Utilization of Fishery-Processing By-Product Squid Pens for Scale-Up Production of Phenazines via Microbial Conversion and Its Novel Potential Antinematode Effect

Abstract

Fishery by-products (FBPs) have been increasingly investigated for the extraction and production of a vast array of active molecules. The aim of this study was to produce phenazine compounds from FBPs via microbial fermentation and assess their novel antinematode effect. Among various FBPs, squid pen powder (SPP) was discovered as the most suitable substrate for phenazine production by Pseudomonas aeruginosa TUN03 fermentation. Various small-scale experiments conducted in flasks for phenazine production indicated that the most suitable was the newly designed liquid medium which included 1% SPP, 0.05% MgSO4, and 0.1% Ca3(PO4)2 (initial pH 7). Phenazines were further studied for scale-up bioproduction in a 14 L bioreactor system resulting in a high yield (22.73 µg/mL) in a much shorter cultivation time (12 h). In the fermented culture broth, hemi-pyocyanin (HPC) was detected as a major phenazine compound with an area percentage of 11.28% in the crude sample. In the bioactivity tests, crude phenazines and HPC demonstrate novel potential nematicidal activity against black pepper nematodes, inhibiting both juveniles (J2) nematodes and egg hatching. The results of this work suggest a novel use of SPP for cost-effective bioproduction of HPC, a novel potential nematodes inhibitor. Moreover, the combination of MgSO4 and Ca3(PO4)2 was also found to be a novel salt composition that significantly enhanced phenazine yield by P. aeruginosa fermentation in this work.

Chitosanase Production from the Liquid Fermentation of Squid Pens Waste by Paenibacillus elgii

“…Nevertheless, several distinctive features of squid pens suggest their potential suitability as a viable chitin source [ 43 ]. For sustainable methodologies, the use of squid pens as a viable C/N source in microbial fermentation processes is a promising avenue for producing high-value-added bioactive materials [ 44 , 45 , 46 , 47 ]. In this study, squid pens were potentially promising in the production of chitosanase by P. elgii TKU051.…”

Novel Black Pepper Antinematode Compounds Produced by Bacillus velezensis RB.EK7 Conversion of Organic Wastes

“…The antinematicidal assays were done following the methods presented in our earlier publications [5,19]. The seek black pepper roots were collected from Buon Ma Thuot, Dak Lak province, Vietnam, and the eggs and J2 nematodes were prepared according to the method of Khan et al [20].…”

“…C/N sources play an important role in enhancing the yield of secondary metabolites produced by microbes during fermentation [4,5,14,19,22]. To get high productivity of ANCs, various organic wastes, including SR, SSP, CR, and GOP, and a commercial medium (CM, yeast extract/peptone = 5/3) were used as C/N (0.8%) sources for fermentation.…”

“…Thus, we evaluated the effect of these compounds against both J2 nematodes and egg hatching. Hemi-pyocyanin, an ANC obtained in our previous work [19], was also used for the comparison, and the results are summarized in Figure 5. In the assays for the antinematode effect, DMSO was used as the negative control and to dissolve the samples.…”

“…In the assays for the antinematode effect, DMSO was used as the negative control and to dissolve the samples. In the negative group, the survival rate of J2 nematodes was approximately 96.74%, and the egg hatching rate was up to 88%; therefore, DMSO was appropriate for dissolving the samples and a suitable negative control in the experiments [19]. As shown in Figure 5a, all the tested compounds could inhibit J2 nematodes by more than 40%; especially, thymine demonstrated slightly higher activity than the positive compound with the inhibition rate of 68% and 60%, respectively, at the tested concentration of 2.5 mg/mL.…”