Autochthonous lactic acid bacteria isolated from pig faeces in Thailand show probiotic properties and antibacterial activity against enteric pathogenic bacteria

Lactic acid bacteria (LAB) play an important role in pig health and performance that arises from their beneficial impacts on the balance of gastrointestinal microbes, ability to fight enteric pathogens, and capacity to support the immune system. The aim of this study was to evaluate the functional and safety aspects of five previously isolated autochthonous LAB strains, (Lactobacillus plantarum 22F, 25F and 31F, Pediococcus acidilactici 72N and Pediococcus pentosaceus 77F) from pig faeces as potential probiotics for a pig feed supplement. The functional and safety properties of the strains were assessed by in vitro tests. The functional properties tested were their abilities in tolerating low pH values under simulated gastric conditions, their cell surface properties (hydrophobicity, auto- and co-aggregation), antibacterial activity against the common enteric pathogenic bacteria in pigs (such as pathogenic Escherichia coli, Salmonella Choleraesuis and Streptococcus suis), and diacetyl production. The safety of the strains was analyzed based on the absent of haemolysis on blood and bile salt hydrolase activity. Although all strains demonstrated diacetyl production, good survivability and antibacterial activities, L. plantarum 22F and 25F showed the best performance with the strongest antibacterial actions against the indicator pathogens. Of the strains, only P. pentosaceus 77F exhibited haemolysis or bile salt hydrolase activity. Furthermore, a principal component analysis revealed that L. plantarum 22F possessed superior functional and safety aspects compared to the other four autochthonous strains and to reference strains L. plantarum JCM 1149 and P. acidilactici DSM 20284. Further in vivo studies using oral administration of the strains are justified to assess their effectiveness as feed supplements for pigs.

Antimicrobial substances from the rare actinomycete Nonomuraea rhodomycinica NR4-ASC07T

Nonomuraea rhodomycinica NR4-ASC07^T is a rare actinomycete isolated from soil in Sirindhorn peat swamp forest. The crude extract of its culture broth exhibited antimicrobial and anticancer against diverse human pathogens and cancer cells. The chemical investigation of the crude extract led to the isolation of two new metabolites named nonomuric acid (1) and 3-hydroxy deoxydaunorubicinol aglycone (2), along with two known bioactive compounds [ε-rhodomycinone (3) and 7-deoxy-13-dihydrocarminomycinone (4)]. Compounds 1 and 3 showed antimalarial activity with the half maximal inhibitory concentration (IC₅₀) of 8.00 and 8.88 μg mL^-1, respectively. Compound 4 inhibited growth of Mycobacterium tuberculosis and Bacillus cereus at the minimum inhibitory concentrations of 50.0 and 12.50 μg mL^-1, respectively. Every compound exhibited cytotoxicity against cancer cells tested at IC₅₀ ≥ 6.34 μg mL^-1. These finding are the first report of bioactive metabolites produced by strain NR4-ASC07^T, suggesting that rare actinomycetes are yet promising sources for novel drug discovery.

Micromonospora globbae sp. nov., an endophytic actinomycete isolated from roots of Globba winitii C. H. Wright

A novel endophytic actinomycete, strain WPS1-2^T, isolated from a root of Globba winitii C. H. Wright, was characterized taxonomically by using a polyphasic approach. Strain WPS1-2^T exhibited identical characteristics to the members of the genus Micromonospora. Single spores were observed directly on substrate mycelia. The cell-wall peptidoglycan of the strain contained meso-diaminopimelic acid and 3-OH-meso-diaminopimelic acid. Whole-cell hydrolysates contained glucose, ribose, arabinose and xylose. The predominant menaquinones were MK-10(H8) and MK-10(H10). The major cellular fatty acids consisted of iso-C15 : 0, iso-C16 : 0 and anteiso-C15 : 0. According to the 16S rRNA gene sequence of the strain, WPS1-2^T showed highest similarity to Micromonospora costi CS1-12^T (99.02 %). Phylogenetic analysis of the gyrase subunit B (gyrB) gene indicated that the strain was related to M. costi CS1-12^T. The DNA G+C content was 73.7 mol%. The strain could be distinguished from closely related type strains by using a combination of morphological, chemotaxonomic, physiological and biochemical data together with DNA-DNA relatedness values. Based on these observations, strain WPS1-2^T is considered to represent a novel species of the genus Micromonospora, for which the name Micromonospora globbae sp. nov. is proposed. The type strain is WPS1-2^T (=KCTC 39787^T=NBRC 112325^T=TISTR 2405^T).

New 2-arylbenzofurans from the root bark of Artocarpus gomezianus and their α-glucosidase inhibitory activity

Two new 2-arylbenzofurans, namely 13-O-methyllakoochin B (1) and artogomezianin (2), were isolated from the root bark of Artocarpus gomezianus, along with six known compounds (3-8). The structures of new compounds were determined by spectroscopic and chemical methods. All of the isolates were evaluated for their α-glucosidase inhibitory activity. Artogomezianin (2) and lakoochin A (3) exhibited strong α-glucosidase inhibitory activity with IC₅₀ values of 18.25 and 26.19 µM, respectively, as compared with the positive control acarbose.

Streptomyces xylanilyticus sp. nov., isolated from soil

A novel actinomycete, strain SR2-123^T, belonging to the genus Streptomyces, was isolated from a soil sample collected from the Sakaerat Environmental Research Station, Thailand Institute of Scientific and Technological Research, Nakhon Ratchasima Province, Thailand. The taxonomic position of the strain was characterized using a polyphasic study. Strain SR2-123^T contained ll-diaminopimelic acid, glucose, mannose and ribose in whole-cell hydrolysates. The N-acyl type of muramic acid was acetyl. Menaquinones were MK-9(H6), MK-9(H8) and MK-9(H4). The predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and iso-C17 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, an unknown phospholipid, unknown glycolipids, an unknown aminophospholipid, unknown lipids and an unknown aminolipid. The DNA G+C content was 74.8 mol%. The strain was closely related to Streptomyces coeruleorubidus JCM 4359^T (98.5 %), Streptomyces flavofungini JCM 4753^T (98.5 %), Streptomyces coerulescens NBRC 12758^T (98. 5 %) and Streptomyces alboflavus JCM 4615^T (98.4 %), based on 16S rRNA gene sequence similarities. The novel strain exhibited low DNA-DNA relatedness values with the type strains (11.4-25.0 %) of closely related species. On the basis of phenotypic and genotypic characteristics, strain SR2-123^T could be distinguished from closely related species of the genus Streptomyces and represents a novel species of the genus Streptomyces for which the name Streptomyces xylanilyticus sp. nov. is proposed. The type strain is SR2-123^T (=TISTR 2493^T=KCTC 39909^T).

Streptomyces cerasinus sp. nov., isolated from soil in Thailand

A novel actinomycete, strain SR3-134^T, belonging to the genus Streptomyces, was isolated from soil collected from the Sakaerat Environmental Research Station, Thailand Institute of Scientific and Technological Research, Nakhon Ratchasima Province, Thailand. The taxonomic position of the strain was characterized by using a polyphasic approach. ll-Diaminopimelic acid, glucose, mannose and ribose were detected in its whole-cell hydrolysates. The N-acyl type of muramic acid was acetyl. The menaquinones were MK-9(H8), MK-9(H6), MK-9(H4) and MK-9(H2). The predominant cellular fatty acids were anteiso-C15 : 0, iso-C16 : 0, C16 : 0, iso-C15 : 0, anteiso-C17 : 0 and iso-C14 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. blast analysis of the almost-complete 16S rRNA gene showed 98.7 % sequence similarities to Streptomyces lanatus JCM 4588^T and Streptomyces psammoticus JCM 4434^T. The DNA G+C content was 71.4 mol%. Strain SR3-134^T showed low DNA-DNA relatedness (12.9±4.0-44.1±1.0 %) to S. lanatus JCM 4588^T and S. psammoticus JCM 4434^T. The new strain could also be distinguished from its closely related strains by differences in their phenotypic characteristics. The results of taxonomic analysis suggested that strain SR3-134^T represented a novel species of the genus Streptomyces for which the name Streptomyces cerasinus sp. nov. is proposed. The type strain is SR3-134^T (=TISTR 2494^T=KCTC 39910^T).

Paenibacillus aurantiacus sp. nov., isolated from ant nest soil

A Gram-stain-positive, rod-shaped and endospore-forming bacterium, strain RC11T, isolated from ant nest soil collected from Udon Thani Province, Thailand was characterized in a taxonomic study based on a polyphasic approach. On the basis of 16S rRNA gene sequence analysis, strain RC11T was affiliated to the genus Paenibacillus and was closely related to Paenibacillus phyllosphaerae LMG 22192T with 98.1 % sequence similarity. Strain RC11T contained meso-diaminopimelic in the cell-wall peptidoglycan. The major menaquinone was MK-7. Anteiso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and C16 : 0 were the predominant cellular fatty acids. Diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol were the major polar lipids. The DNA G+C content was 57.9 mol%. In addition, strain RC11T and P. phyllosphaerae LMG 22192T showed a low level of DNA-DNA relatedness (15.6-33.2 %). Therefore, strain RC11T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus aurantiacus sp. nov. is proposed. The type strain is RC11T (=KCTC 33816T=LMG 29659T=TISTR 2452T).

Sporolactobacillus shoreicorticis sp.nov., a lactic acid-producing bacterium isolated from tree bark

A Gram-stain-positive, lactic acid-producing bacterium designed strain MK21-7T, was isolated from tree bark collected from the north east of Thailand. This strain was a facultatively anaerobic spore-forming rod that was catalase-negative. It contained meso-diaminopimelic acid in the cell wall peptidoglycan and had seven isoprene units (MK-7) as the predominant menaquinone. Major fatty acids of MK21-7T were anteiso-C17 : 0, iso-C16 : 0, anteiso-C15 : 0 and C18 : 1ω9c. Polar lipids were phosphatidglycerol, diphosphatidylglycerol, an unknown phospholipid, three unknown glycolipids and an unknown lipid. The results of 16S rRNA gene sequence analysis indicated that it represented a member of the genus Sporolactobacillus. MK21-7T showed the highest 16S rRNA gene sequence similarity to Sporolactobacillus terrae NBRC 101527T with 98.4 % similarity and exhibited 97.6 % similarity with Sporolactobacillus kofuensis NRIC 0334T, 97.5 % with Sporolactobacillus laevolacticus NRIC 0361T, 97.3 % with Sporolactobacillus nakayamaesubsp.nakayamae NRIC 0347T and 97.1 % with Sporolactobacillus nakayamaesubsp.racemicus NBRC 101524T. Analysis of the phylogenetic relationship based on 16S rRNA and gyrB gene sequencing revealed that the position of MK21-7T was clearly separated from all related species of the genus Sporolactobacillus. It had low DNA-DNA relatedness (22.8-57.2 %) with S. terrae NBRC 101527T and related type strains. The DNA G+C content was 43.1 mol%. On the basis of the results of the phenotypic, genotypic and chemotaxonomic studies, MK21-7T should be classified as representing a novel species of the genus Sporolactobacillus for which the name Sporolactobacillus shoreicorticis sp. nov. is proposed. The type strain is MK21-7T (=NBRC 111517T=LMG 29111T=TISTR 2466T).

Streptomyces krungchingensis sp. nov., isolated from soil

A novel actinomycete, designated strain KC-035T, was isolated from soil collected from Krung Ching Waterfall National Park, Nakhon Si Thammarat Province, Thailand. Its taxonomic position was determined using a polyphasic approach. The strain had morphological and chemotaxonomic properties typical of members of the genus Streptomyces: flexuous spore chain; ll-diaminopimelic acid in the cell-wall peptidoglycan; MK-9(H8), MK-9(H6) and MK-9(H4) as menaquinones; diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside as phospholipids; anteiso-C15 : 0, C16 : 0, iso-C16 : 0, iso-C15 : 0 and iso-C14 : 0 as major cellular fatty acids; and DNA G+C content of 72 mol%. 16S rRNA gene sequence analysis revealed that strain KC-035T showed high similarity to Streptomyces albiflavescens n20T (99.16 %) and Streptomyces siamensis KC-038T (98.43 %) as well as formed a monophyletic clade with them in the phylogenetic tree. On the basis of comparison of phenotypic properties and the low level of DNA-DNA relatedness, strain KC-035T could be distinguished from its closely related Streptomyces species and is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces krungchingensis sp. nov. is proposed. The type strain is KC-035T (=NBRC 110087T=KCTC 29503T=TISTR 2402T).

Preliminary Studies of Lactic Acid Bacteria Isolated from Feces of Thai Newborns

BACKGROUND

The microbiota of human plays an important role in the health improvement, and found abundant in the gastrointestinal tract. In recent years, probiotics have been increasingly used in prevention of certain intestinal diseases. The most important population to study the microbiome is probably in the healthy newborns.

OBJECTIVE

The preliminary study aimed to isolate and identify the gut microbiota of newborns for the assessment of prevalent Lactic Acid Bacteria (LAB) distribution.

MATERIAL AND METHOD

Thirty eight Thai newborns, 0-5 days old of both sexes were subjected for fecal samples collection. Isolated bacteria were cultivated on the MRS selective media and further phenotypically characterized by conventional methods including Gram stain, catalase, and lactic acid production. Genotypic identification was completed by 16S rRNA gene sequencing and phylogenetic analysis.

RESULTS

Forty five isolates of LAB and non-LAB bacteria were obtained from feces of newborns. The most prevalence LAB found in this population were 45% Enterococcus faecalis, 14% E. faecium, 11% E. hirae, 11% Lactobacillus paracasei, and 2% L. gasseri. Unusually, Gram-negative bacteria including Klebsiella pneumoniae, Enterobacter hormaechei, Escherichia fergusonii, Leclercia adecarboxylata, and Shigella flexneri were isolated among LAB strains on the selective MRS media.

CONCLUSION

The gut microbiota was a great resource of beneficial LAB which was remarkably distributed among this population of Thai newborns. Further study on individual LAB isolates for the effective probiotics development would be essentially investigated for future alternative treatment of gastrointestinal diseases.