Tryptic Soy Broth Medium Research Articles

Antibacterial, Antifungal, and Cytotoxic Effects of Endophytic Streptomyces Species Isolated from the Himalayan Regions of Nepal and Their Metabolite Study.

Background/Objectives: Recently, antimicrobial-resistant pathogens and cancers have emerged as serious global health problems, highlighting the immediate need for novel therapeutics. Consequently, we aimed to isolate and characterize endophytic Streptomyces strains from the rhizospheres of the Himalayan region of Nepal and identify specialized metabolites with antibacterial, antifungal, and cytotoxic potential. Methods: To isolate Streptomyces sp., we collected two soil samples and cultured them on an ISP4 medium after pretreatment. We isolated and identified the strains PY108 and PY109 using a combination of morphological observations and 16S rRNA gene sequencing. Results: The BLAST results showed that PY108 and PY109 resembled Streptomyces hundungensis PSB170 and Streptomyces sp. Ed-065 with 99.28% and 99.36% nucleotide similarity, respectively. Antibacterial assays of ethyl acetate (EA) extracts from both isolates PY108 and PY109 in a tryptic soy broth (TSB) medium were conducted against four pathogenic bacteria. They showed significant antibacterial potential against Staphylococcus aureus and Klebsiella pneumoniae. Similarly, these extracts exhibited moderate antifungal activities against Saccharomyces cerevisiae and Aspergillus niger. Cytotoxicity assays on cervical cancer cells (HeLa) and breast cancer cells (MCF-7) revealed significant potential for both extracts. LC-MS/MS profiling of the EA extracts identified 27 specialized metabolites, including diketopiperazine derivatives, aureolic acid derivatives such as chromomycin A, and lipopeptide derivatives. In comparison, GC-MS analysis detected 34 metabolites, including actinomycin D and γ-sitosterol. Furthermore, a global natural product social molecular networking (GNPS)-based molecular networking analysis dereplicated 24 metabolites in both extracts. Conclusions: These findings underscore the potential of endophytic Streptomyces sp. PY108 and PY109 to develop new therapeutics in the future.

Preliminary Study of the Characterization of the Viable but Noncultivable State of Yersinia enterocolitica Induced by Chloride and UV Irradiation.

The viable but non-culturable (VBNC) state is a survival strategy for many foodborne pathogens under adverse conditions. Yersinia enterocolitica (Y. enterocolitica) as a kind of primary foodborne pathogen, and it is crucial to investigate its survival strategies and potential risks in the food chain. In this study, the effectiveness of ultraviolet (UV) irradiation and chlorine treatment in disinfecting the foodborne pathogen Y. enterocolitica was investigated. The results indicated that both UV irradiation and chlorine treatment can induce the VBNC state in Y. enterocolitica. The bacteria completely lost culturability after being treated with 25 mg/L of NaClO for 30 min and a UV dose of 100 mJ/cm². The number of culturable and viable cells were detected using plate counting and a combination of fluorescein and propidium iodide (live/dead cells). Further research found that these VBNC cells exhibited reduced intracellular Adenosine Triphosphate (ATP) levels, and increased levels of reactive oxygen species (ROS) compared to non-induced cells. Morphologically, the cells changed from a rod shape to a shorter, coccobacillary shape with small vacuoles forming at the edges, indicating structural changes. Both condition-induced VBNC-state cells were able to resuscitate in tryptic soy broth (TSB) medium supplemented with Tween 80, sodium pyruvate, and glucose. These findings contribute to a better understanding of the survival mechanisms of Y. enterocolitica in the environment and are of significant importance for the development of effective disinfection strategies.

Enhancing the yield of Xenocoumacin 1 in Xenorhabdus nematophila YL001 by optimizing the fermentation process

Xenocoumacin 1 (Xcn 1), antibiotic discovered from secondary metabolites of Xenorhabdus nematophila, had the potential to develop into a new pesticide due to its excellent activity against bacteria, oomycetes and fungi. However, the current low yield of Xcn1 limits its development and utilization. To improve the yield of Xcn1, response surface methodology was used to determine the optimal composition of fermentation medium and one factor at a time approach was utilized to optimize the fermentation process. The optimal medium composed of in g/L: proteose peptone 20.8; maltose 12.74; K2HPO4 3.77. The optimal fermentation conditions were that 25 °C, initial pH 7.0, inoculum size 10%, culture medium 75 mL in a 250 mL shake flask with an agitation rate of 150 rpm for 48 h. Xenorhabdus nematophila YL001 was produced the highest Xcn1 yield (173.99 mg/L) when arginine was added to the broth with 3 mmol/L at the 12th h. Compared with Tryptic Soy Broth medium, the optimized fermentation process resulted in a 243.38% increase in Xcn1 production. The obtained results confirmed that optimizing fermentation technology led to an increase in Xcn1 yield. This work would be helpful for efficient Xcn1 production and lay a foundation for its industrial production.

Antibacterial and Antivirulence Effects of Kale (Brassica oleracea var. sabellica) on Streptococcus intermedius

Persistent odontogenic infections caused by resistant bacterial species, such as , have consistently been associated with deep-seated infections. This in vitro study aimed to evaluate the antibacterial and antivirulence effects of kale () on . was freshly incubated in tryptic soy broth media. Three experiments per concentration of kale were conducted under aseptic conditions (i.e., disc diffusion, broth microdilution, and reverse-transcription polymerase chain reaction) to evaluate the antibacterial and antivirulence effects. The samples were then treated with 1000, 500, 250, 125, 65, 30, 15, 7, and 3 mg/mL kale; ampicillin (positive control); and tryptic soy broth (negative control). After 24-h incubation, the inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and relative gene expression of the virulence factor (intermedilysin []) were measured. All assays were conducted in triplicate. The findings were reported and analyzed as means ± standard deviations. The agar disc diffusion and relative gene expression were statistically analyzed using one-way analysis of variance and Tukey’s test, with the significance level set at P < 0.05. Kale showed antibacterial effects on by significantly inhibiting bacterial growth and reducing expression only at a concentration of 1000 mg/mL; it yielded an inhibition zone of 11.12 ± 1.59 mm, which was smaller than that with ampicillin. The MIC and MBC ranged from 15 to 65 mg/mL and from 500 mg/mL, respectively. Conversely, the highest concentration of kale yielded significantly less inhibition than did ampicillin. The antibacterial effects of kale may be dose-dependent. Kale can inhibit bacterial growth and suppress expression under in vitro conditions of , which is mainly involved in deep-seated odontogenic infections.

The chronic wound milieu changes essential oils' antibiofilm activity—an in vitro and larval model study

Essential Oils (EOs) are currently being researched as potential antibiofilm agents to combat infections related to chronic wound biofilms. As documented in the literature, EOs’ in vitro antibacterial properties are often assessed using standard microbiological media and conditions that do not accurately reflect the actual environment of a chronic wound. To address this issue, In vitro Wound Milieu (IVWM) medium, which closely resembles the environment of a chronic wound, was applied for culturing S. aureus biofilms (n = 12) in this research. Biofilms cultivated in the standard Tryptic Soy Broth (TSB) medium served as a control for the experiment. Key biofilm features were analyzed and compared. Subsequently, staphylococci were exposed to the activity of thyme or rosemary EOs (T-EO and R-EO, respectively). As proof of concept, the cytotoxicity of T-EO and its antimicrobial in vivo activity were assessed using a G. mellonella larvae model. Key features of biofilm-forming cells were lower in the IVWM than in the TSB medium: biomass (up to 8 times), metabolic activity (up to 9 times), cell number (up to 100 times), and the live/dead cells ratio. Conversely, biofilm thickness was higher (up to 25%) in IVWM. These differences translated into varied responses of the biofilms to EOs exposure. The application of T-EO led to a greater reduction (up to 2 times) in 67% of biofilm-forming strains in IVWM compared to the TSB medium. Conversely, exposure to R-EO resulted in a higher reduction (up to 2.6 times) of 83% of biofilm-forming strains in TSB than in IVWM. The application of T-EO was not only non-toxic to G. mellonella larvae but also increased the survival of larvae infected with staphylococci (from 48 to 85%). Our findings suggest that EOs not only show promise as agents for treating biofilm-related wound infections but also that providing conditions reflecting the specific niche of the human body is of paramount importance in influencing the results obtained. However, before clinical application, challenges related to the methods of assessing their activity, microbial intra-species variability, and different levels of activity of various EOs should be analyzed and standardized.

Correlation between the facial skin microbiome and sensitive skin using the 2bRAD-M technique.

This study aimed to expound on the correlation between facial skin microbiome and sensitive skin (SS) using a novel sequencing technique. We applied the 2bRAD sequencing for the microbiome, which enables accurate characterization of the low-biomass microbiome at species resolution to profile facial skin microbes in SS and non-SS groups. Further, the bacterial colonies were isolated and cultured from skin surfaces to study the pro-inflammatory effect on human keratinocytes by ELISA. We accordingly identified 1142 genera and 4436 strains. In the SS group, the proportions of Actinomyces and Microbotryomycetes were significantly increased, whereas that of Acidimicrobiia was decreased. Kruskal-Wallis analysis revealed significant differences in 11 genera and 35 species, among which the proportions of Dermabacter, Chryseobacterium, Rhodotorula and Peptoniphilus A were increased in the SS group. Analysis of the top 10 genera revealed increased proportions of Cutibacterium, Corynebacterium and Staphylococcus. Moreover, the proportion of Dermabacter hominis was significantly increased by 18.9-fold in the SS group, whereas those of many Streptococcus strains were significantly decreased. Focus on the isolated bacterial colonies from skin surfaces, more yellow colonies were found in SS group when cultured in Tryptic Soy Broth medium for 48 h, and more interleukin-8 was detected on keratinocytes after yellow colonies stimulation, such as S.capitis, M.luteus. This study suggests that more SS-associated microorganisms can be identified using the 2bRAD technique even with a small sample size. Dermabacter hominis and Chryseobacterium was firstly reported with a significantly increase in SS, and the S.capitis, as well as M.luteus, but not S.aureus, may be associated with skin inflammation.

The Comparison of Tolerance Capability of Nitrogen-Fixing Bacteria to Chemical and Biological Pesticides

Due to concerns about the adverse effects of synthetic pesticides on the environment and human health, there is a growing preference for environmentally friendly and safe pesticides. However, hard evidence to verify their low-risk characteristics is scarce. This work attempted to compare the effects of a chemical pesticide (alpha-cypermethrin) and a biopesticide (emamectin benzoate) on the growth of indigenous nitrogen-fixing bacteria. These bacterial strains were isolated from the rhizosphere of bean plant samples obtained from farmers? fields where these two pesticides were sprayed on bean crops. The results revealed that at the field-recommended concentration of both pesticides, the growth of the isolates in both nutrient-rich and nitrogen-free media remained largely unaffected. However, the bacteria?s absolute growth inhibition was recorded as the pesticide concentration increased. When the Tryptic Soy Broth medium was supplemented with a pesticide concentration 10 times higher than the recommended dose, up to 85.7% of the isolated strains were completely inhibited in growth when exposed to alpha-cypermethrin. In contrast, only 17.9% of bacterial strains were completely inhibited when exposed to emamectin benzoate. In a nitrogen-free medium, the proportion of inhibited bacteria was absolute when the medium was supplemented with alpha-cypermethrin and emamectin benzoate at a dosage 10 times higher than the recommended concentration, which reached 92.9% and 28.6%, respectively. The strains that exhibited higher tolerance to both pesticides were identified as Niallia nealsonii ND15 and Rhizobium subbaraonis ND27. Our findings emphasize the importance of minimizing pesticide accumulation in the soil to protect the viability of soil-beneficial bacteria and ensure soil quality for safe and sustainable crop production.. KEYWORDS :Alpha-cypermethrin, Emamectin benzoate, N-fixing bacteria, Pesticides tolerance, Toxicity assessment

Impact of Phylogenetically Diverse Bacterial Endophytes of Bergenia pacumbis on Bergenin Production in the Plant Cell Suspension Cultures.

Plant in vitro cultures are potential sources for secondary metabolites. However, low productivity is often a major drawback for industrial application. Elicitation is an important strategy to improve product formation in vitro. In this context, endophytes are of special interest as biotic elicitors due to their possible interaction with the metabolism of the host plant. A total of 128 bacterial endophytes were isolated from the medicinal plant Bergenia pacumbis and taxonomically classified using 16S rRNA gene sequencing. Five strains belonging to different genera were grown in lysogeny broth and tryptic soy broth medium and cells as well as spent media were used as elicitors in cell suspension cultures of B. pacumbis. Production of the main bioactive compound bergenin was enhanced 3-fold (964 µg/g) after treatment with cells of Moraxella sp. or spent tryptic soy broth medium of Micrococcus sp. These results indicate that elicitation of plant cell suspension cultures with endophytic bacteria is a promising strategy for enhancing the production of desired plant metabolites.

The growth of mercury-resistant bacterial consortium at different levels of pH, temperature, and C:N ratio

The study was conducted to investigate the growth of mercury-resistant bacterial consortium under the influence of different pHs, temperatures, and C:N ratios, as a part of mercury bioremediation research. The consortium consisted of five bacterial isolates selected due to their resistance to HgCl2 up to 100 ppm and was proven to effectively reduce mercury from the culture media. Consortium suspension was inoculated into two sets of media: 1) Tryptic soy broth (TSB) with pHs of 4.8, 6.1, 8.5, and 9.7; 2) Mineral salt with the addition of glucose and peptone to create C:N ratios of 20:1, 30:1, and 40:1 while the pH was set to 7.4. For comparison, a solution containing mercury-contaminated soil was added to the same set of media and regarded as a microbial community. The growth curves show that the bacterial consortium tended to grow better compared to the microbial community, especially in the TSB medium at incubation temperatures of 20 and 35 °C. In the same medium at a temperature of 45 °C, the growth of both consortium and community under high pHs (8.5 and 9.7) was higher than the one under lower pHs (4.8 and 6.1). Meanwhile, in the mineral salt medium, the influence of the inoculant was not remarkable except under an incubation temperature of 35 °C. Moreover, the C:N ratio did not affect the growth of either the bacterial consortium or the microbial community (p > 0.05). The variance analysis also indicated that the growths were significantly different only when the pH was 4.8.

Staphylococcus aureus ST1 promotes persistent urinary tract infection by highly expressing the urease.

Staphylococcus aureus (SA) is a relatively uncommon cause of urinary tract infections (UTIs) in the general population. Although rare, S. aureus-induced UTIs are prone to potentially life-threatening invasive infections such as bacteremia. To investigate the molecular epidemiology, phenotypic characteristics, and pathophysiology of S. aureus-induced UTIs, we analyzed non-repetitive 4,405 S. aureus isolates collected from various clinical sources from 2008 to 2020 from a general hospital in Shanghai, China. Among these, 193 isolates (4.38%) were cultivated from the midstream urine specimens. Epidemiological analysis showed UTI-derived ST1 (UTI-ST1) and UTI-ST5 are the primary sequence types of UTI-SA. Furthermore, we randomly selected 10 isolates from each of the UTI-ST1, non-UTI-ST1 (nUTI-ST1), and UTI-ST5 groups to characterize their in vitro and in vivo phenotypes. The in vitro phenotypic assays revealed that UTI-ST1 exhibits an obvious decline in hemolysis of human red blood cells and increased biofilm and adhesion in the urea-supplemented medium, compared to the medium without urea, while UTI-ST5 and nUTI-ST1 did not show significant differences between the biofilm-forming and adhesion abilities. In addition, the UTI-ST1 displayed intense urease activities by highly expressing urease genes, indicating the potential role of urease in UTI-ST1 survival and persistence. Furthermore, in vitro virulence assays using the UTI-ST1 ureC mutant showed no significant difference in the hemolytic and biofilm-forming phenotypes in the presence or absence of urea in the tryptic soy broth (TSB) medium. The in vivo UTI model also showed that the CFU of the UTI-ST1 ureC mutant rapidly reduced during UTI pathogenesis 72 h post-infection, while UTI-ST1 and UTI-ST5 persisted in the urine of the infected mice. Furthermore, the phenotypes and the urease expression of UTI-ST1 were found to be potentially regulated by the Agr system with the change in environmental pH. In summary, our results provide important insights into the role of urease in S. aureus-induced UTI pathogenesis in promoting bacterial persistence in the nutrient-limiting urinary microenvironment.

Biofilm formation by the interaction of fungi (Candida tropicalis) with various bacteria

Acinetobacter baumannii) ABSTRACT: Background: Biofilms are composed of more than one species or often called polymicrobial biofilms, so research is needed on the formation of polymicrobial biofilms, especially between fungi and bacteria. This study aimed to analyze the total biomass and metabolic activity of biofilms formed from the interaction of fungi (Candida tropicalis) with bacteria (Staphylococcus aureus, MRSA, Pseudomonas aeruginosa, and Acinetobacter baumannii); Methods: Bacterial and fungal cultures were suspended in Tryptic Soy Broth (TSB) medium, then biofilm was cultivated in two 96-well microplates, then the microplates were incubated at 37 degrees Celsius for 48 hours. Detection of the biofilm will be carried out using the Crystal Violet assay and reduction of the tetrazolium salt (3-(4,5-dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide), or MTT assay to obtain the Optical Density (OD) value by using ELISA reader; Results: The results of this study obtained significant data from both parameters, the highest average value was found in the C. tropicalis treatment group (2,412 ± 0.825 on the biomass test results; 1,525 ± 0.473 on the metabolic activity test results), while the lowest was seen in the S. aureus treatment group (0.512 ± 0.224 in the biomass test results; 0.978 ± 0.349 in the metabolic activity test results); and Conclusions: In the total biomass parameter, it was obtained that the biofilm biomass could be formed strongly in each treatment, while the results of the metabolic activity showed that each treatment was able to carry out cell proliferation.

Homoscleromorpha-derived Bacillus spp. as potential sources of biotechnologically-relevant hydrolases and biosurfactants.

Despite hydrolytic exoenzymes and biosurfactants having been gradually reported from the poriferan microbiome, little is known about these bioproducts in microorganisms inhabiting Homoscleromorpha sponges. Here, we investigated the production of hydrolases and biosurfactants in bacteria isolated from three shallow-water homoscleromorph species, Oscarella sp., Plakina cyanorosea, and Plakina cabofriense. A total of 99 of 107 sponge-associated bacterial isolates exhibited activity for at least one of the analyzed hydrolases. Following fermentation in Luria-Bertani (LB) and Tryptic Soy Broth (TSB), two isolates, 80BH11 and 80B1:1010b, showed higher lipase and peptidase activities. Both of them belonged to the Bacillus genus and were isolated from Oscarella. Central composite design leveraged up the peptidase activity in 280% by Bacillus sp. 80BH11 in the TSB medium for 48h at 30°C. The optimized model also revealed that pH 6.5 and 45°C were the best conditions for peptidase reaction. In addition, Bacillus sp. 80BH11 was able to release highly emulsifying and remarkably stable surfactants in the LB medium. Surfactin was finally elucidated as the biosurfactant generated by this sponge-derived Bacillus. In conclusion, we hope to have set the scenery for further prospecting of industrial enzymes and biosurfactants in Homoscleromorpha microbiomes.

Comparative Study of Different Sampling Methods of Biofilm Formed on Stainless-Steel Surfaces in a CDC Biofilm Reactor.

The formation of biofilms in dairy processing plants can reduce equipment efficiency, contribute to surface deterioration, and contaminate dairy products by releasing the microorganisms they contain, which may cause spoilage or disease. However, a more representative identification of microbial communities and physico-chemical characterization requires to detach and recover adequately the entire biofilm from the surface. The aim of this study is to develop an efficient technique for in-plant biofilm sampling by growing a strain of Pseudomonas azotoformans PFl1A on stainless-steel surface in a dynamic CDC biofilm reactor system using tryptic soy broth (TSB) and milk as growth media. Different techniques, namely, swabbing, scraping, sonic brushing, synthetic sponge, and sonicating synthetic sponge were used and the results were compared to a standard ASTM International method using ultrasonication. Their efficiencies were evaluated by cells enumeration and scanning electron microscopy. The maximum total viable counts of 8.65 ± 0.06, 8.75 ± 0.08, and 8.71 ± 0.09 log CFU/cm2 were obtained in TSB medium using scraping, synthetic sponge, and sonicating synthetic sponge, respectively, which showed no statistically significant differences with the standard method, ultrasonication (8.74 ± 0.02 log CFU/cm2). However, a significantly (p < 0.05) lower cell recovery of 8.57 ± 0.10 and 8.60 ± 0.00 log CFU/cm2 compared to ultrasonication were achieved for swabbing and sonic brushing, respectively. Furthermore, scanning electron microscopy showed an effective removal of biofilms by sonic brushing, synthetic sponge, and sonicating synthetic sponge; However, only the latter two methods guaranteed a superior release of bacterial biofilm into suspension. Nevertheless, a combination of sonication and synthetic sponge ensured dislodging of sessile cells from surface crevices. The results suggest that a sonicating synthetic sponge could be a promising method for biofilm recovery in processing plants, which can be practically used in the dairy industries as an alternative to ultrasonication.

Target Mechanism of Iturinic Lipopeptide on Differential Expression Patterns of Defense-Related Genes against Colletotrichum acutatum in Pepper.

Bacillus subtilis KB21 is an isolate with broad spectrum antifungal activity against plant pathogenic fungi. Our aim was to produce and purify antifungal lipopeptides via fermentation using B. subtilis KB21 and verify their antifungal mechanism against pepper anthracnose. When the KB21 strain was cultured in tryptic soy broth medium, the antifungal activity against pepper anthracnose correlated with biosurfactant production. However, there was no antifungal activity when cultured in Luria-Bertani medium. KB21 filtrates showed the highest degree of inhibition of mycelia (91.1%) and spore germination (98.9%) of Colletotrichum acutatum via increases in the biosurfactant levels. Using liquid chromatography-mass spectrometry (LC-MS) and LC-tandem MS (LC-MS/MS) analyses, the component with antifungal activity in the fermentation medium of the KB21 strain was determined to be the cyclic lipopeptide (CLP) antibiotic, iturin A. When the iturin fractions were applied to pepper fruits inoculated with conidia of C. acutatum, the lesion diameter and hyphal growth on the fruit were significantly suppressed. In addition, iturin CLP elevated the gene expression of PAL, LOX, and GLU in the treatments both with and without following fungal pathogens. Overall, the results of this study show that iturin CLPs from B. subtilis KB21 may be potential biological control agents for plant fungal diseases.

Sodium benzoate and sodium bisulfate as preservatives in apple juice and alternative sanitizers for washing cherry tomatoes

Unpasteurized apple ciders and fresh produce have been linked to multistate outbreaks due to contamination by foodborne pathogens. Organic acids such as benzoic acid are effective antimicrobials, and acidified sodium benzoate (NaB) has been reported to be effective in reducing pathogens inoculated on cherry tomatoes and preventing cross-contamination. Sodium bisulfate (SBS) is a powerful acidulant but has not been studied in combination with NaB. The objective of the present study was to characterize the antibacterial activity of SBS and its combination with NaB in tryptic soy broth (TSB) and apple juice, as well as washing cherry tomatoes. The minimum inhibitory concentration and minimum bactericidal concentration of SBS were all 0.5% w/v (corresponding to TSB medium pH of 4.30) and 1.0% w/v (corresponding to TSB medium pH of 2.88), respectively, for Escherichia coli O157:H7 ATCC 43895, Salmonella Enteritidis ATCC 13076, and Listeria monocytogenes Scott A. In TSB, the triple combination of 1.0% w/v SBS, 0.1% w/v NaB, and 0.02% w/v oregano oil (OO) showed the faster inactivation rate of the three bacteria than treatments with one or two antimicrobials; the activity of double combinations followed the order of 0.1% w/v NaB +1.0% w/v SBS > 0.1% w/v NaB +0.5% w/v SBS + 0.02% w/v OO > 0.1% w/v NaB +0.5% w/v SBS. pH was a critical factor in the activity of antimicrobial combinations in TSB, and L. monocytogenes was more resistant than Gram-negative E. coli O157:H7 and S. Enteritis. In apple juice added with 0.05% w/v NaB, 0.25% w/v SBS, and 0.01% w/v OO alone or in combinations, 5 log CFU/mL or greater reductions in 72 h were observed for E. coli O157:H7 and S. Enteritidis in double and triple combinations, while only the triple combination and the SBS-OO combination resulted in the same effect for L. monocytogenes. For cherry tomatoes inoculated with 6.8 log CFU/g E. coli O157:H7, complete decontamination (>6 log CFU/g) was achieved after soaking for 1 min in solutions containing 0.5–1.5% w/v SBS and 0.1% w/v NaB or 1.5% w/v SBS alone, and no pathogens were detected in all wash solutions containing 0.5–1.5% w/v SBS with and without NaB. The lower pH of wash solutions with a higher amount of SBS was a dominant factor in decontamination and prevention of cross-contamination. The present study showed the potential of SBS and its combination with NaB to enhance the safety of apple juice and cherry tomatoes.

The First Complete Genome Resource of a Ralstonia solanacearum Phage UAM5 from Colombia.

The First Complete Genome Resource of a Ralstonia solanacearum Phage UAM5 from Colombia.

Antimicrobial Coating Efficacy for Prevention of Pseudomonas aeruginosa Biofilm Growth on ISS Water System Materials.

Biofilms can lead to biofouling, microbially induced corrosion, physical impediment and eventual loss in function of water systems, and other engineered systems. The remoteness and closed environment of the International Space Station (ISS) make it vulnerable to unchecked biofilm growth; thus, biofilm mitigation strategies are crucial for current ISS operation and future long duration and deep-space crewed missions. In this study, a space flown bacterial strain of Pseudomonas aeruginosa (PA14) was used as a model organism for its ability to form biofilms. Additionally, a novel antimicrobial coating’s ability to reduce biofilm accumulation on stainless steel, Teflon, titanium, and Inconel (all used in the ISS water treatment and handling systems) was analyzed. Coated materials demonstrated reductions of P. aeruginosa biofilm across all materials when tested in a continuous flow system with tryptic soy broth medium. However, the coating lost efficacy in potato dextrose broth medium. These findings were corroborated via scanning electron microscopy. This study illustrates the fundamental importance of using multiple approaches to test antibiofilm strategies, as well as the specificity in which conditions such strategies can be implemented.

Treatment of real aquaculture effluent using bacteria-based bioflocculant produced by Serratia marcescens

Aquaculture effluent contributes to surface water pollution. Coagulation, flocculation, and sedimentation are currently the best practices in aquaculture effluent treatment, and the utilization of chemical coagulants or flocculants is still dominant in assisting the treatment processes. This research aimed to analyze the potential of the bacteria-based bioflocculant produced by Serratia marcescens in treating real aquaculture effluent. S. marcescens was cultivated for 24 h inside tryptic soy broth medium, and the produced bioflocculant was used in raw condition (without extraction). Jar test and one-variable-at-a-time method were used to assess the effect of bioflocculant dosage, and its performance was compared with that of alum, a commonly used coagulant. The bioflocculant produced by S. marcescens worked well with the assistance of CaCl2. The 10% bioflocculant dosage showed a remarkable removal of turbidity and suspended solid (83.95% and 78.82%, respectively) compared with the control (80.98% and 76.99%, respectively). Increasing the bioflocculant dosage had a negative effect on color removal because the bioflocculant solution had a reddish color as a result of prodigiosin secretion by S. marcescens. Zeta potential, particle size distribution, and microscopic analyses revealed that flocculation occurred via the bridging mechanism. The utilization of CaCl2 + bioflocculant showed notable performances in turbidity and suspended solid removal compared with the control reactor while exhibiting a similar efficiency as alum (p < 0.05). Bioflocculant extraction is suggested to be conducted in future research to eliminate its negative effect on the color parameter.

Physical and Chemical Fermentation Conditions Affect the Growth and Metabolite Production of Endophytic Fungi Athelia rolfsii

Background: The effort to explore antimicrobial agents isolated from an endophytic fungus of Coleus amboinicus resulted in the finding of a potential aromatic compound having methoxy, hydroxyl, and methyl groups produced by Athelia rolfsii. This compound exhibited antibacterial activities with IC50 values of &lt;2 μg/mL against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Streptococcus mutans, and Pseudomonas aeruginosa. This study was aimed to determine the effect of varying fermentation conditions (types of media, carbon sources, nitrogen sources, temperature, and pH) on biomass, total metabolites, and bioactive compound production. Materials and Methods: The fungal cultures were subjected to various treatment conditions and incubated for 12 days at 25°C 160 rpm followed by analyzing the biomass, metabolite, and bioactive compound production. Results and Conclusion: The study found that although the maximum total metabolite production was achieved in the Tryptic Soy Broth medium, both biomass and bioactive compound production accumulated at the highest amount in Potato Dextrose Broth and Sabouraud Dextrose Broth media. Adding 1% of different types of carbon sources did not significantly enhance biomass, total metabolite, and bioactive compound production. Three types of organic nitrogen sources used in this study did not significantly affect biomass and total metabolite production, but adding peptone produced the highest amount of bioactive compound. Supplementing inorganic source of nitrogen to the culture medium decreased the production. While pH 5.5 was found to be the optimum condition for total metabolite production, pH 6–7 resulted in higher productivity of the bioactive compound. The total metabolite production was best produced at 25°C, whereas higher temperatures were needed to get optimum bioactive and biomass production. This study found that the total metabolite production was 7.8 times higher when the culture was grown in PDB medium supplemented with 1% sucrose and 1% peptone and incubated at 27°C at pH 6.5; whereas a 15% increase was observed in the bioactive compound production.

Attachment of Shiga Toxin-Producing Escherichia coli (STEC) to Pre-Chill and Post-Chill Beef Brisket Tissue.

Shiga toxin-producing Escherichia coli (STEC) has caused numerous foodborne illness outbreaks where beef was implicated as the contaminated food source. Understanding how STEC attach to beef surfaces may inform effective intervention applications at the abattoir. This simulated meat processing conditions to measure STEC attachment to adipose and lean beef tissue. Beef brisket samples were warmed to a surface temperature of 30 °C (warm carcass), while the remaining samples were maintained at 4 °C (cold carcass), prior to surface inoculation with an STEC cocktail (O26, O45, O103, O111, O121, O145, and O157:H7). Cocktails were grown in either tryptic soy broth (TSB) or M9 minimal nutrient medium. Loosely and firmly attached cells were measured at 0, 3, 5, and 20 min and 1, 3, 8, 12, 24 and 48 h. TSB-grown STEC cells became more firmly attached throughout storage and a difference in loosely versus firmly attached populations on lean and adipose tissues was observed. M9-grown STEC demonstrated a 0.2 log10 CFU/cm2 difference in attachment to lean versus adipose tissue and variability in populations was recorded throughout sampling. Future research should investigate whether a decrease in intervention efficacy correlates to an increase in firmly attached STEC cells on chilled carcasses and/or subprimals, which has been reported.