Cucumber Fermentation Research Articles

Prospects of fibrinolytic proteases of bacteria from sea cucumber fermentation products as antithrombotic agent

Cardiovascular disease is among the largest contributors of premature mortality in the world caused by inflammation of blood vessels. The abnormalities provoke thrombus formation or thrombosis blocking blood vessels leading to strokes, heart attacks and coronary artery diseases. Increasing percentage of cardiovascular cases and deaths due to thrombosis has attracted researchers to look for newer thrombolysis agents. Commonly used drugs to treat thrombosis has been limited due to various side effects. Therefore, the search for sources of safer and cheaper fibrinolytic enzymes for handling thrombolysis continues. This study aimed to evaluate potentials of fibrinolytic protease of bacteria isolated from fermented seafood (sea cucumber) products as antithrombotic agents. Information was initially gathered from scientific publications identified using web-based tools including PubMed (National Center for Biotechnology Information), Science Direct (Scopus) and Web of Science (Thomson Reuters) using combinations of search terms including “fibrinolytic enzyme protease”, “endopeptidase”, “fermented food”, “sea cucumber”, “thrombolysis therapy,” “thrombolytic agent,” “fibrinolytic bacteria,” “fibrinolysis,” “protease producing bacteria,” “fibrin degradation,” “holothurians,” etc. We also searched for these terms in national and international organization technical reports and databases. This literature review reveals the prospects of fibrinolytic protease enzymes from bacteria from fermented seafood, particularly sea cucumber as novel antithrombotic agents.

Comparative genomics of eight Lactobacillus buchneri strains isolated from food spoilage

BackgroundLactobacillus buchneri is a lactic acid bacterium frequently associated with food bioprocessing and fermentation and has been found to be either beneficial or detrimental to industrial food processes depending on the application. The ability to metabolize lactic acid into acetic acid and 1,2-propandiol makes L. buchneri invaluable to the ensiling process, however, this metabolic activity leads to spoilage in other applications, and is especially damaging to the cucumber fermentation industry. This study aims to augment our genomic understanding of L. buchneri in order to make better use of the species in a wide range of applicable industrial settings.ResultsWhole-genome sequencing (WGS) was performed on seven phenotypically diverse strains isolated from spoiled, fermented cucumber and the ATCC type strain for L. buchneri, ATCC 4005. Here, we present our findings from the comparison of eight newly-sequenced and assembled genomes against two publicly available closed reference genomes, L. buchneri CD034 and NRRL B-30929. Overall, we see ~ 50% of all coding sequences are conserved across these ten strains. When these coding sequences are clustered by functional description, the strains appear to be enriched in mobile genetic elements, namely transposons. All isolates harbor at least one CRISPR-Cas system, and many contain putative prophage regions, some of which are targeted by the host’s own DNA-encoded spacer sequences.ConclusionsOur findings provide new insights into the genomics of L. buchneri through whole genome sequencing and subsequent characterization of genomic features, building a platform for future studies and identifying elements for potential strain manipulation or engineering.

Agroindustrial waste as a resource for volatile fatty acids production via anaerobic fermentation

This study evaluated the feasibility of the anaerobic digestion as a sustainable valorisation strategy for volatile fatty acids production from agroindustrial waste (cucumber, tomato and lettuce). High bioconversion efficiencies were reached by operating the reactors at 25 °C, 3 g VS·d−1·L−1 with pH adjustment. Cucumber fermentation achieved the highest bioconversion (52.6%), whereas tomato degradation was the least efficient bioprocess (40.1%) due to the low pH (5.6) that partially inhibited the hydrolytic and acidogenic activities. In all cases, carboxylic acid profiles were mainly composed of volatile fatty acids with even carbon number. The developed microbial community exhibited high hydrolytic and acidogenic activities associated to carbohydrates degradation. This microbial population was dominated by Firmicutes phylum and showed a lack of acetogenic bacteria related with CH4 production, resulting in a remarkably high VFAs accumulation.

Culture fermentation of Lactobacillus in traditional pickled gherkins: Microbial development, chemical, biogenic amine and metabolite analysis.

Fermented cucumber pickles are the lactic acid fermentation products formed through the influence of microorganisms present in the environment. This study investigated the impacts of starter cultures, namely, Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus paraplantarum, typically utilized for the fermentation of traditional pickled gherkins, on fermentation process. The chemical (pH, total acidity and salt) and microbiological (total mesophilic aerobic bacteria, lactic acid bacteria and yeast-mould) changes were observed against the control sample during fermentation process. Moreover, the amounts of biogenic amines (BAs) and metabolites formed as a consequence of fermentation were determined using HPLC. It was found that the chemical analyses provided similar results for all the samples. The amount of total mesophilic aerobic bacteria and yeast-mould colonies in pickle sample containing L. plantarum 49 strain appeared to reduce significantly. The amount of BAs was the lowest for the pickle samples where L. plantarum strains were added. The amount of BAs was below the toxic value that could affect human health. More BAs were synthesized as the fermentation period increased. Lactate was seen to exist in the samples when pyruvate was present, and acetoin was converted into 2.3-butanediol during the fermentation period. It was concluded that the pickle sample for which L. plantarum 49 strain was used displayed a better fermentation profile (i.e., metabolite and biogenic amines) than the remaining samples. Producing a more delicious and reliable product using such characteristics of L. plantarum strains in pickled gherkins is believed to significantly contribute to the food industry.

Fermentation of Cucumber Extract with Hydromagnesite as a Neutralizing Agent to Produce an Ingredient for Dermal Magnesium Products.

Magnesium is an essential element involved in various biochemical processes in the human body. In addition to oral supplementation, topical magnesium application is another conventional form of magnesium delivery for the treatment of skin diseases and muscle inflammation. Cucumber extract is a well-known superfood for human skin. It has been widely used in various skincare product lines because of its known benefits to the skin. The benefit of cucumber extract to the human skin would be significantly enhanced if the cucumber extract was fermented to convert the reducing sugars to beneficial organic acids. In this study, we developed a protocol for lactic acid fermentation of cucumber extract using hydromagnesite as a neutralizing agent. Various lactic acid bacteria were screened for fermentation of cucumber extract. The best fermenting performance was observed with Lactobacillus paracasei, which could convert approximately 13 g/L of reducing sugars (glucose and fructose) to lactic acid and a minor amount of acetic acid within 2 days of incubation. The final fermented cucumber extract contains magnesium in the form of salts of organic acids, which have high absorption ability and bioavailability. The product is a potent ingredient for producing dermal magnesium products.

Effect of Brine Acidification on Fermentation Microbiota, Chemistry, and Texture Quality of Cucumbers Fermented in Calcium or Sodium Chloride Brines.

Commercial fermentation for bulk preservation of cucumbers relies on natural microbiota and approximately 1 M sodium chloride (NaCl) brines, resulting in large volumes of high-salt wastewater. An alternative process utilizing 0.1 M calcium chloride (CaCl2 ) as the only salt was developed to eliminate NaCl from fermentation brines for reduced environmental impact. This study determined the effect of brine acidification on the fermentation microbiota and texture quality of cucumbers fermented in CaCl2 brines. Cucumber fermentations were conducted in sealed glass jars for six independent lots of cucumbers in a randomized complete block design with a full-factorial treatment structure for brine acidification (acetic acid, hydrochloric acid, or nonacidified) and brining salt (1 M NaCl or 0.1 M CaCl2 ). Enterobacteriaceae spp. survived longer and were >1 log colony forming units/mL higher in fermenting cucumbers than in brines. Addition of 25 mM acetic acid to fermentation brines (but not the addition of hydrochloric acid at the same pH) reduced Enterobacteriaceae spp. in brines and cucumbers (P < 0.002) during the initiation of fermentation for both brining salts. However, acidification had no effect on texture quality of fermented cucumbers (P = 0.8235). Despite differences in early fermentation microbiota, fermentation of cucumbers in calcium chloride brines under controlled conditions, with or without acidification, resulted in high retention of tissue firmness. These results differ from fermentations in a commercial setting initiated in brines of neutral pH, indicating that production variables, such as air exposure, interact with brining in CaCl2 to negatively affect the texture quality of fermented cucumbers. PRACTICAL APPLICATION: This study examined the effects of initial brine acidification on the course of lactic acid fermentation and resulting texture quality of cucumbers fermented in calcium or sodium salt brines. Fermentation brines containing acetic acid (the acid in vinegar) reduced the pH of the cucumber and the soil-associated Enterobacteriaceae spp. most rapidly, and favored the conversion of sugars to lactic acid. Interestingly, the texture quality was not affected by brine acidification, and all cucumbers fermented in calcium brines in the absence of air retained their firmness during fermentation and bulk storage.

NEW APPROACH FOR FAST SCREENING OF LACTIC ACID BACTERIA FOR VEGETABLE FERMENTATION

The main goal of this research was to select a Lactobacillus plantarum strains which could be used as starters for fermented vegetables production. A total of 109 L. plantarum strains were screened based on their ability to drop the pH value in pasteurized vegetable-based media (without and with NaCl) after 8 h incubation. The effect of NaCl on the level of acidification after 8 h incubation was more dependent not on its concentration but on the vegetable-based medium and L. plantarum strain. Four L. plantarum strains were selected and used for lab-scale fermentation of cabbage and cucumbers, this resulted in an accelerated acidification of the vegetables in comparison with the spontaneous fermentation. Strong positive correlations between the differences of initial pH value and the values reached after fermentation during 8 h (ΔpH) on vegetable-based media and vegetable fermentations, suggests that the screening process in vegetable-based media after 8 h incubation could be effective. Four L. plantarum strains, selected in this study, can be used as starters for fermented vegetables.

Effect of putative probiont Enterococcus hirae on the hematological parameters of juvenile African catfish, Clarias gariepinus (Burchell, 1822) during pre- and post-challenge against Aeromonas hydrophila

Probiotics have been widely known to have the ability to improve the immune system of livestock and aquatic animal. The present study was carried out to evaluate the effect of dietary supplementation of two probiotic isolates of Enterococcus faecium on hematological parameters of juvenile African catfish, Clarias gariepinus during pre- and post-challenge with aquatic pathogen, Aeromonas hydrophila. The probiotics were previously isolated from vegetable wastes (mung bean sprouts, Vigna radiate and cucumber, Cucumis sativus) which have been fermented for 7 days. The experimental fish (270 tails) with an average weight of 5.13 ± 1.03 g were distributed and divided randomly into i) control (30 tails), fed with commercial diet ii) E1 (30 tails), fed with diets supplemented with 108 CFU/ml of E. faecium isolated from fermented cucumber, iii) E2 (30 tails), fed with 108 CFU/ml of E. faecium isolated from fermented mung bean sprouts. The feeding trial was conducted for 50 days. All experimental groups were then challenged with A. hydrophila (1.5 × 106 CFU/mL) via intraperitoneal injection on day 51. Prior to challenge, blood samples were collected from five fish randomly selected from each group on the day 51 (pre-challenge). After 72 hours of post-challenge, blood samples were again collected from five fish from each groups. The hematological parameters such as total erythrocyte count (RBC), total leucocyte count (WBC), packed cell volume (PCV), hemoglobin (Hb), the derived blood indices of mean corpuscular volume (MCV) and corpuscular hemoglobin concentration (MCHC) were examined. Hematological profiles of pre- and post-challenge infected juvenile catfish were compared with the control groups. The RBC, Hb, WBC, PCV, MCV and MCHC of fish fed with probiotics showed higher significant difference (P&lt;0.05) as compared to control groups during pre- and post-challenge of pathogen. The high level of RBC and WBC during pre- and post-challenge showed the capability of the probiotics to improve the immune response of juvenile African catfish and thus increased the fish disease resistance against A. hydrophila infection. The result suggested that E. faecium could be used effectively as a probiotic in aquaculture.

Assessment of the non-lactic acid bacteria microbiota in fresh cucumbers and commercially fermented cucumber pickles brined with 6% NaCl

Limited documentation of the cucumber fermentation microbiome has impeded the understanding of the role of microbes on the quality of finished products. We characterized the microbiome of fresh and fermented cucumber samples using culture dependent and independent techniques, with an emphasis on the non-lactic acid bacteria (non-LAB) population. Insubstantial microbiome variations were observed among fresh cucumber types with Rhizobium (31.04%), Pseudomonas (14.08%), Pantoea (9.25%), Stenotrophomonas (6.83%), and Acinetobacter (6.5%) prevailing. The relative abundance of LAB remained below 0.4% and 4.0% on fresh cucumbers and day 3 of the fermentations brined with 6% sodium chloride, respectively. Fermentation cover brine samples collected on day 1 harbored Pseudomonas, Pantoea, Stenotrophomonas, Acinetobacter, Comamonas, Wautersiella, Microbacterium, Flavobacterium, Ochrobactrum and the Enterobacteriaceae, Citrobacter, Enterobacter and Kluyvera. Plate counts for presumptive Klebsiella and Pseudomonas from fermentation cover brine samples reached 2.80 ± 0.36 and 2.78 ± 0.83 log of CFU/mL, respectively, in 30% and 60% of the nine tanks scrutinized with selective media. Both genera were found in cover brine samples with pH values at 4.04 ± 0.15. We aim at elucidating whether the low relative abundance of non-LAB in commercial cucumber fermentations, in particular Pseudomonas and Enterobacteriaceae, impacts the quality of fermented cucumbers.

Screening of lactic acid bacteria with cholesterol-lowering and triglyceride-lowering activity in vitro and evaluation of probiotic function

To screen the lactic acid bacteria with cholesterol-lowering and triglyceride-lowering activity in vitro and evaluate their probiotic function. By plate separating, cholesterol-lowering and triglyceride-lowering activity in vitro were determined; and by evaluating the probiotic functions, including tolerances to simulated gastric and intestinal juice, the antibacterial spectrum, and the adhesion ability to Caco-2 cells, the probiotic strains with cholesterol-lowering and triglyceride-lowering activity in vitro were screened, and then were identified by phenotypical and physiological tests and 16Sr DNA. Finally, the cholesterol-lowering and triglyceride-lowering activity in vivo of the strains were evaluated using male Sprague-Dawley rats. Two strains L2-16 and L2-73 with stronger cholesterol-lowering and triglyceride-lowering activity in vitro, stronger tolerance to simulated gastric and intestinal juice and adhesion ability to Caco-2 cells, and wider antibacterial spectrum were screened from traditional Chinese fermented cucumber and were identified as Lactobacillus acidophilus and Enterococcus faecalis, respectively. Compared with a hyperlipidemia diet without lactic acid bacteria, the diet supplemented with Lactobacillus acidophilus L2-16 and Enterococcus faecalis L2-73 significantly reduced serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels, and liver total cholesterol and triglyceride levels in rats (P < 0.05). Moreover, the diet supplemented with Lactobacillus acidophilus L2-16 and Enterococcus faecalis L2-73 significantly increased the fecal elimination of bile acids (P < 0.05). Lactobacillus acidophilus L2-16 and Enterococcus faecalis L2-73 may have application prospect in the production of some fermented foods such as fermented vegetables, milk, or meat, and probiotic preparations with the function to lower the serum lipid and liver lipid levels.

Discovery and quantification of bioactive peptides in fermented cucumber by direct analysis IR-MALDESI mass spectrometry and LC-QQQ-MS

Bioactive peptides have been identified in lactic acid bacteria fermented foods including cultured milk, sourdough, and cured meats; however, their presence has not been investigated in fermented vegetables. In this study, infrared, matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry (MS) was employed to identify bioactive peptides in fermented cucumber. Natural and starter culture fermented cucumbers were prepared in triplicate in sodium chloride brines and compared to acidified cucumbers. Putative matches of known food-derived bioactive peptides were identified by direct analysis using IR-MALDESI-MS. Peptides were confirmed by IR-MALDESI MS/MS and quantified by LC-MS/MS. Three angiotensin converting enzyme (ACE) inhibitory peptides, IPP (0.42–0.49 mg/kg), LPP (0.30–0.33 mg/kg), and VPP (0.32–0.35 mg/kg) were formed in fermented cucumbers. A fourth ACE inhibitory peptide, KP (0.93–1.5 mg/kg), was enhanced 3–5 fold in fermented cucumbers compared with acidified cucumbers. This work demonstrates that lactic acid bacteria fermentation can enhance bioactive peptide content in vegetables.

THE STUDY OF DYNAMIC DESTRUCTION GLUCOSE AT THE DIRECTED FERMENTATION OF CUCUMBERS WITH USE OF LACTIC ACID BACTERIA

The article presents the results of the study of the directed fermentation of cucumbers using strains of lactic acid microorganisms (lactic acid bacteria) in order to intensify the fermentation process and to obtain a finished product of good quality (with good taste, aroma and structure), as on an industrial scale starter cultures are practically not used. The aim of our research was to study the dynamics of glucose degradation in the process of directed fermentation of cucumbers varieties "Vodoley" using lactic acid bacteria and their selection for this process. As strains of lactic acid microorganisms we selected the following: Lactobacillus casei VKM 536, Lactobacillus plantarum VKM V-578, Lactobacillus brevis VKM V-1309. In order to create optimal conditions for the development of the target microflora, to determine the degree of glucose destruction by various strains of microorganisms and to obtain comparative results, all experiments were carried out on model environment. During the research, mathematical models were developed that adequately describe the degree of glucose destruction during the fermentation of cucumbers. Mathematical processing of glucose degradation data in the direct fermentation process was carried out using Microsoft Excel and the SYSTAT TableCurve 2D. It was found that the criterion for the intensity of glucose destruction during the fermentation of cucumbers varieties "Vodoley" is the most adequate use of the investigated strains of lactic acid bacteria L. brevis and L. plantarum. The use of these lactic acid bacteria provides maximum process efficiency (the maximum acceptable duration is 4,47 and 5,36 days when the degree of glucose destruction is more than 99% of the asymptotic value). The use of L. brevis and L. plantarum allows to achieve the maximum degree of glucose destruction, which indicates the potential usefulness of these types of lactic acid bacteria.

Phenotypic and genotypic diversity of Lactobacillus buchneri strains isolated from spoiled, fermented cucumber

Lactobacillus buchneri is a Gram-positive, obligate heterofermentative, facultative anaerobe commonly affiliated with spoilage of food products. Notably, L. buchneri is able to metabolize lactic acid into acetic acid and 1,2-propanediol. Although beneficial to the silage industry, this metabolic capability is detrimental to preservation of cucumbers by fermentation. The objective of this study was to characterize isolates of L. buchneri purified from both industrial and experimental fermented cucumber after the onset of secondary fermentation. Genotypic and phenotypic characterization included 16S rRNA sequencing, DiversiLab® rep-PCR, colony morphology, API 50 CH carbohydrate analysis, and ability to degrade lactic acid in modified MRS and fermented cucumber media. Distinct groups of isolates were identified with differing colony morphologies that varied in color (translucent white to opaque yellow), diameter (1 mm–11 mm), and shape (umbonate, flat, circular or irregular). Growth rates in MRS revealed strain differences, and a wide spectrum of carbon source utilization was observed. Some strains were able to ferment as many as 21 of 49 tested carbon sources, including inulin, fucose, gentiobiose, lactose, mannitol, potassium ketogluconate, saccharose, raffinose, galactose, and xylose, while others metabolized as few as eight carbohydrates as the sole source of carbon. All isolates degraded lactic acid in both fermented cucumber medium and modified MRS, but exhibited differences in the rate and extent of lactate degradation. Isolates clustered into eight distinct groups based on rep-PCR fingerprints with 20 of 36 of the isolates exhibiting >97% similarity. Although isolated from similar environmental niches, significant phenotypic and genotypic diversity was found among the L. buchneri cultures. A collection of unique L. buchneri strains was identified and characterized, providing the basis for further analysis of metabolic and genomic capabilities of this species to enable control of lactic acid degradation in fermented plant materials.

Physical properties of NaCl-free cucumber fermentation cover brine containing CaCl2and glycerin and apparent freezing injury of the brined fruits

Use of glycerin and CaCl2 to reduce the freezing point and improve quality of bulk stored fermented cucumbers brined without NaCl, was explored. The incidence of pre-freezing injury on the fruits, caused by deposition in tanks containing cushion brine prepared with 2.5% CaCl2, was excluded by determining the liquid and fruits densities and buoyancy force. The NaCl-free cover brine thermal properties and freezing point, and the frozen fruits water loss were determined to estimate freezing damage. Cover brines supplemented with 14.5% glycerin, 18% CaCl2, or 14% glycerin and 5% CaCl2 were needed to match the freezing point of the 6% NaCl cover brine, typically used for fermentation. Thermal properties of the NaCl-free cover brine were insignificantly affected by temperature or composition. Water loss was the main freezing injury in brined cucumbers. Supplementation of CaCl2 and/or glycerin in fermentation cover brines helped minimize fermented cucumbers water loss associated with freezing. Practical applications This study presents an assessment of brine composition that can prolong processed pickle quality and bulk storage at temperatures below zero. Fermented cucumbers stored in cover brine containing 14.5 vol % glycerin, 18 wt % CaCl2, or 14 vol % glycerin and 5 wt % CaCl2 have a reduced freezing point, which theoretically extends the window for acceptable product quality. The use of 14% glycerin above the cover boards to reduce the freezing point and, consequently, ice formation on the surface of the open-top tanks is to enable the removal of fermented fruits during winter with minimal tissue injury.

Quality of Cucumbers Commercially Fermented in Calcium Chloride Brine without Sodium Salts

Commercial cucumber fermentation produces large volumes of salty wastewater. This study evaluated the quality of fermented cucumbers produced commercially using an alternative calcium chloride (CaCl2) brining process. Fermentation conducted in calcium brines (0.1 M CaCl2, 6 mM potassium sorbate, equilibrated) with a starter culture was compared to standard industrial fermentation. Production variables included commercial processor(n=6), seasonal variation (June–September, 2 years), vessel size (10,000–40,000 L), cucumber size (2.7–5.1 cm diameter), and bulk storage time (55–280 days). Cucumber mesocarp firmness, color, bloater defects, pH, and organic acids were measured. Complete lactic acid fermentation was achieved, resulting in terminal fermentation pH values of 3.23 ± 0.09 and 3.30 ± 0.12 for CaCl2and NaCl processes, respectively. On average, CaCl2brined, fermented cucumbers were 1.8 N less firm, which remained significant in the finished product(P&lt;0.0001). Color differences evidenced by higher hue and lower chroma values(P&lt;0.0269)were consistent with increased photooxidation in CaCl2brined cucumbers. Commercial implementation of CaCl2brines for cucumber fermentation in open tanks variably resulted in texture and color defects that can impact product quality. Additional research is needed to understand the atypical softening observed at the commercial scale and identify process controls for quality improvements.

Evaluation of the use of malic acid decarboxylase-deficient starter culture in NaCl-free cucumber fermentations to reduce bloater incidence.

Accumulation of carbon dioxide (CO2 ) in cucumber fermentations is known to cause hollow cavities inside whole fruits or bloaters, conducive to economic losses for the pickling industry. This study focused on evaluating the use of a malic acid decarboxylase (MDC)-deficient starter culture to minimize CO2 production and the resulting bloater index in sodium chloride-free cucumber fermentations brined with CaCl2 . Attempts to isolate autochthonous MDC-deficient starter cultures from commercial fermentations, using the MD medium for screening, were unsuccessful. The utilization of allochthonous MDC-deficient starter cultures resulted in incomplete utilization of sugars and delayed fermentations. Acidified fermentations were considered, to suppress the indigenous microbiota and favour proliferation of the allochthonous MDC-deficient Lactobacillus plantarum starter cultures. Inoculation of acidified fermentations with L. plantarum alone or in combination with Lactobacillus brevis minimally improved the conversion of sugars. However, inoculation of the pure allochthonous MDC-deficient starter culture to 107 CFU per ml in acidified fermentations resulted in a reduced bloater index as compared to wild fermentations and those inoculated with the mixed starter culture. Although use of an allochthonous MDC-deficient starter culture reduces bloater index in acidified cucumber fermentations brined with CaCl2 , an incomplete conversion of sugars is observed. Economical losses due to the incidence of bloaters in commercial cucumber fermentations brined with CaCl2 may be reduced utilizing a starter culture to high cell density.

Winterization strategies for bulk storage of cucumber pickles

Cucumbers are commercially fermented and stored in bulk in outdoor open top fiberglass tanks. During winter, snow and ice that accumulates around and on top of tanks influence heat transfer in an unpredictable manner, often compromising quality. This study evaluates the performance of inexpensive and resilient fermentation tank insulation and provides an estimate of heat loss associated with strategies for storage and preservation of fermented cucumbers during winter. Three insulation configurations were explored: conical top-cover, flat top-cover, and perimeter insulation. Changes in temperature during storage were experimentally studied in different tank configurations. A mathematical model was developed to simulate temperature profiles and heat loss in an idealized fermentation/storage vessel. Comparisons of the insulated tank configurations suggested a significant difference in temperature between a flat cover and uncovered tank when exposed to temperatures characteristic of the spring season in Pinconning, MI.

Reassessment of the succession of lactic acid bacteria in commercial cucumber fermentations and physiological and genomic features associated with their dominance

A compositional re-assessment of the microbiota present in commercial cucumber fermentation using culture independent and dependent methods was conducted, with emphasis on lactic acid bacteria (LAB). Two commercial cucumber fermentation tanks were monitored by measuring pH, dissolved oxygen and temperature, and used as sources of samples for microbial plating, genomic DNA extraction and measurement of organic acids and carbohydrates by HPLC. Six additional commercial tanks were included to identify the dominant microorganisms using molecular methods. A comparative analysis of the publically available genome sequences corresponding to the LAB found in cucumber fermentations was completed to gain an understanding of genomic features possibly enabling dominance. Analyses of the microbiota suggest Lactobacillales prevail in cucumber fermentations, including in order of prevalence Lactobacillus pentosus, Lb. plantarum, Lb. brevis, Weissella spp., Pediococcus ethanolidurans, Leuconostoc spp. and Lactococcus spp. It was observed that Lb. pentosus and Lb. plantarum have comparatively larger genomes, higher gene counts, uniquely distribute the ribosomal clusters across the genome as opposed to close to the origin of replication, and possess more predicted amino acids prototrophies and selected biosynthesis related genes. It is theorized that Lb. pentosus and Lb. plantarum dominance in cucumber fermentations is the result of their genetic make-up.

Purification and characteristics of a novel bacteriocin produced by Enterococcus faecalis L11 isolated from Chinese traditional fermented cucumber.

To purify and characterize a novel bacteriocin with broad inhibitory spectrum produced by an isolate of Enterococcus faecalis from Chinese fermented cucumber. E. faecalis L11 produced a bacteriocin with antimicrobial activity against both Escherichia coli and Staphylococcus aureus. The amino acid sequence of the purified bacteriocin, enterocin L11, was assayed by Edman degradation method. It differs from other class II bacteriocins and exhibited a broad antimicrobial activity against not only Gram-positive bacteria, including Bacillus subtilis, S. aureus, Listeria monocytogenes, Sarcina flava, Lactobacillus acidophilus, L. plantarum, L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. bulgaricus and Streptococcus thermophilus, but also some Gram-negative bacteria including Salmonella typhimurium, E. coli and Shigella flexneri. Enterocin L11 retained 91% of its activity after holding at 121°C for 30min. It was also resistant to acids and alkalis. Enterocin L11 is a novel broad-spectrum Class II bacteriocin produced by E. faecalis L11, and may have potential as a food biopreservative.

Bacterial Ecology of Fermented Cucumber Rising pH Spoilage as Determined by Nonculture-Based Methods: Fermented cucumbers spoilage…

Bacterial Ecology of Fermented Cucumber Rising pH Spoilage as Determined by Nonculture-Based Methods: Fermented cucumbers spoilage…