Nitrogen-Fixing and Uricolytic Bacteria Associated with the Gut of Dendroctonus rhizophagus and Dendroctonus valens (Curculionidae: Scolytinae)

The bark beetles of the genus Dendroctonus feed on phloem that is a nitrogen-limited source. Nitrogen fixation and nitrogen recycling may compensate or alleviate such a limitation, and beetle-associated bacteria capable of such processes were identified. Raoultella terrigena, a diazotrophic bacteria present in the gut of Dendroctonus rhizophagus and D. valens, exhibited high acetylene reduction activity in vitro with different carbon sources, and its nifH and nifD genes were sequenced. Bacteria able to recycle uric acid were Pseudomonas fluorescens DVL3A that used it as carbon and nitrogen source, Serratia proteomaculans 2A CDF and Rahnella aquatilis 6-DR that used uric acid as sole nitrogen source. Also, this is the first report about the uric acid content in whole eggs, larvae, and adults (male and female) samples of the red turpentine beetle (Dendroctonus valens). Our results suggest that the gut bacteria of these bark beetles could contribute to insect N balance.     

Microbiota Associated with the Gastrointestinal Tract of the Common House Cricket, Acheta domestica

The location and morphology of the bacteria associated with the gastrointestinal tract of Acheta domestica were studied, and these bacteria were partially characterized. Bacteria were associated with the peritrophic membrane in the midgut and with the gut wall and cuticular structures of the hindgut. No bacteria were associated with the fat bodies. Colony-forming unit determinations indicated that there were three times more cultivatable bacteria in the hindgut than in the midgut. Of these bacteria, 40 to 85% cleared uric acid anaerobically, and 90 to 100% cleared uric acid aerobically. Of the 25 isolates obtained, 21 belonged to the genera Citrobacter, Klebsiella, Yersinia, Bacteroides, and Fusobacterium.     

Uric Acid-Degrading Bacteria in Guts of Termites [Reticulitermes flavipes (Kollar)]

Uricolytic bacteria were present in guts of Reticulitermes flavipes in populations up to 6 × 10⁴ cells per gut. Of 82 strains isolated under strict anaerobic conditions, most were group N Streptococcus sp., Bacteroides termitidis, and Citrobacter sp. All isolates used uric acid (UA) as an energy source anaerobically, but not aerobically, and NH₃ was the major nitrogenous product of uricolysis. However, none of the isolates had an absolute requirement for UA. Utilization of heterocyclic compounds other than UA was limited. Fresh termite gut contents also degraded UA anaerobically, as measured by ¹⁴CO₂ evolution from [2-¹⁴C]UA. The magnitude of anaerobic uricolysis [0.67 pmol of UA catabolized/(gut × h)] was entirely consistent with the population density of uricolytic bacteria in situ. Uricolytic gut bacteria may convert UA in situ to products usable by termites for carbon, nitrogen, energy, or all three. This possibility is consistent with the fact that R. flavipes termites from UA, but they do not void the purine in excreta despite the lack of uricase in their tissues.     

Effect of laboratory containment on the nitrogen metabolism of termites

When Nasutitermes exitiosus, Nasutitermes walkeri and Coptotermes lacteus were brought into the laboratory they rapidly lost, within 24–48 hr, their ability to fix dinitrogen. With N. exitiosus and N. walkeri the loss was linear over the first 26–32 hr at a rate of about 3–4% per hour. N. walkeri completely lost its ability to fix dinitrogen and did not recover it during a further 11 days in the laboratory, whereas N. exitiosus and C. lacteus partially recovered their dinitrogen fixing ability to about 25–50% of the original rate. During laboratory storage of up to 60 days both C. lacteus and N. exitiosus gradually lost total nitrogen, while at the same time their uric acid content increased. The uric acid content of N. walkeri increased during 17 days in the laboratory while total nitrogen remained essentially constant. Xanthine dehydrogenase was not detected in freshly-collected N. walkeri but was detectable after two days of laboratory storage and reached a maximum activity in 8–10 days. The rate of dinitrogen fixation, total nitrogen and uric acid of field populations of N. exitiosus and N. walkeri (tested within 2 hr of collection) remained within close limits over a 6–8 week period, indicating that the changes in these parameters observed in populations kept in the laboratory did not occur in field populations. In field populations of N. walkeri the total nitrogen was about 1.4% of the fresh weight (6.7% of the dry weight) and the uric acid content was about 1.3% of the fresh weight (6.6% of the dry weight), with the amount of total nitrogen present as uric acid being about 31%. In N. exitiosus these values were: total nitrogen about 1.6% of the fresh weight (7.4% of the dry weight), uric acid about 0.6% of the fresh weight (2.9% of the dry weight), with uric acid accounting for about 13% of total nitrogen. When workers of N. walkeri were stored in a container near their nest they lost dinitrogen fixing ability to the same extent as workers brought into the laboratory, indicating that disruption of the nest was sufficient to affect dinitrogen fixation.     

Distribution of chitin/chitosan-like bioflocculant-producing potential in the genus Citrobacter

Some strains belonging to the genera Citrobacter and Enterobacter have been reported to produce chitin/chitosan-like bioflocculants (BFs) from acetate. In this study, to investigate the distribution of the BF-producing potential in the genus Citrobacter and to screen stably and highly BF-producing strains, we obtained 36 Citrobacter strains from different culture collection centers, which were distributed among seven species in the genus, and tested for the flocculating activities of their culture supernatants using a kaolin suspension method. As a result, 21 strains belonging to C. freundii (17 strains in 23 strains tested), C. braakii (two in two), C. youngae (one in one), and C. werkmanii (one in two) showed flocculating activity, but this ability was limited to cells grown on acetate. Gas chromatography/mass spectrometry (GC/MS) analysis of the hydrolysates from the BFs of five selected strains indicated that they consisted of glucosamine and/or N-acetylglucosamine, such as the chitin/chitosan-like BF (BF04) produced by Citrobacter sp. TKF04 (Fujita et al. J Biosci Bioeng 89: 40–46, 2000). Gel filtration chromatography using a high-performance liquid chromatography system revealed that the molecular weight ranges of these BFs varied, but the average sizes were all above 1.66?×?10⁶?Da.     

Pseudocitrobacter gen. nov., a novel genus of the Enterobacteriaceae with two new species Pseudocitrobacter faecalis sp. nov., and Pseudocitrobacter anthropi sp. nov,isolated from fecal samples from hospitalized patients in Pakistan

Four isolates of Gram-negative facultatively anaerobic bacteria, three of them producing NDM-1 carbapenemase, were isolated from hospitalized patients and outpatients attending two military hospitals in Rawalpindi, Pakistan, and studied for their taxonomic position. Initially the strains were phenotypically identified as Citrobacter species. Comparative analysis of 16S rRNA gene sequences then showed that the four strains shared >97%, but in no case >98.3%, 16S rRNA gene sequence similarities to members of the genera Citrobacter, Kluyvera, Pantoea, Enterobacter and Raoultella, but always formed a separate cluster in respective phylogenetic trees. Based on multilocus sequence analysis (MLSA) including partial recN, rpoA, thdF and rpoB gene sequence and respective amino acid sequence analysis it turned out that the strains also here always formed separate clusters. Based on further comparative analyses including DNA–DNA hybridizations, genomic fingerprint analysis using rep- and RAPD-PCRs and physiological tests, it is proposed to classify these four strains into the novel genus Pseudocitrobacter gen. nov. with a new species Pseudocitrobacter faecalis sp. nov. with strain 25 CIT^T (= CCM 8479^T = LMG 27751^T) and Pseudocitrobacter anthropi sp. nov. with strain C138^T (= CCM 8478^T = LMG 27750^T), as the type strains, respectively.     

Dynamics of bacterial community in up-flow anaerobic packed bed system for acid mine drainage treatment using wine wastes as carbon source

The dynamics of the bacterial populations in an up-flow anaerobic packed bed system (UAPB), applied in acid mine drainage treatment using wine wastes as carbon and nutrients source was elucidated by temperature gradient gel electrophoresis (TGGE) analysis. Moreover, TGGE fingerprints of the bacterial communities developed in a UAPB fed with wine wastes and a UAPB fed with pure ethanol were compared. TGGE fingerprinting and phylogenetic analysis showed that the composition of the community in the UAPB fed with wine wastes remained stable during whole time of operation and its bacterial diversity was higher. The bacterial community of the UAPB fed with wine wastes was composed by bacteria affiliated with Desulfovibrio, Clostridium, Citrobacter and Cronobacter genera and with Bacteroidales order, sp. The dominant community developed in the UAPB fed with ethanol was composed by bacteria affiliated with Desulfovibrio sp. The presence of several bacterial groups in the bioreactor fed with wine wastes suggests a synergistic interaction between the different populations. Syntrophic interaction may be the key factor for the utilization of wine wastes, a complex organic substrate, as carbon and electron source for sulphate reduction.     

Diversity of culturable bacterial communities in the intestinal tracts of goldfish (<Emphasis Type="Italic">Carassius auratus</Emphasis>) and their ability to produce <Emphasis Type="Italic">N</Emphasis>-acyl homoserine lactone

Intestinal bacteria isolated from goldfish (Carassius auratus) were identified based on 16 ribosomal RNA (rRNA) gene sequences and screened for their ability to produce N-acyl homoserine lactone (AHL), an autoinducer of the quorum sensing (QS) system. The 230 aerobes/facultative anaerobes that were isolated comprised members of the genera Aeromonas (184 isolates), Citrobacter (11), Enterobacter (2), Shewanella (28), Vagococcus (1), and Vibrio (4). Among these genera, the two most abundant species were Aeromonas veronii (163 isolates) and Shewanella xiamenensis (27). In addition, 142 obligate anaerobes consisting of Cetobacterium somerae (139 isolates), Clostridium frigidicarnis (2), and Cetobacterium sp. (1) were also isolated. One hundred seventy isolates (74.2%) belonging to the genera Aeromonas, Citrobacter, Enterobacter, Shewanella, and Vibrio produced AHL, while 155 (67.7%) and 91 (39.7%) isolates possessed the luxR and luxI gene homologs, respectively. None of the obligate anaerobes produced AHL or possessed luxRI homologs. Total viable counts ranged from 1.2 × 10⁷ to 2.2 × 10⁹ CFU/g, which were accounted for 0.8 to 15.2% of direct counts. Aeromonas veronii, S. xiamenensis, and C. somerae were detected from five goldfish at densities ranging from 4.0 × 10⁶ to 1.7 × 10⁹ CFU/g, indicating that these bacteria are dominant components of the culturable gut flora in goldfish. In addition, members of the genera Aeromonas and Shewanella appeared to communicate with each other by using the QS system to some extent when the concentration of AHL reaches a certain threshold. It is therefore suggested that bacteria with the ability to disrupt AHL secretion in intestinal environments are potential candidates for probionts for preventing opportunistic infections in freshwater fish such as goldfish.     

Investigation of gut microbial communities associated with indigenous honey bee (Apis mellifera jemenitica) from two different eco-regions of Saudi Arabia

The microbial communities associated with the alimentary tract of honey bees are very important as they help with food digestion, provide essential nutrients, protect the host from pathogens, detoxify harmful molecules, and increase host immunity. In this study, the structural diversity of the gut microbial communities of native honey bees, Apis mellifera jemenitica from two different geographical regions (Riyadh and Al-Baha) of Saudi Arabia was analyzed by culture-dependent methods and 16S ribosomal RNA (rRNA) gene sequencing. In this study, 100 bacterial isolates were cultivated and phylogenetic analyses grouped them into three phyla: Proteobacteria, Firmicutes, and Actinobacteria. Bacteria in the phylum Proteobacteria were the most dominant (17 species), followed by Firmicutes (13 species) and Actinobacteria (4 species). Some of the identified bacteria (Citrobacter sp., Providencia vermicola, Exiguobacterium acetylicum, and Planomicrobium okeanokoites) were reported for the first time in the genus Apis, while others identified bacteria belonged to the genera Proteus, Enterobacter, Bacillus, Morganella, Lactobacillus, and Fructobacillus. To the best of our knowledge, this is the first study on the gut microbiota of the local honey bees in Saudi Arabia.     

Dynamics of the intestinal bacterial community in black soldier fly larval guts and its influence on insect growth and development

Black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), is a prominent insect for the bioconversion of various organic wastes. As a saprotrophic insect, the BSF inhabits microbe-rich environments. However, the influences of the intestinal microorganisms on BSF growth and development are not very clear. In this study, the dynamics of the intestinal bacterial community of BSF larvae (BSFL) were analyzed using pyrosequencing. Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were the most prevalent bacterial phyla in the intestines of all larval instars. The dynamic changes in bacterial community compositions among different larval instars were striking at the genus level. Klebsiella, Clostridium, Providencia, and Dysgonomonas were the relatively most abundant bacteria in the 1st- to 4th-instar BSFL, respectively. Dysgonomonas and Providencia also dominated the 5th- and 6th-instar larvae, at ratios of 31.1% and 47.2%, respectively. In total, 148 bacterial strains affiliated with 20 genera were isolated on different media under aerobic and anaerobic conditions. Among them, 6 bacteria, BSF1–BSF6, were selected for further study. The inoculation of the 6 isolates independently into germ-free BSFL feeding on an artificial diet showed that all the bacteria, except BSF4, significantly promoted BSF growth and development compared with the germ-free control. Citrobacter, Dysgonomonas, Klebsiella, Ochrobactrum, and Providencia promoted BSF development significantly by increasing the weight gains of larvae and pupae, as well as increasing the prepupae and eclosion rates. In addition, Citrobacter, Klebsiella and Providencia shortened the BSF life cycle significantly. The results illustrate the promotive effects of intestinal bacteria on BSF growth and development.     

Phenotypic characterization of Astragalus glycyphyllos symbionts and their phylogeny based on the 16S rDNA sequences and RFLP of 16S rRNA gene

In this study, the nitrogen fixing Astragalus glycyphyllos symbionts were characterized by phenotypic properties, restriction fragment length polymorphism (RFLP), and sequences of 16S rDNA. The generation time of A. glycyphyllos rhizobia in yeast extract mannitol medium was in the range 4–6 h. The studied isolates exhibited a low resistance to antibiotics, a moderate tolerance to NaCl, assimilated di- and trisaccharides, and produced acid in medium containing mannitol as a sole carbon source. In the cluster analysis, based on 86 phenotypic properties of A. glycyphyllos symbionts and the reference rhizobia, examined isolates and the genus Mesorhizobium strains were placed on a single branch, clearly distinct from other lineages of rhizobial genera. By the comparative analysis of 16S rRNA gene sequences and 16S rDNA–RFLP, A. glycyphyllos nodulators were also identified as the members of the genus Mesorhizobium. On the 16S rDNA sequence phylogram, the representatives of A. glycyphyllos nodule isolates formed a robust, monophyletic cluster together with the Mesorhizobium species at 16S rDNA sequence similarity of these bacteria between 95 and 99 %. Similarly, the cluster analysis of the combined RFLP–16S rDNA patterns, obtained with seven restriction endonucleases, showed that A. glycyphyllos rhizobia are closely related to the genus Mesorhizobium bacteria. The taxonomic approaches used in this paper allowed us to classify the studied bacteria into the genus Mesorhizobium.     

广西蚕沙细菌组成多样性解析和VBNC菌群的发掘

【目的】解析广西蚕沙中细菌群落组成与多样性,为蚕沙中菌种资源发掘和蚕沙的综合利用提供科学依据。【方法】通过高通量测序技术研究细菌群落组成特征,同时利用常规稀释涂布平板法和基于复苏促进因子(Rpf)的MPN培养系统解析并筛选蚕沙中可培养和活的非可培养(VBNC)状态的优势菌群,并经16SrRNA基因测序对筛选得到的菌株作初步分类鉴定。【结果】高通量测序表明,广西蚕沙样品中细菌归属于10个门、18个纲、27个目、57个科、96个属,其中4个属的丰度达1%以上,优势菌群为变形菌门(Proteobacteria)肠杆菌属(Enterobacter);通过稀释涂布平板法共获得14个属的33株可培养细菌,其中4个属(Citrobacter、Weissella、Chitinophaga、Pseudoclavibacter)在高通量测序中未被检测到;而在MPN培养系统中,基于复苏促进因子的处理组细菌总数最大检出丰度提高了100倍,并从中共检出21株对Rpf敏感的VBNC菌株,其中6个属(Paenibacillus、Caulobacter、Roseomonas、Pantoea、Erwinia、Acine...     

Novel multispecies microbial consortia involved in lignocellulose and 5-hydroxymethylfurfural bioconversion

To develop a targeted metagenomics approach for the analysis of novel multispecies microbial consortia involved in the bioconversion of lignocellulose and furanic compounds, we applied replicated sequential batch aerobic enrichment cultures with either pretreated or untreated wheat straw as the sources of carbon and energy. After each transfer, exponential growth of bacteria was detected using microscopic cell counts, indicating that the substrate was being utilized. In batch, the final bacterial abundances increased from an estimated 5 to 8.7–9.5 log 16S rRNA gene copy numbers/ml. The abundances of fungal propagules showed greater variation, i.e., between 5.4 and 8.0 log ITS1 copies/ml. Denaturing gradient gel electrophoresis analyses showed that the bacterial consortia in both treatments reached approximate structural stability after six transfers. Moreover, the structures of the fungal communities were strongly influenced by substrate treatment. A total of 124 bacterial strains were isolated from the two types of enrichment cultures. The most abundant strains were affiliated with the genera Raoultella/Klebsiella, Kluyvera, Citrobacter, Enterobacter, Pseudomonas, Acinetobacter, Flavobacterium and Arthrobacter. Totals of 43 and 11 strains obtained from the untreated and pretreated substrates, respectively, showed (hemi)cellulolytic activity (CMC-ase and xylanase), whereas 96 strains were capable of growth in 7.5 mM 5-hydroxymethylfurfural. About 50 % of the latter showed extracellular oxidoreductase activity as detected by a novel iodide oxidation method. Also, (hemi)cellulolytic fungal strains related to Coniochaeta, Plectosphaerella and Penicillium were isolated. One Trichosporon strain was isolated from pretreated wheat straw. The two novel bacterial–fungal consortia are starting points for lignocellulose degradation applications.     

Comparative analysis of bacterial community and antibiotic-resistant strains in different developmental stages of the housefly (Musca domestica)

The housefly (Musca domestica) is an important host for a variety of bacteria, including some pathogenic and antibiotic-resistant strains. To further investigate the relationship between the housefly and the bacteria it harbors, it is necessary to understand the fate of microorganisms during the larval metamorphosis. The major bacterial communities in three developmental stages of the housefly (maggot, pupa, and adult fly) were investigated by a culture-independent method, polymerase chain reaction–denaturing gradient gel electrophoresis (PCR?DGGE) analysis of 16S rRNA genes. The bacteria that were identified using DGGE analysis spanned phyla Proteobacteria, Firmicutes, and Bacteroidetes. Changes in the predominant genera were observed during the housefly development. Bacteroides, Koukoulia, and Schineria were detected in maggots, Neisseria in pupae, and Macrococcus, Lactococcus, and Kurthia in adult flies. Antibiotic-resistant bacteria were screened using a selective medium and tested for antibiotic susceptibility. Most resistant isolates from maggots and pupae were classified as Proteus spp., while those from adult flies were much more diverse and spanned 12 genera. Among 20 tested strains across the three stages, 18 were resistant to at least two antibiotics. Overall, we demonstrated that there are changes in the major bacterial communities and antibiotic-resistant strains as the housefly develops.     

Diversity of culturable sulfidogenic bacteria in two oil–water separation tanks in the north-eastern oil fields of India

Sulfidogenic communities in the production waters of onshore oil fields in north-eastern India were examined using a culturing approach. Production water samples were inoculated into medium selective for Sulfate reducing bacteria (SRB) and Thiosulfate Reducing Bacteria (TRB). The total number of viable sulfidogenic microorganisms in the samples obtained from the two production water tanks was approximately 10⁵ MPN ml^?1 (most probable number per ml). Most of the isolates were thermo-tolerant and could be grown between 40 and 45 °C. Hydrogen sulfide production by TRB was significantly higher than by SRB. Based on 16S rRNA gene sequencing, the isolates were grouped in nine different phylotypes. Phylogenetic analysis indicated that most of the SRB were affiliated with the phylum Proteobacteria, encompassing Gram-negative bacteria, belonging to the genera Desulfovibrio, Desulfomicrobium, and Desulfobulbus. However, five isolates grouped with the genus Desulfotomaculum were found to be gram-positive SRB. Most of the thiosulfate reducing isolates was affiliated with the phylum Firmicutes, including Clostridium and Fusibacter and also with the phylum Proteobacteria, including the genera Enterobacter and Citrobacter. Phylotypes related to Clostridium (69%) and Desulfovibrio (53%) dominated the community in the production water samples. This study demonstrates the diversity of the TRB and SRB that play a critical role in the souring mediated corrosion of the oil–water separation tanks in the north-eastern India oil fields.     

Direct Selection for P1-Sensitive Mutants of Enteric Bacteria

A method has been developed to isolate mutants sensitive to coliphage P1 from bacterial genera normally not sensitive to this phage. P1clr100KM was used. This phage is heat inducible and confers kanamycin resistance when present as a prophage (in lysogens). P1-sensitive mutants of Klebsiella, Enterobacter, Citrobacter, and Erwinia have been found. This technique provides a well-known genetic system for the study of many bacterial genera that previously had either no such system or only a marginally useful means of genetic manipulation. It also extends the range of possible intergeneric hybrids that may be constructed and studied.     

Genetic diversity of phosphate-solubilizing peanut (Arachis hypogaea L.) associated bacteria and mechanisms involved in this ability

In this study, attempts were made to analyze mechanisms involved in the bacterial phosphate-solubilizing ability of peanut isolates. Bacteria were taxonomically identified by analysis of 16S rDNA sequence. Levels of soluble P released by the isolates in unbuffered or buffered with Tris–HCl or MES NBRIP-BPB medium as well as the production of D-gluconic acid were determined in their culture. Presence of two of the genes encoding the cofactor PQQ of GDH enzyme was analyzed in the genome of this bacterial collection. 16S rDNA sequence analysis indicated that isolates belong to genera Serratia, Enterobacter, Pantoea, Acinetobacter, Bacillus and Enterococcus. All bacteria showed ability to solubilize tricalcium phosphate either in unbuffered or buffered medium. Nevertheless, addition of buffer solutions reduced levels of Pi liberated by the isolates. Although almost all isolates produced detectable amounts of D-gluconic acid, no correlation with levels of P soluble released were observed. The presence of pqqE and pqqC genes was detected only in Gram negative bacteria. It was concluded from this study that the mechanism involved in phosphate solubilization is organic acids production and, presence of pqq genes in all Gram negative bacteria analyzed encourages to confirm their role in bacterial phosphate solubilizing ability as well to identify genes involved in this PGP trait in Gram positive bacteria.     

Comparison of the Bacterial Communities in Anaerobic, Anoxic, and Oxic Chambers of a Pilot A2O Process Using Pyrosequencing Analysis

A₂O process is a sequential wastewater treatment process that uses anaerobic, anoxic, and oxic chambers for nitrogen and phosphorus removal. In this study, the bacterial communities among these chambers were compared, and the diversity of the bacteria involved in nitrogen and phosphorus removal was surveyed. A pilot-scale A₂O process (50 m³ day^?1) was operated for more than 6 months, and bacterial 16S rRNA gene diversity was analyzed using pyrosequencing. A total of 7,447 bacterial sequence reads were obtained from anaerobic (1,546), anoxic (2,158), and oxic (3,743) chambers. Even though there were differences in the atmospheric condition and functionality, no prominent differences could be found in the bacterial community of the three chambers of the pilot A₂O process. All sequence reads, which were taxonomically analyzed using the Eztaxon-e database, were assigned into 638 approved or tentative genera. Among them, about 72.2 % of the taxa were contained in the phyla Proteobacteria and Bacteroidetes. Phosphate-accumulating bacteria, Candidatus Accumulibacter phosphatis, and two other Accumulibacter were found to constitute 3.1 % of the identified genera. Ammonia-oxidizing bacteria, Nitrosomonas oligotropha, and four other phylotypes in the same family, Nitrosomonadaceae, constituted 0.2 and 0.9 %, respectively. Nitrite-oxidizing bacteria, Nitrospira defluvii, and other three phylotypes in the same family, Nitrospiraceae, constituted 2.5 and 0.1 %, respectively. In addition, Dokdonella and a phylotype of the phylum Chloroflexi, function in nitrogen and/or phosphate removal of which have not been reported in the A₂O process, constituted the first and third composition among genera at 4.3 and 3.8 %, respectively.     

降解尿酸乳酸菌复合菌系的筛选与菌株组合提升降解效果

【背景】高尿酸症由血液中尿酸含量明显升高而导致,利用乳酸菌对人体的益生作用缓解高尿酸血症越来越受到关注。【目的】获得具有降解尿酸能力的乳酸菌复合菌系与纯培养菌株。【方法】以泡菜为样品来源,以尿酸为底物,采用MRS培养基筛选降解尿酸的乳酸菌复合菌系,通过高效液相色谱法测定复合菌系对尿酸的降解能力。【结果】得到一组乳酸菌复合菌系,当培养温度为37 °C、pH值为6.20、静置培养72 h后复合菌系对尿酸的降解率为12.08%;通过优化培养条件,当该菌系在以牛肉膏为单一氮源、初始pH值为5.00、温度为35 °C的条件下培养72 h,尿酸降解率上升至17.19%,降解率比优化前提高了42.3%;从该菌系中分离出两株具有尿酸降解能力的菌株UA-1与UA-2,它们的尿酸降解率分别为10.85%和8.65%;通过形态学观察和16S rRNA基因序列分析,经鉴定两株菌均为布氏乳杆菌(Lactobacillus buchneri)。将两株单菌组合降解尿酸试验发现,UA-1与UA-2比例为2:1的尿酸降解率为20.2%,比原复合菌系的降解能力提高了67.22%。【结论】研究证明了乳酸菌复合菌系对尿酸的降解能力优于单个菌株,为后续利用乳酸菌复合菌系应用提供了数据支持。