Bostrycin production by agro-industrial residues and its potential for food processing

Abstract

Bostrycin, a red antibacterial agent produced by Nigrospora sp. no. 407, is considered for meat processing. To optimize production, the culture conditions of submerged fermentation (SmF) and solid-state fermentation (SSF) were investigated. The optimal SmF conditions were a medium containing 1.0% cane molasses and incubation at 30 °C and 150 rpm for 6 days. In SSF, other than bostrycin, less pigment was produced and the optimal ratio of bagasse to water was 1:2 for 10 days. The production and recovery rate of bostrycin by SmF were 120 mg/L and 40%, respectively. Bostrycin exhibited thermostable, pH-dependent color change and dose-dependent antibacterial activity against Clostridium botulinum. Bostrycin-modified meat turned strong red for at least 24 h and could not be removed by washing; bostrycin maintained its antibacterial activity with a bacteriostasis rate of 91% on Staphylcoccus aureus. This is an easy and inexpensive means of acquiring bostrycin from molasses and sugarcane.

Keywords: Agro-industrial residue; Bostrycin; Meat processing; Reddening agent; Solid-state fermentation.

Fig. 1

Time course of bostrycin production, inhibition activity, and changes in the pH profile of Nigrospora sp. strain no. 407 in submerged culture conducted with the optimal production medium containing 1.0% molasses. Bostrycin production was measured according to the OD₅₀₂ (filled square), inhibition activity was measured according to the diameter of the clear zone in mm (filled triangle), and pH change during cultivation was profiled (filled circle)

Fig. 2

Visual comparison of the meat samples treated with various concentrations of bostrycin at 0 h (A) and 24 h (B). (a) Untreated meat; (b–f) meat treated with increasing concentrations of bostrycin (OD₅₀₂ nm = 1–5)

Fig. 3

Antibacterial activity of bostrycin on the meat samples. Compared with the untreated meat sample (left), a clear bacteria-free solution was obtained from the bostrycin-treated meat sample (right) after 12-h incubation, indicating that bostrycin can inhibit the growth of S. aureus