exacting

(a) having complicated nutritional requirements; especially growing only in special artificial cultures
- fastidious microorganisms
- certain highly specialized xerophytes are extremely exacting in their requirements
fastidious,
(s) severe and unremitting in making demands
- an exacting instructor
- a stern disciplinarian
- strict standards
stern, strict,
(s) requiring precise accuracy
- an exacting job
- became more exigent over his pronunciation
exigent,

fastidious stern strict exigent

unfastidious

exaction