ISOLASI DAN SELEKSI BAKTERI ENDOFIT TUMBUHAN Pontederia crassipes SEBAGAI KANDIDAT AGEN BIOREDUKSI Cr(VI) - Rayi Kuni Isti'anah; Bernadetta Octavia (Kingdom (The Journal of Biological Studies), 2026)
Abstrak Industri penyamakan kulit di Kawasan Industri Piyungan (KIP), Yogyakarta, menghasilkan limbah cair dengan kandungan kromium heksavalen [Cr(VI)] dalam jumlah signifikan yang bersifat toksik dan karsinogenik. Penelitian ini bertujuan untuk mengisolasi dan mengevaluasi bakteri endofit dari tumbuhan Pontederia crassipes (eceng gondok) sebagai agen bioremediasi Cr(VI). Sebanyak tujuh isolat diperoleh dari bagian akar, batang, dan daun, kemudian diseleksi berdasarkan kemampuan resistensi terhadap Cr(VI) melalui uji Minimum Inhibitory Concentration (MIC). Tiga isolat terpilih (PCr5, PCr6, dan PCr7) menunjukkan resistensi tertinggi hingga 2100 mg/L Cr dan bersifat non-patogen berdasarkan uji hemolisis, hipermukoviskositas, virulensi, dan gelatinase. Identifikasi molekuler menunjukkan bahwa ketiga isolat tergolong genus Pediococcus sp. Karakterisasi fisiologi dan biokimia menunjukkan isolat bersifat gram positif, kokus, non-motil, dan fakultatif anaerob. Profil pertumbuhan menunjukkan penurunan laju pertumbuhan pada media yang tersuplementasi Cr yang mengindikasikan efek toksik kromium. Uji bioreduksi menunjukkan bahwa ketiga isolat mampu mereduksi Cr(VI) dengan efektivitas tertinggi pada konsentrasi 50 mg/L, yaitu 54.29%–67.18%. Kata Kunci: Bakteri Endofit, Bioreduksi, Kromium Heksavalen, Pediococcus sp., Pontederia crassipes. AbstractThe leather tanning industry in the Piyungan Industrial Area (KIP), Yogyakarta, generates liquid waste containing significant amounts of hexavalent chromium [Cr(VI)], which is toxic and carcinogenic. This study aims to isolate and evaluate endophytic bacteria from Pontederia crassipes (water hyacinth) as potential agents for Cr(VI) bioremediation. A total of seven isolates were obtained from the plant’s roots, stems, and leaves, and were screened for Cr(VI) resistance using the Minimum Inhibitory Concentration (MIC) test. Three selected isolates (PCr5, PCr6, and PCr7) exhibited the highest resistance, tolerating up to 2100 mg/L of Cr, and were confirmed to be non-pathogenic based on hemolysis, hypermucoviscosity, virulence, and gelatinase tests. Molecular identification revealed that the three isolates belong to the genus Pediococcus. Physiological and biochemical characterization showed that the isolates are gram-positive, cocci-shaped, non-motile, and facultative anaerobes. Growth profile analysis indicated a reduced growth rate in Cr-supplemented media, suggesting a toxic effect of chromium. Bioreduction assays demonstrated that all three isolates were capable of reducing Cr(VI), with the highest reduction efficiency observed at a concentration of 50 mg/L, ranging from 54.29% to 67.18%. Keywords: Endophytic Bacteria, Bioreduction, Hexavalent Chromium, Pediococcus sp., Pontederia crassipes.