Screening of Lactobacillus plantarum Subsp. plantarum with Potential Probiotic Activities for Inhibiting ETEC K88 in Weaned Piglets.

For screening excellent lactic acid bacteria (LAB) strains to inhibit enterotoxigenic Escherichia coli (ETEC) K88, inhibitory activities of more than 1100 LAB strains isolated from different materials, and kept in the lab, were evaluated in this study. Nine strains with inhibition zones, at least 22.00 mm (including that of a hole puncher, 10.00 mm), and good physiological and biochemical characteristics identified by 16S DNA gene sequencing and recA gene multiple detection, were assigned to Lactobacillus (L.) plantarum subsp. plantarum (5), L. fermentum (1), L. reuteri (1), Weissella cibaria (1) and Enterococcus faecalis (1), respectively. As investigated for their tolerance abilities and safety, only strain ZA3 possessed high hydrophobicity and auto-aggregation abilities, had high survival rate in low pH, bile salt environment, and gastrointestinal (GI) fluids, was sensitive to ampicillin, and resistant to norfloxacin and amikacin, without hemolytic activity, and did not carry antibiotic resistance genes, but exhibited broad spectrum activity against a wide range of microorganisms. Antibacterial substance may attribute to organic acids, especially lactic acid and acetic acid. The results indicated that the selected strain L. plantarum subsp. plantarum ZA3 could be considered a potential probiotic to inhibit ETEC K88 in weaned piglets for further research.

Comparative microbiota assessment of wilted Italian ryegrass, whole crop corn, and wilted alfalfa silage using denaturing gradient gel electrophoresis and next-generation sequencing.

The microbiota of pre-ensiled crop and silage were examined using denaturing gradient gel electrophoresis (DGGE) and next-generation sequencing (NGS). Wilted Italian ryegrass (IR), whole crop corn (WC), and wilted alfalfa (AL) silages stored for 2 months were examined. All silages contained lactic acid as a predominant fermentation product. Across the three crop species, DGGE detected 36 and 28 bands, and NGS identified 253 and 259 genera in the pre-ensiled crops and silages, respectively. The NGS demonstrated that, although lactic acid bacteria (LAB) became prevalent in all silages after 2 months of storage, the major groups were different between crops: Leuconostoc spp. and Pediococcus spp. for IR silage, Lactobacillus spp. for WC silage, and Enterococcus spp. for AL silage. The predominant silage LAB genera were also detected by DGGE, but the presence of diverse non-LAB species in pre-ensiled crops was far better detected by NGS. Likewise, good survival of Agrobacterium spp., Methylobacterium spp., and Sphingomonas spp. in IR and AL silages was demonstrated by NGS. The diversity of the microbiota described by principal coordinate analysis was similar between DGGE and NGS. Our finding that analysis of pre-ensiled crop microbiota did not help predict silage microbiota was true for both DGGE and NGS.

Extraction of Fenugreek (Trigonella foenum-graceum L.) Seed Oil Using Subcritical Butane: Characterization and Process Optimization.

In this study, the subcritical butane extraction process of fenugreek seed oil was optimized using response surface methodology with a Box-Behnken design. The optimum conditions for extracted oil from fenugreek seed was as follows: extraction temperature of 43.24 °C , extraction time of 32.80 min, and particle size of 0.26 mm. No significant differences were found between the experimental and predicted values. The physical and chemical properties of the oil showed that the oil could be used as edible oil. Fatty acid composition of oils obtained by subcritical butane under the optimum conditions and by accelerated solvent extraction showed negligible difference. The oils were rich in linoleic acid (42.71%-42.80%), linolenic acid (26.03%-26.15%), and oleic acid (14.24%-14.40%). The results revealed that the proposed method was feasible, and this essay shows the way to exploit fenugreek seeds by subcritical butane extraction under the scope of edible oils.

Process optimization and characterization of fragrant oil from red pepper (Capsicum annuum L.) seed extracted by subcritical butane extraction.

BACKGROUND: Red pepper seeds account for 450-500 g kg-1 of the total pepper weight and are often discarded as waste. In this study, process optimization and characterization of fragrant oil from roasted red pepper seed extracted by subcritical butane extraction were carried out. RESULTS: The optimal conditions of extraction were a temperature of 74.61 °C, a time of 68.65 min and a liquid/solid ratio of 30.24:1. The oil had a refractive index (25 °C) of 1.471, a relative density of 0.900, an acid value of 1.421 mg g-1 oil, an iodine value of 127.035 g per 100 g, a saponification value of 184.060 mg KOH g-1 , an unsaponifiable matter content of 12.400 g kg-1 , a peroxide value of 2.465 meq. O2 kg-1 and a viscosity of 52.094 cP. The main fatty acids in the oil were linoleic acid (72.95%) followed by palmitic acid (11.43%) and oleic acid (10.00%). The oil showed desirable thermal and oxidative stability. A total of 19 volatile compounds, mostly aldehydes and alkenes, were identified from the oil. CONCLUSION: The results indicated that the method is appropriate for the preparation of fragrant red pepper seed oil, and the oil is suitable for used as edible oil. © 2016 Society of Chemical Industry.

Natural Lactic Acid Bacteria Population and Silage Fermentation of Whole-crop Wheat.

Winter wheat is a suitable crop to be ensiled for animal feed and China has the largest planting area of this crop in the world. During the ensiling process, lactic acid bacteria (LAB) play the most important role in the fermentation. We investigated the natural population of LAB in whole-crop wheat (WCW) and examined the quality of whole-crop wheat silage (WCWS) with and without LAB inoculants. Two Lactobacillus plantarum subsp. plantarum strains, Zhengzhou University 1 (ZZU 1) selected from corn and forage and grass 1 (FG 1) from a commercial inoculant, were used as additives. The silages inoculated with LAB strains (ZZU 1 and FG 1) were better preserved than the control, with lower pH values (3.5 and 3.6, respectively) (p<0.05) and higher contents of lactic acid (37.5 and 34.0 g/kg of fresh matter (FM), respectively) (p<0.05) than the control. Sixty LAB strains were isolated from fresh material and WCWS without any LAB inoculation. These LAB strains were divided into the following four genera and six species based on their phenotypic, biochemical and phylogenetic characteristics: Leuconostoc pseudomesenteroides, Leuconostoc citreum, Weissella cibaria, Lactococcus lactis subsp. lactis, Lactobacillus buchneri, and Lactobacillus plantarum subsp. plantarum. However, the prevalent LAB, which was predominantly heterofermentative (66.7%), consisted of Leuconostoc pseudomesenteroides, Leuconostoc citreum, Weissella cibaria, and Lactobacillus buchneri. This study revealed that most of isolated LAB strains from control WCWS were heterofermentative and could not grow well at low pH condition; the selective inoculants of Lactobacillus strains, especially ZZU 1, could improve WCWS quality significantly.

Identification and antimicrobial activity detection of lactic Acid bacteria isolated from corn stover silage.

A total of 59 lactic acid bacteria (LAB) strains were isolated from corn stover silage. According to phenotypic and chemotaxonomic characteristics, 16S ribosomal DNA (rDNA) sequences and recA gene polymerase chain reaction amplification, these LAB isolates were identified as five species: Lactobacillus (L.) plantarum subsp. plantarum, Pediococcus pentosaceus, Enterococcus mundtii, Weissella cibaria and Leuconostoc pseudomesenteroides, respectively. Those strains were also screened for antimicrobial activity using a dual-culture agar plate assay. Based on excluding the effects of organic acids and hydrogen peroxide, two L. plantarum subsp. plantarum strains ZZU 203 and 204, which strongly inhibited Salmonella enterica ATCC 43971(T), Micrococcus luteus ATCC 4698(T) and Escherichia coli ATCC 11775(T) were selected for further research on sensitivity of the antimicrobial substance to heat, pH and protease. Cell-free culture supernatants of the two strains exhibited strong heat stability (60 min at 100°C), but the antimicrobial activity was eliminated after treatment at 121°C for 15 min. The antimicrobial substance remained active under acidic condition (pH 2.0 to 6.0), but became inactive under neutral and alkaline condition (pH 7.0 to 9.0). In addition, the antimicrobial activities of these two strains decreased remarkably after digestion by protease K. These results preliminarily suggest that the desirable antimicrobial activity of strains ZZU 203 and 204 is the result of the production of a bacteriocin-like substance, and these two strains with antimicrobial activity could be used as silage additives to inhibit proliferation of unwanted microorganism during ensiling and preserve nutrients of silage. The nature of the antimicrobial substances is being investigated in our laboratory.

Combined Effects of Lactic Acid Bacteria and Protease on the Fermentation Quality and Microbial Community during 50 Kg Soybean Meal Fermentation Simulating Actual Production Scale.

The improvement in the utilization rate and nutritional value of soybean meal (SBM) represents a significant challenge in the feed industry. This study conducted a 50 kg SBM fermentation based on the 300 g small-scale fermentation of SBM in early laboratory research, to explore the combined effects of lactic acid bacteria (LAB) and acid protease on fermentation quality, chemical composition, microbial population, and macromolecular protein degradation during fermentation and aerobic exposure of SBM in simulated actual production. The results demonstrated that the increase in crude protein content and reduction in crude fiber content were considerably more pronounced after fermentation for 30 days (d) and subsequent aerobic exposure, compared to 3 d. It is also noteworthy that the treated group exhibited a greater degree of macromolecular protein degradation relative to the control and 30 d of fermentation relative to 3 d. Furthermore, after 30 d of fermentation, adding LAB and protease significantly inhibited the growth of undesired microbes including coliform bacteria and aerobic bacteria. In the mixed group, the microbial diversity decreased significantly, and Firmicutes replaced Cyanobacteria for bacteria in both groups' fermentation.

Physicochemical, rheological, antioxidant and immunological properties of four novel non-inulin (poly)saccharides from Asparagus cochinchinensis.

The impacts of four extraction techniques, including hot water, ultrasonic-assisted, complex enzyme-assisted and acid-assisted methods, on the morphological, physicochemical properties and bioactivities of Asparagus cochinchinensis (poly)saccharides (EACP, WACP, UACP, and AACP) were investigated and compared. The four samples were mainly composed of glucose, fructose, and galactose with molar ratios of 50.8:22.7:4.4 for WACP, 53.9:26.0:5.3 for UACP, 35.6:14.1:21.4 for AACP and 45.0:15.6:9.0 for EACP, respectively. The rheological result showed that ACPs were non-Newtonian fluids. EACP with high purity (97.65 %) had good DPPH, O2- and ABTS+ radical scavenging activities, and significantly promoted the proliferation of the RAW264.7 cells at low concentration. UACP had good Fe2+ chelating ability, radical (DPPH, O2- and OH) scavenging activities, which might be attributed to the existence of triple-helix structure. AACP had high yield, molecular weight (17,477.2 Da), high crystallinity (23.33 %), and good radical (OH and ABTS+) scavenging activities. All four significantly stimulated the transcript expression levels of TNF-α, IL-1ß and IL-6, as determined by RT-PCR. These results suggest that the exploitation and utilization of non-inulin (poly)saccharides extracted by ultrasonic-assisted, complex enzyme-assisted and acid-assisted extraction methods are potentially valuable as effective and natural immune adjuvants and antioxidants.

Effects of Probiotic-Fermented Feed on the Growth Profile, Immune Functions, and Intestinal Microbiota of Bamei Piglets.

Purebred Bamei piglets present problems, including slow growth, respiratory disease, and post-weaning stress. This study investigated the effects of Lactobacillus plantarum QP28-1- and Bacillus subtilis QB8-fermented feed supplementation on the growth performance, immunity, and intestinal microflora of Bamei piglets from Qinghai, China. A total of 48 purebred Bamei piglets (25 days; 6.8 ± 0.97 kg) were divided into the following four groups for a 28-day diet experiment: basal feed (CK); diet containing 10% Lactobacillus plantarum-fermented feed (L); diet containing 10% Bacillus subtilis-fermented feed (B); and diet containing a mixture of 5% Lactobacillus plantarum + 5% Bacillus subtilis-fermented feed (H). The daily weight gain and daily food intake of group H increased (p < 0.05), and the feed/weight gain ratios of the groups fed with fermented feed decreased more than that of the CK group. The levels of three immune factors, namely immunoglobulin (Ig)M, IgG, and interferon-γ, were higher (p < 0.05), whereas those of tumor necrosis factor-α, interleukin (IL)-1ß, and IL-6 were lower (p < 0.05) in the fermented feed groups than in the CK group. Total protein was higher (p < 0.05), while urea nitrogen, total cholesterol and triglycerides were lower (p < 0.05) in the mixed-fermented feed group than in the CK group. Analysis of the gut microbiota showed that the addition of fermented feed increased the α-diversity of the gut microbiota, increasing the abundances of probiotics including Lactobacillus, Muribaculaceae, Ruminococcaceae, Prevotellaceae, and Rikenellaceae. Additionally, correlation analysis demonstrated that several of these probiotic bacteria were closely related to serum immunity. In conclusion, fermented feed supplementation rebuilt the intestinal microbiota of Bamei piglets, thereby reducing the feed/weight ratio, improving feed intake, and enhancing immunity.

Investigation on Fermentation Characteristics and Microbial Communities of Wheat Straw Silage with Different Proportion Artemisia argyi.

Mycotoxins, secondary metabolites of fungi, are a major obstacle to the utilization of animal feed for various reasons. Wheat straw (WS) is hollow, and miscellaneous bacteria can easy attach to its surface; the secondary fermentation frequency after silage is high, and there is a risk of mycotoxin poisoning. In this study, a storage fermentation process was used to preserve and enhance fermentation quality in WS through the addition of Artemisia argyi (AA), which is an effective method to use WS resources and enhance aerobic stability. The storage fermentation of WS treated with AA had lower pH and mycotoxin (AFB1 and DON) values than the control due to rapid changes in microbial counts, especially in the 60% AA groups. Meanwhile, the addition of 60% AA improved anaerobic fermentation profiles, showing higher lactic acid contents, leading to increased efficiency of lactic acid fermentation. A background microbial dynamic study indicated that the addition of 60% AA improved the fermentation and aerobic exposure processes, decreased microbial richness, enriched Lactobacillus abundance, and reduced Enterobacter and Aspergillus abundances. In conclusion, 60% AA treatment could improve the quality by increase fermentation quality and improve the aerobic stability of WS silage by enhancing the dominance of desirable Lactobacillus, inhibiting the growth of undesirable microorganisms, especially fungi, and reducing the content of mycotoxins.

Effects of Lactic Acid Bacteria Reducing the Content of Harmful Fungi and Mycotoxins on the Quality of Mixed Fermented Feed.

The contamination of fermented feeds and foods with fungi and mycotoxins is a major food safety issue worldwide. Certain lactic acid bacteria (LAB), generally recognized as safe (GRAS) fermentation probiotics, are able to reduce microbial and mycotoxins contamination. In this study, Lactiplantibacillus (L.) plantarum Q1-2 and L. salivarius Q27-2 with antifungal properties were screened as inoculants for mixed fermenting feed, and the fermentation and nutritional qualities, microbial community, and mycotoxins of mixed fermented feed were analyzed at different fermentation periods (1, 3, 7, 15, and 30 days, respectively). The findings indicated that the utilization of Q1-2 and Q27-2 strains in fermenting feed led to a decrease in pH and an increase in lactic acid concentration and the proportion of Lactiplantibacillus, while effectively restraining the proliferation of undesirable microorganisms. In particular, Q1-2 reduced the relative abundance of fungi including Fusarium and Aspergillus. Compared to the control group, the Q1-2 and Q27-2 groups reduced aflatoxin B1 by 34.17% and 16.57%, and deoxynivalenol by up to 90.61% and 51.03%. In short, these two LAB inoculants could reduce the contents of aflatoxin B1 and deoxynivalenol to the limited content levels stipulated by the Chinese National Standard GB 13078-2017. These findings suggest that the LAB strains of Q1-2 and Q27-2 have potential applications in the feed industry for the mitigation of mycotoxin pollution, thereby enhancing the quality of animal feed.

Lactobacillus nasuensis sp. nov., a lactic acid bacterium isolated from silage, and emended description of the genus Lactobacillus.

Two strains of lactic acid bacteria, designated SU 18(T) and SU 83, were isolated from silage prepared with Sudan grass [Sorghum sudanense (Piper) Stapf.]. The isolates were Gram-stain-positive, catalase-negative, facultatively anaerobic rods that did not produce gas from glucose. The isolates exhibited ≥93.5 % DNA-DNA relatedness to each other and shared the same phenotypic characteristics, which indicated that they belonged to a single species. The DNA G+C content was 58.5-59.2 mol%. On the basis of 16S rRNA gene sequence analysis, the isolates were placed in the genus Lactobacillus. Their closest phylogenetic neighbours were Lactobacillus manihotivorans JCM 12514(T) and Lactobacillus camelliae JCM 13995(T) (95.9 and 96.8 % 16S rRNA gene sequence similarity, respectively, with strain SU 18(T)). Ribotyping revealed that strain SU 18(T) was well separated from L. manihotivorans JCM 12514(T) and L. camelliae JCM 13995(T). Strain SU 18(T) exhibited ≤23.7 % DNA-DNA relatedness with its closest phylogenetic neighbours. The isolates represent a novel species in the genus Lactobacillus, for which the name Lactobacillus nasuensis sp. nov. is proposed. The type strain is SU 18(T) ( = JCM 17158(T)  = CGMCC 1.10801(T)). The description of the genus Lactobacillus is also amended.

Reclassification of Lactobacillus kimchii and Lactobacillus bobalius as later subjective synonyms of Lactobacillus paralimentarius.

Characterization and identification of strain CW 1 ( = JCM 17161) isolated from corn silage were performed. Strain CW 1 was a Gram-positive, catalase-negative and homofermentative rod that produced the DL-form of lactic acid. This strain exhibited more than 99.6% 16S rRNA gene sequence similarity and greater than 82% DNA-DNA reassociation with type strains of Lactobacillus kimchii, L. bobalius and L. paralimentarius. To clarify the taxonomic positions of these type strains, phenotypic characterization, 16S rRNA gene sequencing, ribotyping and DNA-DNA relatedness were examined. The three type strains displayed different L-arabinose, lactose, melibiose, melezitose, raffinose and N-acetyl-ß-glucosaminidase fermentation patterns. Phylogenetic analysis showed that L. paralimentarius is a closer neighbour of L. kimchii and L. bobalius, sharing 99.5-99.9% 16S rRNA gene sequence similarity, which was confirmed by the high DNA-DNA relatedness (≥82%) between L. paralimentarius JCM 10415(T), L. bobalius JCM 16180(T) and L. kimchii JCM 10707(T). Therefore, it is proposed that L. kimchii and L. bobalius should be reclassified as later synonyms of L. paralimentarius.

Microbial community and fermentation characteristic of whole-crop wheat silage treated by lactic acid bacteria and Artemisia argyi during ensiling and aerobic exposure.

Whole-crop wheat silage (WCWS) is an excellent feed material for ruminants. However, microbial fermentation during silage production consumes valuable nutrients, decreasing the quality of silage. The main objective of this study was to assess how the addition of increasing amounts of Artemisia argyi (AA) affected fermentation quality, microbial composition, and mycotoxin production in whole-crop wheat at dough stage (WCWD) silage during ensiling to aerobic exposure compared with Lactiplantibacillus buchneri (LB). The addition of 20% AA, resulted in a lower pH and higher lactic acid content, was found in silage treated with 20% AA, and an obvious increase in the relative abundance of Lactobacillus was detected in silages treated with LB and 20% AA, respectively. Meanwhile, inoculation with 20% AA decreased the abundance of harmful microorganisms, including Acinetobacter, Enterobacter, and Aspergillus. It also reduced the contents of mycotoxins, Aflatoxin B1 (AFB1), and deoxynivalenol (DON) during ensiling and aerobic exposure. These results confirmed that WCWD treated with 20% AA could improve the fermentation quality and enhance the aerobic stability of silage.

Microbial Population Succession and Community Diversity and Its Correlation with Fermentation Quality in Soybean Meal Treated with Enterococcus faecalis during Fermentation and Aerobic Exposure.

This study assessed the effects of Enterococcus faecalis (E. faecalis) in combination with protease on fermentation characteristics and microbial communities during ensiling and aerobic exposure phases of soybean meal (SBM). In this study, response surface methodology (RSM) was used to optimize the optimal growth conditions of E. faecalis ZZUPF95, which produced protease, and fermented SBM under the optimal fermentation conditions. The fermentation test was divided into four groups as follows: CK (Control check), ZZUPF95, Protease and ZZUPF95+Protease groups. Results showed that the best medium ratio of ZZUPF95 was glucose 1%, peptone 2%, inorganic salt 1.47%; fermentation time 36 h, inoculation amount 10%, ratio of material to water 1:1 is the optimal fermentation scheme; after fermentation and aerobic exposure treatment, ZZUPF95 and ZZUPF95 + Protease group can reduce the pH of feed, improve the content of lactic acid in the fermentation system, and have the effect of inhibiting the reproduction of pathogenic bacteria, increasing the content of crude protein and ether extract, and degrading crude fiber; the microbial community of SBM were changed after fermentation and aerobic exposure. This study explored the changes of fermentation quality of SBM, which has certain theoretical value to improve the fermentation mode and storage of SBM.

Dynamics Changes of Microorganisms Community and Fermentation Quality in Soybean Meal Prepared with Lactic Acid Bacteria and Artemisia argyi through Fermentation and Aerobic Exposure Processes.

This study evaluated the effects of Lactiplantibacillus plantarum subsp. plantarum ZA3, Artemisia argyi and their combination, on the fermentation characteristics, microbial community, mycotoxins and crude flavonoids content of fermented soybean meal during fermentation (under anaerobic conditions) and aerobic exposure (under aerobic conditions). The results showed that ZA3, Artemisia argyi and ZA3+ Artemisia argyi groups had lower pH values and higher lactic acid concentrations compared with controls, and additives increased the abundance of Lactiplantibacillus and decreased those of Acetobacter and Enterobacter; in particular, Artemisia argyi and ZA3+ Artemisia argyi reduced the abundance of fungi, such as Aspergillus, Pichia, Fusarium, Cladosporium and Xeromyces. Meanwhile, the contents of mycotoxins were lower in treated groups, and even mycotoxins in the control were significantly reduced after 30 d (p < 0.05). Crude flavonoids that were correlated positively with Lactococcus and negatively with Bacillus, Aspergillus, Enterobacter and Kazachstania were significantly higher in the Artemisia argyi and ZA3+ Artemisia argyi groups (p < 0.05).

Variation of Microbial Community and Fermentation Quality in Corn Silage Treated with Lactic Acid Bacteria and Artemisia argyi during Aerobic Exposure.

Silage, especially whole crop corn silage (WCCS), is an important part of ruminant diets, with its high moisture content and rich nutrient content, which can easily cause contamination by mold and their toxins, posing a great threat to ruminant production, food safety and human health. The objective of this study was to examine effects of lactic acid bacteria (LAB) Lactiplantibacillus (L.) plantarum subsp. plantarum ZA3 and Artemisia argyi (AA) on the fermentation characteristics, microbial community and mycotoxin of WCCS during 60 days (d) ensiling and subsequent 7 d aerobic exposure. The results showed that WCCS treated with LAB and AA both had lower pH value and ammonia nitrogen (NH3-N) contents, and higher lactic and acetic acids concentration compared with other groups after 60 d ensiling. In addition, for microbial communities, Acetobacter and Enterobacter were inhibited in all AA group, while higher abundance of Lactobacilli was maintained; besides, Candida, Pichia and Kazachstania abundances were decreased in both 6% and 12% AA groups. The content of five kinds of mycotoxins were all significantly lower after 7 d of aerobic exposure. As for the total flavonoid (TF), which is significantly higher in all AA treated groups, it was positively correlated with Paenibacillus, Weissella and Lactobacilli, and negatively with Acetobacter, Enterobacteria, Kazachstania and Pichia.

The Effect of Dietary Lactic Acid Bacteria on Intestinal Microbiota and Immune Responses of Crucian Carp (Carassius auratus) Under Water Temperature Decrease.

Temperature changes have a great impact on fish feeding, intestinal microorganisms, metabolism, and immune function. Therefore, it is necessary to develop effective methods to enhance the survival rates and growth of fish under water temperature changes. Lactic acid bacteria (LAB) are promising immunostimulatory feed additive, as demonstrated by their beneficial effects in several fish species. This study investigated the short-term effects of dietary LAB on intestinal microbiota composition and immune responses of crucian carp (Carassius auratus) when water temperature decreased from 30 ± 1°C to 18 ± 1°C. Lactococcus (L.) lactis 1,209 and L. lactis 1,242 with potential probiotics isolated from the intestine of Qinghai naked carp (Gymnocypris przewalskii) were selected as feed additives for the crucian carp feeding experiment. A total of 225 commercially available healthy crucian carp (250 ± 10 g) of similar age were kept in 30°C water for a week and then immediately transferred to 18 ± 1°C water, assigned to three dietary treatments for a 16-day feeding trial randomly: (1) HC, diets without additives (the control group); (2) HT, diets with 106 CFU/ml L. lactis 1,209; and (3) HL, with 106 CFU/ml L. lactis 1,242. Each group was set up with 3 replicates and each with 25 fish. The results showed that the mortality rate of crucian carp in HC, HT, and HL group was 50, 27, and 33%, respectively. High-throughput sequencing results displayed that the composition of the intestinal microorganism varied dynamically in response to different treatments and water temperature decrease. Among them, compared with the HC group, a higher abundance of Firmicutes and Proteobacteria, and a lower of Actinobacteria appeared in HT and HL. The cytokines heat shock protein 70 (HSP-70) in crucian carp intestinal tract significantly decreased when water temperature decreased (p < 0.05).

Bacteriocin-Producing Lactic Acid Bacteria Strains with Antimicrobial Activity Screened from Bamei Pig Feces.

Lactic acid bacteria (LAB), which are characterized by producing various functional metabolites, including antioxidants, organic acids, and antimicrobial compounds, are widely used in the food industry to improve gut health and prevent the growth of spoilage microorganisms. With the continual incidence of foodborne disease and advocacy of consumers for gut health, LAB have been designated as vital biopreservative agents in recent years. Therefore, LAB with excellent antimicrobial properties and environmental tolerance should be explored further. In this study, we focus on screening the LAB strains from a specialty pig (Bamei pig) feces of the Tibetan plateau region and determine their antimicrobial properties and environmental tolerance to evaluate their potential probiotic values. A total of 116 LAB strains were isolated, from which the LAB strain Qinghai (QP)28-1 was identified as Lactiplantibacillus (L.) plantarum subsp. plantarum using 16S rDNA sequencing and recA amplification, showing the best growth capacity, acid production capacities, environmental tolerance, hydrophobicity, antibiotic susceptibility, and bacteriocin production capacity. Furthermore, this strain inhibited the growth of multiple pathogens by producing organic acids and bacteriocin. These bacteriocin-encoding genes were identified using PCR amplification, including plnS, plnN, and plnW. In conclusion, bacteriocin-producing L. plantarum subsp. plantarum QP28-1 stands out among these 116 LAB strains, and was considered to be a promising strain used for LAB-related food fermentation. Moreover, this study provides a convenient, comprehensive, and shareable profile for screening of superior functional and bacteriocin-producing LAB strains, which can be used in the food industry.

Lactococcus fujiensis sp. nov., a lactic acid bacterium isolated from vegetable matter.

Three strains of lactic acid bacteria, designated NJ 317(T), NJ 414 and NJ 415, were isolated from the outer leaves of Chinese cabbages (Brassica rapa L. var. glabra Regel) and characterized taxonomically. The strains were gram-reaction-positive, catalase-negative, facultatively anaerobic cocci that did not produce gas from glucose and formed L-lactic acid. The major fatty acids were C(18 : 1)ω9c, C(16 : 0), C(14 : 0) and summed feature 10. Morphological, physiological and phylogenetic data indicated that the strains belonged to the genus Lactococcus. These strains shared similar phenotypic characteristics and exhibited DNA relatedness values >96.6 % to each other, indicating that they represent a single species. The DNA G+C contents of the three strains were 42.1-42.5 mol%. 16S rRNA gene sequences of the novel strains were determined and aligned with those of other species of the genus Lactococcus. On the basis of phylogenetic analysis the three strains grouped with other members of the genus Lactococcus. Lactococcus lactis and Lactococcus garvieae were the most closely related species, sharing a sequence similarity value of 94.4 % with the three strains. Ribotyping patterns, however, revealed that these strains were well-separated from reference strains of species of the genus Lactococcus and DNA-DNA hybridization studies indicated that the novel strains had low levels (<20.2 %) of DNA relatedness with reference strains of L. lactis, L. garvieae and other type strains of previously described species, showing that they represent a different species. Based on this evidence, strains NJ 317(T), NJ 414 and NJ 415 represent a novel species of the genus Lactococcus, for which the name Lactococcus fujiensis sp. nov. is proposed. The type strain is NJ 317(T) ( = JCM16395(T)  = CGMCC 1.10453(T)).