Restoration of polar-flagellum motility and biofilm-forming capacity in the <i>mmsB1</i> mutant of the alphaproteobacterium <i>Azospirillum brasilense</i> Sp245 points to a new role for a homologue of 3-hydroxyisobutyrate dehydrogenase
Bibliographic record
Abstract
The bacterium Azospirillum brasilense can swim and swarm owing to the rotation of a constitutive polar flagellum (Fla) and inducible lateral flagella, respectively. They also form biofilms on various interfaces. Experimental data on flagellar assembly and social behaviours in these bacteria are scarce. Here, for the first time, the chromosomal coding sequence mmsB1 for a homologue of 3-hydroxyisobutyrate dehydrogenase (protein accession Nos. ADT80774 and E7CWE2) was shown to play a role in the assembly of motile Fla and in biofilm biomass accumulation. In the previously obtained mutant SK039 of A. brasilense Sp245, an Omegon-Km insertion in mmsB1 was concurrent with changes in cell-surface properties and with suppression of Fla assembly (partial) and Fla-dependent motility (complete). Here, the immotile leaky Fla− mutant SK039 was complemented with the expression vector pRK415-borne mmsB1 gene of Sp245. In the complemented mutant, the elevated relative cell hydrophobicity and changed relative membrane fluidity of SK039 returned to the wild-type levels; also, biofilm biomass accumulation increased and even reached Sp245’s levels under nutritionally rich conditions. In strain SK039 (pRK415-mmsB1), the percentage of cells with Fla became significantly higher than that in mutant SK039, and the Fla-driven swimming velocity was equal to that in strain Sp245.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".