Catalyzes the acylation of sphingoid bases to form ceramides. Sphingolipids from Caenorhabditis elegans contain exclusively isosphingoid bases. Exhibits substrate preference for fatty acyl-coA chains containing 24 and 26 carbons. a fatty acyl-CoA + sphing-4-enine = an N-acylsphing-4-enine + CoA + H(+) 15-methylhexadecasphinganine + a fatty acyl-CoA = CoA + H(+) + N-acyl-15-methylhexadecasphinganine a fatty acyl-CoA + sphinganine = an N-acylsphinganine + CoA + H(+) sphinganine + tetradecanoyl-CoA = CoA + H(+) + N-(tetradecanoyl)-sphinganine hexacosanoyl-CoA + sphinganine = CoA + H(+) + N-hexacosanoylsphinganine Lipid metabolism; sphingolipid metabolism. Belongs to the sphingosine N-acyltransferase family.