Efficient biosynthesis of prunin in methanol cosolvent system by an organic solvent-tolerant α-L-rhamnosidase from Spirochaeta thermophila

Prunin of desirable bioactivity and bioavailability can be transformed from plant-derived naringin by the key enzyme α-L-rhamnosidase. However, the production was limited by unsatisfactory properties of α-L-rhamnosidase such as thermostability and organic solvent tolerance. In this study, biochemical characteristics, and hydrolysis capacity of a novel α-L-rhamnosidase from Spirochaeta thermophila (St-Rha) were investigated, which was the first characterized α-L-rhamnosidase for Spirochaeta genus. St-Rha showed a higher substrate specificity towards naringin and exhibited excellent thermostability and methanol tolerance. The Km of St-Rha in the methanol cosolvent system was decreased 7.2-fold comparing that in the aqueous phase system, while kcat/Km value of St-Rha was enhanced 9.3-fold. Meanwhile, a preliminary conformational study was implemented through comparative molecular dynamics simulation analysis to explore the mechanism underlying the methanol tolerance of St-Rha for the first time. Furthermore, the catalytic ability of St-Rha for prunin preparation in the 20% methanol cosolvent system was explored, and 200 g/L naringin was transformed into 125.5 g/L prunin for 24 h reaction with a corresponding space-time yield of 5.2 g/L/h. These results indicated that St-Rha was a novel α-L-rhamnosidase suitable for hydrolyzing naringin in the methanol cosolvent system and provided a better alternative for improving the efficient production yield of prunin.

within the order Spirochaetales

A fully assembled spirochaete genome was identified as a contaminating scaffold in our red abalone (Haliotis rufescens) genome assembly. In this paper, we describe the analysis of this bacterial genome. The assembled spirochaete genome is 3.25 Mb in size with 48.5 mol% G+C content. The proteomes of 38 species were compared with the spirochaete genome and it was discovered to form an independent branch within the family Spirochaetaceae on the phylogenetic tree. The comparison of 16S rRNA sequences and average nucleotide identity scores between the spirochaete genome with known species of different families in Spirochaetia indicate that it is an unknown species. Further, the percentage of conserved proteins compared to neighbouring taxa confirm that it does not belong to a known genus within Spirochaetaceae. We propose the name Candidatus Haliotispira prima gen. nov., sp. nov. based on its taxonomic placement and origin. We also tested for the presence of this species in different species of abalone and found that it is also present in white abalone (Haliotis sorenseni). In addition, we highlight the need for better classification of taxa within the class Spirochaetia.

Machine learning-based motion tracking reveals an inverse correlation between adhesivity and surface motility of the leptospirosis spirochete

Bacterial motility is often a crucial virulence factor for pathogenic species. A common approach to study bacterial motility is fluorescent labeling, which allows detection of individual bacterial cells in a population or in host tissues. However, the use of fluorescent labeling can be hampered by protein expression stability and/or interference with bacterial physiology. Here, we apply machine learning to microscopic image analysis for label-free motion tracking of the zoonotic bacterium Leptospira interrogans on cultured animal cells. We use various leptospiral strains isolated from a human patient or animals, as well as mutant strains. Strains associated with severe disease, and mutant strains lacking outer membrane proteins (OMPs), tend to display fast mobility and reduced adherence on cultured kidney cells. Our method does not require fluorescent labeling or genetic manipulation, and thus could be applied to study motility of many other bacterial species.

Kinetics of tick infection by the relapsing fever spirochete Borrelia hermsii acquired through artificial membrane feeding chambers

The relapsing fever agent Borrelia hermsii is transmitted by the tick Ornithodoros hermsi. To study the B. hermsii-tick interactions required for pathogen acquisition and transmission we developed an artificial membrane feeding system for O. hermsi nymphs and adults that results in a high percentage of engorgement. This system provides the nutritional requirements necessary for the tick to develop, mate, and produce viable eggs. By inoculating the blood with B. hermsii, we were able to obtain infected ticks for quantitative studies on pathogen acquisition and persistence. These ticks subsequently transmitted the spirochetes to mice, validating this system for both acquisition and transmission studies. Using this feeding method, a mutant of the antigenic variation locus of B. hermsii (Vmp-) that is incapable of persisting in mice was acquired by ticks at equivalent densities as the wild-type. Furthermore, Vmp is not required for persistence in the tick, as the mutant and wild-type strains are maintained at similar numbers after ecdysis and subsequent feeding. These results support the theory that Vmp is an adaptation for mammalian infection but unnecessary for survival within the tick. Interestingly, B. hermsii numbers severely declined after acquisition, though these ticks still transmitted the infection to mice. This procedure reduces animal use and provides a safe, highly controlled and well-contained alternative method for feeding and maintaining O. hermsi colonies. Importantly, this system permits quantitative studies with B. hermsii strains through ingestion during the blood meal, and thus more closely recapitulates pathogen acquisition in nature than other artificial systems.

Effect of fine coal gasification slag on improvement of bacterial diversity community during the pig manure composting

In present study, evaluate the effect of fine coal gasification slag (FCGS) as additive on abundance of bacterial diversity during pig manure composting. The six different dosages of FCGS 0% (T1), 2% (T2), 4% (T3), 6% (T4), 8% (T5) and 10% (T6) (dry weight basis) were mixed with original raw materials for 42 days an aerobic composting. The results indicated that FCGS adopted could affect the succession of bacterial diversity in different ways. Among all treatments, Firmicutes, Proteobacteria, Tenericutes, unidentified_Bacteria, and Actinobacteria were the highest abundance in weighted unifrac distance but Firmicutes; Proteobacteria, Actinobacteria, Bacteroidetes, and Spirochaetes were main bacteria in unweighted unifrac distance. The β-diversity and principal component analysis indicated a significant difference in bacterial diversity in all treatments which T4 obtained difference obviously. Therefore, the results showed that T4 was a potential candidate to enhance significantly abundance of bacterial community in PM compost.

Structure of the SthK carboxy-terminal region reveals a gating mechanism for cyclic nucleotide-modulated ion channels

Cyclic nucleotide-sensitive ion channels are molecular pores that open in response to cAMP or cGMP, which are universal second messengers. Binding of a cyclic nucleotide to the carboxyterminal cyclic nucleotide binding domain (CNBD) of these channels is thought to cause a conformational change that promotes channel opening. The C-linker domain, which connects the channel pore to this CNBD, plays an important role in coupling ligand binding to channel opening. Current structural insight into this mechanism mainly derives from X-ray crystal structures of the C-linker/CNBD from hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels. However, these structures reveal little to no conformational changes upon comparison of the ligand-bound and unbound form. In this study, we take advantage of a recently identified prokaryote ion channel, SthK, which has functional properties that strongly resemble cyclic nucleotide-gated (CNG) channels and is activated by cAMP, but not by cGMP. We determined X-ray crystal structures of the C-linker/CNBD of SthK in the presence of cAMP or cGMP. We observe that the structure in complex with cGMP, which is an antagonist, is similar to previously determined HCN channel structures. In contrast, the structure in complex with cAMP, which is an agonist, is in a more open conformation. We observe that the CNBD makes an outward swinging movement, which is accompanied by an opening of the C-linker. This conformation mirrors the open gate structures of the Kv1.2 channel or MthK channel, which suggests that the cAMP-bound C-linker/CNBD from SthK represents an activated conformation. These results provide a structural framework for better understanding cyclic nucleotide modulation of ion channels, including HCN and CNG channels.

Antagonism of Spirillum minus infection in rats towards Trypanosoma lewisi and T. equinum

1. Rats infected with Spirillum, minus are strongly resistant to infection with Trypanosoma lewisi and T. equinum if inoculated with these parasites shortly after inoculation with Spirillum minus. The resistance is most highly developed for a period of from 2 to 4 weeks after inoculation with S. minus.

2. Simultaneous inoculation of rats with S. minus and either of the trypanosomes does not influence the course of the resulting trypanosome infection.

3. Rats inoculated with Trypanosoma equinum during the period of acute infection with Spirillum minus develop only a very slight transient primary infection with the trypanosome and may survive for many weeks, up to 49, whereas control rats die in 5–17 days. Usually the resistant rats ultimately die from a relapse of the Trypanosoma equinum infection.

4. Similarly, in rats inoculated with T. lewisi during the resistant phase due to an infection with Spirillum minus, the primary acute infection with the trypanosome is suppressed and the rats develop a slight or subpatent infection.

5. The non-specific resistance to trypanosomes conferred by the acute S. minus infection soon disappears and is replaced by a specific trypanosome resistance which is active only against reinoculation with the same species of trypanosome. Thus, in this phase of resistance, a rat infected with Trypanosoma equinum is refractory to reinoculation with T. equinum but has no resistance to superinoculation with T. lewisi. Conversely, a rat infected with T. lewisi is refractory to reinoculation with that species but it is as susceptible to superinoculation with T. equinum as a normal rat.

Immobilization of Treponema pallidum in vitro by antibody produced in syphilitic infection

Treponema pallida were extracted from rabbit testicular syphilomas and suspended in a special medium in which the organisms remain motile and infectious for several days. On incubation of such suspensions with syphilitic rabbit or human sera and guinea pig complement, the treponemes became non-motile and lost their capacity to infect rabbits. Various factors affecting this immobilization have been investigated. In a preliminary survey of individual sera, immobilizing antibody could be detected in the majority of sera from syphilitic animals and human beings, but was absent in almost all the normal sera examined. It could be demonstrated that the immobilizing and reagin activities of syphilis sera are due to separate antibodies.

Studies on the life cycle of spirochetes; the life cycle of the Nichols pathogenic Treponema pallidum in the rabbit testis as visualized by means of stained smears

Further evidence for the occurrence of a complex life cycle in the pathogenic Treponema pallidum as visualized by means of stained preparations is presented.

Studies on the life cycle of spirochetes; the life cycle of the Nichols pathogenic Treponema pallidum in the rabbit testis as seen by phase contrast microscopy

A series of observations with the phase contrast microscope on the occurrence of a complex life cycle in the pathogenic Treponema pallidum as it occurs in the syphilitic rabbit testis has been presented and it seems likely from these observations that there are two means of vegetative reproduction, consisting of (1) transverse division (the most important under usual conditions); and (2) the production of gemmae or buds which eventuate into unispirochetal cysts comparable to those described for saprophytic forms, within each of which single spirochetes develop and differentiate, and from which they subsequently emerge. In addition preliminary evidence is presented which suggests that a more complex process is involved in which multispirochetal cysts develop following aggregation of two or more organisms. Within each of these larger cysts numerous organisms develop and subsequently emerge as tangled ropes. Following emergence, they subsequently undergo transverse division and gemmae formation, and so reproduce vegetatively. Subsequent papers will elaborate upon these processes.

Perspectives on the origin of microfilaments, microtubules, the relevant chaperonin system and cytoskeletal motors--a commentary on the spirochaete origin of flagella

The origin of cytoskeleton and the origin of relevant intracellular transportation system are big problems for understanding the emergence of eukaryotic cells. The present article summarized relevant information of evidences and molecular traces on the origin of actin, tubulin, the chaperonin system for folding them, myosins, kinesins, axonemal dyneins and cytoplasmic dyneins. On this basis the authors proposed a series of works, which should be done in the future, and indicated the ways for reaching the targets. These targets are mainly: 1) the reconstruction of evolutionary path from MreB protein of archaeal ancestor of eukaryotic cells to typical actin; 2) the finding of the MreB or MreB-related proteins in crenarchaea and using them to examine J. A. Lake's hypothesis on the origin of eukaryote from "eocytes" (crenarchaea); 3) the examinations of the existence and distribution of cytoskeleton made of MreB-related protein within coccoid archaea, especially in amoeboid archaeon Thermoplasm acidophilum; 4) using Thermoplasma as a model of archaeal ancestor of eukaryotic cells; 5) the searching for the homolog of ancestral dynein in present-day living archaea. During the writing of this article, Margulis' famous spirochaete hypothesis on the origin of flagella and cilia was unexpectedly involved and analyzed from aspects of tubulins, dyneins and spirochaetes. Actually, spirochaete cannot be reasonably assumed as the ectosymbiotic ancestor of eukaryotic flagella and cilia, since their swing depends upon large amount of bacterial flagella beneath the flexible outer wall, but not depends upon their intracellular tubules and the assumed dyneins. In this case, if they had "evolved" into cilia and lost their bacterial flagella, they would immediately become immobile! In fact, tubulin and dynein-like proteins have not been found in any spirochaete.

MORPHOLOGY OF TREPONEMA MICRODENTIUM AS REVEALED BY ELECTRON MICROSCOPY OF ULTRATHIN SECTIONS

Listgarten, M. A. (Harvard School of Dental Medicine and Forsyth Dental Infirmary, Boston, Mass.), W. J. Loesche, and S. S. Socransky. Morphology of Treponema microdentium as revealed by electron microscopy of ultrathin sections. J. Bacteriol. 85:932-939. 1963.-Broth cultures of a strain of Treponema microdentium were harvested on Millipore filters, fixed in osmic acid, and sectioned for electron microscopy. The sections revealed that the spirochetes had an axial filament, made up of two fibrils approximately 150 A in diameter, which was situated between an external envelope approximately 140 A in thickness and a protoplasmic cylinder. The protoplasmic cylinder had a cross-sectional diameter of 100 to 200 mmu, and was surrounded by a double "membrane" consisting of two 40-A electron-dense structures separated by a 45-A space. Cross-sections of spirochetal "granules" revealed that the limiting membrane was continuous with the outer envelope of the spirochetes, and surrounded the protoplasmic cylinder and axial filament.

COLONIAL GROWTH OF ANAEROBIC SPIROCHETES ON SOLID MEDIA

Hardy, Paul H., Jr. (The Johns Hopkins University School of Medicine, Baltimore, Md.), Young C. Lee, and E. Ellen Nell. Colonial growth of anaerobic spirochetes on solid media. J. Bacteriol. 86:616-626. 1963.-A total of 14 strains of treponemes and one of Borrelia vincentii were cultivated as colonies on agar plates inoculated under ordinary atmospheric conditions, but incubated anaerobically. Every spirochete strain produced diffuse colonies with growth located primarily in the agar; in addition, eight treponeme strains also produced discrete colonies with surface growth. These represented stable colonial variants in several strains, and in one the spirochetes in the surface colonies showed permanently altered cellular morphology. Sufficient variation in colonial morphology was noted between strains to suggest that this may have some value in further classification of this group of microorganisms. Several conditions contributed to the successful growth of all strains as colonies, the most important of which was the use of a firm jelling agar preparation, Ionagar No. 2, that permitted preparation of plates with a final agar concentration of 0.7%. Agar concentrations of 0.9%, or above, in media inhibited treponeme growth.

USE OF A BACTERIAL CULTURE FILTRATE AS AN AID TO THE ISOLATION AND GROWTH OF ANEROBIC SPIROCHETES

Hardy, Paul H., Jr. (The Johns Hopkins University School of Medicine, Baltimore, Md.), Young C. Lee, and E. Ellen Nell. Use of a bacterial culture filtrate as an aid to the isolation and growth of anaerobic spirochetes. J. Bacteriol. 87:1521-1525. 1964.-A previously described procedure that permits colonial growth of laboratory-adapted anaerobic spirochetes on surface streaked media was applied to the isolation of new spirochetal strains from human oral microflora. Primary isolates were readily cultivable as colonies, but they were found to be nutritionally dependent upon other microorganisms with which they are normally associated in vivo. Spirochetal growth was first noted around colonies of oral bacteria; pure cultures were then grown on media fortified with the culture filtrate of one such organism-a microaerophilic diphtheroid.

Effects of SR-spirochete infection on Drosophila melanogaster carrying intersex genes

Three sex-transforming genes (ix, tra-D, and dsx) in D. melanogaster were examined with respect to possible interactions with the NSR strain SR-spirochetes. The SR-spirochetes exerted a lethal effect on XY but not on XX individuals, regardless of whether they were phenotypically males, intersexes, or females. These results, taken together with those reported by Sakaguchi and Poulson (1963)on tra and 2X3A intersexes, both of which are resistant to the androcidal action of SR-spirochetes, support the interpretation that male susceptibility is a consequence of the single X condition.

Ultrastructural identification of spirochetes and flagellated microbes at the brush border of the large intestinal epithelium of the rhesus monkey

Spiral-shaped organisms exclusively and intimately populate the brush border of the cecal and colonic epithelium of healthy monkeys (Macaca mulatta). These organisms replace the glycocalyx, destroy most microvilli, and attenuate the terminal web of the brush border. Despite these remarkable alterations, the remaining host cellular structure is unchanged. Two structurally distinct microbes, a spirochete and a flagellate, were recognized by electron microscopy. These spirochetes share the general characteristics of other known spirochetes: they are 3 to 6 mum long and 0.2 to 0.4 mum wide, spiral 2 to 6 times, and have axial fibrils of 6-12-6 and 4-8-4 arrangements. Flagellated microbes are 4 to 6 mum long and 0.2 to 0.4 mum wide, spiral 2 to 4 times, and are characterized by a polar flagellum which originates from the terminal button at each end of the cytoplasmic body. This in vivo ultrastructural study of anaerobic spiral-shaped organisms bypasses the difficulties of in vitro culture techniques and provides a detailed description and identification of these organisms in their host environment.

A virus associated with SR-spirochetes of Drosophila nebulosa

A virus is associated with a strain of transovarially-transmitted SR-spirochetes, NSR, of Drosophila. This virus, designated spv-1, is able to infect and to multiply in another strain of SR-spirochetes, WSR, thereby eliminating the SR condition from the host flies. Spv-1 contains DNA, has a buoyant density of 1.480 in CsCl, and is spherical in shape, measuring 50-60 nm in diameter.