Recently, microbial prodigiosin (PG) has received much attention due to its numerous beneficial applications. The aim of this study was to establish the bioprocessing of marine chitinous wastes (MCWs) for the cost-effective preparation of PG. Of the MCWs, demineralized shrimp shell powders (de-SSP) were found to be a potential source of carbon/nitrogen (C/N) for PG production by bacterial fermentation using Serratia marcescens strains. Further, PG scale-up production was investigated in a 15 L bioreactor system, and the highest yield (6200 mg/L) was achieved during fermentation using 5 L of a novel-designed culture broth that included 1.60% C/N sources (a de-SSP/casein ratio of 7/3), 0.02% K₂SO_4, and 0.05% K₂HPO₄, with an initial pH of 6–7. Fermentation was conducted in the dark at 27.5 °C for 8.0 h. This study was the first to report on the utilization of shrimp wastes for cost-effective, large-scale (5 L/pilot) PG production with high productivity (6200 mg/L) in a short cultivation time. The combination of 0.02% K₂SO₄ and 0.05% K₂HPO₄ was also found to be a novel salt composition that significantly enhanced PG yield. The red compound was purified and confirmed as PG after analyzing its HPLC profile, mass, and UV/vis spectra. The purified PG was then tested for its bioactivities and showed effective anticancer activities, moderated antioxidant activities, and novel anti-NO effects.

This study aimed to establish the culture process for the cost-effective production of prodigiosin (PG) from demineralized crab shell powder (de-CSP), a fishery processing byproduct created via fermentation. Among the tested PG-producing strains, Serratia marcescens TNU02 was demonstrated to be the most active strain. Various ratios of protein/de-CSP were used as the sources of C/N for PG biosynthesis. The PG yield was significantly enhanced when the casein/de-CSP ratio was controlled in the range of 3/7 to 4/6. TNU02 produced PG with a high yield (5100 mg/L) in a 15 L bioreactor system containing 4.5 L of a newly-designed liquid medium containing 1.6% C/N source (protein/de-CSP ratio of 3/7), 0.02% (NH₄)₂SO₄, 0.1% K₂HPO₄, and an initial pH of 6.15, at 27 °C for 8 h in dark conditions. The red pigment was purified from the culture broth and then quantified as being PG by specific Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) and UV spectra analysis. The purified PG demonstrated moderate antioxidant and effective inhibition against four cancerous cell lines. Notably, this study was the first to report on using crab wastes for PG bioproduction with high-level productivity (5100 mg/L) in a large scale (4.5 L per pilot) in a short period of fermentation time (8 h). The salt compositions, including (NH₄)₂SO₄ and K₂HPO₄, were also a novel finding for the enhancement of PG yield by S. marcescens in this report.

Chitin and protein-containing marine by-products (CPCMBPs), including crab shells, squid pens, and shrimp shells, were investigated as the sole carbon/nitrogen (C/N) source for prodigiosin (PG) production by Serratia marcescens TNU01 in a 250 mL Erlenmeyer flask and a 10 L bioreactor system. Among the used C/N source of CPCMBPs, squid pens powder (SPP) showed the most optimum PG productivity. Different ratios of chitin/protein combination were also used as the C/N sources for PG production. With a similar chitin/protein ratio (4/6) of squid pens, a significant PG productivity was achieved when the chitin/protein ratios were controlled in the range of 3/7–4/6. Maximum PG yield (3450 mg/L) by S. marcescens TNU01 was achieved in the bioreactor system containing 3 L medium of 1.75% SPP, 0.03% K₂HPO₄, and 0.05% MgSO₄ at 25 °C for 12 h in dark. The results of in vitro bioassays reveal that the purified PG possesses acetylcholinesterase inhibitory activity and antioxidant as well as anticancer activities. This study suggests that squid pens may have the potential to be used for cost effective production of bioactive PG at a large-scale.

Robusta coffee is a major commercial crop in the Central Highland of Vietnam with high economic and export value. However, this crop is adversely affected by various pathogens, particularly nematodes. This study aimed to screen active anti-nematode rhizobacterial strains for sustainable coffee production. Among more than 200 isolates, the isolate TUN03 demonstrated efficient biocontrol with nearly 100% mortality of J2 coffee nematodes Meloidogyne spp. and 84% inhibition of nematode egg hatching. This active strain was identified as Pseudomonas aeruginosa TUN03 based on its 16S rRNA gene sequence and phylogenetic analysis. In greenhouse tests, the strain TUN03 significantly reduced the coffee nematode population in the rhizome-soil with an 83.23% inhibition rate and showed plant growth-promoting effects. Notably, this is the first report of the nematicidal effect of P. aeruginosa against coffee nematodes. This potent strain further showed an antifungal effect against various crop-pathogenic fungi and was found to be the most effective against Fusarium solani F04 (isolated from coffee roots) with a 70.51% inhibition rate. In addition, high-performance liquid chromatography analysis revealed that this bacterial strain also secretes plant growth regulators including indole acetic acid (IAA), gibberellic acid (GA3), kinetin, and zeatin in significant amounts of 100, 2700, 37, and 9.5 µg/mL, respectively. The data from this study suggest that P. aeruginosa TUN03 may be a potential biocontrol agent and biofertilizer for the sustainable production of Robusta coffee and other crops.