In vitro and in vivo genome-based safety evaluation of Lacticaseibacillus rhamnosus LRa05.

The aim of this study was to comprehensively evaluate the safety of Lacticaseibacillus rhamnosus LRa05 (hereinafter "LRa05") to determine its suitability for use as a probiotic in the food industry. First, we sequenced the genome of LRa05 and then determined whether it contained genes associated with antibiotic resistance, virulence, or pathogenicity. Second, we evaluated the safety of LRa05 in vitro by performing a hemolysis assay and examining its ability to produce biogenic amines, its antimicrobial susceptibility, its capacity to transfer antibiotic resistance genes, its genomic stability, and whether it contained potential virulence factors. Third, we investigated the pathogenicity of LRa05 in mice by oral gavage and intraperitoneal injection. A bioinformatics analysis revealed no evidence that the genome of LRa05 contains genes associated with virulence or antibiotic resistance. In addition, the results of in vitro experiments showed that LRa05 does not produce d-lactic acid or exhibit hemolytic activity and is sensitive to clinically relevant antibiotics. Furthermore, a pathogenicity test revealed that LRa05 exhibits no lethality or toxicity in mice. Taken together, these findings indicate that LRa05 is sufficiently safe to be explored as a potential probiotic for use in the food industry.

Utilization of diverse oligosaccharides for growth by Bifidobacterium and Lactobacillus species and their in vitro co-cultivation characteristics.

Various approaches have been used to study the relationship between prebiotics and probiotics. The utilization of different carbohydrates by probiotics depends on the biochemical properties of the enzymes and substrates required by the microbial strain. However, few studies have systematically analyzed the ability of probiotics to utilize different prebiotics. Here, we investigated the effects of prebiotics from different manufacturers on the proliferation of 13 strains of the Lactobacillus group and the genus Bifidobacterium co-cultured in vitro. Inulin, fructose-oligosaccharide (FOS), and galactose-oligosaccharide (GOS) had broad growth-promoting effects. FOS significantly promoted the proliferation of B. longum. When strains from Lactobacillus group and Bifidobacterium were co-cultured, FOS caused each strain to proliferate cooperatively. GOS was effectively used by L. rhamnosus and L. reuteri for energy and growth promotion. L. casei and L. paracasei fully metabolized inulin; these strains performed better than other strains from Lactobacillus group and Bifidobacterium. Media containing a mixture of oligosaccharides had stronger effects on the growth of B. animalis subsp. lactis, L. acidophilus, and L. rhamnosus than media containing single oligosaccharides. Thus, different oligosaccharides had different effects on the growth of probiotics, providing a scientific basis for the use of synbiotics in health and related fields.

Bifidobacterium longum subsp. longum BL21 ameliorates alcoholic liver disease in mice through enhancement of the hepatic antioxidant capacity and modulation of the gut microbiota.

BACKGROUND: Alcoholic liver disease (ALD) is a chronic liver injury caused by excessive alcohol consumption, could be impacted by gut-liver axis dysfunction. The gut microbiota plays a crucial role in the development and progression of ALD. Given the role of gut-liver axis dysfunction in ALD, strategies targeting gut microbiota modulation have gained interest for therapeutic interventions. Bifidobacterium longum subsp. longum BL21 has shown promise in alleviating gut microbiota disturbances and metabolic regulation in high-fat diet-induced obesity and type 2 diabetes mellitus models. Thus, this study aimed to evaluate the therapeutic effect of BL21 on ALD mice and explore the potential mechanism by which the gut microbiota mediates the amelioration of ALD by BL21. METHODS: A total of 30 mice were randomly assigned to three groups (n = 10 mice/group): a healthy control (CTL) group, an ALD group, and a BL21 group. Each group was fed a Lieber-DeCarli liquid diet with (ALD and BL21) or without alcohol (CTL). The intervention period lasted 6 weeks, after which the effects of BL21 intervention (intragastric administration of 1 billion CFU of BL21 daily) on serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, hepatic oxidative stress, serum inflammatory cytokine levels, and gut microbiota composition in ALD mice were investigated. RESULTS: Dietary BL21 reduced the ethanol-induced abnormal elevation of serum AST and ALT levels in ALD mice (P < 0.001 for both). BL21 treatment significantly attenuated alcohol-induced hepatic oxidative stress by decreasing malondialdehyde concentration and increasing superoxide dismutase, catalase, and glutathione concentrations in the livers of ALD mice. In addition, the serum levels of tumor necrosis factor-alpha, interleukin-1 beta (IL-1ß), and IL-6 were significantly lower (P < 0.001 for both), while that of IL-10 was significantly higher (P < 0.05), in the BL21 group than in the ALD group. Intestinal microbiota analysis showed an increased relative abundance of Escherichia/Shigella, Enterococcus, and Alistipes in the ALD group compared with the CTL group. BL21 intervention increased the relative abundance of Bifidobacterium and Akkermansia compared with the ALD group. CONCLUSION: Dietary BL21 ameliorates ALD via enhancement of the hepatic antioxidant capacity and modulation of the gut microbiota and may therefore be a promising strategy to prevent or treat ALD.

Effects of Bifidobacterium BL21 and Lacticaseibacillus LRa05 on gut microbiota in type 2 diabetes mellitus mice.

Gut dysbiosis causes damage to the intestinal barrier and is associated with type 2 diabetes mellitus (T2DM). We tested the potential protective effects of probiotic BL21 and LRa05 on gut microbiota in type 2 diabetes mellitus mice and determined whether these effects were related to the modulation of gut microbiota.Thirty specific pathogen-free C57BL/6J mice were randomly allocated to three groups-the (CTL) control group, HFD/STZ model (T2DM) group, and HFD/STZ-probiotic intervention (PRO) group-and intragastrically administered strains BL21 and LRa05 for 11 weeks. The administration of strains BL21 and LRa05 significantly regulated blood glucose levels, accompanied by ameliorated oxidative stress in mice. The BL21/LRa05-treated mice were protected from liver, cecal, and colon damage. Microbiota analysis showed that the cecal and fecal microbiota of the mice presented significantly different spatial distributions from one another. Principal coordinate analysis results indicated that both T2DM and the BL21/LRa05 intervention had significant effects on the cecal contents and fecal microbiota structure. In terms of the fecal microbiota, an abundance of Akkermansia and Anaeroplasma was noted in the PRO group. In terms of the cecal content microbiota, enrichment of Akkermansia, Desulfovibrio, Bifidobacterium, Lactobacillus, and Limosilactobacillus was noted in the PRO group. The probiotics BL21 and LRa05 prevent or ameliorate T2DM by regulating the intestinal flora and reducing inflammation and oxidative stress. Our results suggest that BL21 and LRa05 colonize in the cecum. Thus, BL21/LRa05 combined with probiotics having a strong ability to colonize in the colon may achieve better therapeutic effects in T2DM. Our study illustrated the feasibility and benefits of the combined use of probiotics and implied the importance of intervening at multiple intestinal sites in T2DM mice.

Sustained ameliorative effect of Lactobacillus acidophilus LA85 on dextran sulfate sodium-induced colitis in mice.

Ulcerative colitis (UC) is a type of inflammatory bowel disease associated with immune system dysfunction caused by gut dysbiosis. This study aimed to investigate the alleviating effect of Lactobacillus acidophilus LA85 on colitis and its underlying mechanism using mouse models of dextran sulfate sodium (DSS)-induced UC. The UC mouse models were established by treating C57BL/6J male mice with 2.5% (w/v) DSS in drinking water for 7 days. These mice received supplementation with either L. acidophilus LA85 (1 × 109 colony-forming units/day) or 200 µL of sterile water once daily (LA85-treated and UC model mice, respectively). The disease activity index (DAI), colon length, and histological changes in the colons of mice were then analyzed at Day 21, and the effects of L. acidophilus LA85 on the gut microbiota and serum inflammatory cytokines were also investigated. Compared with the UC model mice, L. acidophilus LA85-treated UC mice showed significant reductions in a variety of colitis symptoms, including weight loss, the DAI score, colon shortening, and colon tissue damage. Lactobacillus acidophilus LA85 supplementation also significantly decreased the serum concentrations of tumor necrosis factor α and interleukin-6 while increasing the serum concentration of IL-10. Furthermore, LA85 supplementation improved the diversity and composition of the gut microbiota, both of which had been decreased by DSS. In particular, L. acidophilus LA85-treated UC mice showed higher relative abundances of Akkermansia and Romboutsia than the UC model mice. These results demonstrate that L. acidophilus LA85 can alleviate inflammatory diseases of the intestine, such as inflammatory bowel disease, by regulating immune responses and restoring the gut microbiota. PRACTICAL APPLICATION: Ulcerative colitis is a type of inflammatory bowel disease caused by imbalance of gut microbiota. This study showed that L. acidophilus LA85 can alleviate DSS-induced colitis in mice through regulation of inflammatory cytokines, protection of intestinal barrier, and regulation of specific gut microbiota. L. acidophilus LA85 is a promising probiotic candidate for the treatment of UC.

Changes in the gut microbiota composition of healthy young volunteers after administration of Lacticaseibacillus rhamnosus LRa05: A placebo-controlled study.

The gut microbiota promotes gastrointestinal health in humans; however, the effect of probiotics on the gut microbiota of healthy adults has not been documented clearly. This placebo-controlled study was conducted to assess the effect of Lacticaseibacillus rhamnosus LRa05 supplementation on the gut microbiota of healthy adults. The subjects (N = 100) were randomized 1:1 to receive (1) maltodextrin (placebo, CTL group) and (2) maltodextrin + strain LRa05 (1 × 1010 colony-forming units/day, LRa05 group). The duration of the intervention was 4 weeks, and changes in the gut microbiota from before to after the intervention were investigated using 16S rRNA high-throughput sequencing. In terms of alpha diversity, no significant difference in the composition of the gut microbiota was found between the LRa05 and CTL groups. 16S rRNA sequencing analysis showed that the relative abundance of Lacticaseibacillus significantly increased after supplementation with LRa05. Furthermore, a decreasing trend in the abundance of Sellimonas and a significant decrease in the salmonella infection pathway were observed in the LRa05 group compared with the CTL group. These findings indicate the potential of LRa05 to colonize the human gut and reduce the abundance of harmful bacteria in the microbiota.

Milk fermentation by monocultures or co-cultures of Streptococcus thermophilus strains.

Direct vat-set starter cultures are the key ingredient for the production of fermented dairy products. The characteristics of the strains used for fermentation determine the fermentation time, texture and flavor of the fermented milk products. In this study, a large-scale analysis of the acid production rate, texture, carbon source utilization characteristics of Streptococcus thermophilus strains was conducted. All 100 S. thermophilus strains were divided into six groups according to the acid production rate and into two groups according to the consistency texture. A universal medium, basing on the carbon sources metabolic properties were optimized (0.5% lactose and 3.5% glucose), to culture all of the tested strains. Among them 40 strains were used to test pH-controlled conditions using this universal culture medium. After 5-7 h of fermentation, the optical density (OD) values of all fermented products exceeded 10, suggesting the potential for high-density cultivation of S. thermophilus. Although the OD could be further increased by adding more glucose, this may have hindered subsequent lyophilization because of high residual lactic acid in the fermented product. Next, the application of Streptococcus thermophilus strains in fermented milk was studied. Monocultures and co-cultures of strains were evaluated and compared. The results revealed the existence of symbiotic or competitive relationships between different S. thermophilus strains. Based on the findings, the mixing ratio of three symbiotic S. thermophilus strains was optimized. A co-culture of these three strains yielded fermented milk with high viscosity, low post-acidification, good sensory properties and processability.

Bifidobacterium BLa80 mitigates colitis by altering gut microbiota and alleviating inflammation.

This study was conducted to explore the therapeutic effect of the probiotic Bifidobacterium animalis subsp. lactis BLa80 on inflammatory bowel disease. A model of ulcerative colitis (UC) was induced in C57BL/6 mice by administering of 2.5% dextran sulphate sodium (DSS) for 8 days. After developing UC, some mice were treated via intragastric administration of BLa80 at a dose of 109 colony-forming units to assess the preventive effects of BLa80 on DSS-induced UC. Compared with non-treated UC model mice, BLa80-treated mice had reduced colon shortening and improvements in colonic tissue structure. Treatment with BLa80 also decreased the serum concentrations of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin (IL) 6 and IL-17 in mice. 16S rRNA gene sequencing revealed that BLa80 increased gut microbial diversity in mice and modulated UC-associated imbalances in the gut microbiota. BLa80 selectively promoted the growth of beneficial bacteria, including Romboutsia and Adlercreutzia, the abundances of which were negatively correlated with concentration of cellular inflammatory factors. In summary, the study results demonstrated that pretreatment with B. lactis BLa80 reduced intestinal inflammation and altered the gut microbiota, implying that BLa80 is a promising probiotic strain with potential therapeutic function in UC.

Protective effects of Lacticaseibacillus rhamnosus Hao9 on dextran sulphate sodium-induced ulcerative colitis in mice.

AIMS: Some probiotics used as food additives or food supplements had an anti-inflammatory effect. We tested the potential protective effects of probiotic Lacticaseibacillus rhamnosus Hao9 (Hao9) in mice with dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) and determined whether these effects were related to the modulation of gut microbiota and amelioration of inflammation. METHODS AND RESULTS: Ulcerative colitis mouse model was established by feeding mice with 2.5% (w/v) DSS in drinking water for 7 days. We analysed the disease activity index (DAI), colon length and histological changes in the colon. In addition, we investigated the effects of Hao9 (1 × 109 colony forming unit/day) and curcumin (CUR) (200 mg/kg/day) on gut microbiota and serum inflammatory cytokines. In this study, CUR was used as a positive control. The results showed that both Hao9 and CUR effectively reduced body mass loss and DAI, restored colon length, alleviated colonic pathological variations and reduced histological scores compared with the UC group. Hao9 reduced the serum concentrations of proinflammatory cytokines (tumour necrosis factor alpha, interleukin [IL]-6 and IL-1ß) and increased the concentration of the anti-inflammatory cytokine IL-10. In addition, Hao9 promoted the growth of Faecalibaculum and Romboutsia in the gut and helped to maintain intestinal homeostasis. CONCLUSIONS: Hao9 had a protective effect against DSS-induced colitis, and the mechanisms underlying Hao9 may involve controlling inflammation and maintaining host micro-ecological balance. This study provided experimental evidence for the application of Hao9 in the treatment of ulcerative colitis and suggested that Hao9 may be a promising candidate as a dietary supplement against colitis. SIGNIFICANCE AND IMPACT OF THE STUDY: The comparison of probiotics and prebiotics in terms of therapeutic efficacy in UC helps us to understand their different patterns of regulation of intestinal microbiota.

Lacticaseibacillus rhamnosus Hao9 exerts antidiabetic effects by regulating gut microbiome, glucagon metabolism, and insulin levels in type 2 diabetic mice.

Introduction: Type 2 diabetes mellitus (T2DM) is a metabolic disease that has led to a significant global public health burden. Methods: In this work, we investigated the effects of Lacticaseibacillus rhamnosus Hao9 on T2DM in mice with high-fat diet- and streptozotocin (STZ)-induced diabetes (diabetic mice) and explored the underlying mechanisms. Results: We found that 109 colony forming units (CFUs) of Hao9 per day significantly reduced fasting blood glucose and insulin levels (p < 0.001) in diabetic mice. Moreover, Hao9 enhanced liver antioxidant capacity and significantly decreased glucose-6-phosphatase and phosphoenolpyruvate carboxykinase expression in the livers of diabetic mice (p < 0.001). Hao9 also reduced the serum concentrations of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNFα), interleukin-1ß (IL1ß), and IL6 (p < 0.05) and improved intestinal barrier function in diabetic mice. The composition of the gut microbiome was modulated by Hao9, with an increased abundance of Roseburia, Eubacterium, and Lacticaseibacillus, and decreased abundance of Escherichia/Shigella. Notably, Lacticaseibacillus was detected at both weeks 5 and 12 post-treatment, suggesting sustained colonization of the gut by Hao9. Discussion: The supplementation of Hao9 improved gut microbiota, glucose metabolism, and insulin levels significantly in T2DM mice. That means Hao9 contributes to improving T2DM symptoms with its potential beneficial effects. Therefore, Hao9 is a promising dietary supplement for the treatment of T2DM.

Paeonol protects against hypertension in spontaneously hypertensive rats by restoring vascular endothelium.

The present study focused on the effect of paeonol, one of the main components of Guizhi Fuling Pill, on blood pressure, cerebral blood flow, and vascular endothelium injury in spontaneously hypertensive rats to provide theoretical basis for the treatment of hypertension. After treatment with paeonol, the mean arterial pressure (MAP) of LSHRT and HSHRT rats decreased gradually with the prolongation of treatment time. The systolic blood flow velocity (Vs), diastolic blood flow velocity (Vd) and mean blood flow velocity (Vm) were significantly increased after paeonol treatment (p < 0.05). Paeonol effectively improved the blood pressure and increased the cerebral blood flow velocity in spontaneously hypertensive rats. This may be related to the fact that paeonol reduced the blood viscosity and the oxidative stress and improved the antioxidant capacity. Moreover, paeonol protected vascular endothelial cells and reduced vascular endothelial injury in spontaneously hypertensive rats.

The plasticity of indigenous microbial community in a full-scale heavy oil-produced water treatment plant.

Indigenous microbial communities are main and promising performers for bioremediation due to their excellent adaptability, degradation capability, and inherent plasticity. Treating heavy oil-produced water (HOPW) is a challenge owing to the high recalcitrance and heterogeneity of chemicals it contains. A full-scale HOPW treatment plant was built at a capacity of 10,000 m3/d with the indigenous microbial community. After the treatment, the outlet water reached the design standard. The microbial community structures in all treatment stages were analyzed by using Illumina MiSeq 16S rRNA gene sequencing. The composition of microbial community changed greatly with the changes in environmental conditions, especially with the only artificially regulated parameter of dissolved oxygen. In the anaerobic stage, the community converted the recalcitrant chemical oxygen demand to biological oxygen demand (BOD), and played a major role in enhancing the biodegradability of HOPW. During the aerobic stage, the community mainly mineralized BOD. These results suggest that the structures of indigenous microbial community differed in different treatment stages to accomplish the corresponding functions. Based on these findings, it is proposed that exploiting the plasticity of microbial communities for bioremediation is feasible, especially treating wastewater with varied components.

Genome sequence of Pseudomonas aeruginosa DQ8, an efficient degrader of n-alkanes and polycyclic aromatic hydrocarbons.

Pseudomonas aeruginosa DQ8, which was isolated from the crude oil polluted soil in the Daqing oilfield of China, can efficiently degrade diesel, crude oil, n-alkanes, and polycyclic aromatic hydrocarbons (PAHs). Here, we present a 6.8-Mb assembly of its genome sequence. We have annotated 23 coding sequences (CDSs) responsible for catabolism of n-alkanes and PAHs.

Genome sequence of the welan gum-producing strain Sphingomonas sp. ATCC 31555.

Sphingomonas sp. strain ATCC 31555 can produce an anionic heteropolysaccharide, welan gum, which shows excellent stability and viscosity retention even at high temperatures. Here we present a 4.0-Mb assembly of its genome sequence. We have annotated 10 coding sequences (CDSs) responsible for the welan gum biosynthesis and 55 CDSs related to monosaccharide metabolism.

Genome sequences of Pseudomonas luteola XLDN4-9 and Pseudomonas stutzeri XLDN-R, two efficient carbazole-degrading strains.

Pseudomonas luteola XLDN4-9 and Pseudomonas stutzeri XLDN-R are two efficient carbazole-degrading pseudomonad strains. Here we present 4.63- and 4.70-Mb assemblies of their genomes. Their annotated key genes for carbazole catabolism are similar, which may provide further insights into the molecular mechanism of carbazole degradation in Pseudomonas.

Genome sequence of a highly efficient aerobic denitrifying bacterium, Pseudomonas stutzeri T13.

Pseudomonas stutzeri T13 is a highly efficient aerobic denitrifying bacterium. Information about the genome of this aerobic denitrifying bacterium has been limited until now. We present the draft genome of P. stutzeri T13. The results could provide further insight into the aerobic denitrification mechanism in strain T13.

Genome sequence of a cold-adaptable sulfamethoxazole-degrading bacterium, Pseudomonas psychrophila HA-4.

Pseudomonas psychrophila HA-4 is a cold-adaptable, sulfamethoxazole-degrading bacterium. The genes related to its cold adaptation mechanism and sulfamethoxazole metabolism were unknown. We present the draft genome of strain HA-4. It could provide further insight into the sulfamethoxazole-degrading mechanism of strain HA-4.

Genome sequence of Xanthomonas campestris JX, an industrially productive strain for Xanthan gum.

Xanthomonas campestris JX, a soil bacterium, is an industrially productive strain for xanthan gum. Here we present a 5.0-Mb assembly of its genome sequence. We have annotated 12 coding sequences (CDSs) responsible for xanthan gum biosynthesis, 346 CDSs encoding carbohydrate metabolism, and 69 CDSs related to virulence, defense, and plant disease.

Carotenoids play a positive role in the degradation of heterocycles by Sphingobium yanoikuyae.

BACKGROUND: Microbial oxidative degradation is a potential way of removing pollutants such as heterocycles from the environment. During this process, reactive oxygen species or other oxidants are inevitably produced, and may cause damage to DNA, proteins, and membranes, thereby decreasing the degradation rate. Carotenoids can serve as membrane-integrated antioxidants, protecting cells from oxidative stress. FINDINGS: Several genes involved in the carotenoid biosynthetic pathway were cloned and characterized from a carbazole-degrading bacterium Sphingobium yanoikuyae XLDN2-5. In addition, a yellow-pigmented carotenoid synthesized by strain XLDN2-5 was identified as zeaxanthin that was synthesized from ß-carotene through ß-cryptoxanthin. The amounts of zeaxanthin and hydrogen peroxide produced were significantly and simultaneously enhanced during the biodegradation of heterocycles (carbazole < carbazole + benzothiophene < carbazole + dibenzothiophene). These higher production levels were consistent with the transcriptional increase of the gene encoding phytoene desaturase, one of the key enzymes for carotenoid biosynthesis. CONCLUSIONS/SIGNIFICANCE: Sphingobium yanoikuyae XLDN2-5 can enhance the synthesis of zeaxanthin, one of the carotenoids, which may modulate membrane fluidity and defense against intracellular oxidative stress. To our knowledge, this is the first report on the positive role of carotenoids in the biodegradation of heterocycles, while elucidating the carotenoid biosynthetic pathway in the Sphingobium genus.

Metabolic characterization and genes for the conversion of biphenyl in Dyella ginsengisoli LA-4.

A complete bph gene cluster (bphLA-4) containing 12,186 bp was amplified from Dyella ginsengisoli LA-4. The bphLA-4 was composed of bphABCXD, and an additional gene encoding a meta-fission product hydrolase was located in the bphX region. BphLA-4 was independently transcribed by the two operons, bphA1A2orf1A3A4BCX0 and bphX1orf2X2X3D, and significantly differed from bphKF707. Both benzoate and catechol induced the expression of both operons. 2-Hydroxypenta-2,4-dienoate was identified as the intermediate of the biphenyl degradation by strain LA-4. This finding suggested that there existed a novel lower pathway of biphenyl degradation in strain LA-4.