FAQs

Switching agar suppliers in a high-volume tissue culture facility is a high-risk decision. A change in agar batch can cause systematic shifts in contamination rate, differentiation rate or rooting rate without any other formulation change — and the cause may only become apparent several subculture generations after the switch.

Structured supplier transition process — three phases:

Phase 1 — Documentary evaluation (1–2 weeks): Request and compare the following from candidate suppliers: ① product specification sheet (upper and lower limits for gel strength, sulfate, ash, pH, moisture and heavy metals — all as specific numerical ranges, not "passes specification"); ② COAs from the three most recent production batches (to assess batch-to-batch consistency — focus on the standard deviation of gel strength); ③ production certifications (ISO certification, raw material origin documentation); ④ minimum order quantity and pack size options (25 kg bulk bags vs. small packs).

Immediately exclude any supplier whose gel-strength coefficient of variation (CV) across batches exceeds 8%.

Phase 2 — Parallel small-scale trial (4–8 weeks): Request samples from at least three different production batches (minimum 500 g each). Run parallel comparison trials: keep the existing formulation 100% unchanged — substitute only the agar raw material. Cover the facility's principal species (e.g., orchid + banana + one sensitive indicator species) at 5 vessels × 3 replicates each. Observe: contamination rate, first-generation multiplication coefficient, explant surface morphology (any hyperhydricity), medium colour and clarity.

Phase 3 — Pilot scale-up (8–16 weeks): After a successful small-scale trial, introduce the new supplier agar on 1–2 production lines representing 10–20% of total capacity. Run 2–3 full subculture cycles before completing the transition. Retain existing supplier inventory as emergency backup stock — three months' supply is recommended.

Fig. Agar for plant tissue culture