Domain: Healthcare — Microbiology-Immunology
Target concept: Klebsiella pneumoniae Detection

Video generation prompt: Inoculate Klebsiella pneumoniae into nitrate reduction medium and incubate at 37°C for 24 hours. After incubation, add α-naphthylamine and sulfanilic acid reagent, gently mix, and allow to stand.

Evaluation guide:
(i) Target concept: Visual confirmation of nitrate reduction capability in Klebsiella pneumoniae via colorimetric detection.
Minimum mechanism: Presence of viable K. pneumoniae → nitrate-to-nitrite conversion during incubation → nitrite + sulfanilic acid → diazonium intermediate → coupling with α-naphthylamine → red azo dye formation; all steps require correct biological, chemical, and procedural prerequisites.
(ii)Storyline: [Phase 1: Setup] Tube with clear liquid medium visible; sterile loop approaches and contacts surface → inoculation event (loop submerges, withdraws). [Phase 2: Incubation cue] Same tube placed inside labeled 37°C incubator (or timer + thermal label overlay) → static shot held. [Phase 3: Detection] Tube retrieved; two distinct reagent bottles approach and dispense drops into tube → visible liquid entry. [Phase 4: Reaction] Swirling motion induces vortex → fluid rotation stops → tube becomes motionless → red/pink color emerges uniformly within liquid column and persists. All phases occur from fixed frontal viewpoint; no cutaways; tube remains centered and fully in frame; lighting consistent; no extraneous hands/tools beyond those required.

Manual:
Experimental Procedure
1. Inoculate Klebsiella pneumoniae into nitrate reduction broth using sterile loop.
2. Incubate tube at 37°C for 24 hours.
3. Add α-naphthylamine and sulfanilic acid reagents to same tube.
4. Gently mix by swirling.
5. Allow tube to stand undisturbed.
Observation of Experimental Phenomena
Red or pink color develops in the broth after reagent addition and standing — indicates nitrate reduced to nitrite by Klebsiella pneumoniae.
Summary of Experimental Principles
Klebsiella pneumoniae reduces nitrate (NO₃⁻) to nitrite (NO₂⁻); nitrite reacts with sulfanilic acid to form diazonium salt, which couples with α-naphthylamine to yield a stable red azo dye.

Prompt Grounding rubric:
level_1: No test tube of nitrate broth is shown being inoculated with Klebsiella pneumoniae, no 37°C incubation cue (incubator or thermal label) appears, no α-naphthylamine or sulfanilic acid reagent is added, and no standing/observation period is depicted.
level_2: A test tube or reagent bottle appears, but the inoculation step is missing or performed on the wrong medium, the 37°C incubation cue is absent, or the reagents are added to a different tube than the one that was inoculated.
level_3: The nitrate broth tube, the inoculating loop, both reagent sources (α-naphthylamine and sulfanilic acid), and a 37°C incubation cue all appear in the correct order (inoculation, incubation, reagent addition into the same tube, then a stationary standing period), even if some visual detail such as bottle labeling is imprecise.
level_4: Everything required for the 3-point level holds, and the reagents are added directly into the identical tube that was inoculated and incubated, with the camera holding on that single tube throughout: no swap to an unlabeled duplicate tube and no substitution of inoculation tools mid-sequence (e.g., a syringe appearing where a loop was used).
level_5: Everything required for the 4-point level holds, and the full sequence (loop entering and leaving the broth, the tube being placed into and removed from the 37°C incubation setting, both reagents entering the same tube, the brief swirling motion, and the subsequent still standing period) plays out as one unbroken, unambiguous chain on the same tube with no jump cuts hiding any step.

Scientific and Causal Correctness rubric:
level_1: No red or pink color ever appears in the broth, the broth's color is unchanged from before reagent addition throughout the entire clip, or the reagents are shown added to an uninoculated tube or to a solid agar surface instead of the liquid nitrate broth.
level_2: A red/pink tint appears, but not confined to the inoculated-and-incubated tube (e.g. it shows up in an unrelated container or above the tube), or it appears before the reagents are added, or it appears without the tube ever having gone through the 37°C incubation step.
level_3: A red or pink color develops only in the tube that was both inoculated with Klebsiella pneumoniae and incubated, appearing only after both reagents are added and the tube is swirled, and the color fills the liquid evenly rather than sitting only at the surface or as scattered specks.
level_4: Everything required for the 3-point level holds, and the tube shows no red/pink tint at all before reagent addition, the color appears only after swirling mixes the reagents in, and the color remains once the tube goes still for the standing period rather than fading or reversing.
level_5: Everything required for the 4-point level holds, and the red/pink color fills at least about 80% of the visible liquid column with even intensity, no separate brown or dark precipitate layer appears that would suggest a side reaction unrelated to the nitrite–diazonium–azo dye pathway, and the color stays visually constant for the remainder of the standing period rather than drifting in hue or patchiness.

Spatiotemporal Consistency rubric:
level_1: The tube's position or background changes abruptly between shots (e.g., jumping from bench to incubator with no transition), the lighting abruptly swings from bright daylight to a dark room with no cause, the tube's glass visibly warps or distorts its shape between frames, the inoculating loop appears or disappears without entering/leaving the broth, or the reagent bottles appear already touching the liquid surface with no approach motion.
level_2: The tube reorients or spins more than about 90 degrees without any visible hand or holder, a reagent droplet appears already dissolved in the liquid with no entry motion, the shadow cast by the tube flips direction with no matching light change, the incubator background disappears and reappears with no transition, or the swirling motion starts and stops abruptly with the liquid inside not responding to the movement.
level_3: The same tube stays identifiable and in a consistent position throughout each phase; the loop enters and exits the broth smoothly; the reagent bottles approach and dispense into the tube without jumping; and the swirling shows a continuous rotational flow of the liquid that settles gradually once the hand stops.
level_4: Everything required for the 3-point level holds, and the liquid responds naturally to the swirling (the meniscus rises and dips with the rotation and a visible vortex forms and relaxes rather than the surface staying flat), with no object passing through the tube wall and no sudden switch in camera angle (e.g., top-down to side-on) without a visible camera move.
level_5: Everything required for the 4-point level holds, and every phase transition (bench to incubator, incubator back to bench, swirl to stillness) plays out with continuous, unbroken motion of the same tube; the tube's shape and any label stay geometrically consistent as it moves; and no frame shows the tube, loop, or reagent bottles flickering, popping in, or duplicating.