4.2 Proximate Compositions of the Acid Pre-treated and Alkali Pre-treated cowpea waste
The acid-treated cowpea had a greater ash level of 4.18 percent, while the alkali-treated cowpea had just 1.34 percent, according to proximate analyses of both the acid and alkali-treated dried unfermented cowpea waste samples. The alkali-treated cowpea, on the other hand, had a greater carbohydrate content of 23.54 percent, compared to 18.86 percent for the acid-treated cowpea. This could be related to the fact that, according to (Damisa et al., 2008) acid pretreatment of residues normally does not eliminate lignin from the substrate, but only alters the lignin CHO linkage. This is also in line with the findings of (Houghton et al., 2006), who claimed that acidic substrate treatment could allow cellulose to re-anneal, resulting in horrification of cellulose into micro fibrils instead. Moisture content, crude fat, crude protein, and crude fiber content were also determined, as indicated in Table i.
4.3. Screening for glutamic acid producing bacteria
All of the microorganisms studied produced glutamic acid, which was qualitatively identified using paper chromatography. Table ii shows that among the seven isolates proved to be Pseudochrobactrum saccharolyticum and screened for L-glutamic acid synthesis, the isolate from the chicken-pen produced the highest glutamic acid yield of 0.61g/L, while the isolate from the sheep-pen produced the lowest glutamic acid yield of 0.21g/L. This observed disparity in glutamic acid yield could be attributed to Pseudochrobactrum saccharolyticum s nutritional diversity's variety and adaptation, which is usually associated with the nature of the environment from which they were previously separated. This study's maximum glutamic acid production of 0.61g/L is significantly lower than (Hadia et al., 2012) who reported a concentration of 1.5g/L after screening. This difference may be accounted for by the higher biotin concentration of 10 µg used in this study as opposed to the lower concentration of 50 µg used by (Hadia et al., 2012).
4.4.0 Scanning Electron Microscope
In this work, SEM was used to examine the material's surface morphology in order to determine whether CC has enough carbonaceous material to be acceptable for gasification utilizing a downdraft gasification system. The data was collected across a specific area of the sample's surface, and a two-dimensional image was created, as shown in Plates A1, A2 and B1, B2 that indicated spatial changes in characteristics.
4.4.1. FTIR analysis of the result showed that a lot of numbers of peaks were detected, informing the complex structure material of corn cob and corn husk in figure i and ii
4.4.2 Effect of bead size on glutamic acid production from cowpea waste using corn cob and corn husk matrix
Figure i and ii shows the production of glutamic acid from cowpea waste by bacteria immobilized in corn cob and husk beads with diameters of 1, 2, 3, and 4 mm.
The volume of glutamic acid produced increased gradually as the bead size increased from 1 mm to 2 mm, then decreased as the bead size increased (Fig. iii and fig iv). As shown in Figures iii and iv, the bead size 2 mm produced the highest volume of glutamic acid, indicating that the number of pore spaces made available and the number of cells filling each space are optimal for substrate consumption (Kareem et al., 2013). Larger sizes resulted in smaller beads, indicating that smaller beads had more surface area per unit volume and thus higher productivity (Kareem et al., 2014). Because the cells in larger beads have less access to the substrate, it reacts with the molecules and produces a product (Sevda and Rodrigues, 2011). Using a corn cob matrix, immobilized Pseudochrobactrum saccharolyticum produced (9.4 g/L) from acid treated cowpea waste and (8.2 g/L) from alkaline treated cowpea waste, whereas a corn husk matrix produced 7.8 g/L and 6.2 g/L from acid and alkaline treated cowpea waste, respectively. This could be because they are biotin auxotrophs who release L-glutamic acid in response to biotin deficiency. Pseudochrobactrum saccharolyticum is a glutamic acid-producing bacteria, according to (Ahmed et al., 2008).
4.4.3 Effect of bead weight on glutamic acid production from cowpea waste using corn cob matrix
Production of glutamic acid from cowpea waste by bacteria immobilized in 1, 2, 3 and 4 kg diameter corn cob beads is shown in Fig. iii and iv. There was a gradual increase in volume of glutamic acid produced with bead size from 1 kg to 3 kg and thereafter decrease with increase in bead weight (Fig. v and fig vi). As illustrated in Fig. v and vi, highest volume of glutamic acid produced was obtained with bead weight 3 kg, which indicate that this weight is maximum for substrate utilization.
4.4.4 Effect of bead reusability on glutamic acid production from cowpea waste using corn cob matrix
Figures vii and viii show the effect of using immobilized bacteria repeatedly on the generation of glutamic acid from cowpea waste. The results demonstrated that bacteria cells that had been immobilized may be employed again and again without losing their activity. During cell re-use, it was discovered that immobilized Pseudochrobactrum saccharolyticum produced the most glutamic acid from cowpea waste. For the acid treated cowpea waste (Fig. vii), it retained 66 percent, 53 percent, and 35 percent glutamic acid yield for the second, third, and fourth cycles, respectively, and for the alkaline treated cowpea waste (Fig. vii), it retained 58 percent, 46 percent, and 32 percent glutamic acid yield for the second, third, and fourth cycles, respectively. Similarly For the acid treated cowpea waste (Fig. viii), it retained 69 percent, 45 percent, and 30 percent glutamic acid yield for the second, third, and fourth cycles, respectively, and for the alkaline treated cowpea waste (Fig. viii), it retained 54 percent, 40 percent, and 30 percent glutamic acid yield for the second, third, and fourth cycles, respectively. This is marginally better than the findings of (Anwar et al., 2009) who discovered that immobilized cells retained 30% of their original activity. This could be due to blockage of cells within the matrix after the sixth cycle (Kareem et al., 2013).
4.4.5 HPLC analysis
HPLC was used to determine the quantitative concentration of amino acids, and the amino acid profile is depicted in Figure ix (a and b). There are seventeen amino acids found in the sample, and their separation was reasonably resolved. Methionine, leucine, lysine, cysteine, phenylalanine, tyrosine, arginine, isoleucine, threonine, and valine were discovered to be present, along with seven non-essential amino acids.