High-pressure processing (HPP) is considered effective for sterilizing minimally processed vegetable-based products. This study found that HPP could not completely inactivate the microorganisms in pickles. Candida albicans (C. albicans), an opportunistic pathogen in pickles, survived HPP exposure, while its death rate did not increase significantly with a further increase in holding time and pressure. It was striking that the biofilm formation and hyphae growth of C. albicans survived from 400 MPa HPP increased. Transcriptome analysis showed that 400 MPa affected more C. albicans genes than 300 MPa. The treatment at 300 MPa mainly facilitated transmembrane transport changes, while 400 MPa modified several metabolic processes. Furthermore, different pressure conditions caused various changes in important biofilm/hyphae-related genes, many of which were downregulated after 300 MPa treatment while upregulated after exposure to 400 MPa (NDT80, BRG1, GZF3, UME6, SET3, PES1, XOG1, RHR2, and SUN41). In addition, the GDH3, HGT9, and AAT21 genes may also play a vital role in the C. albicans tolerance of HPP. These findings emphasized the potential increased risk caused by the inability of HPP to inactive yeasts in food industry.

Probiotics are receiving significant attention due to their considerable health advantages. However, research involving the effect of probiotic biofilm and planktonic cells on the health of the host is limited. This study ascertained that the biofilm cells of Lactiplantibacillus paraplantarum LR-1 displayed stronger immunomodulation activity than their planktonic counterparts. Furthermore, the LR-1 biofilm cells more distinctly influenced the relative abundance of the intestinal marker bacteria than the planktonic cells. In comparison to the planktonic cells and the control group, the biofilm cells exhibited a stronger potential positive effect on the metabolism of the mice. Correlation analysis revealed the interaction between the metabolites, genera, and immune factors, which could explain the mechanism behind the beneficial effect of LR-1 biofilm or planktonic cells on host health. The results of this study enhance the understanding of the beneficial impact of probiotic biofilm cells while providing references for further investigation.

Since ulcerative colitis (UC) has become a global concern, Lactiplantibacillus is considered an effective, safe strategy for alleviating intestinal inflammation in UC patients. The most advanced fourth-generation probiotics involve beneficial bacteria enclosed in biofilms with multiple advantages. However, the difference between the effect of probiotic biofilm and planktonic cells on UC remains unclear. This study indicated that the biofilm cells of Lactiplantibacillus LR-1 were more successful in increasing the colon length, relieving intestinal inflammation, and repairing colon damage, regulating the host immunity than the planktonic cells. Furthermore, the LR-1 biofilm cells helped prevent a decline in the Eubacterium hallii and Salinimicrobium levels and increased Kocuria and Candidatus Bacilloplasma abundance. Untargeted metabolomics analysis results suggested that the LR-1 biofilm was more successful in promoting the intestinal metabolism recovery of the UC mice than the planktonic cells. Finally, the phenotype-microbiota-metabolism network was conducted to reveal the relationship between these factors.

Pickles are typical traditional Chinese fermented vegetables. Complex microbiota interacts throughout the fermentation and deterioration process. Minimal studies are available involving quorum sensing (QS) signaling in pickles. This study investigated the changes in the general pickle properties and microbial diversity at 4 d, 31 d, and 79 d. The QS signaling activity of various strains isolated at these key time points was screened using biosensor strains, while the types of signal molecules were further identified using UHPLC/QTOF-MS/MS. At 4 d, Lactobacillus represented the dominant genus, while Lactobacillus plantarum was identified as the bacteria with AI-2-producing ability. At 31 d, the dominant genus was also Lactobacillus, while the relative abundance of Pediococcus displayed a distinct increase. At this time point, L. plantarum represented the AI-2-producing bac-teria, followed by Lactobacillus brevis, Pediococcus sp., Enterobacter sp., and Bacillus megaterium. At 79 d, Lacto-bacillus was displaced by Enterobacter as the dominant microorganisms, while the AI-2-producing bacteria were identified as L. plantarum, Enterobacter sp., B. megaterium, Klebsiella sp., and Staphylococcus sp. Moreover, AHL activity was only present in isolates from the 79-d brine and was identified as C4-HSL and C6-HSL. In addition, the luxS gene was amplified via cDNA reversely transcription from the total RNA extracted from the brine at all three time points using the L. plantarum luxS primers. The AHL-related genes were only amplified in the RNA of 79-d brine samples using Klebsiella pneumoniae- and Bacillus cereus-related primers. This study presented theo-retical references for QS during pickle fermentation and deterioration.

The quality of pickled vegetables is essentially safeguarded through various processing techniques. In this study the effects of high hydrostatic pressure processing (HPP), pasteurization (Pt), nisin, HPP + nisin and Pt + nisin on fermented radishes (Raphanus sativus L.) were compared. The effects of the different treatments on firmness were not immediately apparent, however, the HPP-treated pickles maintained their hardness best during storage. Compared with Pt, the non-thermal treatments were found to have moderate effects on the colors, both immediately after treatment and during storage. Both HPP and Pt reduced microbes, while HPP + nisin completely inactivated bacteria. The activities of polyphenol oxidase (PPO), peroxidase (POD) and pectin methylesterase (PME) were most inactivated via Pt, followed the action of HPP and then by that of the nisin. The sensory evaluation suggested that non-thermal pickled radish might be better accepted by consumers. Moreover, Pt had the strongest ability to reduce oxalic acid and sulfur-containing compounds, while the effects of HPP were relatively moderate, and HPP not only effectively reduced sulfur-containing compounds, but also helped to retain the favorable factors in the pickles. The findings of this study, thus, indicate that HPP could be a promising alternative to traditional pasteurization in the processing and storage of fermented vegetables.

The persistence of Staphylococcus aureus within biofilm can lead to contamination of medical devices and life-threatening infections. Luckily, lactic acid bacteria (LAB) have an inhibitory effect on the growth of these bacteria. This study aims to select LAB strains from fermented vegetables, and analyze their potential inhibition activities against S. aureus. In total, 45 isolates of LAB were successfully isolated from Sichuan pickles, and the CFS of Lactiplantibacillus plantarum LR-14 exerted the strongest inhibitory effect against S. aureus. Moreover, S. aureus cells in planktonic and biofilm states both wrinkled and damaged when treated with the CFS of L. plantarum LR-14. In addition, whole genome sequencing analysis indicates that L. plantarum LR-14 contains various functional genes, including predicted extracellular polysaccharides (EPS) biosynthesis genes, and genes participating in the synthesis and metabolism of fatty acid, implying that L. plantarum LR-14 has the potential to be used as a probiotic with multiple functions.

The use of probiotics has recently become a considerably promising research area. The most advanced fourth-generation probiotics involve beneficial bacteria enclosed in biofilms. However, differences in the effects of probiotics in biofilm and those in planktonic states are, as yet, unclear. In this study, it was ascertained that the biofilm mode of Lactobacillus paraplantarum L-ZS9 had a comparatively higher density and stronger resistance. Untargeted metabolomics analysis suggested a significant distinction between planktonic and biofilm cells, with amino acids and carbohydrate metabolism both more active in the biofilm mode. Furthermore, the in vivo experiment showed that the biofilm strain displayed better immunomodulation activity, which could increase the relative abundance of Lactobacillus in the intestinal microbiota of dogs. The relative abundance of intestinal microbiota participating in carbohydrate metabolism was higher in the biofilm probiotic-treated dogs. Correlation analysis between L-ZS9-producing metabolites, dog intestinal microbiome diversity and dog blood immune indexes (sIgA or IgG) revealed the interaction between these three components, which might explain the mechanisms by which biofilm L-ZS9 regulated the intestinal microbiome and immunity activity of the host, through the production of various metabolites. Findings of this study will, thus, enhance understanding of the beneficial effects of biofilm probiotics, as well as provide references for further investigation.

This study aimed to investigate whether and how pgm,fba,and gap overexpression can affect the stress resistance,adhesiveness,and biofilm formation of Lactobacillus plantarum LR-1.Results showed that the overexpression of the pgm and fba genes enhanced the heat,acid and bile salt resistance,biofilm formation and adhesiveness of L.plantarum LR-1.The transcriptional level of the gap gene had no significant effect on the stress resistance,biofilm formation or adhesiveness.The up-regulation of pgm,fba,and gap increased the transcriptional levels of tuf and luxS in this strain with the first two being more effective than the last one.Furthermore,bioinformatic analyses suggested that pgm and fba could be associated with genes related to multiple pathways.These results provide a new understanding of the role of glycolytic pathway-related genes in regulating the stress resistance,adhesiveness,and biofilm formation of L.plantarum.

Traditional Chinese fermented vegetables are a type of brine-salted fermented vegetable product. During the spontaneous fermentation, various compounds are produced, degraded, and converted, influencing the quality of the fermented pickle. To ascertain the effect of different containers on the fermentation process of the pickles, this study investigated the bacterial diversity and the chemical composition characteristics of the pickle (radish) fermented in commonly used containers including glass jars (GL), porcelain jars (PO), and plastic jars (PL). The correlation between chemical compounds and microbial community was further analyzed. The changes in pH values suggested that PL may facilitate the quickest fermentation of the pickles, while the process in PO progressed at the lowest rate. The PL brine samples contained higher levels of lactic acid and threonine, while more abundant volatile chemical compounds were evident in PO. The container materials had no significant influence on the microbial structure, wherein Lactobacillus was the absolute dominant genus in all containers. But container material did have an effect on the abundance of specific genus, such as Lactococcus and Pediococcus. The correlation between these major genera was also analyzed and gene function prediction indicated that the top three pathways were: carbohydrate metabolism, amino acid metabolism, and energy metabolism. Lactobacillus negatively correlated with methionine, tyrosine, lysine, and arginine, but positively correlated with ammonia, and lactic acid and acetic acid both just correlated with Pediococcus. This study provides new insights into the microbiota succession and chemical compounds involved in the vegetable fermentation.

The Sichuan pickles of chili peppers, cowpeas and radishes were separately fermented for 12 days in order to identify the distinct microfloras and their correlations with the metabolites in different products. The chili pickle presented a slow fermentation process, high bacterial diversity within six phyla, and sixteen marker genera. Moreover, free amino acids accumulated in chili pickle and its main volatiles were alcohols and esters. Fast acidification and limited bacterial diversity within three phyla were found in Sichuan cowpea and radish pickles. The cowpea pickle was characterized by Lactobacillus and Pediococcus, as well as alcohols and alkenes. The radish pickle featured Lactococcus and Fructobacillus, as well as sulfides and aldehydes. Correlation analysis indicated that the metabolites, especially volatiles, were closely associated with not only the dominant bacteria but also those in low abundance.

Pickled radish produced using the traditional fermentation method that radishes being fermented with the aged brine in the pottery altar is exceptionally popular and widely consumed around China. Although this traditional technique is usually associated with the production of high-quality fermented radish, the main features of radish prepared using this method remain unclear. This study revealed the characteristics of microbial diversity and flavors in radish fermented with aged brine in traditional pottery containers. At the phylum level, Firmicutes was the highest during the fermentation process. At the genus level, the abundance of Lactobacillus dominated. As for fungal composition, Pichia and Candida were the main genera, and the abundance of Pichia was significantly higher than Candida. This study also identified the volatile flavor compounds, some of them for the first time, and PCA revealed the separation between samples was dominated by dimethyl trisulfide and piperidine-2-thione. The correlation analysis suggested that Lactobacillus was negatively associated with 13 flavors, of which ten flavors were free amino acids (FAA). Enterobacteriaceae unclassified was correlated positively with 18 flavors, of which 14 were FAA. This study provided insight into the characteristics of fermented pickles produced using traditional fermentation techniques, and the relationship between microbiota and flavors.

为研究黑臭河道沉积物资源化利用方式,评估沉积物资源化以后对营养盐去除效果和研究其去除机制,以北京市某黑臭河道沉积物(S)为供试样品,对其进行氧化并负载金属离子改性,最终得到氧化-载钠改性沉积物(MS).选取S和MS两种材料,评估其对氮和磷的去除效果,通过采用动力学、热力学等手段,进一步阐明改性材料对氮、磷去除机制.结果表明,在环境温度为35℃,固液比1∶50(g∶ml)的条件下,经氧化-载钠联合改性材料对氮(初始浓度20 mg/L)的去除效果均达到90％以上,其中对磷(初始浓度10 mg/L)的去除率最高可达98％;准二级动力学模型能更好的描述改性材料的吸附动力学行为(R2＞0.93),且动力学和吸附等温分析结果显示,Langmuir模型可以更好地描述两种材料的吸附等温线,改性材料对氮和磷的最大吸附量分别达到0.891和0.474 mg/g;热力学研究结果表明,吸附过程中,标准反应焓变(△H0)、标准反应熵变(△S0)均为正值,标准吉布斯自由能变(△G0)为负值,且随着温度的升高,△G0呈下降趋势.研究显示,MS具有更高的吸附性能,对氮、磷的吸附主要是材料表面活性吸附点位起主导作用,并且吸附过程是个吸热、自发进行的过程,更高的温度更有利于吸附.在同一温度下,随着氮、磷初始浓度的增加,MS对氮、磷的解吸比吸附过程更容易发生.

Malodorous rivers are among the major environmental problems of cities in developing countries. In addition to the unpleasant smell, the sediments of such rivers can act as a sink for pollutants. The excessive amount of ammonia nitrogen (NH3−N) in rivers is the main factor that causes the malodour. Therefore, a suitable method is necessary for sediment disposition and NH3−N removal in malodorous rivers. The sediment in a malodorous river (PS) in Beijing, China was selected and modified via calcination (PS-D), Na+ doping (PS-Na) and calcination–Na+ doping (PS-DNa). The NH3−N removal efficiency using the four sediment materials was evaluated, and results indicated that the NH3−N removal efficiency using the modified sediment materials could reach over 60%. PS-DNa achieved the highest NH3−N removal efficiency (90.04%). The kinetics study showed that the pseudo-second-order model could effectively describe the sorption kinetics and that the exterior activated site had the main function of P sorption. The results of the sorption isotherms indicated that the maximum sorption capacities of PS-Na, PS-D and PS-DNa were 0.343, 0.831 and 1.113 mg g−1, respectively, and a high temperature was favourable to sorption. The calculated thermodynamic parameters suggested that sorption was a feasible or spontaneous (ΔG < 0), entropy-driven (ΔS > 0), and endothermic (ΔH > 0) reaction.

Abstract Sediment microbial communities from plain river networks exert different effects on pollutant transformation and migration in lake basins. In this study, we examined millions of Illumina reads (16S rRNA gene amplicons) to compare lake, lake wetland, and estuary bacterial communities through a technically consistent approach. Results showed that bacterial communities in the sampled lake sediments had the highest alpha‐diversity (Group B), than in sampled lake wetland sediments and estuary sediments. Proteobacteria was the most abundant (more than 30%) phyla in all the sediments. The lake sediments had more Nitrospirae (1.63%–11.75%) and Acidobacteria (3.46%–10.21%) than the lake wetland and estuary sediments, and estuary sediments had a greater abundance of the phylum Firmicutes (mean of 22.30%). Statistical analysis (LEfSe) revealed that lake wetland sediments contained greater abundances of the class Anaerolineaceae, orders Xanthomonadales, Pseudomonadales, and genera Flavobacterium, Acinetobacter. The lake sediments had a distinct community of diverse primary producers, such as phylum Acidobacteria, order Ignavibacteriales, and families Nitrospiraceae, Hydrogenophilaceae. Total phosphorus and organic matter were the main factors influencing the bacterial communities in sediments from several parts of the lake wetland and river estuary (p < .05). The novel insights into basin pollution control in plain river networks may be obtained from microbial distribution in sediments from different basin regions.

Phosphorus (P) sorption in sediments plays a significant role in trophic status of a lake. This study investigated the characteristics of P sorption in sediments from three lakes with different trophic statuses (moderately eutrophic, lightly eutrophic and moderately trophic) through kinetic, batch equilibrium and thermodynamic experiments. Results show that pseudo-second-order kinetics best describe P sorption in sediments from the three lakes. Fitting by modified Langmuir and Freundlich isotherms indicates that the moderately trophic lake sediment has higher sorption capacity (maximum of 0.848 mg g-1 at 35°C) than the sediments of the other two lakes at different temperatures (5, 15, 25 and 35°C). Thermodynamic results indicate that the processes of P sorption of the three sediments are spontaneous, entropy-driven and endothermic reactions. The risk of P release in sediments was analysed according to the calculated results of isotherms combined with the change in P fraction. Sediments from the moderately eutrophic lake act as a source in summer. The lightly eutrophic and moderately trophic lakes act as sources in spring and winter, and a pool in summer and autumn, respectively. Furthermore, the amounts of reductant-soluble P, calcium-bound P and iron-bound P are significantly related to the sorption capacity of sediments from the three lakes (p < 0.05). The different sediments have different P release risk, and P fraction in sediment is one of the significant factors of P sorption.

Utilization of sediment resources and excessive phosphorus (P) in malodorous river caught the interest of numerous researchers. This study investigated P sorption with modified sediments from malodorous rivers through kinetics, equilibrium, and thermodynamic experiments. Results indicated that sorption rate followed the pseudo-second-order model (R-2 > 0.93), and when the temperature increased, the P removal efficiency of modified sediment samples increased (the highest value of 93.2%). Modified sediment materials, which are oxidation (PS-N), Na-doped (PS-Na), and oxidation-Na doped (PS-NNa), presented higher P sorption capacities than raw sediment due to changes in their surface structure. PS-NNa showed the highest sorption capacity (1.43 mg g(-1)) in comparison other sediment materials. Data from isotherm experiments were well described by Langmuir isotherm model, and calculated thermodynamic parameters illustrated occurrence of spontaneous (Delta G < 0), entropy-driven P sorption (Delta S > 0) and endothermic reactions (Delta H > 0).

Malodorous river is one of the main environmental problems in the cities of China.The suitable method of the disposal of the sediment and excess phosphorus (P) in malodorous river need to be found.There fore,it is significant to study the method of the resource of the sediment in malodorous river to remove the excess P in water.The sediment in Liangshui River (PS) in Beijing was chosen and modified using oxidation (PS-N),Na+ doped (PS-Na),and oxidation-Na+ doped (PS-NNa).The P removal efficiency using the four sediment materials was evaluated,and the results indicated that the P removal efficiency using modified sediment materials could reached more than 60％,and PS-NNa had the highest P removal efficiency (94.7％).The sorption isotherms and kinetic were used to study the sorption mechanism of the four sediment materials.The results indica ted that the maximum sorption capacities of PS-Na,PS-N,and PS-NNa were 0.83,1.03 and 1.42 mg · g-1,respectively,and the high temperature was favor of sorption.The kinetic study indicated that the pseudo-second order model could better describe the sorption kinetics,and the exterior activated site had the main function of P sorption.In addition,the three modified sediment materials had the obvious advantage of P removal compared with other P sorption materials.

Sediment microbial communities play an important role in lake trophic status. This study determined millions of Illumina reads (16S rRNA gene amplicons) to compare the bacterial communities in moderately eutrophic, lightly eutrophic, and moderately trophic regions using a technically consistent approach. The results indicated that the sediments from moderately eutrophic and trophic lake had the higher bacterial diversity than lightly eutrophic lake. Proteobacteria was the most abundant phylum (22.7%-86.2%) across samples from three regions. The sediments from moderately eutrophic region were enriched with Chloroflexi and Nitrospirae. Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes were enriched in the sediments from lightly eutrophic lake. The sediments from moderately trophic lake contained a high abundance of Acidobacteria and Deltaproteobacteria because of the low pH of the sediments in this lake. In moderately eutrophic region, Nitrospira held an absolute predominance, while Lysobacter and Flavobacterium were the most predominant genera in lightly eutrophic region. Temperature was the main factor influencing the bacterial community in the three lakes. The bacterial communities in the sediment samples obtained from moderately eutrophic lake were associated with nutrient concentration, whereas organic matter and total nitrogen contents mainly influenced the bacterial communities in sediments obtained from lightly eutrophic lake and moderately trophic lake, respectively.