Source tracking of fecal contamination in Asian green mussels (Perna viridis) harvested in Manila Bay, Philippines by molecular detection and genotyping of Cryptosporidium spp

Manila Bay, a multipurpose body of water located around Metro Manila, Philippines, is progressively deteriorating because of massive pollution. Reports have shown that the bay and its aquatic resources (i.e., seafood) are contaminated with fecal matter and enteric pathogens, posing a threat to public health and industry. This problem raises the need for a microbial source tracking methodology as a part of the rehabilitation efforts in the bay. Bivalve mollusks cultivated in water can serve as sentinel species to detect fecal pollution and can complement water monitoring. With the use of polymerase chain reaction and DNA sequence analysis, this study detected Cryptosporidium spp. in Asian green mussels (Perna viridis) cultivated and harvested in Manila Bay and sold in Bulungan Seafood Market, Parañaque, Philippines, from 2019 to 2021 with an overall occurrence of 8.77% (n = 57). The analysis of the 18S rDNA segment revealed three genotypes from Cryptosporidium-positive samples, namely, Cryptosporidium sp. rat genotype IV (60%), C. galli (20%), and C. meleagridis (20%). These findings suggest fecal pollution in bivalve cultivation sites coming from sewage, nonpoint, and agricultural sources. The presence of C. meleagridis, the third most common cause of human cryptosporidiosis, in mussels poses a threat to human health. Thus, there is a need to establish routine detection and source tracking of Cryptosporidium spp. in Manila Bay and to educate seafood consumers on food safety.

Variations in active proteases of Blastocystis sp. obtained from water and animal isolates from the Philippines

Blastocystis sp. is a commonly encountered gut protozoan with unclear pathogenicity. The presence of proteases in this organism may be related to its potential pathogenicity or other physiological differences. This study aimed to identify the various proteases that may be present in different subtypes (STs) of Blastocystis sp. using azocasein assay and gelatin zymography. In this study, cysteine, serine, aspartic protease, metalloproteases, and unknown proteases were identified in Blastocystis sp. cultures obtained from animal and water samples belonging to ST1-ST5 and ST7. Azocasein assay and gelatin zymography were conducted on different batches of protease extracts, which showed varying results. Cysteine protease was the most commonly encountered. Protease activity in general is not associated with ST or source (animal or water). However, the presence of cysteine protease alone was associated with animal samples, whereas the presence of more than two protease types was associated with water samples. Azocasein assay and gelatin zymography were conducted on different batches of protease extracts, which showed varying results. Protease activity and the types present may change over time. Blastocystis sp. shows high protease diversity, including possible novel types.