Among 12 marine bacterial strains from the China coast that exhibited interesting bioactivity (positive for both antimicrobial and cytotoxic activities), only four strains, namely, NJ6-3-1, NJ6-3-2, NB-6, and YTHM-17, had a KS domain or A domain when screened for PKS and NRPS genes using a PCR. Interestingly, two of these strains belonging to Pseudoalteromonas and associated with the marine sponge Hymeniacidon perleve were positive for both PKS and NRPS, whereas the other two strains of Pseudoalteromonas did not have a PKS or NRPS gene. A molecular phylogeny analysis and DGGE analysis of the Pseudoalteromonas sp. indicated that they had a specific affinity with the host marine sponge Hymeniacidon perleve. Furthermore, an analysis of a partial sequence of Pseudoalteromonas sp. NJ6-3-2 isolated from the marine sponge Hymeniacidon perleve obtained from genomic walking using a computational approach indicated a relatively complete PKS module including auxiliary domains (DH, KR, and Cy).