The impacts of ultrasound-assisted protein hydrolysate coating on the quality parameters and shelf life of smoked bonito fillets stored at 4±1ºC

Innovative bioactive protein hydrolysates (PH), produced from Rainbow trout (Oncorhynchus mykiss W., 1792) by-products, were used as a coating on smoked fillets of bonito (Sarda sarda) for extension of the quality and shelf life during chilled storage for 60 days. Three fillet groups were prepared as control group without coating (CG), normal hydrolysate coated group (NHCG), and ultrasound-assisted hydrolysate coated group (UHCG). Total volatile basic nitrogen (TVB-N) and TBA values exceeded the acceptable limits on the 39th and 33rd days for CG respectively; 60th day for NHCG and UHCG. However TBA of UHCG was significantly lower than NHCG. Total aerobic mesophilic bacteria (TAMB) and total aerobic psychrophilic bacteria (TAPB) loads reached 6.32±0.06 and 7.30±0.12 log cfu/g for CG on the 39th day. TAMB and TAPB values of NHCG and UHCG have remained within the limits of consumable until the end of the storage. PH coatings prolonged the storage of fillets by delaying chemical, physical, and microbial degradation. Results showed that ultrasound-assisted PH could be used as a coating for smoked bonito at refrigerated conditions, delaying oxidation and microbial degradation.

Extremophilic Microorganisms in Central Europe

Extremophiles inhabit a wide variety of environments. Here we focus on extremophiles in moderate climates in central Europe, and particularly in Slovenia. Although multiple types of stress often occur in the same habitat, extremophiles are generally combined into groups according to the main stressor to which they are adapted. Several types of extremophiles, e.g., oligotrophs, are well represented and diverse in subsurface environments and karst regions. Psychrophiles thrive in ice caves and depressions with eternal snow and ice, with several globally distributed snow algae and psychrophilic bacteria that have been discovered in alpine glaciers. However, this area requires further research. Halophiles thrive in salterns while thermophiles inhabit thermal springs, although there is little data on such microorganisms in central Europe, despite many taxa being found globally. This review also includes the potential use of extremophiles in biotechnology and bioremediation applications.

Effect The Addition Different Concentrations of Sodium Triphosphate and Sodium Lactate on The Microbial Count of Cold Ground Beef Meat

This study was conducted in the laboratories of Al-Musaib Technical College, Al-Furat Al-Awsat Technical University with the aim of studying the effect of adding sodium triphosphate salts at concentrations of 0, 0.5, 1, 1.5 and 2% and sodium lactate at concentrations of 0, 0.5, 1, 1.5 and 2% on the microbial count of ground beef and cooled for 24 hours at a temperature at 4 C. The results of the study indicated an increase in the rate of the total count of bacteria, psychrophilic bacteria, coliforms, yeasts and molds in all ground meat samples, not treated with salt, than the permissible limits. As samples of ground meat not treated with trisodium and sodium lactate salts recorded the highest rate in the total Count of bacteria after 24 hours of cold storage at 4 ° C, when they reached 6.544 CFU The Count of these bacteria decreased by increasing the concentration of salts, so the minimal count of bacteria was at a concentration of 2% when adding both salts of sodium triphosphate and sodium lactate together as 3.426 CFU. also found a clear reduction in the count of Psychrophilic bacteria at a concentration of 2% for both salts as recorded the last treatment rate 2.127 CFU It is the minimal count compared to the other treatments, while the control treatments recorded the highest count 6.400 CFU. Also, the addition of different concentrations of sodium triphosphate and sodium lactate led to a gradual decrease in the counts of coliform bacteria, with an increase in the salt concentration, as it reached 1.204 CFU At aconcentration of 2%, while the control treatment was recorded 6.431 CFU It is a the highest value. Also there is a significant difference was found (P <0.05). In the count of yeasts and molds, which were significantly decreased by increasing the concentration of both salts, as they were 1.079 CFU In the last treatment, while the highest count recorded since reached 4.361 CFU When salts are not added. This is a clear indication of the existence of a synergistic action of these salts to reduce the increasing counts of bacteria, yeasts and molds by inhibiting these microbial species with increased concentration.

Potential Applications of Antibacteria in Edible Coating as Fish Preservative

Fish is a product that breaks down quickly due to biochemical reactions that cause a decrease in the quality of its nutritional and sensory values. Natural preservatives make fish safer for consumption than fish preserved with formalin. Edible coating is a preservative that can be eaten, can prevent biological, chemical and physical changes, is able to prevent mass transfer, acts as a moisture barrier, be contained antimicrobial/antibacterial and antioxidants, increases shelf life, as well as protects food from microbial contamination. Antimicrobial/antibacterial compounds added to edible coatings are able to inhibit food degradation and/or remodel toxic compounds such as free radicals. Antimicrobials can be obtained from plant extracts such as alkaloids, flavonoids, saponins, tannins, phenolic acids, and eugenol. These compounds can slow the growth of bacteria in fish namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus sp., Staphylococcus aureus, Psychrotrophic and Psychrophilic bacteria counts, Enterobacteriaceae, and lactic acid bacteria. This article reviews the application of various antibacterial compounds from various plants that are added to edible coatings as preservatives in fish.

LitR directly upregulates autoinducer synthesis and luminescence in Aliivibrio logei

LitR is a master-regulator of transcription in the ainS/R and luxS/PQ quorum sensing (QS) systems of bacteria from Vibrio and Aliivibrio genera. Here, we for the first time directly investigated the influence of LitR on gene expression in the luxI/R QS system of psychrophilic bacteria Aliivibrio logei. Investigated promoters were fused with Photorhabdus luminescens luxCDABE reporter genes cassette in a heterological system of Escherichia coli cells, litR A. logei was introduced into the cells under control of Plac promoter. LitR has been shown to upregulate genes of autoinducer synthase (luxI), luciferase and reductase (luxCDABE), and this effect doesn’t depend on presence of luxR gene. To a much lesser degree, LitR induces luxR1, but not the luxR2 — the main luxI/R regulator. Enhanced litR expression leads to an increase in a LuxI-autoinducer synthesis and a subsequent LuxR-mediated activation of the luxI/R QS system. Effect of LitR on luxI transcription depends on lux-box sequence in luxI promoter even in absence of luxR (lux-box is binding site of LuxR). The last finding indicates a direct interaction of LitR with the promoter in the lux-box region. Investigation of the effect of LitR A. logei on luxI/R QS systems of mesophilic Aliivibrio fischeri and psychrophilic Aliivibrio salmonicida showed direct luxR-independent upregulation of luxI and luxCDABE genes. To a lesser degree, it induces luxR A. fischeri and luxR1 A. salmonicida. Therefore, we assume that the main role of LitR in cross-interaction of these three QS systems is stimulating the expression of luxI.

DETERMINATION OF SOME MICROBIOLOGICAL, CHEMICAL AND HISTOLOGICAL PROPERTIES OF SALAMI AND SAUSAGES SOLD IN MARKETS

Salami and Sausage are ready to eat meat products that can pose a risk for human health. This study was aimed to determine the some microbiological, chemical and histological properties of 31 salami and 23 sausages from different companies offered for sale in markets, Turkey. The total aerobic mesophilic bacteria (TAMB), yeast and mould enumeration, lactic acid bacteria and psychrophilic bacteria count were evaluated. The water activity, pH, moisture content, and ash content were analysed. The mean TAMB value of salami and sausage samples were 2.30 log CFU/g and 2.80 log CFU/g, respectively (P>0.05). The water activity was found as 0.97 for both samples. The pH value of salami and sausage samples were 5.94 and 5.87, respectively (P>0.05). Moisture content was higher in salami samples (63.80%) than sausage samples (62.00%) (P>0.05). The average ash content in salami samples was 2.15%, while it was 2.80% in sausage samples (P>0.05). In conclusion, the microbiological and chemical analysis of sausage and salami products were within the range of Turkish standards. However, histological analysis revealed that some packed sausage and salami products sold in market are manufactured from lower-value trimmed food.

Plastic Degradation by Extremophilic Bacteria

Intensive exploitation, poor recycling, low repeatable use, and unusual resistance of plastics to environmental and microbiological action result in accumulation of huge waste amounts in terrestrial and marine environments, causing enormous hazard for human and animal life. In the last decades, much scientific interest has been focused on plastic biodegradation. Due to the comparatively short evolutionary period of their appearance in nature, sufficiently effective enzymes for their biodegradation are not available. Plastics are designed for use in conditions typical for human activity, and their physicochemical properties roughly change at extreme environmental parameters like low temperatures, salt, or low or high pH that are typical for the life of extremophilic microorganisms and the activity of their enzymes. This review represents a first attempt to summarize the extraordinarily limited information on biodegradation of conventional synthetic plastics by thermophilic, alkaliphilic, halophilic, and psychrophilic bacteria in natural environments and laboratory conditions. Most of the available data was reported in the last several years and concerns moderate extremophiles. Two main questions are highlighted in it: which extremophilic bacteria and their enzymes are reported to be involved in the degradation of different synthetic plastics, and what could be the impact of extremophiles in future technologies for resolving of pollution problems.

Efficiency of sweet whey fermentation with psychrophilic methanogens

Sweet whey is a waste product from the dairy industry that is difficult to manage. High hopes are fostered regarding its neutralization in the methane fermentation. An economically viable alternative to a typical mesophilic fermentation seems to be the process involving psychrophilic bacteria isolated from the natural environment. This study aimed to determine the feasibility of exploiting psychrophilic microorganisms in methane fermentation of sweet whey. The experiments were carried out under dynamic conditions using Bio Flo 310 type flow-through anaerobic bioreactors. The temperature inside the reactors was 10 ± 1 °C. The HRT was 20 days and the OLR was 0.2 g COD/dm3/day. The study yielded 132.7 ± 13.8 mL biogas/gCODremoved. The CH4 concentration in the biogas was 32.7 ± 1.6%, that of H2 was 8.7 ± 4.7%, whereas that of CO2 reached 58.42 ± 2.47%. Other gases were also determined, though in lower concentrations. The COD and BOD5 removal efficiency reached 21.4 ± 0.6% and 17.6 ± 1.0%, respectively.