was carried out on cell-free supernatants. Assessment of optimum incubation time was carried out on two isolates with the highest α-glucosidase inhibitory and antioxidant activities. The two isolates were used to ferment reconstituted skim milk. Cell-free supernatant of the fermented skim milk was fractionated using filters of 10 and 3 kDa. Then, peptides in fractions of ≤ 3 kDa were identified.

The highest α-glucosidase inhibitory activity was seen inLactobacillus rhamnosusBD2 and Lactobacillus kefiriYK4 as 73.58 and 64.31%, respectively. The highest antioxidant activity was observed in Lactobacilluskefiri JK5and Lactobacilluskefiri JK17 as 44.31 and 41.57%, respectively. When Lactobacillus rhamnosusBD2 and Lactobacillus kefiriYK4 were cultured in reconstituted skim milk, their α-glucosidase inhibitory activities respectively decreased to 25.72 and 36.16% while the antioxidant activities respectivelyincreased to 74.53 and 80.92%.Fractionation of the cell-free supernatants from fermented reconstituted skim milk of Lactobacillus kefiriYK4 showed that the highest antioxidant activity was included in fractions greater than 10 kDa. Although fractions of 3 kDa or less exhibited quite high antioxidant activities. Identification of peptides in fractions of 3 kDa or less showed that the peptides were mostly derived form β-casein. Of these peptides, two peptides with sequences of FPPQSVand YQEPVLGPVRGPFPIIV have been reported to include antioxidant activities.

Traditional fermented products are appropriate sources for the isolation of indigenous bacteria with probiotic characteristics and potential similar or better than commercial probiotics. In this study, Lactobacillusspecies were isolated from jug cheese, atype of Iraniantraditional cheese, and their potentialprobiotic characteristics were studied.

Study of the probiotic species included hemolytic activity, antibiotic susceptibility, inhibitory activity against pathogenic bacteria, low pH and bile salts tolerance, viability in gastrointestinal tract conditions and adhesion ability to HT-29 cells.

Results showed that the isolates included no hemolytic activity and were susceptible or intermediate susceptibility to most antibiotics. Of four isolates, Lacto-bacillus plantarumKMJC4showed the strongest antibacterial activity (MIC = 6.25 mg ml-1) against Escherichiacoli, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus and Salmonella entericasubsp. enterica serovar Typhimurium. All the isolates, except Lactobacillus curvatusKMJC3, preserved their viability after transition through the simulated gastrointestinal tract conditions above 106CFUml-1. Lactobacillus acidipiscisKMJC2and Lactobacillus plantarumKMJC4showed the lowest and the highestadhesion rates to HT-29 cells with 3.55 and 6.80 Log10CFU ml-1 (42.51 and 71.35%), respectively. Lactobacillus plantarumKMJC4 included a better bacterial inhibitory activity and adhesion to HT-29 cells than that Lactobacillus rhamnosusGG did as control. Lactobacillus brevisKMJC1 demonstrated appropriate probiotic characteristics such asantibacterial activity, viability in low pH, bile salts and gastrointestinal tract conditions and adhesion capability to HT-29 cells.In conclusion,Lactobacillus plantarum KMJC4 andLactobacillus brevisKMJC1 were introduced as probiotic capable strains.Based on the results from the current in vitrostudy, finding probiotics with similar or better characteristics than commercial probiotics within indigenous bacteria is quite possible. In vivoassessment of the bacteria can be considered in future studies, investigating using possibilities of these bacteria in food industries to produce functional fermented foods and in pharmaceutical industries in form of probiotic capsules

 Probiotic bacteria as food additives have led to a significant growth in functional food levels. Functional foods present multiple challenges to probiotic viability and stability. In the present study, Bacillus coagulans LBSC DSM 17654, a probiotic strain, was incorporated into various foods to assess its stability during processing and storage and ability to decrease food calorie contents.

 Bacillus coagulans LBSC was used to prepare various beverages and foods such as hot and cold non-alcoholic beverages, breakfast cereals, oral rehydration salts, confections, frostings, convenience foods, frozen dairy desserts, condiments, relishes, fermented milk beverages and cough syrups. The bacterial process and storage stabilities were assessed using relative viability estimation. Stability of Bacillus coagulans LBSC was assessed in aqueous suspensions following ICH guidelines [Q1A (R2)] under various temperatures (0-100 ºC). Strain was assessed for its in vitro calorie restriction capabilities when incorporated into foods.

 Bacillus coagulans LBSC survived well during food processing (relative viability of 99.46% ±0.49) and storage (relative viability of 99.22% ±0.51) conditions. The bacterium was stable in aqueous suspension and tolerated high temperatures well (relative viabilities of 99.56% ±0.21 and 97.59% ±0.01 at 80 and 90 ºC, respectively). Bacillus coagulans LBSC showed significant in vitro calorie decreases in probiotic supplemented foods, compared to foods with no supplementations (p < 0.05). In conclusion, Bacillus coagulans LBSC exhibited good stability in aqueous media at high temperatures. Bacillus coagulans LBSC was not only stable in a wide spectrum of food categories, it could grow on foods to decrease food calorie under in vitro conditions; suggesting its uses as a functional food ingredient for better management of obesity and ageing and their associated health risks.

 Nanostructures of FeOOH are approved substitutions for iron salts in treatment of iron deficiencies. These particles can be promising additives to develop iron fortified foods. Researchers are interested to develop cost-effective techniques for the fabrication of food-grade FeOOH nanostructures. Relatively, polyethylenimine is commonly used to fabricate FeOOH nanoellipsoids. However, food industries need to develop novel protocols, which can be used in food processing. In this study, a simple economic technique was developed for the fabrication of food-grade FeOOH nanoellipsoids.

 Ferric chloride hexahydrate (FeCl3.6H2O) was used as iron precursor. BG-11 broth medium was used to cultivate Chlorella vulgaris microalgae. The Chlorella vulgaris culture supernatant was used for the fabrication of FeOOH nanostructures as an approved low-cost medium by the Food and Drug Administration. Nanoellipsoids of FeOOH were synthesized via hydrolysis of ferric ions in culture supernatants with no addition of other chemicals.

 Results showed that the prepared nanoellipsoids were β-FeOOH with 51.4-nm average length and 9.2-nm average width. The XRD analysis demonstrated that the secretory compound from Chlorella vulgaris included no negative effects on formation of FeOOH nanocrystals. The current developed technique can be introduced as a promising approach in fabrication of food-grade nanoparticles. Furthermore, the prepared structures can be used for the supplement formulation in pharmaceutical industries.