Seroprevalence and risk factors of Streptococcus ovis infection in Tibet, China

Sheep septicemic streptococcosis is an acute, febrile, and septic zoonotic disease caused by Streptococcus ovis. There are few reports of this disease especailly at high-altitude areas of Tibet, China. A cross-sectional study was conducted at five different counties of Shigatse area (a city in Tibet territory) from 2021 to 2022. Sera from 1458 randomly selected sheep and goats from 50 flocks were tested for antigens of Streptococcus ovis using a commercial ELISA kit. The individual animal level prevalence was 6.93% (95% CI: 5.7-8.4), and the flock prevalence level was 84% (95% CI: 70.9-92.8). At the individual animal level, year and management type were significantly associated with seropositivity by binary logistic regression analysis. Prevalence of Streptococcus in 2021 significantly differed from 2022 (OR = 2.16, 95% CI: 1.39-3.39). The prevalence of Streptococcus varied between management types with herds having higher odds of disease than intensive farms (OR = 2.64, 95% CI: 1.71-4.10). Hence, our study reports for the first time on seroepidemiology and risk factors of Streptococcus ovis infection, laying a theoretical foundation for preventing and controlling streptococcosis in Tibet area.

An Update on Novel Taxa and Revised Taxonomic Status of Bacteria Isolated from Domestic Animals Described in 2018 to 2021

Novel bacterial taxonomy and nomenclature revisions can have significant impacts on clinical practice, disease epidemiology, and veterinary microbiology laboratory operations. Expansion of research on the microbiota of humans, animals, and insects has significant potential impacts on the taxonomy of organisms of clinical interest. Implications of taxonomic changes may be especially important when considering zoonotic diseases. Here, we address novel taxonomy and nomenclature revisions of veterinary significance. Noteworthy discussion centers around descriptions of novel mastitis pathogens in Streptococcaceae, Staphylococcaceae, and Actinomycetaceae; bovine reproductive tract pathogens in Corynebacteriaceae; novel members of Mannheimia spp., Leptospira spp., and Mycobacterium spp.; the transfer of Ochrobactrum spp. to Brucella spp.; and revisions to the genus Mycoplasma.

Synthesis of a Novel Lantibiotic Using Mutacin II Biosynthesis Apparatus

Owing to extensive metagenomic studies, we now have access to numerous sequences of novel bacteriocin-like antimicrobial peptides encoded by various cultivable and noncultivable bacteria. However, relatively rarely, we even have access to these cultivable strains to examine the potency and the targets of the predicted bacteriocins. In this study, we evaluated a heterologous biosynthetic system to produce biologically active nonnative novel lantibiotics, which are modified bacteriocins. We chose Streptococcus mutans, a dental pathogen, as the host organism because it is genetically easy to manipulate and is inherently a prolific producer of various bacteriocins. We chose the S. mutans T8 strain as the host, which produces the lantibiotic mutacin II, to express 10 selected homologs of mutacin II identified from GenBank. These lantibiotic peptides either are novel or have been studied very minimally. The core regions of the selected lantibiotic peptides were fused to the leader sequence of the mutacin II peptide and integrated into the chromosome such that the core region of the native mutacin II was replaced with the new core sequences. By this approach, using the mutacin II biosynthesis machinery, we obtained one bioactive novel lantibiotic peptide with 52% different residues compared to the mutacin II core region. This unknown lantibiotic is encoded by Streptococcus agalactiae and Streptococcus ovuberis strains. Since this peptide displays some homology with nukacin ISK-1, we named it nukacin Spp. 2. This study demonstrated that the mutacin II biosynthesis machinery can be successfully used as an efficient system for the production of biologically active novel lantibiotics. IMPORTANCE In this study, we report for the first time that Streptococcus mutans can be used as a host to produce various nonnative lantibiotics. We showed that in the T8 strain, we could produce bioactive lacticin 481 and nukacin ISK-1, both of which are homologs of mutacin II, using T8's modification and secretion apparatus. Similarly, we also synthesized a novel bioactive lantibiotic, which we named nukacin Spp. 2.

Streptococcus vicugnae sp. nov., isolated from faeces of alpacas (Vicugna pacos) and cattle (Bos taurus), Streptococcus zalophi sp. nov., and Streptococcus pacificus sp. nov., isolated from respiratory tract of California sea lions (Zalophus californianus)

Four novel independent strains of Streptococcus spp. were isolated from faeces of alpaca (SL1232^T), cattle (KCJ4950), and from respiratory tract of wild California sea lions (CSL7508^T, CSL7591^T). The strains were indole-, oxidase- and catalase-negative, non-spore-forming, non-motile Gram-positive cocci in short and long chains, facultative anaerobes. The 16S rRNA gene of SL1232^T and KCJ4950 shared 99.40-99.60% nucleotide similarity to strains of S. equinus, S. lutetiensis, S. infantarius, and the 16S rRNA gene of CSL7508^T and CSL7591^T demonstrated 98.72 and 98.92% similarity, respectively, to S. marimammalium. All other known Streptococcus species had the 16S rRNA gene sequence similarities of ≤95%. The genomes were sequenced for the novel strains. Average nucleotide identity (ANI) analysis for strains SL1232^T and KCJ4950, showed the highest similarity to S. equinus, S. lutetiensis, and S. infantarius with 85.21, 87.17, 88.47, 85.54, 87.47 and 88.89%, respectively, and strains CSL7508^T and CSL7591^T to S. marimammalium with 87.16 and 83.97%, respectively. Results of ANI were confirmed by pairwise digital DNA-DNA hybridization and phylogeny, which also revealed that the strains belong to three novel species of the genus Streptococcus. Phenotypical features of the novel species were in congruence with closely related members of the genus Streptococcus and gave negative reactions with the tested Lancefield serological groups (A-D, F and G). MALDI-TOF mass spectrometry supported identification of the species. Based on these data, we propose three novel species of the genus Streptococcus, for which the name Streptococcus vicugnae sp. nov. is proposed with the type strain SL1232^T (=NCTC 14341^T=DSM 110741^T=CCUG 74371^T), Streptococcus zalophi sp. nov. is proposed with the type strain CSL7508^T (=NCTC 14410^T=DSM 110742^T=CCUG 74374^T) and Streptococcus pacificus sp. nov. is proposed with the type strain CSL7591^T (=NCTC 14455^T=DSM 111148^T=CCUG 74655^T). The genome G+C content is 36.89, 34.85, and 35.34 % and draft genome sizes are 1906993, 1581094 and 1656080 bp for strains SL1232^T, CSL7508^T, and CSL7591^T, respectively.

Isolation and characterization of Streptococcus respiraculi sp. nov. from Marmota himalayana (Himalayan marmot) respiratory tract

Two bacterial strains were individually isolated from Marmota himalayana respiratory tracts; the animals were from the Tibet-Qinghai Plateau, PR China. The isolates were Gram-stain-positive, catalase-negative, coccus-shaped, chain-forming organisms. Analysis of 16S rRNA gene sequences indicated that the type strain HTS25^T shared 98.0, 97.4, 97.2 and 97.1 % similarity with Streptococcus cuniculi, Streptococcus acidominimus, Streptococcus marmotae and Streptococcus himalayensis respectively. Sequence analysis of the sodA and rpoB genes indicated that HTS25^T was closely related to S. marmotae (similarities of 94.7 and 91.4 % respectively). Analysis of groEL sequences showed interspecies similarity of 84.8 % between HTS25^T and S. himalayensis. A whole-genome phylogenetic tree reconstructed from 81 core genes from the genomes of 17 members of the genus Streptococcus was used to validate that HTS25^T forms a distinct subline from other recognized species of the genus Streptococcus. DNA-DNA hybridization of HTS25^T showed a maximum estimated DNA reassociation value of 32.1 % to Streptococcus cuniculi CCUG 65085^T. On the basis of the results of phenotypic and phylogenetic analyses, we propose that the two isolates be classified as representing a novel species of the genus Streptococcus, named Streptococcus respiraculi sp. nov. The type strain is HTS25^T (=DSM 101998^T=CGMCC 1.15531^T). The genome of Streptococcus respiraculi sp. nov. strain HTS25^T (2 067 971 bp) contains 2001 genes with an average DNA G+C content of 42.7 mol%.