Isolation and Identification of Chitinolytic Bacteria as Biocontrol Agent of Pathogenic Fungi on Gold Silkworm Cocoon Cricula trifenestrata

Abstract

Aims: Cricula trifenestrata is one of natural insects which has not been domesticated yet, thus called as the wild silkworm. C. trifenestrata is known as a silk producer which has high economic and market value. However, the fungi attack on C. trifenestrata cocoon decreased quality and quantity of silk yarn. Chitinolytic bacteria have a high potential as biological control against pathogenic fungi. This research aimed to isolate, select, characterize, and identify chitinolytic bacteria as pathogenic fungi growth inhibitors on C. trifenestrata cocoon. Methodology and results: Chitinolytic bacteria was isolated from the uninfected and infected cocoon while fungi was isolated from the uninfected cocoon. Inhibition test was conducted by Fokkema method and chitinase activity was measured by Spindler method. A total of 36 chitinolytic bacteria and 10 suspected pathogenic fungi isolates have been isolated. Fungal pathogenicity test showed that isolate CSAJ.2 was suspected as fungal pathogen. In vitro inhibition test indicated that chitinolytic bacteria isolate BSEP.3 could inhibit the growth of pathogenic fungi CSAJ.2 with percentage of inhibition 50%. Isolate BSEP.3 showed highest chitinase activity (5.11 U/mL) at the 15 th h. It able to inhibit the growth of pathogenic fungi with percentage of inhibition of 47.5% and 46.25%, respectively. Conclusion, significance and impact of study: Identification of bacteria targeted on 16S rRNA gene showed that isolate BSEP.3 had 98% identity with Bacillus amyloliquefaciens B5 while identification of fungi using ITS region of the rDNA showed that isolate CSAJ.2 had 100% identity with Trichoderma virens TV242. Chitinase crude extract was effective to be used as a biological control agent of T. virens CSAJ.2.

Antibacterial activity in vitro investigation of eucheuma cottonii extract from aru islands against pathogenic bacteria

“…The isolates were incubated at room temperature for 24 hours. The bacterial colonies that appeared were then transferred to a slant agar medium to be used as test isolates (Yunita et al, 2016;Yunita et al, 2022).…”

The potential of endophytic bacteria isolated from atung fruit seeds as antibacterial against skin pathogens

“…However, due to inappropriate and prolonged use of antibiotics, the sensitivity to several types of antibiotics begins to decrease over time so that some of these pathogens develop into new strain that leads to Multidrug Resistance Organisms (MDROs) (Calfee, 2022). Considering the high risk of resistance from the use of antibiotic drugs that have been described, the use of endophytic bacterial isolates as antimicrobials has various advantages, apart from avoiding the side effects of using drugs, the ability to protect the host it is attached to is an advantage possessed by endophytic bacteria, including fight pathogens, by producing secondary metabolites in the form of bioactive compounds that function as antimicrobials by inhibiting the growth of other organisms (Sirri et al, 2022;Yunita et al 2016).…”

Endophytic bacteria associated with Myristica fragrans Houtt: Improved media, bacterial population, preliminary characterization, and potential as antibacterials

“…Previous studies have examined the dynamics and diversity of endophytic bacteria, characterization and identification, as well as the benefit of bacterial isolates to promote plant growth and health (Kobayashi and Palumbo 2000) such as nitrogen fixation (Sturz at al. 1997), inducing drought resistance, and controlling herbivores and parasites (Kirchhorf et al 1997), as well as a source of secondary metabolites that have ability as antibacterial against plant pathogens (Mugiastuti et al 2020) or even to control pathogenic fungi (Yunita et al 2016). However, studies on the benefits of endophytic bacterial isolates in health and medicine, such as inhibiting the growth of pathogenic bacteria in humans, need to be further studied.…”