Highly efficient rice straw utilization for poly-(γ-glutamic acid) production by Bacillus subtilis NX-2

Improvement of poly-γ-glutamic acid biosynthesis in a moving bed biofilm reactor by Bacillus subtilis NX-2

“…The concentrations of residual glucose and residual glutamate in the broth were measured enzymatically using a biosensor (SBA-40C, Shandong Academy of Sciences, China). The method for determination of c-PGA concentration was described elsewhere (Zhang et al, 2012b;Tang et al, 2015a).…”

“…These yielded production rates of 0.75 g/L/h (Chen et al, 2010), 0.48 g/L/h (Bajaj and Singhal, 2010), and 0.91 g/L/h (Kumar and Pal, 2015), respectively. Our previous studies have also utilized straw hydrolysate as a carbon source in batch-fed fermentation with B. subtilis NX-2 or added cell immobilization devices in APFB systems to synthesize c-PGA, which improved c-PGA production rates to 0.81 g/L/h (Tang et al, 2015a) and 0.97 g/L/h , respectively. Although the MBBR system in the present work does not provide the highest production rate, the plastic carrier used is more costeffective and easier to use than the more costly and complex APFB system.…”

Microbial synthesis of poly-γ-glutamic acid: current progress, challenges, and future perspectives

“…As shown in Table 1 , many B. subtilis strains have been widely used for producing γ-PGA, and B. subtilis CGMCC 1250 produces 101.1 g/L γ-PGA, demonstrating the potential this organism has for γ-PGA production [ 49 ]. More importantly, simple enrichment and screening procedures without mutagenesis or genetic manipulation identified native strains that can produce more than 20 g/L of γ-PGA [ 50 ]. Bacillus licheniformis, Gram-positive, endospore-forming bacterium, shares many similarities with B. subtilis, and this non-pathogenic organism has also been exploited for the production of γ-PGA.…”

Efficient production of poly γ‐d‐glutamic acid from the bloom‐forming green macroalgae, Ulva sp., by Bacillus sp. SJ‐10

“…There are several reports on the economic production strategy of γ‐PGA, which showed 40–60% reduction in raw material costs using renewable raw materials, livestock manure, agroindustrial residues, and monosodium glutamate production residues. However, these were necessary for acid hydrolysis pretreatment of raw materials derived from agroindustrial residues, and additional nutrients supplement in the case of livestock manure when it was used as the primary medium (Chen et al, ; Tang, Lei, et al, , Tang, Xu, et al, ; Yong et al, ; Zhang et al, ). Therefore, the production of γ‐ d ‐PGA by Ulva degrading SJ‐10 is a viable production method that is an ecofriendly bioconversion that does not require additional pretreatments.…”

“…However, production is expensive, and for increasing the application of γ‐PGA, further research is necessary for identifying economical γ‐PGA production. Numerous studies on γ‐PGA production have investigated terrestrial renewable sources such as rice straw, mushroom powder, dairy manure, and glutamic acid wastewater for reducing production costs (Chen, Chen, Sun, & Yu, ; Tang, Lei, et al, , Tang, Xu, et al, ; Yong et al, ; Zhang, Feng, Zhou, Zhang, & Xu, ).…”