Publication Date: 2024
Emergent Materials (25225731)8pp. 1715-1725
Due to the probiotic characteristics of Bacillus subtilis and Bacillus coagulans, bacterial debris not only strengthens the immune system but also qualifies as a merit for biomedical products like toothpaste and implants for Hydroxyapatite (HA) synthesis. Since synthetic HA has caused some disadvantages, including raising proinflammatory cytokines like interleukin-6, the current study investigates the effects of bio-mediated HA synthesis from Bacillus subtilis and Bacillus coagulans on cell proliferation. As per the flow cytometry and MTT results, the probiotic HA not only exhibits anticancer activity against MCF-7 but also enhances the viability of L-929, PBMC, and MG-63 cells. Additionally, it promotes osteogenic mineralization, a finding supported by alkaline phosphatase activity, alizarin red staining, and the real-time PCR assay. It should be mentioned that this probiotic debris-mediated HA not only elevate the healthy cells’ viability but also regulate the cytokine secretion in order to facilitate immune system functionality and adaptation. The data suggest that this bioproduct is proposed for cancer therapy, bone development, and sanitation. Graphical Abstract: (Figure presented.) © Qatar University and Springer Nature Switzerland AG 2024.
Publication Date: 2023
Cell Journal (Yakhteh) (22285806)25(11)pp. 753-763
Objective: Multipotent cells derived from human exfoliated deciduous teeth (SHED) possess the ability to differentiate into various cell types, including osteoblasts. This study aims to simulate the growth induction and osteogenic differentiation of SHED cells using probiotics and their resultant biomaterials. Materials and Methods: This experimental study proceeded in two stages. Initially, we evaluated the effect of autoclaved nutrient agar (NA) grown probiotic Bacillus coagulans (B. coagulans) on the SHED and MG-63 cell lines. Subsequently, probiotics grown on the Pikovskaya plus urea (PVKU) medium and their synthesised hydroxyapatite (HA) were identified using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and Fourier transform infrared spectroscopy (FTIR), and then used to stimulate growth and osteogenic differentiation of the SHED cell line. Osteoblast cell differentiation was assessed by morphological changes, the alkaline phosphatase (ALP) assay, and alizarin red staining. Results: There was a substantial increase in SHED cell growth of about 14 and 33% due to probiotics grown on NA and PVKU medium, respectively. The PVKU grown probiotics enhanced growth and induced stem cell differentiation due to HA content. Evidence of this differentiation was seen in the morphological shift from spindle to osteocyte-shaped cells after five days of incubation, an increase in ALP level over 21 days, and detection of intracellular calcium deposits through alizarin red staining-all indicative of osteoblast cell development. Conclusion: The osteogenic differentiation process in stem cells, improved by the nano-HA-containing byproducts of probiotic bacteria in the PVKU medium, represents a promising pathway for leveraging beneficial bacteria and their synthesised biomaterials in tissue engineering. © 2023 Royan Institute (ACECR). All rights reserved.
Publication Date: 2022
Journal of Applied Microbiology (13652672)132(6)pp. 4130-4149
It has been more than a decade since Acetobacter senegalensis was isolated, identified and described as a thermotolerant strain of acetic acid bacteria. It was isolated from mango fruits in Senegal and used for industrial vinegar production in developing countries, mainly in sub-Saharan Africa. The strain was tested during several spirit vinegar fermentation processes at relatively high temperatures in accordance with African acclimation. The upstream fermentation process had significant stress factors, which are highlighted in this review so that the fermentation process can be better controlled. Due to its high industrial potential, this strain was extensively investigated by diverse industrial microbiologists worldwide; they concentrated on its microbiological, physiological and genomic features. A research group based in Belgium proposed an important project for the investigation of the whole-genome sequence of A. senegalensis. It would use a 454-pyrosequencing technique to determine and corroborate features that could give this strain significant diverse bio-industrial applications. For instance, its application in cocoa bean fermentation has made it a more suitable acetic acid bacterium for the making of chocolate than Acetobacter pasteurianus. Therefore, in this paper, we present a review that summarizes the current research on A. senegalensis at its microbial and genomic levels and also its specific bio-industrial applications, which can provide economic opportunities for African agribusiness. This review summarizes the physiological and genomic characteristics of Acetobacter senegalensis, a thermotolerant strain isolated from mango fruits and intended to be used in industrial vinegar fermentation processes. It also explores other bio-industrial applications such as cocoa fermentation. Vinegar fermentation is usually performed with mesophilic strains in temperate regions of the world. Developing countries, such as Senegal, import vinegar or make ‘fake’ vinegar by diluting acetic acid obtained from petrochemicals. The use of a thermotolerant Acetobacter senegalensis strain as a solid functional starter culture, as well as the design of a new adapted bioreactor, has significantly contributed to food security and the creation of small- to medium-sized enterprises that produce mango vinegar in West Africa. © 2022 Society for Applied Microbiology.
Publication Date: 2022
Applied Food Biotechnology (23455357)9(4)pp. 275-286
In recent years, green synthesis of nanobiomaterials has received more attentions than chemical synthesis due to their ecofriendly and compatibility. The aims of this study were to investigate synthesis of nanobiomaterials from probiotics and characterize these nanobiomaterials. Material and Methods: Bacillus subtilis and Bacillus coagulans were cultured in media containing insoluble calcium phosphate and urea, and produced nano-hydroxyapatite and nano-calcite. Productions were surveyed in three stages. First, produced particles were assessed on the surface of the dried bacteria at room temperature. In the second stage, dried bacteria were burned at 600 ºC. In the final stage, hydroxyapatite was purified using nanofilters. Characterization and elemental analysis of the biomaterials were studied using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, energy dispersive X-ray and X-ray fluorescence. Results and Conclusion: It was shown that nano-calcite and braided nano-hydroxyapatite on the dried biomass surface and nano-hydroxyapatite were made only in media containing insoluble calcium phosphate supplemented by urea, which was induced by phosphatase and urease. Removing organic matters by heat treatment led to the further purity of the particles. The X-ray fluorescence results revealed purity of the nano-hydroxyapatite, which was achieved by filtration of particles after burning. The ratio of calcium to phosphorus in B. coagulance sample reached 1.8, which was close to stoichiometric hydroxyapatite. Since nanobiomaterials are made from probiotics, these particles can be appropriate candidates to use in food industries, sanitation and medicine. Braided nano-hydroxyapatite can substitute needle-like types of food additives for infants and elderly people because of its safety. © 2022,Applied Food Biotechnology.All Rights Reserved.
Publication Date: 2022
Food and Chemical Toxicology (18736351)168
Although polymeric membrane has superior properties, its applications in biomedical and food industrial fields are minimal. Biofouling is a significant concern in the membrane, created from particular interactions between the membrane and untreated water content. This research showed that a careful superhydrophilic modification of polyethersulfone membrane could address those drawbacks that have hindered their utility. Hence, a combination of chemical and physical modification showed far-reaching effects on surface behavior, affecting manifold aspects of its bacterial attachment, protein adsorption resistance, and hydrophilicity. The contact angle measurement results decreased from 30° to 0° in 26 s, and surface free energy increased by 33%, demonstrating the shifting surface wettability behavior toward the Superhydrophilicity. Besides, increasing the average surface roughness on the nanoscale and forming 70–110 nm jagged structures results in a marked reduction in protein adsorption, bacterial adhesion, and biofouling formation, confirmed by the results of Flow cytometry analysis and microtiter plate assay. An improved understanding of antifouling and antibacterial properties will greatly assist in food industries since it can be applied to enhance the durability of food and chemical materials. This is important as it gives us a simple way of improving packing reliability, reducing costs and amounts of undesirable waste products. © 2022 Elsevier Ltd
Publication Date: 2020
Journal of Water Process Engineering (22147144)33
Nitrate is currently one of the most significant causes of water pollution in many parts of the world due to its detrimental effects on humans and the environment. The purpose of this study was to find a novel immobilization method based on bacterial adsorption to adhesive coating material, for use in water denitrification. The fractal formation capability of polydopamine (PDA) allowed coating of the surface of in-house asymmetric polyethersulfone (PES) beads (1.65–2.35 mm in diameter), and immobilizing the denitrifying bacteria Pseudomonas stutzeri with noticeable denitrification potential, on the surface of hyper-branched PDA coated beads. For surface characterization, SEM, wettability measurement, and ATR-FTIR spectroscopy were performed. Nitrate and nitrite concentrations were measured by APHA standard method 4500-NO3 −-B and a colourimetric method using two reagents respectively. The effects of temperature, pH and different carbon sources (Acetic acid, methanol, and ethanol) on the denitrification process were also investigated. The results revealed that the bacterial immobilization on PES surface with fractal patterns of PDA (with fractal dimension (Df) value of 1.57) was successful, and the optimum parameters for nitrate removal were established as 25 °C, pH = 8, and 420 mg/L ethanol as the carbon source. Finally, this research showed that under the optimum conditions the immobilized bacteria exhibited 100 % removal efficiency for 28 mg of NO3–N in 22 h (removal rate: 8.06 mg NO3-N/h/mg biomass of bacteria). We found that the immobilization of bacteria on the PDA coated beads is practicable and that the denitrification rate is adequate. © 2019 Elsevier Ltd
Publication Date: 2019
Journal fur Verbraucherschutz und Lebensmittelsicherheit (16615751)14(4)pp. 389-398
In this study, we investigated the clonality, antibiotic susceptibility and presence of different enterotoxin genes among 49 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from 131 fresh raw meat samples in Tehran, Iran during 2016. 47% of beef, 30% of chicken and 27% of turkey samples were MRSA positive. PhenePlate (PhP typing) revealed the presence of 12 PhP types consisting of five common types and seven single types, and 86% of the strains harbored staphylococcal cassette chromosome mec (SCCmec) type III and type 3 cassette chromosome recombinases (ccr). Moreover, SCCmec type IVa was positive in all isolates with SGA prophage types. High level resistance to ciprofloxacin, erythromycin, tobramycin and kanamycin was also observed. The rate of resistance to most of the antibiotics tested was higher in chicken samples compared to other meat samples. Out of eleven different enterotoxin genes found, sea, sek and seq were the dominant genes in all strains. Our results illustrate the presence and persistence of highly resistant clonal groups of enterotoxin-producing MRSA in meat samples. These isolates had PhP and SCCmec types and prophage patterns which were similar to the clinical isolates previously reported in Iran, supporting the notion of dissemination of the MRSA in the hospital, community, as well food products in Iran. © 2019, Bundesamt für Verbraucherschutz und Lebensmittelsicherheit (BVL).
Publication Date: 2019
Frontiers in Microbiology (1664302X)10(MAR)
Acetic acid bacteria are very vulnerable to environmental changes; hence, they should get acclimated to different kinds of stresses when they undergo downstream processing. In the present study, Acetobacter senegalensis LMG 23690T, a thermo-tolerant strain, was acclimated sequentially to different carbon sources including glucose (condition Glc), a mixture of glucose and ethanol (condition EtOH) and a mixture of glucose and acetic acid (condition GlcAA). Then, the effects of acclimation on the cell proteome profiles and some phenotypic characteristics such as growth in culture medium containing ethanol, and tolerance to freeze-drying process were evaluated. Based on the obtained results, despite the cells acclimated to Glc or EtOH conditions, 86% of acclimated cells to GlcAA condition were culturable and resumed growth with a short lag phase in a culture medium containing ethanol and acetic acid. Interestingly, if A. senegalensis LMG 23690T had been acclimated to condition GlcAA, 92% of cells exhibited active cellular dehydrogenases, and 59% of cells were culturable after freeze-drying process. Proteome profiles comparison by 2D-DiGE and MS analysis, revealed distinct physiological status between cells exposed to different acclimation treatments, possibly explaining the resulting diversity in phenotypic characteristics. Results of proteome analysis by 2D-DiGE also showed similarities between the differentially expressed proteins of acclimated cells to EtOH condition and the proteome of acclimated cells to GlcAA condition. Most of the differentially regulated proteins are involved in metabolism, folding, sorting, and degradation processes. In conclusion, acclimation under appropriate sub-lethal conditions can be used as a method to improve cell phenotypic characteristics such as viability, growth under certain conditions, and tolerance to downstream processes. © 2019 Shafiei, Leprince, Sombolestani, Thonart and Delvigne.
Publication Date: 2019
Molecular Biology Research Communications (2322181X)8(3)pp. 103-111
Although there are many health advantages assigned to different live bacteria such as probiotics, some health threatening effects have also been reported. For example, live bacteria can transfer antibiotic resistance genes to other commensal and opportunistic bacteria of gastrointestinal tract. Recently, it was shown that using killed bacteria have some advantages over live ones. In this research, heat, paraformaldehyde and ozone killing methods were used to kill the bacteria. Acetobacter cerevisiae, Lactobacillus acidophilus, Bifidobacterium lactis and traditional vinegar and fermented dairy product (Kumeh) derived bacteria were killed and their antibacterial activity against Streptococcus mutans and Escherichia coli was investigated. To identify the bacteria isolated from the traditional products, 16S rDNA gene was partially sequenced. The gene analysis showed vinegar and Kumeh derived bacteria were Acetobacter pasteurianus and Lactobacillus crustorum (LcK) strains respectively. The S. mutans growth inhibition was detected in the all concentrations of all killed samples. However, generally, E. coli showed more resistant to the killed bacteria than S. mutans and the antibacterial effect of heat-killed bacteria against E. coli was not observed in the all concentrations for some killed bacteria. Among the pathogenic bacteria, S. mutans was the most sensitive one to the killed bacteria with 70% of reduction in its viability. In conclusion, this research showed that different killed bacteria had different effects on other bacteria and the killing method showed an impact on these effects. Overall, paraformaldehyde-killed L. crustorum (LcK) showed the best antibacterial activity against S. mutans; about 70% decrease in bacterial viability. © 2020, Shiraz University.
Publication Date: 2019
Journal of Applied Microbiology (13652672)127(4)pp. 1101-1112
Aims: The formation of metabolically inactive and nongrowing cells is an inevitable by-product of intensive fermentation. This study investigated whether co-feeding can be used to resuscitate nongrowing Acetobacter senegalensis cells to enable them to produce gluconic acid in successive fermentation runs at 38°C. Methods and Results: In the first fermentation cycle, 75 g l−1 of glucose were converted to gluconic acid. Subsequently, however, stationary-phase cells were unable to initiate a new fermentation cycle. The majority of stationary-phase cells (97%) were nonculturable on glucose at 38°C. In addition, 54 and 41% of cells contained non-active cellular dehydrogenases and a compromised cell envelope respectively. Co-feeding stationary-phase cells with a mixture of ethanol, glucose and acetic acid for 7 h enabled these cells to grow on 75 g l−1 of glucose and produce gluconic acid. Additionally, 74% of cells contained active forms of cellular dehydrogenases after 7 h of co-feeding. However, co-feeding did not improve cell envelope integrity. Quantification of cellular NAD content showed that stationary-phase cells contained moderately reduced levels of total NAD (NADt) as compared with exponential-phase cells. Interestingly, the analysis of stationary-phase cells showed that co-feeding resulted in higher levels of NADt and NADH, suggesting that the regeneration of NADH is one of the limiting factors of glucose consumption. Expression of catalase and superoxide dismutase was increased in stationary-phase cells, but analysis of protein carbonylation and lipid peroxidation did not confirm an extensive oxidative stress. Conclusions: Co-feeding with favourable nutrients may enable resuscitation of cells and utilization of less-favourable carbon sources in successive cycles. Significance and Impact of the Study: This study proposed a unique method for resuscitation of nongrowing cells during high-temperature fermentation. By applying this method, cells can be used for consecutive fermentation cycles. © 2019 The Society for Applied Microbiology
Publication Date: 2019
International Journal Of Aquatic Biology (23225270)7(3)pp. 166-174
The gastrointestinal tract of fishes is a complex ecosystem occupied by a large number of microorganisms, some of them could have potentially-valuable features. This research was conducted to study Bacillus species in the intestine of farmed rainbow trout to examine their probiotic properties, and to provide a new source of probiotics. A total of 23 farmed rainbow trout were sampled and their intestine samples were cultured. Following the morphological assay and biochemical analysis, isolated Bacilli were amplified by polymerase chain reaction and universal primers 27f and 1492r. Bacillus subtilis and B. amyloliquefaciens were isolated from 5 and 3 samples, respectively. Bacillus tequilensis, B. cereus and B. licheniformis were isolated from 1 sample. Probiotic properties of B. subtilis strain MSM 24, B. amyloliquefaciens strain TMM 25 and B. licheniformis strain MR 78 were confirmed. Since probiotic bacteria cause no foodborne diseases, their existence in farmed trout intestines, and their penetration into the fish tissues do not pose any risk to consumers’ health. © 2019 Iranian Society of Ichthyology.
Publication Date: 2018
Journal of Isfahan Medical School (10277595)36(468)pp. 131-141
Probiotics are one of the innovative, effective and accepted ways to mitigate acuteness, and to help cure some diseases at the present era. However, there are some limitations in manufacturing and using live bacteria. Paraprobiotics are of the new methods that can handle these problems at the large scale. They are defined as non-viable form of probiotics that can be utilized as intact or broken cells, and also as cell extract. Treatment of some diseases in human and animals has been demonstrated in case of using edible or topical application of paraprobiotics. In this review, after introducing paraprobiotics and their production techniques, their effects on human health is presented based on researches conducted during the past two decades, especially recent studies. © 2018, Isfahan University of Medical Sciences(IUMS). All rights reserved.
Publication Date: 2017
Bioprocess and Biosystems Engineering (16157605)40(5)pp. 769-780
Much research has been conducted about different types of fermentation at high temperature, but only a few of them have studied cell viability changes during high-temperature fermentation. In this study, Acetobacter senegalensis, a thermo-tolerant strain, was used for gluconic acid production at 38 °C. The influences of different carbon sources and physicochemical conditions on cell viability and the resuscitation of viable but nonculturable (VBNC) cells formed during fermentation were studied. Based on the obtained results, A. senegalensis could oxidize 95 g l− 1 glucose to gluconate at 38 °C (pH 5.5, yield 83%). However, despite the availability of carbon and nitrogen sources, the specific rates of glucose consumption (qs) and gluconate production (qp) reduced progressively. Interestingly, gradual qs and qp reduction coincided with gradual decrease in cellular dehydrogenase activity, cell envelope integrity, and cell culturability as well as with the formation of VBNC cells. Entry of cells into VBNC state during stationary phase partly stemmed from high fermentation temperature and long-term oxidation of glucose, because just about 48% of VBNC cells formed during stationary phase were resuscitated by supplementing the culture medium with an alternative favorite carbon source (low concentration of ethanol) and/or reducing incubation temperature to 30 °C. This indicates that ethanol, as a favorable carbon source, supports the repair of stressed cells. Since formation of VBNC cells is often inevitable during high-temperature fermentation, using an alternative carbon source together with changing physicochemical conditions may enable the resuscitation of VBNC cells and their use for several production cycles. © 2017, Springer-Verlag Berlin Heidelberg.
Among dairy products, yogurt is one of the most consumed and most popular foodstuffs in Iran. Furthermore, a lot of research and practical work have been carried out about isolation of lactic acid bacteria (LAB) from yogurt, especially traditional yogurt and related products. Interest in traditional fermented dairy products, such as yogurt, continues in the area of isolation of new LAB that can complement or replace currently used starters and/or that can be candidates as beneficial microorganisms for prevention or treatment purposes. A long history of production of dairy products in Iran as well as its climate diversity make the production of a wide range of dairy products possible, particularly in rural regions. In this perspective, such products are potentially good candidates for isolating new strains of probiotics. This chapter focuses on the isolation of LAB from dairy products, especially traditional Iranian yogurt and its derivate products. Therefore, the scientific reports of isolation of many LAB, including Lactobacillus (L. casei, L. rhamnosus, L. lactis, L. bulgaricus, L. acidophilus, L. helveticus, L. plantarum, L. brevis, L. pentosus, L. paracasei, L. fermentum, L. helveticus, and L. delbrueckii), Streptococcus (S. lactis, S. diacetylactis, S. thermophiles, S. fecalis, and S. acidominimus), Leuconostoc mesenteroides, Enterococcus (E. durans, E. faecium, E. faecalis, and E. avium), Lactococcus lactis, and Pediococcus, from traditional Iranian yogurt and its derivate products has been summarized and analyzed. © 2017 Elsevier Inc. All rights reserved.
Publication Date: 2016
Journal of Bioscience and Bioengineering (13474421)121(2)pp. 166-171
The activity of bacterial strains significantly influences the quality and the taste of vinegar. Previous studies of acetic acid bacteria have primarily focused on the ability of bacterial strains to produce high amounts of acetic acid. However, few studies have examined the production of gluconic acid during acetous fermentation at high temperatures. The production of vinegar at high temperatures by two strains of acetic acid bacteria isolated from apple and cactus fruits, namely AF01 and CV01, respectively, was evaluated in this study. The simultaneous production of gluconic and acetic acids was also examined in this study. Biochemical and molecular identification based on a 16s rDNA sequence analysis confirmed that these strains can be classified as Acetobacter pasteurianus. To assess the ability of the isolated strains to grow and produce acetic acid and gluconic acid at high temperatures, a semi-continuous fermentation was performed in a 20-L bioreactor. The two strains abundantly grew at a high temperature (41°C). At the end of the fermentation, the AF01 and CV01 strains yielded acetic acid concentrations of 7.64% (w/v) and 10.08% (w/v), respectively. Interestingly, CV01 was able to simultaneously produce acetic and gluconic acids during acetic fermentation, whereas AF01 mainly produced acetic acid. In addition, CV01 was less sensitive to ethanol depletion during semi-continuous fermentation. Finally, the enzymatic study showed that the two strains exhibited high ADH and ALDH enzyme activity at 38°C compared with the mesophilic reference strain LMG 1632, which was significantly susceptible to thermal inactivation. © 2015 The Society for Biotechnology, Japan.
Publication Date: 2016
Current Microbiology (03438651)73(3)pp. 366-373
The Bacillus species have many applications in the preparation of various enzymes, probiotic, biofertilizer, and biomarkers for which the survival of resting cells and spore formation under different conditions are important. In this study, water and saline along with different mineral substances such as calcium carbonate, calcium phosphate, and silica were used for the detection of survival and preservation of Bacillus amyloliquefaciens. The results showed intensive death of resting cells at 8 °C, but significant survival at 28 °C after one month. However, preservation by minerals significantly decreased the rate of death and induced sporulation at both the temperatures. The resting cells were maintained at room temperature (about 60 % of the initial population survived after a month) in the presence of tricalcium phosphate. The results showed that temperature has more effect on sporulation compare with starvation. The sporulation in normal saline at 28 °C was 70 times more than that at 8 °C; meanwhile, addition of tricalcium phosphate increases sporulation by 90 times. Also, the FTIR data showed the interaction of tricalcium phosphate with spores and resting cells. The discrimination of sporulation from non-sporulation state was performed by nucleic acid staining with thiazole orange and detected by flow cytometry. The flow cytometric studies confirmed that the rates of sporulation in pure water were significantly more at 28 °C. This is the first report on the detection of bacterial spore with thiazole orange by flow cytometry and also on the interaction of tricalcium phosphate with spores by FTIR analyses. © 2016, Springer Science+Business Media New York.
Publication Date: 2015
Communications in Agricultural and Applied Biological Sciences (13791176)80(1)pp. 37-43
Six strains of acetic acid bacteria were isolated from Moroccan local products and their potential as industrial strains was evaluated in lab-bioreactor. Three of them, namely TAV01, AF01 and CV01, isolated from traditional apple vinegar, apple and cactus fruit, respectively were selected and their responses to high temperature were assessed. Morphological and biochemical identification confirmed that these strains belong to Acetobacter species. Their growth and acetic acid production were compared with the thermoresistant reference strain, Acetobacter senegalensis and mesophilic strains of Acetobacter pasteurianus. The two strains AF01 and CV01 showed abundant growth and noticeable acetic acid production ability at high temperatures (38 to 41°C). A thermophilic character was observed for AF01 strain. Indeed, this bacterium grew better at 38 than 30°C.
Publication Date: 2014
Microbial Cell Factories (14752859)13(1)
Background: Loss of viability is one of the most important problems during starter culture production. Previous research has mostly focused on the production process of bacterial starters, but there are few studies about cellular protein deterioration causing cell defectiveness during storage. In the present study, we investigated the influence of storage temperature (-21, 4, 35°C) on the cellular protein modifications which may contribute to the senescence of freeze-dried Acetobacter senegalensis.Results: Heterogeneous populations composed of culturable cells, viable but non-culturable cells (VBNC) and dead cells were generated when freeze-dried cells were kept at -21 and 4°C for 12 months whereas higher storage temperature (35°C) mainly caused death of the cells. The analysis of stored cell proteome by 2D-DiGE demonstrated a modified pattern of protein profile for cell kept at 4 and 35°C due to the formation of protein spot trains and shift of Isoelectric point (pI). Quantification of carbonylated protein by ELISA showed that the cells stored at 4 and 35°C had higher carbonylated protein contents than fresh cells. 2D-DiGE followed by Western blotting also confirmed the carbonylation of cellular proteins involved in translation process and energy generation. The auto-fluorescent feature of cells kept at 35°C increased significantly which may be an indication of protein glycation during storage. In addition, the percentage of cellular unsaturated fatty acid and the solubility of cellular proteins decreased upon storage of cells at higher temperature suggesting that peroxidation of fatty acids and possibly protein lipidation and oxidation occurred.Conclusions: High storage temperature induces some deteriorative reactions such as protein oxidation, lipidation and glycation which may cause further protein modifications like pI-shift, and protein insolubility. These modifications can partly account for the changes in cell viability. It can also be deduced that even moderate carbonylation of some critical cellular proteins (like ribosomal proteins) may lead to VBNC formation or death of freeze-dried bacteria. Moreover, it seems that other mechanisms of biomolecule deterioration preceding protein carbonylation lead to VBNC formation under very low storage temperature. © 2014 Shafiei et al.; licensee BioMed Central Ltd.
Publication Date: 2013
International Journal of Food Microbiology (18793460)163(2-3)pp. 204-213
Acetic acid bacteria (AAB) are used in production of vinegars. During acetic acid fermentation, AAB encounter various aggressive conditions which may lead to a variety of cellular disorders. Previous researches mainly studied the influences of different carbon sources on tolerance of AAB to ethanol and acetic acid. In this study, different techniques were used comparatively to investigate the effects of preadaptation on the ability of A. senegalensis to tolerate ethanol and acetic acid. In general, the carbon sources used for preadaptation of A. senegalensis exhibited significant effects on the tolerance of cells to stressors. Flow-cytometric assessments of preadapted cells in ethanol showed that 87.3% of the cells perform respiration after exposure to a stress medium containing 5% (v/v) ethanol and 3% (w/v) acetic acid. However, 58.4% of these preadapted cells could keep their envelope integrity under the stress condition. They could also grow rapidly (μ. max= 0.39/h) in the stress medium (E5A3) with a high yield (>. 80%). A. senegalensis grown in glucose exhibited a low tolerance to acetic acid. Analysis of their respiration capacity, membrane integrity and culturability revealed that almost all the population were dead after exposure to 5% (v/v) ethanol and 3% (w/v) acetic acid. In contrast, exposure of A. senegalensis preadapted in a mixture of glucose and acetic acid to a stress medium containing 5% (v/v) ethanol and 3% (w/v) acetic acid, exhibited an intact respiration system and cellular membrane integrity in 80.3% and 50.01% of cells, respectively. Moreover, just 24% of these cells could keep their culturability under that stress condition.In summary, cell envelope integrity, growth and culturability are more susceptible to pH and acetic acid stresses whereas respiration system is less subjected to damages under stress condition. In addition, preadaptation of A. senegalensis in a mixture of glucose and acetic acid enables it to tolerate and grow in ethanol and acetic acid. © 2013 Elsevier B.V.
Publication Date: 2010
World Academy of Science, Engineering and Technology (20103778)71pp. 177-180
Vinegar or sour wine is a product of alcoholic and subsequent acetous fermentation of sugary precursors derived from several fruits or starchy substrates. This delicious food additive and supplement contains not less than 4 grams of acetic acid in 100 cubic centimeters at 20°C. Among the large number of bacteria that are able to produce acetic acid, only few genera are used in vinegar industry most significant of which are Acetobacter and Gluconobacter. In this research we isolated and identified an Acetobacter strain from Iranian apricot, a very delicious and sensitive summer fruit to decay, we gathered from fruit's stores in Isfahan, Iran. The main culture media we used were Carr, GYC, Frateur and an industrial medium for vinegar production. We isolated this strain using a novel miniature fermentor we made at Pars Yeema Biotechnologists Co., Isfahan Science and Technology Town (ISTT), Isfahan, Iran. The microscopic examinations of isolated strain from Iranian apricot showed gram negative rods to cocobacilli. Their catalase reaction was positive and oxidase reaction was negative and could ferment ethanol to acetic acid. Also it showed an acceptable growth in 5%, 7% and 9% ethanol concentrations at 30°C using modified Carr media after 24, 48 and 96 hours incubation respectively. According to its tolerance against high concentrations of ethanol after four days incubation and its high acetic acid production, 8.53%, after 144 hours, this strain could be considered as a suitable industrial strain for a production of a new type of vinegar, apricot vinegar, with a new and delicious taste. In conclusion this is the first report of isolation and identification of an Acetobacter strain from Iranian apricot with a very good tolerance against high ethanol concentrations as well as high acetic acid productivity in an acceptable incubation period of time industrially. This strain could be used in vinegar industry to convert apricot spoilage to a beneficiary product and mentioned characteristics have made it as an amenable strain in food and agricultural biotechnology.
