Growth Rate Of Bacteria Research Articles

Efficacy of two contact lens disinfecting solutions in reducing growth rate of bacteria and eradication of biofilms

Efficacy of two types of contact lens disinfecting (CLD) solutions, most frequently purchased from Jordanian pharmacies by contact lens wearers, was investigated for reducing growth rate of methicillin resistant and methicillin sensitive Staphylococcus aureus, Serratia marcesence, S. liquefacience and Acinetobacter spp., previously isolated from In-use disinfecting solutions in CL cases. Each species was cultured in a clean and dirty conditions (to mimic real situation) of two fresh CLD solutions separately: A and B whose active agents are: Polyhexamethylene biguanide hydrochloride and Polyaminopropyl biguanide respectively. Log reduction of these bacteria have exceeded ISO 14729 acceptable criteria (3 log) and reached up to 5 log reduction. Dirty conditions have marked effect in reducing efficacy of CLD solution (A) to kill bacterial species under test. Biofilms produced by S. marcescens and S. liquefaciens were reduced by more than 50% after 24 hrs. using either CLD solutions, though it was less than that reduced after 4 hrs. Biofilm of methicillin resistant Staphylococcus aureus (MRSA) was the most affected by either CLD solutions after 4 hours. This study concluded that CL wearers should pay great consideration to cleaning and disinfection practices to decrease bacterial growth, reduce chances of biofilm formation.

Effect of Physicochemical Characteristics and Storage Atmosphere on Microbiological Stability and Shelf-Life of Minimally Processed European Sea Bass (Dicentrarchus labrax) Fillets

The aim of the present work was to evaluate the effect of various hurdles such as aw and pH as well as the storage atmosphere on the microbiological and sensory changes of minimally processed (lightly brined or marinated with acetic or citric acid) European sea bass (Dicentrarchus labrax) fillets. The results indicated that the shelf-life of brined fillets stored aerobically was 6 d while that of vacuum and MAP-stored was 12 d, since a reduced growth rate of spoilage bacteria was recorded. The physicochemical characteristics such as aw and water phase salt (WPS) were not considerably changed, while the oxygen levels into the packages ensure the microbiological safety of the product. The fillets marinated with acetic acid exhibited a longer shelf-life at 30 and 40 d under aerobic and reduced oxygen conditions, respectively, while the products marinated with citric acid were at 25 and 35 d respectively. A low pH resulted in reduced or even limited microbial levels, especially for the fillets marinated with acetic acid; something that ensures microbiological safety as well. The low or limited microbial levels in conjugation with the sensory attributes indicated that spoilage may be due to other mechanisms such as autolysis rather than microbial activity. Overall, the present work highlights the potential for further research and development of minimally processed, microbiologically safe and stable with extended shelf-life value added seafood to satisfy the corresponding consumer demands.

Enhancing butanol production by Clostridium beijerinckii through cathodic electrofermentation approach

AbstractBACKGROUNDBiobutanol, produced by solventogenic bacteria like Clostridium beijerinckii through acetone, butanol, and ethanol (ABE) fermentation, is a promising green alternative to fossil fuels. However, this ABE fermentation suffers drawbacks, such as a relatively low productivity that limits its industrial deployment. Electro‐fermentation (EF) can modify the intracellular ratio of oxidized nicotinamide adenine dinucleotide to reduced nicotinamide (NAD+/NADH), a critical factor for butanol synthesis by C. beijerinckii, thus allowing higher product titers (or productivity) to be reached.RESULTSThe present study focuses on glucose‐based ABE‐EF at laboratory‐scale. Three replicate EF reactors (300 mL) were constructed and used to grow C. beijerinckii. Different cathode materials were electrochemically characterized and tested. The effect of voltage application on process productivity was assessed by performing chronoamperometry tests at constant cathode potential (Ecat), ranging from −0,7 to −1,0 V vs Ag/AgCl. These trials were compared with a benchmark ABE fermentation that was performed without voltage application. Poising Ecat at −0,8 V vs Ag/AgCl resulted in the optimal EF scenario. In these conditions, the specific growth rate of bacteria was 73% higher than the benchmark ABE fermentation, with a productivity of 125,6 mg‐butanol/L/h, a process yield of 0,15 g‐butanol/g‐glucose, and a selectivity for butanol of 87% (34%, 25%, and 11% higher than the benchmark fermentation, respectively). The addition of 0,5 mM neutral red as redox mediator in the broth led to a further improvement of butanol productivity (152,9 mg L h−1), requiring a very low energy consumption of 0,02 kWh/kg‐butanol to run the EF process.CONCLUSIONApplying EF enhances the ABE fermentation in terms of butanol production, selectivity, and energy consumption. © 2023 Society of Chemical Industry (SCI).

EDUKASI PENTINGNYA MENGKONSUMSI PROBIOTIK SEBAGAI UPAYA PENCEGAHAN TERJADINYA DYSBIOSIS DI KELURAHAN SETIARATU KOTA TASIKMALAYA

Dysbiosis is a condition where there is an imbalance in the number of microorganisms in the human digestive tract. Basically, in normal conditions, colonies of microorganisms tend to act as normal flora that helps the process of nutrition digestion and maintain the immune system. However, when the number of colonies increases significantly, the body will begin to experience various diseases symptoms. The occurrence of dysbiosis in the end will be able to cause systemic abnormalities, such as interference with the absorption of nutrients that potentially cause metabolic abnormalities. Probiotics are live microorganisms which when administered in appropriate doses will benefit the health of the host. The ability of probiotics in symbiosis with microorganisms that exist in the intestine can suppress the growth rate of harmful bacteria (pathogens), and in the end will be able to improve the immune system. Setiaratu area is an area that borders the location of Tasikmalaya Ministry of Health Poltekkes. In this community service, outreach activities and creation of leaflets about the importance of probiotics consumption as an effort to prevent the occurrence of dysbiosis has been conducted in the district of Setiaratu. This community service was carried out in conjunction with Community Service Program of Poltekkes Kemenkes Tasikmalaya. After this PKM activity, it is hoped that the public can be expected to increase knowledge about dysbiosis and the use of probiotics to prevent and curative dysbiosis, especially in Setiaratu area.

Effect of tartary buckwheat sourdough fermented by different exogenous lactic acid bacteria on antifreeze property of frozen dough

In this study, tartary buckwheat combined with compound strains was fermented to make sourdough and applied to improve frozen dough. The results showed that the compound bacteria had a certain synergistic effect, and the bacterial colony growth in tartary buckwheat substrate was better than single bacteria, especially in LF+WC group, the lactic acid bacteria growth rate was the fastest, and a large amount of fructose (11.82 mmol/kg) and EPS (3.132 g/kg) were generated after 12 h fermentation. In addition, the binding water content of tartary buckwheat sourdough in LF+WC group decreased by 0.48%, content of non-flowing water and free water increased by 0.18% and 0.3%, respectively, the glutenin subunit degradation was less, α-helix and β-rotation content decreased by 0.43% and 2.34%, respectively, after 13 weeks of freezing. So that gluten can maintain a more uniform and regular network structure. Therefore, LF+WC tartary buckwheat sourdough has good antifreezing protection effect.

The Effect of Atranes on the Growth of <i>Rhodococcus qingshengii</i> VKM Ac-2784D in the Presence of Various Carbon Sources and on Its Ability to Degrade Naphthalene

Abstract—Rhodococcus qingshengii VKM Ac-2784D isolated from the rhizosphere of Elytrigia repens, is a promising oil degrader. To increase its biotechnological potential, the effect of atranes (potential growth stimulants) on its growth and naphthalene degradation was studied. The effect of the studied atranes on R. qingshengii VKM Ac-2784D was shown to depend on the nature of the carbon source: addition of atranes had practically no effect on the growth rate of bacteria in the rich BTN medium; in the media 8E and 8E with glucose, it baused short-term activation of growth, characterized by a shorter lag phase. In the presence of naphthalene, atranes had a predominantly negative effect on the growth of R. qingshengii VKM Ac-2784D. The studied atranes had a negative effect on the rate of naphthalene decomposition by R. qingshengii VKM Ac-2784D, and also decreased the cell wall hydrophobicity and the synthesis of extracellular biosurfactants. It may therefore be assumed that the studied compounds will have a negative effect on the rate of naphthalene decomposition by this microorganism.

Microbial growth kinetics as a method to model and predict the development of starter cultures

A comparative study was conducted on the growth rate of lactic acid bacteria involved in starter cultures for the production of lactic acid products. Based on the data obtained, with respect to the rate of development, it is possible to predict their development as monocultures or as cultures in symbiotic relationship. In order to achieve the set objective, culture of lactic acid microorganisms was carried out in a bioreactor for 24 hours. Data on the rate of development in the different phases, represented by the acid formation curve, are reported for the following strains: Lactobacillus delbrueckii ssp. bulgaricus S22; Streptococcus thermophilus S1; Lacticaseibacillus casei ssp. rhamnosus AS15; Lactobacillus casei ssp. shirota 51C. The conclusions drawn allow the correct and predictable use of the investigated strains of lactic acid bacteria in starter cultures for the production of lactic acid products.

Evaluation of possibility of cultivation of acid resistant bacteria on solid egg-based and agar cultural media.

The increase in the number of patients at risk for opportunistic infections caused by rare bacteria, which include individual representatives of acid-resistant bacteria (ARB), is a serious problem in modern health care. Significant difficulties in the etiological diagnosis of mycobacteriosis, nocardiosis, and actinomycosis are associated not only with the problem of identifying the main pathogens but also with certain difficulties in isolating pathogens from biological material. The research provides data on 402 strains of ARB, which were isolated from various biological materials obtained from patients during examination for tuberculosis. All samples of biological material were negative on the Mycobacterium tuberculosis complex. The isolates were identified on the MALDI-ToF mass spectrometer. The cultural characteristics of ARB were evaluated on the solid Löwenstein-Jensen egg-based culture media, universal chromogenic media, and 5% blood agar with lamb blood. The studies carried out indicate the possibility of culturing ARB representatives on agar media. At the same time, based on the comparison of the growth properties of ARB, it was found that the universal chromogenic media provides more acceptable conditions for the isolation of nontuberculous mycobacteria (NTM) compared to blood agar. The comparison of the growth rate of bacteria did not reveal significant differences for fastly growing NTM. For slowly growing species, the growth rate on blood agar was lower than on chromogenic media and on the Löwenstein-Jensen media. Thus, the use of a universal chromogenic media during incubation makes it possible to isolate and preidentify representatives of the ARB under the conditions of standard operating procedures of the microbiological laboratory.

Экологиялық тізбектер және олардың математикалық-компьютерлік моделдері

The article deals with the problem of studying the structures and evolutions of ecological chains at the level of microorganisms using mathematical and computer models. Several mathematical models have been constructed based on the laws of biological kinetics. Computer experiments were developed using these models. Mathematical models describing the dependence of the concentration of bacterial biomass, substrates and protozoa on time have been created. With the help of the Mathcad package, graphical solutions of mathematical models were obtained and analyzed. Graphs of the states of ecological chains with changes in the rate of penetration of the nutrient substrate into the system were created and these states were studied. Mathematical models describing the mutual competition of 6 different bacteria were developed in Mathcad environment. The parameters characterizing the biomass concentration of each bacterium were established. This parameter included: saturation constant of bacteria, saturation constant of protozoa, maximum value of specific growth rate of bacteria, maximum value of specific growth rate of protozoa, and economic growth coefficient of protozoa. Graphical solution of mathematical models have been analyzed. These models characterize the dynamics of the concentration of bacterial biomass. A computer experiment representing competition between bacterial species was developed. The results of mutual competition of ten different bacterial colonies were obtained on the basis of numerical and graphical methods. The software has been compiled in Microsoft Visual Basic 6.0 environment.

PCL/Collagen/UA Composite Biomedical Dressing with Ordered Microfiberous Structure Fabricated by a 3D Near-Field Electrospinning Process.

In this work, a functionalized polycaprolactone (PCL) composite fiber combining calf-type I collagen (CO) and natural drug usnic acid (UA) was prepared, in which UA was used as an antibacterial agent. Through 3D near-field electrospinning, the mixed solution was prepared into PCL/CO/UA composite fibers (PCUCF), which has a well-defined perfect arrangement structure. The influence of electrospinning process parameters on fiber diameter was investigated, the optimal electrospinning parameters were determined, and the electric field simulation was conducted to verify the optimal parameters. The addition of 20% collagen made the composite fiber have good hydrophilicity and water absorption property. In the presence of PCUCF, 1% UA content significantly inhibited the growth rate of Gram-positive and negative bacteria in the plate culture. The AC-PCUCF (after crosslinking PCUCF) prepared by crosslinking collagen with genipin showed stronger mechanical properties, water absorption property, thermal stability, and drug release performance. Cell proliferation experiments showed that PCUCF and AC-PCUCF had no cytotoxicity and could promote cell proliferation and adhesion. The results show that PCL/CO/UA composite fiber has potential application prospects in biomedical dressing.

Contribution of -Omics Technologies in the Study of Porphyromonas gingivalis during Periodontitis Pathogenesis: A Minireview.

Periodontitis is a non-communicable chronic inflammatory disease characterized by the progressive and irreversible breakdown of the soft periodontal tissues and resorption of teeth-supporting alveolar bone. The etiology of periodontitis involves dysbiotic shifts in the diversity of microbial communities inhabiting the subgingival crevice, which is dominated by anaerobic Gram-negative bacteria, including Porphyromonas gingivalis. Indeed, P. gingivalis is a keystone pathogen with a repertoire of attributes that allow it to colonize periodontal tissues and influence the metabolism, growth rate, and virulence of other periodontal bacteria. The pathogenic potential of P. gingivalis has been traditionally analyzed using classical biochemical and molecular approaches. However, the arrival of new techniques, such as whole-genome sequencing, metagenomics, metatranscriptomics, proteomics, and metabolomics, allowed the generation of high-throughput data, offering a suitable option for bacterial analysis, allowing a deeper understanding of the pathogenic properties of P. gingivalis and its interaction with the host. In the present review, we revise the use of the different -omics technologies and techniques used to analyze bacteria and discuss their potential in studying the pathogenic potential of P. gingivalis.

Unveiling the effects of soluble starch, ethanol, and sodium acetate on the interactions of functional microorganisms and nitrogen removal in a partial nitritation and anammox biofilm system

Different organic matters have different effects on the nitrogen removal performance of partial nitritation and anammox (PN/A) biofilm system. In this study, the effects of adding soluble starch, ethanol, and sodium acetate on the functional microorganisms and nitrogen removal in the PN/A biofilm system are investigated. The results show that ethanol had the strongest effects on the ammonium-oxidizing bacteria (AOB) growth, enrichment, and ammonium nitrogen removal rate, followed by soluble starch and sodium acetate. However, the suppression of anaerobic ammonium oxidation bacteria (AnAOB) and decrease in total nitrogen removal rate were affected the most by ethanol, followed by soluble starch and sodium acetate. In addition, the enrichment of nitrifying oxidizing bacteria (NOB) was the most strongly influenced by ethanol, followed by soluble starch and sodium acetate. Furthermore, the enrichment of phylum Proteobacteria was facilitated by ethanol > soluble starch > sodium acetate. The enrichment of phylum Nitrospirae and genus Nitrospira were influenced by ethanol > soluble starch > sodium acetate. However, the suppression of the phylum Planctomycetes and the genus Candidatus Brocadia were affected by ethanol > soluble starch > sodium acetate. These results show that the PN/A biofilm system is suitable for the treatment of ammonium nitrogen wastewaters containing organic salt (sodium acetate) but not for treating wastewaters containing organic alcohol (ethanol) and macromolecular organic matter (soluble starch).

Using pulse electric fields (PEF) for selective inactivation of coliform bacteria

Coliform bacteria usually originate from the intestine, and the contamination typically occurs when there is a lack of sterility in food industry. PEF-induced selective nonthermal pasteurisation method might pasteurise coliform bacteria while leaving the needed bacteria intact. To evaluate this hypothesis, we chose Escherichia coli dh5α (E. coli) strain as a representation of coliform bacteria for this study. We also used Streptococcus thermophilus bacteria strain as a representation of lactobacteria used in milk by-products. The obtained results of PEF application showed that selective death of bacteria after PEF treatment can be induced. PEF was applied on bacteria. Then the clonogenic assay, the metabolic activity, and bacterial growth in the bioreactor were evaluated. By applying PEF treatment on E. coli and S. thermophilus their survival was monitored. We found the PEF parameters under which coliform bacteria E. coli were killed more than 100 times effectively than S. thermophilus. We postulate that it is the result of the bacteria size. Here we show that a PEF-induced selective nonthermal pasteurisation method could be applied in the industry where coliform bacteria can be eliminated while leaving other needed bacteria intact. We showed this by measuring the metabolic activity, the ability to form colonies, and the change in bacteria growth rate in the bioreactor.

Heterologous expression of antimicrobial peptides S-thanatin and bovine lactoferricin in the marine diatom Phaeodactylum tricornutum enhances native antimicrobial activity against Gram-negative bacteria

The increase in resistance of bacterial strains to existing antibiotics represents a major public health concern. Antibiotics are an invaluable tool still frequently used in agriculture as they can both improve feed/energy conversion ratios in livestock and treat pathogenic infections. However, the misuse of these compounds has contributed to escalating antimicrobial resistance (AMR). The rapid increase in drug-resistant infections has presented a serious challenge to antimicrobial therapies. Research is currently being carried out to identify alternative antimicrobial compounds to use in animal production although to date, no effective alternatives to production-purpose antibiotics (PPAs) have been developed. Recent reports indicate that lysate of marine diatom Phaeodactylum tricornutum was able to significantly lower the maximal growth rate of Gram-negative bacteria. We have engineered P. tricornutum to accumulate antimicrobial recombinant proteins, S-thanatin and bovine lactoferricin (bLFcin). Transgenic P. tricornutum expressing heterologous S-thanatin and bLFcin demonstrated significantly enhanced antimicrobial activity against Gram-negative bacteria Enterobacter cloacae ATCC 13047 and Vibrio natriegens ATCC 14048 respectively. The lysate of transgenic strain Pt_LFcin1.15, expressing bLFcin, lowered maximal growth rate (μmax) of V. natriegens by 33.2 %, which was a 15.5 % further reduction than by wild type (WT) lysate. The lysate of the optimized bLFcin-expressing transgenic strain Pt_LFcin2.3 lowered V. natriegens μmax by 38.5 %, which was a 27.4 % further reduction than by WT lysate. The S-thanatin-expressing transgenic cell lysate of strain Pt_S-Tha1.11 lowered E. cloacae μmax by 61.3 %, which was a 38.1 % greater reduction than by WT lysate. These statistically significant results (p < 0.01) demonstrate that microalgae can be engineered to express a range of naturally occurring antimicrobial and anti-inflammatory compounds which can substitute for PPAs and treat serious bacterial infections.

Selecting Better Biocatalysts by Complementing Recoded Bacteria.

In vivo selections are powerful tools for the directed evolution of enzymes. However, the need to link enzymatic activity to cellular survival makes selections for enzymes that do not fulfill a metabolic function challenging. Here, we present an in vivo selection strategy that leverages recoded organisms addicted to non-canonical amino acids (ncAAs) to evolve biocatalysts that can provide these building blocks from synthetic precursors. We exemplify our platform by engineering carbamoylases that display catalytic efficiencies more than five orders of magnitude higher than those observed for the wild-type enzyme for ncAA-precursors. As growth rates of bacteria under selective conditions correlate with enzymatic activities, we were able to elicit improved variants from populations by performing serial passaging. By requiring minimal human intervention and no specialized equipment, we surmise that our strategy will become a versatile tool for the in vivo directed evolution of diverse biocatalysts.

Selecting Better Biocatalysts by Complementing Recoded Bacteria**

AbstractIn vivo selections are powerful tools for the directed evolution of enzymes. However, the need to link enzymatic activity to cellular survival makes selections for enzymes that do not fulfill a metabolic function challenging. Here, we present an in vivo selection strategy that leverages recoded organisms addicted to non‐canonical amino acids (ncAAs) to evolve biocatalysts that can provide these building blocks from synthetic precursors. We exemplify our platform by engineering carbamoylases that display catalytic efficiencies more than five orders of magnitude higher than those observed for the wild‐type enzyme for ncAA‐precursors. As growth rates of bacteria under selective conditions correlate with enzymatic activities, we were able to elicit improved variants from populations by performing serial passaging. By requiring minimal human intervention and no specialized equipment, we surmise that our strategy will become a versatile tool for the in vivo directed evolution of diverse biocatalysts.

Antibacterial Activity of Ferulic Acid Ester against Ralstonia solanacearum and Its Synergy with Essential Oils

Ralstonia solanacearum is one of the ten most harmful plant bacteria worldwide, and traditional agrochemicals are not very effective in controlling this pathogen. Moreover, excessive pesticides always bring organic residues and resistant strains, which cause the unsustainability of the environment. In this paper, ferulic acid and essential oils are used as antibacterial materials. These compounds are natural substances with low toxicity and environmental safety. Through the structural optimization and the analysis of binary combined bacteriostatic efficiency, the MIC values of chlorobutyl ferulate (2e) and peppermint essential oil (EO1) were 0.64 mg/mL and 2.02 mg/mL, respectively, and the MIC value of 2e-EO1 (mass ratio 1:1.5) was 0.40 mg/mL. The growth rate of bacteria treated with 2e-EO1 was inhibited, the OD590nm value of cell membrane decreased by 57.83%, and the expression levels of hrpB, pehC, pilT, polA, aceE, egl, and phcA were downregulated to 18.81%, 30.50%, 14.00%, 44.90%, 86.79%, 23.90%, and 27.56%, respectively. The results showed that 2e-EO1 had a synergistic inhibitory effect against R. solanacearum. It significantly affected the formation of the bacterial cell membrane and the expression of pathogenic genes. Consequently, 2e-EO1 provides the potential to become a green pesticide and can promote the sustainability of the agricultural ecological environment.

Insight into the temperature stimulation on the self-healing properties of cement-based materials

The concrete constructions under the complex and variable external loads easily produce structural cracks, severely limiting the service life. Traditional methods for crack repairing such as spraying and chemical grouting, are usually with the high cost and potential environmental problems. In recent years, microbial self-healing has aroused great attention in the crack repair of concrete due to its environmental safety and high self-healing potential. Nevertheless, previous studies have shown that the healing efficiency of microbial cement stones at low temperatures was not ideal. Temperature stimulation seems to be feasible to accelerate the healing process because temperature is one of the critical factors impacting microbial mineralization. To verify the applicability of temperature stimulation to the regulation of microbial healing efficiency, this paper investigated the changes in growth rate, urease activity, cell shape, and mineralization rate of Sporosarcina pasteurii under temperature stimulation at first. And then, the healing properties of cement stones without cracking and cracked cement stones under temperature stimulation were evaluated. The interaction mechanism of temperature stimulation on the healing properties was revealed by establishing the relationship between the microstructure parameters and macro performance. This paper proved that it was capable to improve the healing efficiency of microbial cement stones by temperature stimulation. Besides, the results showed that at 7 ∼ 37 °C, the growth rate and mineralization rate of bacteria were improved by raising the culturing temperature. Moreover, we found that temperature stimulation impacted the growth and the mineralization of bacteria, thus, influencing the microstructure and healing properties of microbial cement stones. In addition, the healing efficiency was dominated by microbial mineralization rather than cement hydration at 7 ∼ 43 °C. More importantly, the temperature stimulation on the microbial cement stones with Sporosarcina pasteurii should be limited within 43 °C. This paper provides a reference for the research on the improvement of the healing efficiency in microbial cement materials with temperature stimulation.

The antibacterial effect of silver anode treatment on raw milk

Silver has been used as an indirect antibacterial method by the food sector. In this study, the antibacterial effect of silver on raw milk was examined using the silver anode method. The samples were divided into two groups comprising silver-containing and non-silver-containing samples. Then, the two groups were stored at 5 °C, 10 °C, and 25 °C. The changes in the bacterial flora of the raw milk samples were observed at hours 0, 12, 24, and 36. The antibacterial effect of the silver anode treatment on both groups was observed after 12 h. The antibacterial effect increased with increasing storage time. The decreases in the Pseudomonas spp., coliform bacteria, and lactic acid bacteria counts of the silver-containing group were significantly different than those of the control group after 36 h (p < 0.05). The decreases in the Pseudomonas spp. and coliform bacteria counts were greater than the decrease in the lactic acid bacteria count. The Pseudomonas spp. count decreased during the storage period depending on temperature while the growth rates of coliform and lactic acid bacteria decreased with decreasing storage temperature in the silver anode-treated group. The strongest antibacterial effect was observed at 25 °C for Pseudomonas spp. and at 5 °C for coliform and lactic acid bacteria. The results of the study revealed that the silver anode method had a strong antibacterial effect on Pseudomonas spp. and coliform bacteria and a poor antibacterial effect on lactic acid bacteria. Silver ion release into the milk samples was consistently below the legal limits at all storage temperatures.

The effect of fishing season and storage conditions on the quality of European plaice (Pleuronectes platessa)

The combined effect of fishing season (September/April) and storage conditions on the quality of European plaice (Pleuronectes platessa) was investigated. Investigated storage conditions were; fillets packaged in vacuum or a modified atmosphere (MA; 70% CO2, 20% N2, 10% O2) and stored at 4 °C. As a control, whole fish on ice (0 °C) was used, representing the commercial standard. Plaice showed in general lower quality in April than September, demonstrated by a faster microbial evolution, higher content of biogenic amines, and higher rate of ATP degradation representing by K- and H-values. MA-fillets and whole fish on ice showed lower K- and H-values and biogenic amines content than fillets packaged in vacuum. VP-fillets had the lowest microbial quality as demonstrated by the shortest lag-phase of psychrotrophic aerobic plate count and aerobic bacteria, and the highest maximum specific growth rate of H2S-producing bacteria. MA packaging significantly reduced microbial growth; however, MA-fillets showed the lowest water content and the highest drip loss and water holding capacity. No differences between groups were observed in colour intensity or hue angle at the storage end. Despite the significant seasonal variations, MA packaging stands out as the best solution to maintain the freshness of convenient retail plaice products.