Potato Slices Research Articles

Freeze-thawing and osmotic dehydration pretreatments on physicochemical properties and quality of orange-fleshed sweet potato slice during hot air drying.

Freeze-thawing and osmotic dehydration pretreatments on physicochemical properties and quality of orange-fleshed sweet potato slice during hot air drying.

Simulation of Transport Phenomena for Microwave Freeze‐Drying of Potato Slices Using Finite Element Analysis

ABSTRACTThis research intended to investigate the transport phenomena that occur during microwave freeze‐drying (MFD) of potato slices using drying kinetics and finite element analysis (FEA). The impacts of microwave power levels and potato slice thickness on drying rate constant (DR) and average moisture diffusion (DAVG) were analyzed using MFD kinetics and were then incorporated in the simulation. It was found that the DR and DAVG were in the range of 301.3 × 10−3–775.4 × 10−3 min−1 and 1.045 × 10−10–3.336 × 10−10 m2/s, respectively. In the sublimation phase, the DR and DAVG were higher than those in the desorption phase. The DR and DAVG increased as the microwave power level increased but decreased as the thickness increased. The FEA of temperature and moisture distribution within the potato slices demonstrated the outward transfer of heat and mass from the center to the exterior and closely matched the experimental data with an error margin of within 5%, leading to the proposed schematic shrinkage model corresponding to the MFD simulation.

Experimental Investigation of Two-Pass Solar Dryer with V-Corrugated Absorber for Potato Slice Drying

Reducing the moisture level of food items can help prevent bacterial development and deterioration, extend shelf life, reduce packaging, and improve storage for convenient transportation. In this paper, a two-pass solar dryer with V-Corrugated absorber plate is developed. Its experimental performance evaluation in forced convection is carried out for potato chip drying. Various parameters like Hourly Variation of Solar Radiation Intensity, Temperature Distribution Curves inside Solar Dryer, Collector Efficiency Curve, Hourly Mass Loss of Potato Slices and Moisture Removal Comparison with Conventional Open Sun Drying Method are calculated and presented graphically. The peak temperature of the absorber plate reached 69.30C, and the air temperature at the collector outlet recorded the highest value at 57.50C. The average temperature difference of 28.580C is obtained for heat transfer by convection between the modified corrugated absorber plate and the air. An important finding in this experimental investigation was that there is an average 6.50C difference in temperature between the hot air exiting the collector and the air available at the bottom of the lower tray of the drying chamber, which should be reduced by applying means of avoiding heat loss. The highest collector efficiency is calculated as 88.9 % at 2 PM. The lowest efficiency is calculated at 9 AM as 66.8 %. The thermal inertia of the system adds to the collector efficiency in the last 2 hours of the experimentation and hence collector performs better than in the morning hours, though the insolation is nearly the same for the first and last two hours of sunshine. The percentage reduction in drying time was found to be 38.9 % for 50 % moisture removal from potato slices as compared to open sun drying.

Integrated solar dryer and distillation system with PCM and injection, powered by PVT panels and solar concentrator

This research introduces a novel hybrid system integrating solar drying, solar distillation, and photovoltaic thermal panels, aimed at drying agricultural products, producing clean drinking water, and conserving energy. The system enhances the drying air temperature using thermal energy storage materials and a solar dish concentrator connected to a hot water storage tank, ensuring continuous operation even after sunset. The solar distiller, equipped with energy storage materials and an air injection system, is integrated with an external condenser to condense water vapor before expulsion, thereby increasing freshwater productivity. The results revealed that the developed system achieved an accumulative freshwater productivity of 87.1 L per day. The rates of water removal from dried potato slices ranged from 0.18 to 0.91 kg/h between 8:00 am and 10:00 pm. Additionally, the system achieved a gain output ratio of 1.38, indicating a significant improvement in energy efficiency. This innovative system offers practical solutions to address energy and freshwater scarcity, especially in remote regions of the Middle East and North Africa (MENA) region, which are characterized by high solar irradiance. The implementation of such hybrid systems could contribute to sustainable development by reducing reliance on conventional energy sources and mitigating environmental pollution.

Lemon juice pretreatment as a strategy to preserve the quality and enhance the texture of cooked potato slices of different sizes

Potatoes are an important food crop worldwide and are rich in essential nutrients. However, cooking can reduce their nutritional value and alter their texture. This study aimed to investigate the impact of pretreating potato slices with lemon juice. The slices were immersed in 5% lemon juice solution for 3 h, rinsed with distilled water for another 3 h, then cooked at 100°C for 20 min. Findings revealed that lemon juice pretreatment (LJP) notably improved the texture, mouthfeel, and overall acceptability of the cooked potato slices of different sizes (CPS-Ds). Additionally, LJP significantly increased vitamin C and total phenolic contents, slightly decreased pH levels, and preserved the desired color of CPS-Ds. Consumer sensory evaluations also indicated a positive response to LJP samples, suggesting its potential application in the food industry. The study confirmed that LJP is an effective, sustainable, consumer-friendly, and cost-efficient technique for improving the quality of cooked potato slices.

Anti-browning action of melatonin is dependent on the type of tissue in minimally processed sweet potatoes

This study explored the impact of exogenous melatonin on oxidative damage, protective mechanisms against oxidation, and reactions leading to browning, as well as the accumulation of antioxidants in minimally processed white-fleshed and orange sweet potato roots. Sweet potato roots with white and orange pulp were subjected to minimal processing and immersion in melatonin solutions at concentrations of 0, 10, 100, and 1000 µmol L−1. Following packaging, these were stored at 5 ± 2 °C for 20 days. Results indicate that increasing melatonin concentrations significantly reduced browning symptoms in both white and orange sweet potato slices. This reduction was associated with decreased levels of hydrogen peroxide (H2O2), thiobarbituric acid-reactive substances (TBARs), and electrolyte leakage, indicating reduced cell membrane damage. Enhanced protection was observed through increased activity of antioxidant enzymes superoxide dismutase, catalase, and ascorbate peroxidase and higher levels of antioxidant metabolites, including vitamin C and phenolic compounds, as confirmed by in vitro assays for antioxidant capacity (FRAP and DPPH), however, the levels of total carotenoids, anthocyanins, and yellow flavonoids did not show a significant difference between the melatonin treatments. Notably, sweet potato slices treated with higher melatonin doses of 100 and 1000 µmol L−1 exhibited reduced phenylalanine ammonia-lyase activity and phenolic compound accumulation. This effect, coupled with lower polyphenol oxidase (PPO) and peroxidase (POD) activities, likely contributed to prolonged preservation quality by maintaining cellular redox homeostasis.

Modeling of moisture content during baking with different approaches for effective diffusivity and evaluation of quality variables in baked potato slices.

Baking is a healthier alternative to frying, since texture, color, smell, and flavor are developed, without adding oil. The objective was to estimate the moisture content in potato slices, during baking using Fick's law of diffusion to model internal moisture transport and to assess the impact on quality attributes. Moisture transport kinetics were examined at three baking temperatures of 120, 130, and 140°C. Fick's law was employed to estimate average moisture content using different methods: considering both a constant (method of slopes by subperiods, MSS; and method of successive approximations, MSA) and a variable (represented as a quadratic function of time, QFT) behavior of effective diffusivity (De). Three quality variables were analyzed: water activity (aw, dew point hygrometry), total color difference (∆E, colorimetry), and fracturability (F, universal testing machine). The diffusivity estimated with the time-varying De method provided a more realistic description of moisture migration during baking. The aw, ∆E, and F for baked potato slices ranged from 0.234 to 0.276, 17.9 to 24.6, and 5.20 to 5.49 N, respectively. These attributes imply improved stability and extended shelf life, showing typical colors and texture changes for baked snacks. These changes are linked to variations in diffusivity, influenced by the size and quantity of micropores within the food structure. This study could allow an accurate prediction of mass transfer by considering variable De, facilitating the optimization of baking conditions. PRACTICAL APPLICATION: The analysis of the moisture content using Fick's law, considering a time-varying diffusivity, enables the optimization of the baking process for foods. This helps minimize the occurrence of defective products.

Effect of basil seed gum coating and ultrasound pretreatment on frying time, oil uptake, hardness, color indexes, and sensory properties of potato slices

Fried food products have low oil content with improved nutritional quality, higher crispiness, and better sensory attributes. Edible coatings can decrease the excessive oil uptake in deep-fat fried food products. Furthermore, ultrasound treatment before frying process decreased oil uptake of food products. So, in this study, the impact of gum edible coating and ultrasonic pretreatment (at two different power levels of 75 and 150 W) on the frying time of potato slices, and moisture percent, oil uptake, texture hardness, surface area change, color parameters (lightness, redness, yellowness, and total color change), and sensory attributes of fried potato slices were examined. Edible coating with basil seed gum (BSG) and ultrasonic pretreatment significantly increased the frying time of the slices (p < 0.05). The average moisture content of the fried slices changed from 49.48 % to 60.55 %, and was further increased by edible coating and ultrasonic treatment. The highest (26.92 %) and lowest (14.56 %) oil uptake were for the uncoated and coated-sonicated (150 W) fried potato slices, respectively. The ultrasound pretreatment significantly increased the hardness of fried potato slices (p < 0.05). The low and high intensity ultrasonic pretreatment (75 W and 150 W, respectively) significantly decreased the crust area change of fried potato slices (p < 0.05). The average lightness index of the fried samples changed from 63.30 to 71.58, and increased with increasing ultrasonic power. The minimum redness, yellowness, and total color change indexes were for the coated and high-power sonicated (150 W) samples, respectively. The highest appearance, odor, texture, flavor, and overall acceptance were for the coated and high-power sonicated (150 W) sample.

Synergistic Effect of Advanced Refractance Window Drying on Quality Characteristics of Potato Slices and Numerical Process Optimization

Synergistic Effect of Advanced Refractance Window Drying on Quality Characteristics of Potato Slices and Numerical Process Optimization

Effect of different pre-treatments on the physical properties, frying kinetics and organoleptic physiognomies of fried sweet potato (Ipomoea batatas) chips

The study explored the effects of different pre-treatments: freezing pre-treatment (FP), osmotic dehydration (OSD) and air-drying pre-treatments (ADP) on the physical and quality properties of fried sweet potato. The physical and quality properties of pre-treated fried sweet potato slices were assessed for percentage weight loss after frying, shrinkage ratio, the kinetics of moisture loss (frying kinetics), organoleptic properties and mathematical modeling of fried sweet potato slices. The results showed that OSD of pre-treated fried sweet potato slices recorded the highest percentage weight loss (46 %) and lowest shrinkage ratio (19 %) after frying compared to the ADP (41.5 %, 36 %) and FP (36.5 %, 46 %) fried sweet potato samples, respectively. OSD pre-treated fried sweet potato preserved the sensory properties of the ADP and FP fried sweet potato compared to the untreated sample. Among the three pre-treatments, OSD was found to enhance the frying kinetics compared to the ADP and FP samples. First order model best fitted well to the experimental results of frying kinetics (R2 > 0.99) compared to Page model.

Mitigation of acrylamide in fried food systems using a combination of zein-pectin hydrocolloid complex and a food-grade l-asparaginase

Acrylamide, a Maillard reaction product, formed in fried food poses a serious concern to food safety due to its neurotoxic and carcinogenic nature. A “Green Approach” using L-Asparaginase enzyme from GRAS-status bacteria synergized with hydrocolloid protective coating could be effective in inhibiting acrylamide formation. To fill this void, the present study reports a new variant of type-II L-asparaginase (AsnLb) from Levilactobacillus brevis NKN55, a food-grade bacterium isolated using a unique metabolite profiling approach. The recombinant AsnLb enzyme was characterized to study acrylamide inhibition ability and showed excellent specificity towards L-asparagine (157.2 U/mg) with Km, Vmax of 0.833 mM, 4.12 mM/min respectively. Pretreatment of potato slices with AsnLb (60 IU/mL) followed by zein-pectin nanocomplex led to >70% reduction of acrylamide formation suggesting synergistic effect of this dual component system. The developed strategy can be employed as a sustainable treatment method by food industries for alleviating acrylamide formation and associated health hazard in fried foods.

Effect of Adding Vitamin to Cooking Oil on Peroxide Value

The aim of this research is to reduce the number of peroxides in two frying oil samples by using one of the natural antioxidants which is vitamin E, one of the chemical specifications that assess the oil is the peroxide number, which is the number of free radicals formed in the oil and the number of peroxides increases during exposure to heat, moisture, oxygen, bad storage conditions, light or other conditions. These peroxides have a harmful effect on the consumer health (Carcinogenic substances). The vitamin E had a clear impact on the peroxide value, as when conducting the experiment and using oil to fry potato slices, the number of peroxides was high before adding vitamin E which score approximately (Peroxide number is 5.6 for 15 minutes, 9.8 for 30 minutes, and 11.6 for 45 minutes). After using vitamin E in amount of 10 microgram per 100 ml of oil, the effect was clear of vitamin E on the number of peroxide as it decreased significantly. Which scored (5 for 15 minutes, 8.1 for 30 minutes, 8.9 for 45 minutes), When vitamin E added by 20 microgram the result was (4.8 for 15 minutes, 5.5 for 30 minutes, 6.5 for 45 minutes). 50 micrograms per 100 oils shown to have no significant effect on the peroxide value. it was found that the best concentration is 20 micrograms for a sample of 100 ml of oil.

Experimental testing on the performance of solar dryer equipped with evacuated tube collector, rock bed heat storage and reflectors

Agricultural products can be dried in an open sun; but such drying method has poor quality of the product causes to grow bacteria and microorganisms and long drying time. In order to alleviate those draw backs of open sun drying, direct solar dryers were developed; but this type of dryer reduces the product quality due to direct exposure of solar radiation. Then, an indirect solar dryer became more important and efficient method. However, the most solar dryers were developed with less efficient flat plate solar collectors. A few solar dryers were developed using efficient solar collector called evacuated tube solar collector (ETC) but they have low overall performance. The goal of this research is to create a dependable solar dryer system for drying agricultural products. It was a solar dryer system with an independent rock bed thermal storage unit and an evacuated tube collector having reflectors. In this case, a rock bed has been a well-insulated with thermal insulation and its top surface is covered by a transparent double-glass. This system is intended to dry potato slice that weigh of 7.5 kg sample having a wet base initial moisture level of 80.1 %, until it reaches the ideal moisture content of 7–13 %. The solar dryer has been developed from drying chamber having size of (length x breadth x height) of 85 cm×61 cm x 62 cm, evacuated tube collector area of 1.3 m2, and rock bed volume of 0.137 m3 (with a solar absorber area of 0.52 m2 and a depth of 0.26 m). The solar dryer system was built and tested with loading slices at various air flow rates and open sun. Here, at a 0.016 m3/s air flow rate as compared to lower and higher air flow rates, more moisture reduction (9.3 % within eight hours and 0.664 kg/h), higher efficiency of the solar collector (62.02 %), more heat production from the system (20.79 MJ, of which 4837.8 kJ was recovered from the rock bed), and higher dryer efficiency (23.87 %) were attained. Compared to open-sun drying, 20 % less time was needed for drying. In addition, the study examined the significance of the reflectors and the rock bed. In comparison to the situation of utilizing ETC alone and 30 % of the drying period in relation to the open sun, the introduction of a reflector on the collector increased the average net heat obtained from the collector by 5.1 %. In another instance, the slice's moisture content was lowered to 12.37 % in under eight hours using ETC alone, while the dryer's efficiency was 29.82 %. However, the drying rate rise by 3.7 % in comparison to the dryer equipped with ETC alone because of the enhanced heat output in the dryer, which used ETC with a rock bed's help.

Pulsed electric field effect on acrylamide reduction and quality attributes of continuous-style Lamoka potato chips

Potato chips are a popular snack, well-liked because of their texture-flavor combination. Potato chips are made by frying slices of potato in vegetable oil to achieve a crispy texture. Frying potato slices initiates the Maillard reaction, resulting in chemical changes that enhance taste, color, and texture, but also undesired acrylamides, which are suspected carcinogens. The application of pulsed electric field (PEF) technology is commonly used in French fry processing operations to prolong cutting blade sharpness and reduce waste, energy consumption, and water usage. Despite these attributes, PEF systems have not yet gained widespread adoption by potato chip producers. In the current study, Lamoka potatoes were PEF-treated prior to continuous frying into potato chips. The effect of specific energy at 0.75 kJ/kg (Low-PEF) and 1.5 kJ/kg (High-PEF) and electric field strength of 1 kV/cm, frequency of 24 kV, and pulse width of 6 μs versus untreated (control) samples was studied, then batches of 250 g of slices were fried at 170 °C or 185 °C for two frying times to obtain potato chips with acrylamide levels below the California Proposition 65 limit (275 ng/g). The Lamoka potato chip product quality metrics that were assessed include moisture, fat, reducing sugars, asparagine, acrylamide, chip color, and texture. PEF treatment of Lamoka potatoes resulted in chips fried in 10 % less time, lower oil content by 8 %, and a decrease of reducing sugars by 19.2 %, asparagine by 42.0 %, and acrylamide by 28.9 %. The PEF fried chips were lighter in color but maintained textural attributes compared to continuous frying cooking. The process of frying potato slices at 170 °C for 150 s with High-PEF yielded potato chips with acrylamide content below the California Proposition 65 limit; which speaks to the health implications for consumers and the quality and safety of these chips.

The use of chitosan aerogels as an adsorbent for the regeneration of frying oil

One of the most commonly used food preparation methods is deep-fat frying. The improvement of the quality of used frying oil (UFO) is important because the reuse of frying oil could provide significant savings to the food industry. This study aimed to enhance the quality of used sunflower oil by using chitosan aerogels (CA), which can be considered as novel adsorbents with an increased surface area compared to chitosan powder. Aerogels are novel nanostructured materials with high porosity and large surface area. In this study, CA were produced by drying the 2% (w/v) chitosan gels using supercritical drying. In the study, 32 consecutive deep-fat frying were performed using potato slices in sunflower oil at 180 ± 5 °C. The effect of the adsorbent concentration (0.5, 1, and 2% (w/w)) and different adsorption temperatures (90, 135, and 180 °C) were studied by examining the UFO before and after the adsorption treatments. The physicochemical properties of the oil were analyzed by determining free fatty acid (FFA) content, total polar compounds (TPC), smoke point, p-anisidine value (p-AnV), and color (CIE L*, a*, b*). Moreover, the structural changes of aerogels after the adsorption process were investigated by Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). CA could reduce the % FFA values from 0.44% to 0.18% due to the ionic interaction between CA and FFA. In addition, TPC value and the smoke point increased after the treatments. The p-AnV was compensated with CA, indicating that secondary oxidation products were adsorbed. Moreover, CA caused a darker color after the adsorption treatments. Additionally, compared with magnesium silicate, the same concentrations of CA were found more effective in improving all the quality parameters of oil except for the L* values.

Genipin crosslinked L-asparaginase CLEAs effectively mitigate acrylamide in deep-fried sweet potato chips

Crosslinked enzyme aggregates of L-asparaginase (A-CLEAs) were prepared using genipin, a non-toxic crosslinker. The process parameters for the preparation of A-CLEAs were optimized using a 3-level factorial design, which predicted the optimized conditions to be 60 mg/mL BSA, 2 mg/mL genipin and a crosslinking time of 4 h. The model which was validated experimentally, resulted in a recovery of 90% activity of L-asparaginase. While the optimum pH shifted to a slightly acidic range, the optimum temperature remained unchanged. A-CLEAs displayed the best pH stability at pH 9 (48%) after 24 h of incubation. At 50 °C, the deactivation rate constant (Kd) of A-CLEA decreased by 24%. A-CLEAs showed excellent reusability, retaining 79% of their initial activity after 10 cycles of use. The formation of a dark-blue coloured pigmented A-CLEA and the presence of the carboxymethyl group of genipin in FTIR spectrum confirmed the crosslinking reaction. The increase in the β-sheet content of A-CLEA, correlated with its improved stability. The improved thermostability with regards to structural integrity was well established by TGA-DSC analyses. Morphologically, A-CLEAs showed a highly clustered ball-like appearance. As a model example, the ability of genipin crosslinked A-CLEAs to reduce acrylamide in sweet potato chips was checked. The asparagine content of sweet potato was found to be 2906 ± 15.02 mg/kg as quantified by HPTLC. Analysis of acrylamide by GC-FID showed a 94% reduction in sweet potato chips on contact of sweet potato slices with A-CLEAs for 40 min.

Green synthesis of metal nanoparticles and study their anti-pathogenic properties against pathogens effect on plants and animals

According to an estimate, 30% to 40%, of global fruit are wasted, leading to post harvest losses and contributing to economic losses ranging from $10 to $100 billion worldwide. Among, all fruits the discarded portion of oranges is around 20%. A novel and value addition approach to utilize the orange peels is in nanoscience. In the present study, a synthesis approach was conducted to prepare the metallic nanoparticles (copper and silver); by utilizing food waste (Citrus plant peels) as bioactive reductants. In addition, the Citrus sinensis extracts showed the reducing activity against metallic salts copper chloride and silver nitrate to form Cu-NPs (copper nanoparticles) and Ag-NPs (Silver nanoparticles). The in vitro potential of both types of prepared nanoparticles was examined against plant pathogenic bacteria Erwinia carotovora (Pectobacterium carotovorum) and pathogens effect on human health Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Moreover, the in vivo antagonistic potential of both types of prepared nanoparticles was examined by their interaction with against plant (potato slices). Furthermore, additional antipathogenic (antiviral and antifungal) properties were also examined. The statistical analysis was done to explain the level of significance and antipathogenic effectiveness among synthesized Ag-NPs and Cu-NPs. The surface morphology, elemental description and size of particles were analyzed by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy and zeta sizer (in addition polydispersity index and zeta potential). The justification for the preparation of particles was done by UV–Vis Spectroscopy (excitation peaks at 339 nm for copper and 415 nm for silver) and crystalline nature was observed by X-ray diffraction. Hence, the prepared particles are quite effective against soft rot pathogens in plants and can also be used effectively in some other multifunctional applications such as bioactive sport wear, surgical gowns, bioactive bandages and wrist or knee compression bandages, etc.

Comprehensive study on potato drying in convective air dryer: experimental observations, mathematical modeling, and model validation

We studied the drying kinetics of sliced potatoes (Solanum tuberosum) using a tray dryer. An experiment was conducted on how the drying rate was impacted by air temperature, sample thickness, and air velocity. The study was conducted under varying temperature ranges (50°C, 60°C, and 70°C), air velocities (0.6 ms−1, 0.7 m s−1, and 0.8 m s−1), and potato slice thickness (2 mm, 4 mm, and 6 mm). The findings revealed that a higher air temperature was correlated with an increase in the drying rate, while thicker layers demonstrated a decrease in the drying rate. We further evaluated five mathematical models, with the Page Model emerging as the most suitable based on the lowest residual standard error (RSE) and Akaike's Information Criteria (AIC), which are 0.06421 and -1123.947, respectively. After plotting the predicted moisture ratio against the experimental moisture ratio, we observed an exceptional predictive accuracy (R2 > 0.99) across various conditions. These findings underscore the critical importance of precise parameter control for optimizing potato drying processes in industrial settings, providing valuable insights for enhanced efficiency and resource utilization. Further exploration into real-time optimization and scalability can extend the practical applications of this study.

In vitro and in vivo antifungal efficacy of individual and consortium Bacillus strains in controlling potato black scurf and possible development of spore-based fungicide

Potato is a major crop whose yield and quality are impacted by the pathogenic fungus Rhizoctonia solani. Here, a control approach based on the use of endophytic bacillus spores and bacterial consortia was assessed as an innovative solution to improve tuber productivity and health. Endophytic potato bacteria extracted from several organs (leaves, stems and roots) evaluated for their antagonistic activity against R. solani by the double culture technique and their ability to rot potato slices. Additionally, the ability of Bacillus strains to generate hydrolytic enzymes and produce lipopeptides (using ESI-MS/MS mass spectrometry) was assessed. Then, the effectiveness of selected bacterial strains, either individually or in consortium (after carrying out compatibility tests) in the suppression of R. solani was evaluated in the greenhouse. Six endophytes not affecting potato tubers and having an antagonistic effect against R. solani were identified: B. halotolerans SpS5, B. velezensis KnL15, B. aryabhattai FaR1, B. amyloliquefaciens LiR9, B. haynesii ReR10 which produce several types and combinations of lipopeptides belonging to different families (iturins, fengycins and surfactins) as well as hydrolytic enzymes (chitinase, protease and cellulase). The vegetative and sporulating strain SpS5, as well as the 5 other Bacillus and their Sps5-based consortia, were found to be very effective in increasing the yield of healthy, high-quality tubers and reducing disease severity. Based on the results mentioned above, a microbial fungicide from the spores of (i) B. halotolerans SpS5 for which we sequenced the whole genome or (ii) bacterial consortia could be developed to combat black scurf potato and other fungal infections.

MzmL, a novel marine derived N-acyl homoserine lactonase from Mesoflavibacter zeaxanthinifaciens that attenuates Pectobacterium carotovorum subsp. carotovorum virulence.

Quorum sensing (QS) is a conserved cell-cell communication mechanism widely distributed in bacteria, and is oftentimes tightly correlated with pathogen virulence. Quorum quenching enzymes, which interfere with QS through degrading the QS signaling molecules, could attenuate virulence instead of killing the pathogens, and thus are less likely to induce drug resistance. Many Gram-negative bacteria produce N-acyl homoserine lactones (AHLs) for interspecies communication. In this study, we isolated and identified a bacterial strain, Mesoflavibacter zeaxanthinifaciens XY-85, from an Onchidium sp. collected from the intertidal zone of Dapeng Reserve in Shenzhen, China, and found it had strong AHL degradative activity. Whole genome sequencing and blast analysis revealed that XY-85 harbors an AHL lactonase (designated MzmL), which is predicted to have an N-terminal signal peptide and share the "HXHXDH" motif with known AHL lactonases belonging to the Metallo-β-lactamase superfamily. Phylogenetic studies showed MzmL was closest to marine lactonase cluster members, MomL and Aii20J, instead of the AiiA type lactonases. Ultra performance liquid chromatography-mass spectrometry analysis confirmed that MzmL functions as an AHL lactonase catalyzing AHL degradation through lactone hydrolysis. MzmL could degrade both short- and long-chain AHLs with or without a substitution of oxo-group at the C-3 position, and retained full bioactivity under a wide range of temperatures (28-100°C) and pHs (4-11). Furthermore, MzmL significantly reduced Pectobacterium carotovorum subsp. carotovorum virulence factor production in vitro, such as biofilm formation and plant cell wall degrading enzyme production, and inhibited soft rot development on potato slices. These results demonstrated that MzmL may be a novel type of AHL lactonase with good environmental stability, and has great potential to be developed into a novel biological control agent for bacterial disease management.